JP2018046268A - Light-emitting element module, atomic oscillator, electronic device, and moving object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element module capable of reducing the influence of return light on a light emitting element while reducing the increase in size, and to provide an atomic oscillator, an electronic device and a moving body provided with such a light emitting element module. To do. SOLUTION: The lid comprises a light emitting element that emits light, a base having a recess in which the light emitting element is housed, and a lid that covers the opening of the recess and is joined to the base. It has a projecting portion that is provided so as to project on the opposite side of the base and has a hole through which the light passes, and a window portion that is provided by closing the hole in the projecting portion and allows the light to pass through. A light emitting element module characterized in that the surface of the window portion on the light emitting element side is inclined with respect to a surface having the optical axis of the light as a normal line. [Selection diagram] Fig. 4

Description

  The present invention relates to a light emitting element module, an atomic oscillator, an electronic device, and a moving object.

  Conventionally, for example, a light emitting element module including a light emitting element that emits laser light is known.

  As the light emitting element module, for example, a semiconductor laser, a laser medium excited by laser light from the semiconductor laser, an optical part having an optical element that converts the wavelength of the laser light from the laser medium, and the optical part are accommodated. There is known an optical pickup device including a package to be used (see Patent Document 1). In such an optical pickup device, a window is provided in the package, and laser light wavelength-converted from the optical element is emitted to the outside of the package through the window.

JP 7-98881 A

  However, in the optical pickup device according to Patent Document 1, since the window provided in the package is provided orthogonal to the laser light emission direction, the laser light (reflected light) reflected by the window is reflected in the package. There is a problem in that the stability of the laser light emitted from the semiconductor laser (particularly the stability of the wavelength) is lowered due to the return to the semiconductor laser.

  On the other hand, in recent years, with the miniaturization of devices equipped with light emitting element modules, there is a high demand for miniaturization of light emitting element modules.

  An object of the present invention is to provide a light emitting element module capable of reducing the influence of return light on a light emitting element while reducing the increase in size, and to provide an atomic oscillator, an electronic apparatus, and a mobile including the light emitting element module To provide a body.

The above object is achieved by the present invention described below.
The light emitting element module of the present invention includes a light emitting element that emits light,
A base having a recess in which the light emitting element is accommodated;
A lid that covers the opening of the recess and is joined to the base;
The lid is
A protruding portion provided on the opposite side of the base and having a hole through which the light passes;
A window portion that is provided by closing the hole in the projecting portion and transmits the light;
A surface of the window portion on the light emitting element side is inclined with respect to a surface having an optical axis of the light as a normal line.

  According to such a light emitting element module of the present invention, the light emitting element side surface of the window portion is inclined with respect to the surface having the optical axis of the light as a normal line, so that light from the light emitting element is transmitted through the window portion. Return light that is reflected and returned to the light-emitting element can be reduced. Furthermore, since the window part is provided in the protrusion part, the separation distance of a window part and a light emitting element can be enlarged. Therefore, coupled with the decrease in the light density as the light from the light emitting element travels, the return light can be effectively reduced. In the light emitting device module of the present invention, the window portion is provided on the protruding portion of the lid so that, for example, the lid does not have the protruding portion and the concave portion of the base is enlarged (deeply) so that the window portion and the light emitting element are separated. Compared with the case where the distance is increased, the entire light emitting element module can be reduced in size. Therefore, according to the light emitting element module of the present invention, it is possible to reduce the influence of the return light on the light emitting element while reducing the size.

  In the light emitting element module of the present invention, it is preferable that an inclination angle of a surface on the light emitting element side of the window portion with respect to a surface having the optical axis of the light as a normal line is in a range of 5 ° to 45 °.

  Thereby, it is possible to reduce the influence of the return light on the light emitting element while exhibiting the necessary optical characteristics of the window with a relatively simple configuration.

  In the light emitting element module according to the aspect of the invention, it is preferable that the lid includes a first portion that supports the protruding portion and a second portion that is bonded to the base and is thinner than the first portion. .

  Thus, since the 2nd part joined with a base is thinner than the 1st part, joining of a lid and a base can be easily performed by seam welding etc., for example. Further, since the first portion is thicker than the second portion, it is possible to ensure the mechanical strength necessary for the lid. Further, since the first portion is thicker than the second portion, it is possible to reduce the stress generated in the first portion when the lid and the base are joined.

  In the light emitting element module according to the aspect of the invention, it is preferable that the outer peripheral surface of the protruding portion has a flat flat portion that follows the outer shape of the first portion when viewed from the direction along the optical axis of the light.

  Thereby, when joining the 2nd part of a lid and a base, a protrusion part does not become obstructive and can join a lid and a base more easily.

  In the light emitting element module according to the aspect of the invention, the inner wall surface of the hole of the projecting portion has a step portion that is inclined with respect to a plane having the optical axis of the light as a normal line and supports the window portion. It is preferable.

  Thereby, it becomes easy to provide a window part with an appropriate position and inclination angle with respect to a protrusion part.

In the light emitting device module of the present invention, the width at the intensity of 1 / e ² (e is the base of natural logarithm) of the peak intensity of the light on the surface along the opening on the base side of the hole is W [mm]. In this case, the width L [mm] of the opening on the base side of the hole preferably satisfies the range of W <L <20 × W.

  Thereby, the portion (center portion) excluding the portion (outer peripheral portion) where the change in energy density is large among the light emitted from the optical element is efficiently incident into the hole while reducing the excessive enlargement of the protruding portion. be able to.

In the light emitting element module of the present invention, it is preferable that the center of the window portion is shifted with respect to the optical axis of the light.
Thereby, it can reduce that the light which does not pass a window part arises, reducing the enlargement of a window part. Therefore, it is possible to reduce the adverse effect on the light emitting element and the like due to the irregular reflection of the light deviated from the window while reducing the size of the light emitting element module.

In the light emitting element module according to the present invention, it is preferable that a side surface of the window portion is located outside a light flux of the light.
Thereby, light can be allowed to pass through both main surfaces of the window portion, and irregular reflection of light on the side surface of the window portion can be reduced.

The atomic oscillator according to the present invention includes the light emitting element module according to the present invention.
According to such an atomic oscillator, since it includes the light emitting element module that can reduce the influence of the return light on the light emitting element while reducing the size increase, the wavelength variation of the light from the light emitting element is reduced, An atomic oscillator having excellent oscillation characteristics can be realized using light.

The atomic oscillator of the present invention comprises an optical element that allows the light from the light-emitting element to pass through, and a holder that holds the optical element.
It is preferable that the holder has a through hole into which the protrusion provided in the light emitting element module can be inserted.

  Thereby, the relative positioning of the light emitting element module and the holder can be performed easily and with high accuracy by inserting the protruding portion into the through hole of the holder. Therefore, the light emitted from the light emitting element module can be appropriately incident on the optical element.

In the atomic oscillator of the present invention, the window is provided between the light emitting element and the optical element,
The window side surface of the optical element is inclined with respect to a surface having the optical axis of the light as a normal,
The center of the optical element is preferably shifted with respect to the optical axis of the light.
Thereby, it is possible to reduce the occurrence of light that does not pass through the optical element while reducing the increase in size of the optical element.

An electronic apparatus according to the present invention includes the light emitting element module according to the present invention.
According to such an electronic apparatus, since the light emitting element module that can reduce the influence of the return light on the light emitting element is reduced while reducing the size, the electronic apparatus having high characteristics using high-quality light is provided. Can be realized.

The moving body of the present invention includes the light emitting element module of the present invention.
According to such a moving body, since the light emitting element module that can reduce the influence of the return light on the light emitting element can be reduced while reducing the size, the moving body having high characteristics using high-quality light is provided. Can be realized.

1 is a schematic diagram showing an atomic oscillator according to a first embodiment of the present invention. It is a cross-sectional side view of the atomic oscillator shown in FIG. FIG. 3 is a plan view of the atomic oscillator shown in FIG. 2. It is sectional drawing of the light emitting element module with which the atomic oscillator shown in FIG. 2 and FIG. 3 is provided. It is a top view of the light emitting element module shown in FIG. It is a top view of the lid with which the light emitting element module shown in FIG. 4 is provided. It is the schematic which shows the light emitting element and window part of a light emitting element module with which the atomic oscillator which concerns on 2nd Embodiment of this invention is provided. It is a figure which shows the state in which the center of a window part and the optical axis of light correspond. It is the schematic which shows the modification of arrangement | positioning of the window part shown in FIG. It is the schematic which shows the light emitting element and window part of a light emitting element module with which the atomic oscillator which concerns on 3rd Embodiment of this invention is provided. It is the schematic which shows the modification of the window part shown in FIG. It is the schematic which shows the window part and optical system unit of a light emitting element module with which the atomic oscillator which concerns on 4th Embodiment of this invention is provided. It is a figure which shows schematic structure at the time of using the atomic oscillator of this invention for the positioning system using a GPS satellite. It is a figure which shows an example of the moving body of this invention.

