CN105628247A - Ultra-high resolution temperature sensor based on external liquid bag and spectrum valley point - Google Patents

Abstract

The invention discloses an ultrahigh resolution temperature sensor based on an external liquid bag and a spectrum valley pointFlat signal light composition; the signal light adopts broadband light or sweep frequency light; the liquid bag is connected with the vertical waveguide, and the metal block is arranged in the vertical waveguide and can move; the vertical waveguide and the horizontal waveguide are connected. The invention has compact structure, small volume and convenient integration, and the sensitivity of the temperature sensor can reach-2.3037 multiplied by 10⁹nm/℃。

Description

Ultra-high resolution temperature sensor based on external liquid capsule and spectral valley point

technical field

The invention relates to an ultra-high resolution and nanoscale temperature sensor, in particular to an ultra-high resolution temperature sensor based on an external liquid capsule structure and a spectrum valley point.

Background technique

Temperature sensors are one of the most widely used sensors in practical applications. From the cold and heat meters in our lives, thermometers to large instruments and temperature control equipment on integrated circuits, temperature sensors are everywhere. Although traditional temperature sensors such as RTDs, platinum resistance thermometers, and bimetallic switches have their own advantages, they are no longer suitable for miniature and high-precision products. The advantages of semiconductor temperature sensors such as high sensitivity or resolution, small size, low power consumption, and strong anti-interference ability make them widely used in semiconductor integrated circuits.

Waveguides based on surface plasmons can break through the diffraction limit and realize nanoscale optical information processing and transmission. Surface plasmon is a kind of surface electromagnetic wave propagating on the metal surface formed by the coupling of the electromagnetic wave and the free electrons on the metal surface when the electromagnetic wave is incident on the interface between the metal and the medium. According to the properties of surface plasmons, many devices based on surface plasmon structures have been proposed, such as filters, circulators, logic gates, optical switches, etc. These devices are relatively simple in structure, which is very convenient for optical circuit integration.

At present, according to the properties of surface plasmons, the proposed temperature sensor is 70pm/°C or -0.65nm/°C. Although these surface plasmon temperature sensors are small, they do not have high sensitivity or resolution.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an ultra-high resolution temperature sensor with an MIM structure that is easy to integrate.

To achieve the above object, the present invention takes the following design scheme:

The ultra-high resolution temperature sensor based on the external liquid bag and the spectrum valley point of the present invention is composed of an external liquid bag, a metal block, a vertical waveguide, a horizontal waveguide, two metal films and a horizontal signal light; The signal light adopts broadband light or frequency-sweeping light; the liquid capsule is connected to the vertical waveguide, and the metal block is arranged in the vertical waveguide and can move; the vertical waveguide is connected to the horizontal waveguide.

The material in the liquid capsule is a material with a high thermal expansion coefficient.

The substance with high expansion coefficient is alcohol or mercury.

The shape of the liquid capsule is cube, sphere, ellipsoid or irregular shape.

The metal is gold or silver.

The metal is silver.

The horizontal waveguide and the vertical waveguide are waveguides of MIM structure.

The medium in the horizontal waveguide is air.

The wavelength range of the signal light is a spectrum signal of 700nm-1000nm.

The beneficial effect of the present invention compared with prior art is:

1. Compact structure, small size, very easy to integrate.

2. The sensitivity of the temperature sensor can reach -2.3037×10 ⁹ nm/℃, and the response time is at the level of microseconds.

Description of drawings

Fig. 1 is a two-dimensional structural schematic diagram of the first embodiment of the temperature sensor of the present invention.

In the figure: external liquid capsule 1 metal block 2 vertical waveguide 3 metal film 4 horizontal waveguide 5 metal film 6 horizontal signal light 200

Fig. 2 is a schematic diagram of the two-dimensional structure of the second embodiment of the temperature sensor of the present invention.

