CN115967002A - A multi-channel fast selection and tunable single-frequency fiber laser and its use method - Google Patents

Abstract

The invention relates to the technical field of lasers, in particular to a multichannel fast selection and tunable single-frequency fiber laser and a using method thereof, wherein the laser comprises a 980nm pump, the 980nm pump is connected with a WDM wavelength division multiplexer, the WDM wavelength division multiplexer is connected with a 1*N optical switch, each channel port of a 1*N optical switch is respectively connected with erbium-doped fiber phase-shift gratings of N different ITU channels, each erbium-doped fiber phase-shift grating is packaged and carries out temperature control through a TEC temperature control unit, the WDM wavelength division multiplexer is connected with an isolator, the output end of the isolator is connected with the input end of an optical amplifier, and finally, laser is output from the output end of the optical amplifier. The laser system can work in two modes, namely a multi-channel quick selection mode and a wavelength large-range continuous tuning mode. By means of the optical switch, large-range wavelength tuning of N channels can be achieved, meanwhile, a set of pumping and light path system is multiplexed by the N-channel grating, and cost is obviously reduced.

Description

A multi-channel fast selection and tunable single-frequency fiber laser and its use method

technical field

The invention relates to the technical field of lasers, in particular to a multi-channel fast selection and tunable single-frequency fiber laser and a usage method.

Background technique

An important existing single-frequency fiber laser is a distributed feedback fiber laser. The 1.5μm band distributed feedback fiber laser is a fiber with a π phase shift made on a photosensitive (doping-sensitized or hydrogen-carrying-sensitized) erbium-doped fiber The grating is used as a laser resonator. The length and reflectivity of the grating meet the requirements that the laser gain is greater than the loss. The pump laser in the 980nm band passes through the 980/1550nm wavelength division multiplexer to pump the phase shift grating resonator. Due to the short length of the phase shift grating The upper distribution feedback structure realizes single-frequency laser output.

The laser wavelength is related to the temperature and strain of the grating. The temperature coefficient of the laser wavelength is about 10pm/°C. The epoxy resin glue is fixed, and the temperature coefficient of the laser can reach more than 30pm/℃ at this time. The wavelength can be tuned within a certain range by changing the temperature of the grating, but this tuning range is limited by the temperature control capability and is generally small. For example, a temperature change of 30°C corresponds to a wavelength change range of 0.9nm. In order to achieve the tuning range of 9nm, the temperature control change needs to be 300°C, which cannot be realized by the commonly used TEC (semiconductor refrigeration) temperature control technology. At the same time, the grating will be broken in such a large wavelength change range.

For this reason, the present application designs a multi-channel fast selection and tunable single-frequency fiber laser and a tuning method, which can realize wavelength selection output and wide-range tuning.

Contents of the invention

In order to make up for the deficiencies in the prior art, the invention provides a multi-channel fast selection and tunable single-frequency fiber laser and a tuning method.

A multi-channel fast selection and tunable single-frequency fiber laser, including a 980nm pump, the output port of the 980nm pump is connected to the 980nm port of a WDM wavelength division multiplexer, and the COM common port of the WDM wavelength division multiplexer is connected to 1 The COM common port of the *N optical switch is connected, and each channel port of the 1*N optical switch is respectively connected with N different ITU channel Erbium-doped fiber phase-shift gratings, each Erbium-doped fiber phase-shift grating is packaged and controlled by TEC temperature The temperature of the unit is controlled to change the wavelength within a certain range. The 1550nm port of the WDM wavelength division multiplexer is connected to the isolator, the output of the isolator is connected to the input of the optical amplifier, and finally the laser is output from the output of the optical amplifier.

Further, in order to better realize the present invention, the 980nm pump is a single-mode semiconductor laser with a wavelength in the 980nm band; the WDM wavelength division multiplexer is a 980nm/1550nm wavelength division multiplexer; the isolator is 1550nm (generally a band, and its bandwidth needs to cover the wavelength range of N channels) isolator; the 1*N optical switch and the TEC temperature control unit are linked and controlled by the drive control unit; the erbium-doped fiber phase shift grating is in a A fiber grating with a π phase shift written on an erbium-doped fiber, and the phase shift position is at the center of the grating or slightly off the center.

Based on the above-mentioned multi-channel fast selection and tunable single-frequency fiber laser, the realization method of its multi-channel fast selection function is that the 980nm pump power is 300mW or 200mW, and the laser output by the erbium-doped fiber phase-shift grating is generally low At 1mW, the final output power of the optical amplifier reaches more than 10mW; the drive control unit controls the 1*N optical switch to have one and only one channel selected at a certain moment, and at this time the erbium-doped fiber phase-shift grating corresponding to the channel is pumped Excite and output a single-frequency laser corresponding to the wavelength of the channel.