  Hereinafter, a light-emitting element module, an atomic oscillator, an electronic apparatus, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

1. Atomic Oscillator First, the atomic oscillator of the present invention (the atomic oscillator including the light emitting element module of the present invention) will be described.

<First Embodiment>
FIG. 1 is a schematic diagram showing an atomic oscillator according to the first embodiment of the present invention.
The atomic oscillator 10 shown in FIG. 1 has a quantum phenomenon in which, when alkali metal atoms are simultaneously irradiated with two resonant lights having different wavelengths, the two resonant lights are transmitted without being absorbed by the alkali metal atoms. It is an atomic oscillator that uses interference effects (CPT: Coherent Population Trapping). This phenomenon due to the quantum interference effect is also called an electromagnetically induced transparency (EIT) phenomenon.

  As shown in FIG. 1, the atomic oscillator 10 includes a light emitting element module 1, an atomic cell unit 20, an optical system unit 30 provided between the light emitting element module 1 and the atomic cell unit 20, and a light emitting element. And a control unit 50 that controls the operation of the module 1 and the atomic cell unit 20. Hereinafter, first, an outline of the atomic oscillator 10 will be described.

The light emitting element module 1 includes a Peltier element 2, a light emitting element 3, and a temperature sensor 4. The light emitting element 3 emits linearly polarized light LL including two types of light having different frequencies. The light LL (light beam) emitted from the light emitting element 3 is emitted with a predetermined radiation angle, and the cross-sectional intensity distribution of the emitted light LL forms a Gaussian distribution. Here, the “radiation angle” indicates a spread angle with the optical axis a of the light LL as the central axis. Specifically, the “radiation angle” refers to an angle at 1 / e ² of the peak intensity of the light LL. When the cross-sectional intensity distribution of the light LL does not form a Gaussian distribution, the “radiation angle” refers to an angle at half the peak intensity of the light LL. A portion inside the radiation angle of the light LL is called a light beam. The temperature sensor 4 detects the temperature of the light emitting element 3. In addition, the Peltier element 2 adjusts the temperature of the light emitting element 3 (heating or cooling the light emitting element 3).

  The optical system unit 30 includes a neutral density filter 301 (optical element), a lens 302 (optical element), and a quarter wavelength plate 303 (optical element). The neutral density filter 301 reduces the intensity of the light LL from the light emitting element 3 described above. The lens 302 adjusts the radiation angle of the light LL (for example, the light LL is converted into parallel light). The quarter-wave plate 303 converts the two types of light having different frequencies included in the light LL from linearly polarized light to circularly polarized light (right circularly polarized light or left circularly polarized light).

  The atomic cell unit 20 includes an atomic cell 201, a light receiving element 202, a heater 203, a temperature sensor 204, and a coil 205.

  The atomic cell 201 has light transparency, and an alkali metal is sealed in the atomic cell 201. The alkali metal atom has a three-level energy level composed of two different ground levels and excited levels. The light LL from the light emitting element 3 enters the atomic cell 201 via the neutral density filter 301, the lens 302, and the quarter wavelength plate 303. The light receiving element 202 receives and detects the light LL that has passed through the atomic cell 201.

  The heater 203 heats the alkali metal in the atomic cell 201 to make at least a part of the alkali metal into a gas state. Further, the temperature sensor 204 detects the temperature of the atomic cell 201. The coil 205 applies a magnetic field in a predetermined direction to the alkali metal in the atomic cell 201 to cause Zeeman splitting of the energy level of the alkali metal atom. In such a state where the alkali metal atom is Zeeman split, when the circularly polarized resonant light pair as described above is irradiated to the alkali metal atom, the desired energy among the plurality of levels where the alkali metal atom is Zeeman split. The number of alkali metal atoms at the level can be made relatively larger than the number of alkali metal atoms at other energy levels. Therefore, the number of atoms that express the desired EIT phenomenon increases and the desired EIT signal increases, and as a result, the oscillation characteristics of the atomic oscillator 10 can be improved.

  The control unit 50 includes a temperature control unit 501, a light source control unit 502, a magnetic field control unit 503, and a temperature control unit 504. The temperature control unit 501 controls energization to the heater 203 based on the detection result of the temperature sensor 204 so that the inside of the atomic cell 201 becomes a desired temperature. The magnetic field control unit 503 controls energization to the coil 205 so that the magnetic field generated by the coil 205 is constant. Further, the temperature control unit 504 controls energization of the Peltier element 2 based on the detection result of the temperature sensor 4 so that the temperature of the light emitting element 3 becomes a desired temperature (in the temperature range).

  The light source control unit 502 controls the frequencies of the two types of light included in the light LL from the light emitting element 3 so that the EIT phenomenon occurs based on the detection result of the light receiving element 202. Here, when these two types of light become resonant light pairs having a frequency difference corresponding to the energy difference between the two ground levels of the alkali metal atoms in the atomic cell 201, the EIT phenomenon occurs. The light source control unit 502 includes a voltage-controlled crystal oscillator (not shown) whose oscillation frequency is controlled so as to be stabilized in synchronization with the above-described control of the two types of light frequencies. An output signal of the controlled crystal oscillator (VCXO) is output as an output signal (clock signal) of the atomic oscillator 10.

  The outline of the atomic oscillator 10 has been described above. Hereinafter, a more specific configuration of the atomic oscillator 10 will be described with reference to FIGS. 2 and 3.

  FIG. 2 is a cross-sectional side view of the atomic oscillator shown in FIG. FIG. 3 is a plan view of the atomic oscillator shown in FIG. In the following, for convenience of explanation, the upper side in FIG. 2 is also referred to as “upper” and the lower side is also referred to as “lower”.

  As shown in FIG. 2, the atomic oscillator 10 includes a light emitting element module 1, an atomic cell unit 20, an optical system unit 30 holding the light emitting element module 1, an atomic cell unit 20, and an optical system unit 30. And a control unit 50 that is electrically connected to the light emitting element module 1 and the atomic cell unit 20 and a package 60 that houses them.

  The light emitting element module 1 includes a Peltier element 2, a light emitting element 3, a temperature sensor 4, and a package 5 that accommodates these. The light emitting element module 1 will be described in detail later.

  The optical system unit 30 includes a neutral density filter 301, a lens 302, a quarter-wave plate 303, and a holder 304 that holds these. Here, the holder 304 has a columnar through-hole 305 that is open at both ends. The through-hole 305 is a light LL passage region, and in the through-hole 305, a neutral density filter 301, a lens 302, and a quarter wavelength plate 303 are arranged in this order. As shown in FIG. 3, the neutral density filter 301 is fixed to the holder 304 with an adhesive or the like (not shown) in a posture inclined with respect to a plane having the optical axis a as a normal line. The lens 302 and the quarter-wave plate 303 are fixed to the holder 304 with an adhesive or the like (not shown) in a posture along a plane having the optical axis a as a normal line. Further, the light emitting element module 1 is attached to the end of the through hole 305 on the side of the neutral density filter 301 (left side in FIG. 2) by an attachment member (not shown). Such a holder 304 is made of, for example, a metal material such as aluminum and has heat dissipation. Thereby, heat dissipation of the light emitting element module 1 can be performed efficiently.

  The optical system unit 30 can omit at least one of the neutral density filter 301 and the lens 302 depending on the intensity, emission angle, etc. of the light LL from the light emitting element 3. The optical system unit 30 may include optical elements other than the neutral density filter 301, the lens 302, and the quarter wavelength plate 303. Further, the order of arrangement of the neutral density filter 301, the lens 302, and the quarter wavelength plate 303 is not limited to the order shown in the figure, and is arbitrary.

  The atomic cell unit 20 includes an atomic cell 201, a light receiving element 202, a heater 203, a temperature sensor 204, a coil 205, and a package 206 that houses these.