In the figure: external liquid capsule 1 metal block 2 vertical waveguide 3 metal film 4 horizontal waveguide 5 metal film 6 horizontal signal light 200

Fig. 3 is a transmission spectrum diagram of signal light with different wavelengths.

Fig. 4 is a graph showing the relationship between transmission spectrum and temperature.

Fig. 5 is a graph showing the relationship between the wavelength shift amount of the trough point of the transmission spectrum and the temperature.

detailed description

The specific structure and embodiments of the present invention are described below in conjunction with the accompanying drawings.

The temperature sensor shown in Figure 1 consists of an external liquid bag 1, a metal block 2, a vertical waveguide 3, a horizontal waveguide 5, two metal films 4, 6 (not etched metal films) and a horizontal signal light 200 (surface plasmons formed on the surface of the waveguide); the signal light adopts broadband light or frequency-sweeping light; the external liquid capsule 1 is connected to the vertical waveguide 3, and the metal block 2 is set in the vertical waveguide and can be moved; the vertical waveguide 3 is connected to the horizontal waveguide 5; the liquid capsule is spherical, and its radius R is 0.1mm. The material in the liquid capsule 1 has a relatively low specific heat capacity and is a material with a high thermal expansion coefficient. The material in the liquid capsule 1 (temperature sensitive cavity) is high The material with thermal expansion coefficient, the material with high thermal expansion coefficient is alcohol or mercury, the material with high thermal expansion coefficient is preferably alcohol; the metal is gold or silver, the best is silver, and the thickness of the metal film (represented by h ₁ below) adopts a value range above 100nm , the thickness of 100nm is the best; the metal block 2 is set in the vertical waveguide 3 and can be moved, the length m of the moving metal block 2 adopts the value range of 80nm-150nm, and the length of 125nm is the best, the distance level of the movable metal block 2 The distance s of waveguide 5 adopts 0nm-200nm distance range, and is determined by the position of metal block 2, and this metal block 2 is gold or silver, and the best is silver; Vertical waveguide 3 and horizontal waveguide 5 are connected; Vertical waveguide 3 and horizontal waveguide 5 are connected; The horizontal waveguide 5 is a waveguide of MIM structure, that is, the MIM waveguide is a metal-insulator-metal structure, and the insulator is a non-conductive transparent material; the non-conductive transparent material is air, silicon dioxide or silicon; the vertical waveguide 3 is located at the upper end of the horizontal waveguide 5 The width b of the vertical waveguide 3 adopts the value range of 30nm-60nm, and the width of 35nm is the best, the length M of the vertical waveguide 3 adopts a value above 200nm, and the length of 300nm is the best; the left edge of the vertical waveguide 3 to The distance a of the left edge of the metal film 6 adopts a value range of 350nm-450nm, with 400nm being the best. The width d of the horizontal waveguide 5 adopts a value range of 30nm-100nm, and the width of 50nm is the best. The medium in the horizontal waveguide 5 adopts air; the distance c between the lower edge of the horizontal waveguide 5 and the edge of the metal film 6 adopts a value range greater than 150nm The wavelength range of signal light adopts 700nm-1000nm spectrum signal; the volume of alcohol is changed by changing the temperature, and its expansion pushes the movable metal block 3 to move to the horizontal waveguide 5 to change the length of the air section in the vertical waveguide 4, thereby changing The transmittance of the signal light can obtain the information of the temperature change according to the information of the movement of the valley point of the transmission spectrum. When the temperature drops back to the initial temperature, under the action of the external atmospheric pressure, the metal block 3 will return to the position of initial pressure balance, which is convenient for the next detection.

The downward movement of the movable metal block 3 will change the transmittance of the signal light. The downward movement of the movable metal block 3 is controlled by temperature, so the change of temperature affects the position of the valley point of the transmission spectrum of the signal light. According to the valley point of the transmission spectrum The information of the temperature change can be obtained from the information of the movement.