Based on the above-mentioned multi-channel fast selection and tunable single-frequency fiber laser, the realization method of its wide-range tunable wavelength function is that the 1*N optical switch works in linkage with the TEC temperature control unit of the erbium-doped fiber phase-shift grating, The 1*N optical switch needs to connect to the next channel from one channel to the target channel in turn. The specific steps are as follows:

S1, when it is necessary to tune from the shortest wave to the longest wave, start from channel 1, connect to channel 2, channel 3, and then channel N;

S2, when the 1*N optical switch is located on a certain channel, the TEC temperature control unit of the erbium-doped fiber phase-shift grating controls its temperature from low to high, so that its wavelength moves from the lower boundary of the channel to the upper boundary;

S3, when the laser wavelength of the erbium-doped fiber phase-shift grating reaches the upper boundary of the channel, the 1*N optical switch connects to the next channel, and the TEC temperature control unit of the next channel’s erbium-doped fiber phase-shift grating also makes its wavelength Move from the lower boundary of the channel to the upper boundary;

S4, the remaining channels are similar, so that the wavelength of the entire laser system is shifted from short wavelength to long wavelength;

S5, if it is necessary to move from long-wave to short-wave, the 1*N optical switch is sequentially strobed downward, and the corresponding erbium-doped fiber phase-shift grating of each channel controls the temperature to move the wavelength from the upper boundary of the channel to the lower boundary .

Further, in order to better realize the present invention, the range between the upper boundary and the lower boundary of the channel is 0.8nm (corresponding to one ITU channel), and the temperature change rate of each channel is the same.

The beneficial effects of the present invention are:

The laser system of the present invention can work in two modes, one is a multi-channel fast selection mode, and the other is a continuous tuning mode with a wide range of wavelengths. Through the optical switch, wide-range wavelength tuning of N channels can be realized. At the same time, the N-channel grating multiplexes a set of pumping and optical path systems, which significantly reduces costs.

Description of drawings

Fig. 1 is the structural schematic diagram of existing single-frequency laser;

Fig. 2 is a structural schematic diagram of the present invention.

In the figure,

1. 980nm pump, 2. WDM wavelength division multiplexer, 3. 1*N optical switch, 4. Erbium-doped fiber phase shift grating, 5. TEC temperature control unit, 6. Isolator, 7. Optical amplifier, 8 , Drive control unit.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. The components of the embodiments of the invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "middle", "upper", "lower", "horizontal", "inner" and "outer" are based on those shown in the accompanying drawings. Orientation or positional relationship, or the orientation or positional relationship that the inventive product is usually placed in use, is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, so as to Specific orientation configurations and operations, therefore, are not to be construed as limitations on the invention. In addition, the terms "first", "second", etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that a component is absolutely level or overhanging, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and it does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "arrangement", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. connected, or integrally connected. It can be a mechanical connection or an electrical connection. It can be directly connected, or indirectly connected through an intermediary, and can be internally connected between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

Some embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. In the case of no conflict, the following embodiments and features in the embodiments can be combined with each other.

Fig. 2 is a specific embodiment of the present invention, which is a multi-channel fast selection and tunable single-frequency fiber laser. As shown in the figure, 980nm pump 1 generally refers to a single-mode semiconductor laser with a wavelength in the 980nm band (generally 970~980nm), WDM wavelength division multiplexer 2 refers to 980nm/1550nm wavelength division multiplexer, isolator 6 is 1550nm Isolator, the 980nm pump 1 optical output port is connected to the 980nm port of the WDM wavelength division multiplexer 2, the COM common terminal of the WDM wavelength division multiplexer 2 is connected to the COM common terminal of the 1*N optical switch 3, 1*N Each channel port of the optical switch 3 is connected to N erbium-doped fiber phase-shift gratings 4 with different ITU channels (wavelengths). Change the wavelength in a certain range (usually the temperature control range is 30°C, and the wavelength change range is ≧0.8nm, of which 0.8nm means 100GHz corresponds to an ITU channel interval). 1*N optical switches 3 and N TEC temperature control units 5 are controlled in linkage by the drive control unit 8 . The 1550nm port of the WDM wavelength division multiplexer 2 is connected to the input end of the 1550nm optical isolator, the output end of the isolator 6 is connected to the input end of the optical amplifier 7, and finally the laser is output from the output end of the optical amplifier 7. Wherein the erbium-doped fiber phase-shift grating 4 is a fiber grating with a π phase shift written on a section of erbium-doped fiber, and the phase shift position is at the center of the grating or a position slightly deviated from the center. The phase-shift grating is pumped at 980nm and excited It can output single-frequency narrow-linewidth laser.