  In the atomic cell 201, gaseous alkali metals such as rubidium, cesium, and sodium are sealed. Further, in the atomic cell 201, a rare gas such as argon or neon, or an inert gas such as nitrogen may be sealed together with an alkali metal gas as a buffer gas, if necessary.

  Although not shown, the atomic cell 201 includes, for example, a pair of windows that form a body portion having a columnar through hole and an internal space hermetically sealed by sealing both openings of the through hole of the body portion. Part (different from the window parts 56, 56A, 56B). Here, the light LL incident into the atomic cell 201 is transmitted through one of the pair of windows, and the light LL emitted from the atomic cell 201 is transmitted through the other window. . Therefore, the constituent material of each window portion is not particularly limited as long as it has transparency to the light LL, and examples thereof include glass materials and crystal. On the other hand, the constituent material of the body portion is not particularly limited, and examples thereof include a metal material, a resin material, a glass material, a silicon material, and a crystal. From the viewpoint of workability and bonding with each window portion, a glass material, It is preferable to use a silicon material. In addition, the joining method of the body portion and each window portion is determined according to these constituent materials and is not particularly limited. For example, a direct joining method, an anodic joining method, or the like can be used.

  The light receiving element 202 is disposed on the side opposite to the light emitting element module 1 with respect to the atomic cell 201. The light receiving element 202 is not particularly limited as long as it can detect the intensity of the light LL (resonant light pair) transmitted through the atomic cell 201. For example, a photodetector (such as a solar cell or a photodiode) Light receiving element).

  Although not shown, the heater 203 is, for example, disposed on the above-described atomic cell 201 or connected to the atomic cell 201 via a thermally conductive member such as metal. The heater 203 is not particularly limited as long as the atomic cell 201 (more specifically, an alkali metal in the atomic cell 201) can be heated. Examples of the heater 203 include various heaters having a heating resistor, Peltier elements, and the like. It is done.

  Although not shown, the temperature sensor 204 is disposed in the vicinity of the atomic cell 201 or the heater 203, for example. The temperature sensor 204 is not particularly limited as long as the temperature of the atomic cell 201 or the heater 203 can be detected. Examples of the temperature sensor 204 include various known temperature sensors such as a thermistor and a thermocouple.

  Although not shown, the coil 205 is, for example, a solenoid type coil wound around the outer periphery of the atomic cell 201 or a pair of Helmholtz type opposed via the atomic cell 201. The coil 205 generates a magnetic field in the atomic cell 201 in a direction (parallel direction) along the optical axis a of the light LL. Thereby, the gap between different energy levels in which the alkali metal atoms in the atomic cell 201 are degenerated can be widened by Zeeman splitting to improve the resolution and reduce the line width of the EIT signal. Note that the magnetic field generated by the coil 205 may be either a DC magnetic field or an AC magnetic field, or may be a magnetic field in which a DC magnetic field and an AC magnetic field are superimposed.

  Although not shown, the package 206 includes, for example, a plate-like base and a lid joined to the base, and the above-described atomic cell 201, light receiving element 202, heater 203, and temperature sensor are interposed therebetween. An airtight space for housing 204 and the coil 205 is formed. Here, the substrate directly or indirectly supports the atomic cell 201, the light receiving element 202, the heater 203, the temperature sensor 204, and the coil 205. A plurality of terminals electrically connected to the light receiving element 202, the heater 203, the temperature sensor 204, and the coil 205 are provided on the outer surface of the base. On the other hand, the lid has a bottomed cylindrical shape with one end opened, and the opening is closed by the base. In addition, a window portion 207 having transparency to the light LL is provided at the other end portion (bottom portion) of the lid.

  A constituent material of the package 206 other than the base body and the window portion of the lid is not particularly limited, and examples thereof include ceramics and metals. Moreover, as a constituent material of the window part 207, a glass material etc. are mentioned, for example. The method for joining the base and the lid is not particularly limited, and examples thereof include brazing, seam welding, energy beam welding (laser welding, electron beam welding, etc.) and the like. Further, the inside of the package 206 is preferably depressurized from the atmospheric pressure. Thereby, the temperature of the atomic cell 201 can be controlled easily and with high accuracy. As a result, the characteristics of the atomic oscillator 10 can be improved.

  The support member 40 has a plate shape, and the atomic cell unit 20 and the optical system unit 30 described above are placed on one surface thereof. The support member 40 has an installation surface 401 that follows the shape of the lower surface of the holder 304 of the optical system unit 30. A stepped portion 402 is formed on the installation surface 401. The step portion 402 engages with the step portion on the lower surface of the holder 304 to restrict the holder 304 from moving to the atomic cell unit 20 side (right side in FIG. 2). Similarly, the support member 40 has an installation surface 403 along the shape of the lower surface of the package 206 of the atomic cell unit 20. A stepped portion 404 is formed on the installation surface 403. This stepped portion 404 engages with an end surface (the left end surface in FIG. 2) of the package 206 to restrict the package 206 from moving toward the optical system unit 30 (the left side in FIG. 2).

  Thus, the relative positional relationship between the atomic cell unit 20 and the optical system unit 30 can be defined by the support member 40. Here, since the light emitting element module 1 is fixed to the holder 304, the relative positional relationship of the light emitting element module 1 with respect to the atomic cell unit 20 and the optical system unit 30 is also defined. Here, the package 206 and the holder 304 are each fixed to the support member 40 by a fixing member such as a screw (not shown). The support member 40 is fixed to the package 60 by a fixing member such as a screw (not shown). Moreover, the support member 40 is comprised, for example with metal materials, such as aluminum, and has heat dissipation. Thereby, heat dissipation of the light emitting element module 1 can be performed efficiently.

  As shown in FIG. 3, the control unit 50 includes a circuit board 505, two connectors 506 a and 506 b provided on the circuit board 505, a rigid wiring board 507 a connected to the light emitting element module 1, an atom A rigid wiring board 507b connected to the cell unit 20, a flexible wiring board 508a connecting the connector 506a and the rigid wiring board 507a, and a flexible wiring board 508b connecting the connector 506b and the rigid wiring board 507b. And a plurality of lead pins 509 penetrating the circuit board 505.

  Here, an IC (Integrated Circuit) chip (not shown) is provided on the circuit board 505, and the IC chip serves as the temperature control unit 501, the light source control unit 502, the magnetic field control unit 503, and the temperature control unit 504 described above. Function. The circuit board 505 has a through hole 5051 through which the support member 40 described above is inserted. The circuit board 505 is supported with respect to the package 60 via a plurality of lead pins 509. The plurality of lead pins 509 are electrically connected to the circuit board 505.

  In addition, the structure which electrically connects the circuit board 505 and the light emitting element module 1, and the structure which electrically connects the circuit board 505 and the atomic cell unit 20 are the connector 506a, 506b of illustration, and the rigid wiring board 507a. 507b and flexible wiring boards 508a and 508b, other known connectors and wirings may be used.

  The package 60 is made of, for example, a metal material such as Kovar, and has a magnetic shielding property. Thereby, it is possible to reduce the external magnetic field from adversely affecting the characteristics of the atomic oscillator 10. Note that the inside of the package 60 may be depressurized or atmospheric pressure.

(Detailed description of light emitting element module)
4 is a cross-sectional view of a light emitting element module provided in the atomic oscillator shown in FIGS. FIG. 5 is a plan view of the light-emitting element module shown in FIG. 6 is a plan view of a lid provided in the light emitting element module shown in FIG. In the following, for convenience of explanation, the upper side in FIG. 4 is also referred to as “upper” and the lower side is also referred to as “lower”.

  As shown in FIG. 4, the light-emitting element module 1 includes a Peltier element 2, a light-emitting element 3, a temperature sensor 4, and a package 5 that stores them.

  The package 5 includes a base 51 having a recess 511 opened on the upper surface, and a lid 52 that closes an opening (upper opening) of the recess 511, and the Peltier element 2 and the light emitting element 3 are interposed between the base 51 and the lid 52. And an internal space S that is an airtight space in which the temperature sensor 4 is housed. Such a package 5 is preferably in a reduced pressure (vacuum) state. As a result, the influence of the temperature change outside the package 5 on the light emitting element 3 and the temperature sensor 4 in the package 5 can be reduced, and temperature fluctuations of the light emitting element 3 and the temperature sensor 4 in the package 5 can be reduced. it can. Note that the inside of the package 5 does not have to be in a reduced pressure state, and an inert gas such as nitrogen, helium, or argon may be sealed therein.