The volume expansion coefficient of alcohol is α _ethanol = 1.1×10 ^-3 /°C, and the density at room temperature (20°C) is ρ = 0.789g/cm ³ . The linear expansion coefficient of silver is α _Ag =19.5×10 ^-6 °C. Compared with the expansion coefficient of alcohol, the expansion of silver under the same temperature change is negligible. In the present invention, the influence of temperature change on the volume of silver is no longer considered. According to the volume of the liquid capsule and the cross-sectional area of the movable metal block, the relationship between the position change of the metal block and the temperature can be calculated, and a proportional coefficient σ is defined to represent the moving distance of the metal block corresponding to the change of unit temperature

$\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; l</span>}}}{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; l</span>}}}{\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

This formula can also be used as a measure of the temperature sensitivity of the structure. According to this formula, it can be concluded that the cross-sectional area of the circular absorbing cavity and the width of the movable metal block have a relatively large influence on the position change of the metal block, and b=35nm is selected comprehensively. σ=1.32×10 ⁹ nm/°C, this result is the relationship between the amount of movement of the metal block and the temperature.

In the embodiment shown in Fig. 2, another kind of temperature sensor structure schematic diagram is given, and the temperature sensor consists of an external liquid bag 1, a metal block 2, a vertical waveguide 3, a horizontal waveguide 5, two metal films 4, 6 (metal film that has not been etched) and a horizontal signal light 200 (surface plasmons formed on the surface of the waveguide); the signal light adopts broadband light or frequency-sweeping light; the external liquid capsule 1 is connected to the vertical waveguide 3 , the metal block 2 is arranged in the vertical waveguide and can be moved; the vertical waveguide 3 and the horizontal waveguide 5 are connected; the section of the fluid capsule is a regular hexagonal cone, and its side length r is 0.1mm. The fluid capsule 1 (temperature sensitive The material in the cavity) has a relatively low specific heat capacity and a material with a high thermal expansion coefficient. The material in the liquid capsule 1 is a material with a high thermal expansion coefficient. The material with a high thermal expansion coefficient is alcohol or mercury, and the material with a high thermal expansion coefficient is preferably alcohol; The metal is gold or silver, preferably silver, and the metal film thickness _h1 adopts a value range above 100nm, and the thickness of 100nm is the best; the metal block 2 is set in the vertical waveguide 3, and can be moved, and the length of the metal block 2 is m The value range of 80nm-150nm is used, and the length of 125nm is the best. The distance s between the movable metal block 2 and the horizontal waveguide 5 is in the range of 0nm-200nm, and is determined by the position of the metal block 2. The metal block 2 is gold or Silver, preferably silver; the vertical waveguide 3 and the horizontal waveguide 5 are connected; the vertical waveguide 3 and the horizontal waveguide 5 are waveguides with a MIM structure, that is, the MIM waveguide is a metal-insulator-metal structure, and the insulator adopts a non-conductive transparent material; The conductive transparent material adopts air, silicon dioxide or silicon; the vertical waveguide 3 is located at the upper end of the horizontal waveguide 5; The length M is above 200nm, preferably 300nm; the distance a from the left edge of the vertical waveguide 3 to the left edge of the metal film 6 is in the range of 350nm-450nm, preferably 400nm. The width d of the horizontal waveguide 5 adopts a value range of 30nm-100nm, and the width of 50nm is the best, and the medium in the horizontal waveguide 5 is air; the distance c between the lower edge of the horizontal waveguide 5 and the edge of the metal film 6 adopts a value range greater than 150nm The wavelength range of signal light adopts 700nm-1000nm spectrum signal; the volume of alcohol is changed by changing the temperature, and its expansion pushes the movable metal block 3 to move to the horizontal waveguide 5 to change the length of the air section in the vertical waveguide 4, thereby changing The transmittance of the signal light can obtain the information of the temperature change according to the information of the movement of the valley point of the transmission spectrum. When the temperature drops back to the initial temperature, under the action of the external atmospheric pressure, the metal block 3 will return to the position of initial pressure balance, which is convenient for the next detection.