  The constituent material of the base 51 is not particularly limited, but is a material having an insulating property and suitable for making the internal space S an airtight space, such as oxide ceramics such as alumina, silica, titania, zirconia, etc. Various ceramics such as nitride ceramics such as silicon nitride, aluminum nitride, and titanium nitride, and carbide ceramics such as silicon carbide can be used.

  In addition, the base 51 has a step portion 512 formed so as to surround the outer periphery of the bottom surface of the recess 511 above the bottom surface of the recess 511. As shown in FIG. 5, connection electrodes 62a, 62b, 62c, 62d, 62e, and 62f are provided on the upper surface of the stepped portion 512. These connection electrodes 62a, 62b, 62c, 62d, 62e, and 62f (hereinafter also referred to as “connection electrodes 62a to 62f”) are respectively formed on the lower surface of the base 51 through through electrodes (not shown) that penetrate the base 51. The external mounting electrodes 61a, 61b, 61c, 61d, 61e, and 61f (hereinafter also referred to as “external mounting electrodes 61a to 61f”) provided are electrically connected.

  The constituent materials of the connection electrodes 62a to 62f and the external mounting electrodes 61a to 61f are not particularly limited. For example, gold (Au), gold alloy, platinum (Pt), aluminum (Al), aluminum alloy, silver (Ag) ), Silver alloy, chromium (Cr), chromium alloy, nickel (Ni), copper (Cu), molybdenum (Mo), niobium (Nb), tungsten (W), iron (Fe), titanium (Ti), cobalt ( Examples thereof include metal materials such as Co), zinc (Zn), and zirconium (Zr).

  A frame-like (annular) seal ring 53 is provided on the upper end surface of the base 51. The seal ring 53 is made of a metal material such as Kovar, and is joined to the base 51 by brazing or the like. The lid 52 is joined to the base 51 through the seal ring 53 by seam welding or the like.

  As shown in FIGS. 4 and 6, the lid 52 has a plate-shaped main body 54, a cylindrical protrusion 55 provided on the main body 54, and a hole formed inside the protrusion 55. And a window portion 56 that closes 551 (opening).

  The main body portion 54 includes a first portion 54a supporting the protruding portion 55, a second portion 54b joined to the base 51 (more specifically, the base 51 via the seal ring 53), And a third portion 54c connecting the second portions 54a and 54b. The plate surface 540 (upper surface) of the main body portion 54 is parallel to a surface having the optical axis a of the light LL emitted from the light emitting element 3 as a normal line. Here, the thicknesses t2 and t3 of the second and third portions 54b and 54c are respectively thinner than the thickness t1 of the first portion 54a. Further, the thickness t2 of the second portion 54b and the thickness t3 of the third portion 54c are equal to each other. In the present embodiment, when the outer peripheral portion of the main body 54 having the thickness t2 is divided into two parts in plan view with the inner peripheral edge 531 of the seal ring 53 as a boundary, the outer part of the two parts is It can be said that the inner portion is the second portion 54b and the inner portion is the third portion 54c. Further, the outer peripheral portion of the first portion 54a is continuously reduced in thickness toward the third portion 54c, whereby the upper surface and the lower surface of the first portion 54a are connected to the upper surface and the lower surface of the third portion 54c. It is connected continuously. Further, the first portion 54a is formed with a hole 541 penetrating in the thickness direction. The hole 541 allows at least a part of the light LL from the light emitting element 3 to pass therethrough. The constituent material of the main body 54 is not particularly limited, and a metal material is preferably used. Among them, it is preferable to use a metal material having a linear expansion coefficient approximate to that of the base 51. Therefore, for example, when the base 51 is a ceramic substrate, it is preferable to use an alloy such as Kovar as the constituent material of the main body 54.

  The protrusion 55 is provided in the center of the first portion 54a in a plan view and is included in the first portion 54a. The projecting portion 55 has, on its inside, a hole 551 communicating with the hole 541 of the main body portion 54 described above, a hole 552 communicating with the hole 551 on the opposite side of the hole 551 from the hole 541, and have. Each of the holes 551 and 552 allows at least a part of the light LL from the light emitting element 3 to pass therethrough. Here, the width (diameter) of the hole 552 is larger than the width (diameter) of the hole 551, whereby a stepped portion 553 is formed between the hole 551 and the hole 552. The step portion 553 is inclined at an inclination angle θ with respect to the plate surface 540 of the main body portion 54 described above. In the present embodiment, the stepped portion 553 is inclined so as to face one side (the right side in FIGS. 4 and 6) in the longitudinal direction of the lid 52. Further, as shown in FIG. 6, a pair of curved surfaces 555 along the cylindrical surface and a pair of flat surfaces provided between the pair of curved surfaces 555 are arranged on the outer peripheral surface of the protrusion 55. Part 554. The pair of flat portions 554 is along the outer shape of the first portion 54a of the main body portion 54 in plan view.

  The constituent material of the projecting portion 55 may be different from the constituent material of the main body portion 54, but it is preferable to use a metal material whose linear expansion coefficient approximates that of the constituent material of the main body portion 54. More preferably, it is the same as the constituent material. The protruding portion 55 is formed separately from the main body portion 54 and may be bonded by a known bonding method, or may be formed integrally (collectively) with the main body portion 54 using a mold or the like. Also good.

  Inside the hole 552, a window portion 56 made of a plate-like member that transmits the light LL is installed. The window part 56 is joined to the step part 553 described above by a known joining method, and closes the opening on the hole 552 side of the hole 551 of the protrusion part 55 described above. Here, since the stepped portion 553 is inclined at the inclination angle θ with respect to the plate surface 540 of the main body portion 54 as described above, the window portion 56 is also inclined at the inclination angle θ with respect to the plate surface 540 of the main body portion 54. Inclined. Therefore, in the present embodiment, the surface 560 (lower surface) on the light emitting element 3 side of the window portion 56 and the surface (upper surface) opposite to the light emitting element 3 are also on one side in the longitudinal direction of the lid 52 (FIG. 4 and FIG. 6 is inclined to the right). The window part 56 has transparency to the light LL from the light emitting element 3. The constituent material of the window portion 56 is not particularly limited, and examples thereof include a glass material. The window portion 56 may be an optical component such as a lens or a neutral density filter.

  Moreover, the planar view shape of the window part 56 is not specifically limited, but this embodiment is a hexagon. Since the planar view shape of the window portion 56 is hexagonal, the opening of the circular hole 551 can be accurately formed even if the area of the window portion 56 is small compared to the case where the planar view shape of the window portion 56 is quadrangular. Can be blocked. Further, compared to a case where the planar view shape of the window portion 56 is circular, for example, when a plurality of window portions 56 are cut out and formed from one substrate (mother board), there are fewer wasted portions and more windows are formed. The portion 56 can be formed.

  As shown in FIG. 4, the lid 52 is positioned by engaging the main body 54 and the protrusion 55 with the holder 304 of the optical system unit 30 described above. More specifically, the protrusion 55 is inserted into the through hole 305 of the holder 304, and the plate surface 540 of the main body 54 abuts against the positioning surface 306 of the holder 304, so that the direction of the light axis 3 of the light emitting element 3 Positioning of the lid 52 and the light emitting element module 1 is performed. Further, in a state where the protruding portion 55 is inserted into the through hole 305 of the holder 304, the side surfaces of the protruding portion 55 (more specifically, the pair of curved surface portions 555 described above) abut against the inner wall surface of the through hole 305. Thus, the lid 52 and the light emitting element module 1 are positioned in a direction perpendicular to the optical axis a of the light emitting element 3.

  The Peltier element 2 is disposed on the bottom surface of the concave portion 511 of the base 51 of such a package 5. The Peltier element 2 is fixed to the base 51 with, for example, an adhesive. As shown in FIG. 4, the Peltier element 2 includes a pair of substrates 21 and 22 and a joined body 23 provided between the substrates 21 and 22. The substrates 21 and 22 are each made of a material having excellent thermal conductivity such as a metal material or a ceramic material. In addition, an insulating film is provided on the surfaces of the substrates 21 and 22 as necessary. The lower surface of the substrate 21 is fixed to the base 51 of the package 5, while the upper surface of the substrate 21 is provided with a pair of terminals 24 and 25 as shown in FIG. The substrate 22 is provided so as to expose the pair of terminals 24 and 25. The pair of terminals 24 and 25 are electrically connected to connection electrodes 62a and 62b provided on the package 5 via wirings 81a and 81b which are wire wirings (bonding wires). The joined body 23 includes a plurality of joined bodies of two different kinds of metals or semiconductors that generate a Peltier effect when energized from a pair of terminals 24 and 25.

  In such a Peltier element 2, one of the substrates 21 and 22 is the heat generating side and the other is the heat absorbing side due to the Peltier effect generated in the joined body 23. Here, the Peltier element 2 has a state in which the substrate 21 is on the heat generation side and the substrate 22 is on the heat absorption side, and a state in which the substrate 21 is on the heat absorption side and the substrate 22 is on the heat generation side, depending on the direction of the supplied current. And can be switched. Therefore, even if the range of environmental temperature is wide, the temperature of the light emitting element 3 and the like can be adjusted to a desired temperature (target temperature). Thereby, the bad influence (for example, wavelength fluctuation of light LL) by a temperature change can be reduced more. Here, the target temperature of the light-emitting element 3 is determined according to the characteristics of the light-emitting element 3 and is not particularly limited, but is, for example, about 30 ° C. or more and 40 ° C. or less. In order to keep the temperature of the light emitting element 3 at the target temperature, the Peltier element 2 is actuated in a timely manner based on information from the temperature sensor 4 to heat or cool the light emitting element 3.

  The Peltier element 2 has a metal layer 26 provided on the upper surface of the substrate 22. The metal layer 26 is made of, for example, a metal having excellent thermal conductivity such as aluminum, gold, and silver. On the upper surface of the metal layer 26, the light emitting element 3, the temperature sensor 4, and the relay members 71 and 72 are provided. Has been placed.

  The light emitting element 3 is, for example, a semiconductor laser such as a vertical cavity surface emitting laser (VCSEL). A semiconductor laser can emit two types of light having different wavelengths by superimposing (modulating) a high-frequency signal on a DC bias current. The light emitting element 3 has a pair of terminals (not shown). One of the terminals is a drive signal terminal, and the other terminal is a ground terminal. The drive signal terminal is electrically connected to the connection electrode 62c provided in the package 5 via the wiring 82a, the relay member 71, and the wiring 82b. On the other hand, the grounding terminal is electrically connected to the connection electrode 62d provided on the package 5 through the wiring 82c, the metal layer 26, and the wiring 82d.

  The temperature sensor 4 is a temperature detection element such as a thermistor or a thermocouple, for example. The temperature sensor 4 has a pair of terminals (not shown). One of the terminals is a detection signal terminal, and the other terminal is a ground terminal. The detection signal terminal is electrically connected to the connection electrode 62e provided in the package 5 through the wiring 83a, the relay member 72, and the wiring 83b. On the other hand, the grounding terminal is electrically connected to the connection electrode 62f provided in the package 5 through the metal layer 26 and the wiring 83c.

  The wirings 82a, 82b, 82c, 82d, 83a, 83b, and 83c are wire wirings (bonding wires), respectively. Here, the wiring 82b is composed of a plurality of wire wirings. Thereby, the electrical resistance of the wiring 82b can be reduced, and the loss of the drive signal supplied to the light emitting element 3 can be reduced. From the same viewpoint, each of the wirings 82c and 82d is composed of a plurality of wire wirings.

  The relay member 71 includes a base portion 711 having insulating properties and a conductive wiring layer 712 provided on the upper surface of the base portion 711. The base 711 is made of, for example, a ceramic material. A metal layer (not shown) is bonded to the lower surface of the base 711, and the metal layer is bonded to the metal layer 26 via a bonding material (not shown) such as a brazing material. The wiring layer 712 is made of the same material as the connection electrodes 62a to 62f described above. The wiring layer 712 has a longitudinal shape and is formed on a part of the upper surface of the base 711. Thereby, even if the electrostatic capacitance between the wiring layer 712 and the metal layer 26 is reduced and a high frequency signal is used as the drive signal supplied to the light emitting element 3, the loss of the drive signal can be reduced. In addition, the size of the base 711 can be secured to some extent, and as a result, the relay member 71 can be easily mounted.

  The electrical connection between the light emitting element 3 and the connection electrodes 62c and 62d is performed via the relay member 71 and the like, whereby the temperature of the wirings 82a, 82b, 82c, and 82d is also adjusted by the Peltier element 2. Therefore, temperature fluctuations of the wirings 82a, 82b, 82c, and 82d are reduced, and accordingly, temperature fluctuations of the light emitting element 3 can be reduced.

  The relay member 72 can be configured similarly to the relay member 71 described above. However, since the high-frequency signal is not used for the temperature sensor 4, the wiring layer included in the relay member 72 may be provided over the entire upper surface of the base.

  By electrically connecting the temperature sensor 4 and the connection electrodes 62e and 62f via the relay member 72 and the like, the temperature of the wirings 83a, 83b, and 83c is also adjusted by the Peltier element 2. Therefore, temperature fluctuations of the wirings 83a, 83b, and 83c are reduced, and accordingly, temperature fluctuations of the temperature sensor 4 can be reduced. That is, the temperature sensor 4 can be hardly affected by the heat from the connection electrodes 62e and 62f. Therefore, the detection accuracy of the temperature sensor 4 can be increased, and as a result, the temperature of the light emitting element 3 can be controlled with high accuracy.

  As described above, the light emitting element module 1 as described above covers the light emitting element 3 that emits the light LL, the base 51 having the recess 511 in which the light emitting element 3 is accommodated, and the opening of the recess 511. And a lid 52 joined to the base 51. Further, the lid 52 is provided so as to protrude to the opposite side of the base 51, and is provided with a protrusion 55 having a hole 551 for allowing the light LL to pass therethrough, and a window for closing the hole 551 of the protrusion 55 and transmitting the light LL. Part 56. A surface 560 (lower surface) of the window portion 56 on the light emitting element 3 side is inclined with respect to a surface having the optical axis a of the light LL as a normal line, that is, the plate surface 540 of the main body portion 54.

  According to the light emitting element module 1 of the present invention, the surface 560 of the window 56 on the light emitting element 3 side is inclined with respect to a surface (plate surface 540) having the optical axis a of the light LL as a normal line. Therefore, the return light reflected from the light emitting element 3 by the window 56 and returning to the light emitting element 3 can be reduced. Furthermore, since the window part 56 is provided in the protrusion part 55, the separation distance of the window part 56 and the light emitting element 3 can be enlarged. Therefore, coupled with the decrease in the light amount density as the light LL from the light emitting element 3 travels, the return light can be effectively reduced. In the light emitting element module 1, the window portion 56 is provided in the protruding portion 55, so that, for example, the lid 52 does not have the protruding portion 55, and the concave portion 511 of the base 51 is enlarged (deeply). Compared with the case where the separation distance from the element 3 is increased, the entire light emitting element module 1 can be reduced in size. For this reason, according to the light emitting element module 1, it is possible to reduce the influence of the return light on the light emitting element 3 while reducing the increase in size.

  In addition, the inclination angle θ of the surface 560 on the light emitting element 3 side of the window portion 56 with respect to the surface having the optical axis a of the light LL as a normal line is preferably in the range of 5 ° to 45 °, preferably 7 ° or more. It is more preferably within a range of 40 ° or less, and further preferably within a range of 10 ° or more and 30 ° or less. In particular, in the present embodiment, the inclination angle θ is 15 °. When the inclination angle θ is within the above-described range, the influence of the return light on the light emitting element 3 (for example, temperature) is exhibited while exhibiting necessary optical characteristics of the window portion 56 (for example, sufficient transmittance of the light LL). Wavelength fluctuation of the light LL due to the rise) can be reduced.

  In addition, the inclination direction of the surface 560 on the light emitting element 3 side of the window portion 56 is not limited to the illustration. For example, in FIG. 6, the window portion 56 is rotated clockwise by 30 °, 60 °, 90 °, 180 °, 210 It may be arranged in a rotated state.

  Further, as described above, the inner wall surface of the hole 551 of the projecting portion 55 has a stepped portion 553 that is inclined with respect to a plane having the optical axis a of the light LL as a normal line and supports the window portion 56. doing. Thereby, it becomes easy to provide the window part 56 with respect to the protrusion part 55 by a proper position and the above-mentioned inclination angle (theta).