As the movable metal block 3 moves downwards so that the distance to the horizontal waveguide 5 changes, the transmittance of the signal light also changes accordingly. As shown in FIG. 3 , the transmittance of light with a wavelength of 700nm-1000nm at different wavelengths of the structure when the value of s is different. The initial position of the metal block is the position at the initial temperature (such as 20°C), and its value s=160nm; From the figure, it can be seen that the wavelength position of the trough point of the transmittance of the horizontal waveguide 5 decreases with the decrease of s Small and gradually reddened. Since the change of the position of the movable metal block 3 is related to temperature. When the temperature of the alcohol area increases by dT=1.189×10 ^-8 ℃, the position of the movable metal block 3 will move downward by 15.7 nm due to the thermal expansion of the alcohol. Moving down the movable metal block 3 will change the length of the horizontal waveguide 5 , and finally the transmittance of the horizontal waveguide 5 will also change accordingly. The movement of the movable metal block 3 caused by the unit change of temperature is consistent with the scanning interval in this paper, so the change of the transmittance of the horizontal waveguide 5 caused by the change of the value s of the position of the movable metal block 3 can be calculated by Indirect expression of temperature change. Then the amount of s in the result of Figure 3 can be replaced by temperature, and the result is shown in Figure 4. From Fig. 4, it can be obtained that the change law of the transmittance of the horizontal waveguide caused by the change of s caused by the change of temperature T is consistent with that of Fig. 3. In addition, it can also be seen from Fig. 3 that when the temperature changes by dT=1.189×10 ^-8 ℃, the wavelength of the trough point in the horizontal waveguide transmittance diagram moves very greatly. Therefore, the temperature information can be known according to the spectral characteristics of the output light from the horizontal waveguide 5 . After fine scanning, the wavelength diagram of each temperature point corresponding to the trough point of the transmittance is obtained, and the relationship diagram is shown in Figure 5. The black line with square points in the figure is the data point obtained from the simulation, and the black line is the curve obtained after fitting according to the simulation data. The sensitivity of the temperature sensor can be expressed by dλ/dT. According to the simulated data in Figure 5, the sensitivity of the temperature sensor varies greatly and is in a fluctuating state, which is not easy to characterize the performance of the temperature sensor, so a straight line is obtained by interpolating the original data. According to the expression of the sensitivity of the temperature sensor, it can be concluded that the sensitivity of the temperature sensor of the present invention is the slope of the black curve: dλ/dT=-2.3037×10 ⁹ nm/°C. In addition, if the volume of the alcohol holding chamber is increased, the sensitivity of the corresponding movable metal block 3 to temperature will increase, and the sensitivity of the temperature sensor will also increase accordingly.

Although this patent has introduced some specific examples, as long as it does not depart from the spirit specified in the claims of this patent, various modifications will be obvious to those skilled in the art.

Claims (9)

1. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point, it is characterised in that: it is made up of an external liquid capsule, metal derby, a vertical waveguide, a horizontal waveguide, two metal films and a horizontal signal light; Described flashlight adopts broadband light or frequency sweep light; Described liquid capsule and vertical waveguide connect, and described metal derby is arranged in vertical waveguide, and can move; Described vertical waveguide and horizontal waveguide connect.

2. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, in described liquid capsule, material is the material of high thermal expansion coefficient.

3. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 2, the material of described high expansion coefficient is ethanol or hydrargyrum.

4. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, described liquid capsule be shaped as cube shaped, spherical, elliposoidal or irregularly shaped.

5. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, described metal is golden or silver-colored.

6. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 5, described metal is silver.

7. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, described horizontal waveguide and vertical waveguide are the waveguide of mim structure.

8. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, the medium in described horizontal waveguide is air.

9. the ultrahigh resolution temperature sensor based on external liquid capsule and spectrum valley point described in claim 1, described signal light wavelength ranges for the spectrum signal of 700nm-1000nm.