Here, as described above, the light LL emitted from the light emitting element 3 is emitted with a predetermined radiation angle (a spread angle with the optical axis a of the light LL being the central axis). When the width (diameter) at the intensity of 1 / e ² (e is the base of natural logarithm) of the peak intensity of the light LL on the surface along the opening on the base 51 side of the hole 551 is W [mm] The width L (diameter) [mm] of the opening on the base 51 side of the hole 551 preferably satisfies the range of W <L <20 × W, and preferably satisfies the range of 2 × W <L <18 × W. More preferably, it is more preferable to satisfy the range of 5 × W <L <15 × W. In particular, in the present embodiment, the width L is 5.4 × W. When the width L is within the above-described range, the central portion excluding the outer peripheral portion having a large energy density change in the light LL emitted from the light emitting element 3 is reduced while reducing the excessive enlargement of the protruding portion 55. It is possible to make the light incident efficiently into 551.

  Further, as described above, the lid 52 includes the first portion 54a that supports the protruding portion 55, and the second portion 54b that is joined to the base 51 and is thinner than the first portion 54a. Thus, since the 2nd part 54b joined to the base 51 is thinner than the 1st part 54a, the joining of the lid 52 and the base 51 can be easily performed by seam welding or the like. Further, since the first portion 54a is thicker than the second portion 54b, the required mechanical strength of the lid 52 can be ensured. Further, since the first portion 54a is thicker than the second portion 54b, the stress generated in the first portion 54a when the lid 52 and the base 51 are joined is reduced, and the window portion 56 is detached from the protruding portion 55. This can be reduced.

  Further, as described above, the outer peripheral surface of the protruding portion 55 has the flat flat portion 554 that follows the outer shape of the first portion 54a when viewed from the direction along the optical axis a of the light LL. In particular, in the present embodiment, the outer peripheral surface of the protruding portion 55 has a pair of flat portions 554. Thereby, when the 2nd part 54b of the lid 52 and the base 51 are joined, it can reduce that the protrusion part 55 becomes obstructive, Therefore The joining of the lid 52 and the base 51 can be performed more easily. it can. In the present embodiment, a pair of curved surface portions 555 is provided between the pair of flat portions 554. By having such a curved surface portion 555, the necessary mechanical strength of the protruding portion 55 can be ensured.

  The atomic oscillator 10 has been described above. Such an atomic oscillator 10 includes the light emitting element module 1 as described above. Thereby, the influence which return light has on the light emitting element 3 can be reduced while increasing the size. For this reason, the wavelength fluctuation of the light LL from the light emitting element 3 can be reduced, and the atomic oscillator 10 having excellent oscillation characteristics can be realized using the light LL.

  Further, as described above, the atomic oscillator 10 holds the neutral density filter 301, the lens 302, and the quarter wavelength plate 303 that are “optical elements” that allow the light LL from the light emitting element 3 to pass therethrough. Holder 304. And the holder 304 has the through-hole 305 which can penetrate the protrusion part 55 with which the light emitting element module 1 is provided. Accordingly, by inserting the protruding portion 55 into the through hole 305 of the holder 304, the relative positioning between the light emitting element module 1 and the holder 304 can be easily and highly accurately performed. Therefore, the light LL emitted from the light emitting element module 1 can be appropriately incident on the neutral density filter 301. In addition, since the main body 54 and the protrusion 55 come into contact with the holder 304 in this way, the temperature rise of the lid 52 can be reduced by heat radiation from the holder 304 made of a metal material and having excellent heat radiation. .

Second Embodiment
FIG. 7 is a schematic view showing a light emitting element and a window portion of a light emitting element module provided in the atomic oscillator according to the second embodiment of the present invention. FIG. 8 is a diagram illustrating a state in which the center of the window portion and the optical axis of light coincide with each other. FIG. 9 is a schematic view showing a modification of the arrangement of the window portions shown in FIG.
In the following description, the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 7, FIG. 8, and FIG. 9, the same configurations as those of the above-described embodiment are denoted by the same reference numerals.

In the light emitting element module 1A shown in FIG. 7, the geometric center O56 of the window portion 56A does not coincide with the optical axis a of the light LL, but is shifted with respect to the optical axis a. The window portion 56A is a flat plate member having a hexagonal shape in plan view, like the window portion 56 in the first embodiment, and the surface 560 is inclined with respect to the surface having the optical axis a as a normal line. ing. Further, a part of the side surface 563 (outer peripheral surface) of the window portion 56A is located outside the light flux L1 of the light LL. Specifically, the edge 5601 (outer periphery) of the surface 560 (incident side surface) of the window portion 56A is located outside the light flux L1 of the light LL over the entire periphery. The light beam L1 is inside the line drawn at the radiation angle θ1. The “radiation angle” means an angle at 1 / e ² of the peak intensity of the light LL as described above. However, when the cross-sectional intensity distribution of the light LL does not form a Gaussian distribution, the “radiation angle” refers to an angle at half the peak intensity of the light LL.

  Here, when the window 56A is changed from the state indicated by the two-dot chain line in FIG. 8 to the state indicated by the solid line in FIG. 8, the position of the center O56 is not changed while the center O56 is positioned on the optical axis a. When the window portion 56A is inclined, a portion of the light LL that does not pass through the window portion 56A is generated. In FIG. 8, light LL does not pass through the window portion 56A in a portion distal to the light emitting element 3 of the window portion 56A (the left portion of the window portion 56A indicated by a solid line in FIG. 8). The portion of the light LL that does not pass through the window portion 56A may be absorbed or reflected by a portion other than the window portion 56A of the lid 52 (see FIG. 4). As a result, the amount (light quantity) of the light LL emitted from the window portion 56A is reduced, or a portion of the light LL that does not pass through the window portion 56A is diffusely reflected and reaches the light emitting element 3 or the atomic cell 201, thereby causing an unexpected influence. (See FIGS. 2 and 3).

  In order to reduce the influence or the like of the portion of the light LL that does not pass through the window portion 56A, in the present embodiment, as described above, the window portion 56A is arranged as shown in FIG. The position of the window portion 56A shown in FIG. 7 can be realized by moving the window portion 56A in the arrow A1 direction from the position of the window portion 56A shown by the solid line in FIG.

Specifically, as described above, the center O56 of the window portion 56A is shifted with respect to the optical axis a of the light LL. Thus, without changing the size of the window portion 56A (the plane area of the surface 560) from the size of the window portion 56A indicated by the two-dot chain line in FIG. 8 and the size of the window portion 56A indicated by the solid line in FIG. The edge 5601 of the surface 560 of the part 56A can be positioned outside the light flux L1 of the light LL. That is, the edge 5601 of the surface 560 can be positioned outside the light beam L1 of the light LL with the minimum size of the window portion 56A. Thereby, it is possible to reduce the occurrence of the light LL that does not pass through the window portion 56A while reducing the increase in size of the window portion 56A. Therefore, the light LL (specifically, a portion that is 1 / e ² or 1/2 or more of the maximum light intensity of the light LL) can be appropriately passed through the window portion 56A. As a result, it is possible to reduce the light amount of the light LL emitted from the window portion 56A and reduce the adverse effect on the light emitting element 3 and the like due to the irregular reflection of the light LL deviated from the window portion 56A. Further, since the size of the window portion 56A can be reduced, a large number of window portions 56A can be manufactured from one substrate (for example, a sheet-like glass substrate). Therefore, cost reduction and productivity improvement can be achieved.

  Even if the edge 5601 is positioned outside the light beam L1 by increasing the size of the window 56A (plane area of the surface 560) while the center O56 of the window 56A is positioned on the optical axis a. Good.

  In FIG. 9, the modification of 56 A of window parts of this embodiment is shown. In FIG. 9, the side surface 563 (entire region of the side surface 563) of the window portion 56 </ b> A is located outside the light flux L <b> 1 of the light LL. In other words, the edge 5601 of the surface 560 and the edge 5611 of the surface 561 (outgoing side surface) are respectively located outside the light flux L1 of the light LL. Thereby, since the light LL can be passed through both main surfaces (surfaces 560 and 561) of the window portion 56A, irregular reflection of the light LL on the side surface 563 of the window portion 56A can be reduced.

Here, the side surface 563 of the window portion refers to a surface excluding both main surfaces (surfaces 560 and 561) and connecting both main surfaces (surfaces 560 and 561). The surface 560 is located on the light emitting element 3 side of the window portion 56A and is a main surface on which the light LL is incident. On the other hand, the surface 561 is located on the opposite side of the window portion 56A from the light emitting element 3, and is a main surface from which the light LL is emitted.
Further, the fact that the side surface 563 is located outside the light beam L1 includes a case where a part of the side surface 563 is located outside the light beam L1.

  7 and 9 described above, the light LL from the light emitting element 3 is reflected by the window 56A and returned to the light emitting element 3 can be reduced.

<Third Embodiment>
FIG. 10 is a schematic view showing a light emitting element and a window portion of a light emitting element module provided in an atomic oscillator according to the third embodiment of the present invention. FIG. 11 is a schematic diagram showing a modification of the window shown in FIG.
In the following description, the third embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. 10 and 11, the same reference numerals are given to the same configurations as those in the above-described embodiment.

  In the light emitting element module 1B shown in FIG. 10, coating films 565 and 566 are provided on both main surfaces (surfaces 560 and 561) of the window portion 56B. The window part 56B has the same configuration as the window part 56A shown in FIG. The coating films 565 and 566 are made of, for example, an antireflection film (AR coat). Thereby, it can reduce that the light LL from the light emitting element 3 reflects in the window part 56B. For this reason, a decrease in the light amount of the light LL passing through the window portion 56B can be reduced, so that the light amount of the light LL reaching the atomic cell 201 can be increased (see FIGS. 2 and 3). The coating films 565 and 566 are not limited to antireflection films, and may be formed of films having other functions.

  The coating film 565 is provided in almost the entire region (excluding the edge 5601) of the surface 560 (incident side surface) of the window portion 56B. Similarly, the coating film 566 is provided on almost the entire surface (the portion excluding the edge 5611) of the surface 561 (surface on the emission side). The center O565 of the coating film 565 and the center O566 of the coating film 566 are located on the central axis A56 of the window portion 56B. Further, the centers O565 and O566 are not positioned on the optical axis a, but are shifted from the optical axis a. The central axis A56 is an axis that passes through the center O56 of the window portion 56B and extends in the thickness direction of the window portion 56B.

  Further, the edge 5651 of the coating film 565 is located outside the light flux L1 of the light LL over the entire circumference. Similarly, the edge 5661 of the coating film 566 is located outside the light flux L1 of the light LL over the entire circumference. Thereby, since the light LL can be more appropriately passed through the coating films 565 and 566, reflected light or the like from the window portion 56B to the light emitting element 3 can be reduced. Therefore, the amount of light LL reaching the atomic cell 201 can be increased. Moreover, it can reduce that reflected light reaches the light emitting element 3 and the atomic cell 201, and has a bad influence.

  In FIG. 11, the modification of window part 56B provided with the coating films 565 and 566 of this embodiment is shown. In FIG. 11, the coating films 565 and 566 are arranged in accordance with regions through which the light LL passes, respectively. Specifically, the center O565 of the coating film 565 is located on the right side in FIG. 11 with respect to the center axis A56 of the window portion 56B. On the other hand, the center O566 of the coating film 566 is located on the left side in FIG. 11 with respect to the central axis A56 of the window portion 56B. That is, the center O565 of the coating film 565 and the center O566 of the coating film 566 are shifted in opposite directions with respect to the center axis A56 with the center axis A56 interposed therebetween.

  As described above, the light LL from the light emitting element 3 is reflected by the window 56B and returned to the light emitting element 3 by the window 56B provided with the coating films 565 and 566 shown in FIGS. Can be reduced.

  Note that one of the coating films 565 and 566 may be omitted as appropriate. However, by providing both of the coating films 565 and 566, it is possible to further enhance the effect of reducing the adverse effects caused by the reflected light.

<Fourth embodiment>
FIG. 12 is a schematic view showing a window portion and an optical system unit of a light emitting element module included in an atomic oscillator according to the fourth embodiment of the invention.
In the following description, the fourth embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted. In FIG. 12, the same components as those in the above-described embodiment are denoted by the same reference numerals.

  As shown in FIG. 12, in the atomic oscillator 10C, the geometric center O301 of the neutral density filter 301C included in the optical system unit 30 does not coincide with the optical axis a and is shifted with respect to the optical axis a. . In addition, the neutral density filter 301C is a flat plate-like member similar to the neutral density filter 301 in the first embodiment, and is inclined with respect to a plane having the optical axis a as a normal line. The side surface 3015 (outer peripheral surface) of the neutral density filter 301C is located outside the light flux L1 of the light LL. In other words, the edge 3012 of the surface 3011 on the window 56A side of the neutral density filter 301C and the edge 3014 of the surface 3013 on the side opposite to the window 56A of the neutral density filter 301C are respectively luminous fluxes of the light LL. It is located outside of L1.

  Here, as shown in FIG. 12, a window portion 56 </ b> A is provided between the light emitting element 3 and the neutral density filter 301 </ b> C as an “optical element”. The surface 3011 on the window 56A side of the neutral density filter 301C is inclined with respect to a plane whose normal is the optical axis a of the light LL, and the center O301 of the neutral density filter 301C is the optical axis of the optical LL. It is shifted with respect to a. Thus, similarly to the window portion 56A, the side surface 3015 of the neutral density filter 301C is placed outside the luminous flux L1 of the light LL without excessively increasing the size of the neutral density filter 301C (plane area of the surface 3011). Can be positioned. Therefore, it is possible to more effectively reduce the reduction in the amount of light LL emitted from the neutral density filter 301C while reducing the size of the neutral density filter 301C. As a result, it is possible to exhibit excellent oscillation characteristics using the light LL by increasing the amount of light LL reaching the atomic cell 201 while reducing the increase in size of the atomic oscillator 10C.

  In this way, when the “optical element” arranged within the range in which the light LL has a radiation angle is inclined with respect to the optical axis a, the geometrical shape of the “optical element” with respect to the optical axis a. It is effective to shift the center. Therefore, even when “optical elements” other than the window portion 56A and the neutral density filter 301C are disposed in such a range so as to be inclined with respect to the optical axis a, the geometrical characteristics of the “optical elements” are not limited. It is effective to arrange the center at a position shifted from the optical axis a.

Further, even if the light LL is in the region after passing through the lens 302, if the light LL again has a radiation angle (for example, when parallel light passes through the lens and has a radiation angle), the radiation angle is obtained. It is also preferable that the geometric center of the “optical element” that allows the light LL having the light to pass through be shifted from the optical axis a.
Since the atomic oscillator 10C including the neutral density filter 301C shown in FIG. 12 as described above can also reduce the influence of the return light on the light emitting element 3 while reducing the size, high quality light. An atomic oscillator 10C having high characteristics using LL can be realized.

2. Electronic Device The light emitting element modules 1, 1A, 1B and the atomic oscillators 10, 10C as described above can be incorporated into various electronic devices. Hereinafter, the electronic apparatus of the present invention will be described.

  FIG. 13 is a diagram showing a schematic configuration when the atomic oscillator of the present invention is used in a positioning system using a GPS satellite.

A positioning system 1100 shown in FIG. 13 includes a GPS satellite 1200, a base station device 1300, and a GPS receiver 1400.
The GPS satellite 1200 transmits positioning information (GPS signal).

  The base station device 1300 receives the positioning information from the GPS satellite 1200 with high accuracy via, for example, the antenna 1301 installed at the electronic reference point (GPS continuous observation station), and the reception device 1302 receives the positioning information. A transmission apparatus 1304 that transmits positioning information via an antenna 1303.

  Here, the receiving device 1302 is an electronic device including the atomic oscillator 10 (light emitting element module 1) of the present invention described above as the reference frequency oscillation source. In addition, the positioning information received by the receiving device 1302 is transmitted by the transmitting device 1304 in real time.

  The GPS receiver 1400 includes a satellite receiver 1402 that receives positioning information from the GPS satellite 1200 via the antenna 1401, and a base station receiver 1404 that receives positioning information from the base station device 1300 via the antenna 1403. Prepare.

  The receiving device 1302 that is an “electronic device” included in the positioning system 1100 as described above includes the light-emitting element module 1 (or the light-emitting element modules 1A and 1B). Thereby, the influence which return light gives to the light emitting element 3 can be reduced, reducing an enlargement. For this reason, the receiving device 1302 having high characteristics using the light LL from the light emitting element 3 can be realized.

  Note that the electronic device including the light emitting element module of the present invention is not limited to the above-described one, and for example, a smartphone, a tablet terminal, a watch, a mobile phone, a digital still camera, an ink jet type ejection device (for example, an ink jet printer), a personal computer (Mobile personal computers, laptop personal computers), TVs, video cameras, video tape recorders, car navigation devices, pagers, electronic notebooks (including those with communication functions), electronic dictionaries, calculators, electronic game devices, word processors, work Station, videophone, TV monitor for crime prevention, electronic binoculars, POS terminal, medical equipment (eg electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish finder Various measuring instruments, gauges (e.g., gages for vehicles, aircraft, and ships), a flight simulator, terrestrial digital broadcasting, can be applied to a mobile phone base station or the like.

3. Mobile Object FIG. 14 is a diagram showing an example of the mobile object of the present invention.

  In this figure, a moving body 1500 has a vehicle body 1501 and four wheels 1502, and is configured to rotate the wheels 1502 by a power source (engine) (not shown) provided in the vehicle body 1501. In such a moving body 1500, the atomic oscillator 10 (light emitting element module 1) is incorporated.

  The moving body 1500 as described above includes the light-emitting element module 1 (or the light-emitting element modules 1A and 1B) described above. Thereby, the influence which return light gives to the light emitting element 3 can be reduced, reducing an enlargement. For this reason, the mobile 1500 with high characteristics using the light LL from the light emitting element 3 can be realized.

  The light emitting element module, the atomic oscillator, the electronic device, and the moving body of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to these.

  Moreover, the structure of each part of this invention can be substituted by the thing of the arbitrary structures which exhibit the same function of embodiment mentioned above, and arbitrary structures can also be added.

  In the above-described embodiment, the case where the present invention is applied to an atomic oscillator that resonantly transitions cesium or the like using the quantum interference effect of two types of light having different wavelengths has been described. However, the present invention is not limited to this. In addition, the present invention can be applied to an atomic oscillator that makes a resonance transition of rubidium or the like by utilizing a double resonance phenomenon caused by light and microwaves.

  Moreover, although the case where the light emitting element module of this invention was used for the atomic oscillator was demonstrated to the example in embodiment mentioned above, it is not limited to this, It can use for all the devices using a light emitting element. For example, the light emitting element module of the present invention can be applied to a magnetic sensor, a quantum memory, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Light emitting element module, 2 ... Peltier element, 3 ... Light emitting element, 4 ... Temperature sensor, 5 ... Package, 10 ... Atomic oscillator, 20 ... Atomic cell unit, 21 ... Substrate, 22 ... Substrate, 23 ... Assembly, 24 ... Terminal, 25 ... Terminal, 26 ... Metal layer, 30 ... Optical system unit, 40 ... Support member, 50 ... Control unit, 51 ... Base, 52 ... Lid, 53 ... Seal ring, 54 ... Body part, 54a ... First Part 54b ... Second part 54c ... Third part 55 ... Projection part 56 ... Window part 60 ... Package 61a ... External mounting electrode 61b ... External mounting electrode 61c ... External mounting electrode 61d ... External mounting Electrode, 61e ... external mounting electrode, 61f ... external mounting electrode, 62a ... connection electrode, 62b ... connection electrode, 62c ... connection electrode, 62d ... connection electrode, 62e ... connection electrode, 62f ... connection electrode, DESCRIPTION OF SYMBOLS 1 ... Relay member, 72 ... Relay member, 81a ... Wiring, 81b ... Wiring, 82a ... Wiring, 82b ... Wiring, 82c ... Wiring, 82d ... Wiring, 83a ... Wiring, 83b ... Wiring, 83c ... Wiring, 201 ... Atomic cell , 202 ... light receiving element, 203 ... heater, 204 ... temperature sensor, 205 ... coil, 206 ... package, 207 ... window, 301 ... neutral density filter (optical element), 302 ... lens (optical element), 303 ... 1 / 4-wavelength plate (optical element), 304 ... holder (heat radiating member), 305 ... through hole, 306 ... positioning surface, 401 ... installation surface, 402 ... step portion, 403 ... installation surface, 404 ... step portion, 501 ... temperature control 502, light source control unit, 503 ... magnetic field control unit, 504 ... temperature control unit, 505 ... circuit board, 506a ... connector, 506b ... connector, 507a ... Wiring board, 507b ... rigid wiring board, 508a ... flexible wiring board, 508b ... flexible wiring board, 509 ... lead pin, 511 ... recess, 512 ... stepped portion, 531 ... inner peripheral edge, 540 ... plate surface, 541 ... hole, 551 ... hole, 552 ... hole, 553 ... step portion, 554 ... flat portion, 555 ... curved surface, 560 ... surface, 711 ... base, 712 ... wiring layer, 1100 ... positioning system, 1200 ... GPS satellite, 1300 ... base station Device, 1301 ... Antenna, 1302 ... Receiver, 1303 ... Antenna, 1304 ... Transmitter, 1400 ... GPS receiver, 1401 ... Antenna, 1402 ... Satellite receiver, 1403 ... Antenna, 1404 ... Base station receiver, 1500 ... Moving Body, 1501 ... Vehicle body, 1502 ... Wheel, 5051 ... Through-hole, LL ... Light, S ... Internal space, a ... optical axis, θ ... tilt angle, L ... width, t1 ... thickness, t2 ... thickness, t3 ... thickness, 1A ... light emitting element module, 1B ... light emitting element module, 10C ... atomic oscillator, 56A ... window, 56B ... Window, 301C ... Neutral filter, 561 ... Face, 563 ... Side, 565 ... Coating film, 566 ... Coating film, 3011 ... Face, 3012 ... Edge, 3013 ... Face, 3014 ... Edge, 3015 ... Side, 5601 ... Edge, 5611 ... Edge, 5651 ... Edge, 5661 ... Edge, A1 ... Arrow, A56 ... Center axis, L1 ... Light flux, O301 ... Center, O56 ... Center, O565 ... Center, O566 ... Center, θ1 ... Radiation angle

Claims (13)

A light emitting element that emits light;
A base having a recess in which the light emitting element is accommodated;
A lid that covers the opening of the recess and is joined to the base;
The lid is
A protruding portion provided on the opposite side of the base and having a hole through which the light passes;
A window portion that is provided by closing the hole in the projecting portion and transmits the light;
A light emitting element module, wherein a surface of the window portion on the light emitting element side is inclined with respect to a surface having an optical axis of the light as a normal line.   2. The light emitting element module according to claim 1, wherein an inclination angle of a surface on the light emitting element side of the window portion with respect to a surface having the optical axis of the light as a normal line is in a range of 5 ° to 45 °.   3. The light emitting device module according to claim 1, wherein the lid includes a first portion that supports the protruding portion, and a second portion that is bonded to the base and is thinner than the first portion. .   4. The light emitting element module according to claim 3, wherein an outer peripheral surface of the protruding portion has a flat flat portion that is along an outer shape of the first portion when viewed from a direction along the optical axis of the light.   5. The step according to claim 3, wherein an inner wall surface of the hole of the projecting portion has a step portion that is inclined with respect to a surface having the optical axis of the light as a normal line and supports the window portion. The light emitting element module of description. When the width at the intensity of 1 / e ² (e is the base of natural logarithm) of the peak intensity of the light on the surface along the base side opening of the hole is W [mm], the base of the hole 6. The light emitting element module according to claim 1, wherein a width L [mm] of the opening on the side satisfies a range of W <L <20 × W.   The light emitting element module according to any one of claims 1 to 6, wherein a center of the window portion is shifted with respect to an optical axis of the light.   The light emitting element module according to claim 7, wherein a side surface of the window portion is positioned outside a light flux of the light.   An atomic oscillator comprising the light emitting element module according to claim 1. An optical element that allows the light from the light emitting element to pass through, and a holder that holds the optical element,
The atomic oscillator according to claim 9, wherein the holder has a through hole through which the protrusion provided in the light emitting element module can be inserted. The window is provided between the light emitting element and the optical element;
The window side surface of the optical element is inclined with respect to a surface having the optical axis of the light as a normal,
The atomic oscillator according to claim 10, wherein a center of the optical element is shifted with respect to an optical axis of the light.   An electronic apparatus comprising the light emitting element module according to claim 1.   A moving body comprising the light emitting element module according to claim 1.

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