For the realization of the multi-channel fast selection function, the drive control unit 8 controls the 1*N optical switch 3 to have and only one channel is selected at a certain moment. At this time, the erbium-doped fiber phase-shift grating 4 corresponding to the channel is pumped and excited, and the output A single-frequency laser corresponding to the wavelength of the channel. The power of the 980nm pump 1 used is 300mW or 200mW. The single-frequency laser output by the erbium-doped fiber phase-shift grating 4 is generally lower than 1mW, and the final output power of the optical amplifier 7 reaches more than 10mW. The laser system can realize the arbitrary output of the designed multi-channel wavelength, and at the same time, only one pump light source and one set of optical path system are used, which reduces the system cost.

For the realization of the wavelength tunable function in a large range, in this working state, the 1*N optical switch 3 needs to cooperate with the TEC temperature control unit 5 of the erbium-doped fiber phase-shift grating 4 and is controlled by the drive control unit 8 . The 1*N optical switch 3 needs to connect to the next channel sequentially from a certain channel until the target channel. For example, when it is necessary to tune from the shortest wave to the longest wave, start from channel 1 and connect to channel 2, channel 3, and channel N in sequence. At the same time, when the 1*N optical switch 3 is located on a certain channel, the TEC temperature control unit 5 of the erbium-doped fiber phase-shift grating 4 controls its temperature from low to high, so that its wavelength moves from the lower boundary of the channel to the upper boundary (the range is 0.8nm), when the laser wavelength of the erbium-doped fiber phase shift grating 4 reaches the upper boundary of the channel, the optical switch connects to the next channel. The TEC temperature control unit 5 of the erbium-doped fiber phase-shift grating 4 of the next channel also shifts its wavelength from the lower boundary to the upper boundary of the channel. The remaining channels are similar, allowing the wavelength of the entire laser system to be shifted from short to long wavelengths. If it is necessary to move from long-wave to short-wave, the optical switch is sequentially strobed downward, and the corresponding erbium-doped fiber phase-shift grating 4 of each channel controls the temperature so that its wavelength moves from the upper boundary of the channel to the lower boundary. The rate of temperature change should be the same for each channel.

To give a specific example: for an erbium-doped fiber, its emission spectrum range can effectively cover C10~C60 channels, that is, 1529.16nm~1570.01nm, and the number of channels N of the 1*N optical switch 3 can be 50 at most. In this example, it is a 1*10 optical switch. Channels 1 to 10 of the optical switch are respectively connected to 10 erbium-doped fiber phase shift gratings 4, that is, channel 1 is connected to λ1, channel 2 is connected to λ2, and so on, and channel 10 is connected to λ10. Among them, λ1 corresponds to ITU channel C30 (wavelength is 1553.33nm), λ2 corresponds to ITU channel C29 (wavelength is 1554.13nm), and λ10 corresponds to ITU channel C21 (wavelength is 1560.61nm). Erbium-doped fiber phase-shift grating 4 changes in the temperature range of 30 degrees, and the wavelength range is >0.8nm. When erbium-doped fiber phase-shift grating 4 is at 25 degrees, the corresponding wavelength corresponds to the ITU wavelength. When tuning, its wavelength can be controlled. The wavelength range is ITU wavelength ±0.4nm.

The tuning wavelength of the laser system is from 1552.93nm (C30-0.4nm) to 1561.01nm (C21+0.4nm), and the optical switch needs to be gated from channel 1 to channel 10 in sequence. Move the temperature of the grating 4 so that its wavelength moves from 1552.93nm (C30-0.4nm) to 1553.73nm (C30+0.4nm, or C29-0.4nm) at a certain speed (for example, 0.4nm/min), when the wavelength reaches At 1553.73nm, channel 1 is disconnected, the wavelength of λ1 remains unchanged, and channel 2 of the optical switch is selected. At this time, the temperature of the λ2 erbium-doped fiber phase shift grating is changed to change its wavelength from C29-0.4nm to C29+0.4nm. The speed of change is consistent with the previous channel. And so on, until the channel 10 of the optical switch is selected, and the laser wavelength of the λ10 erbium-doped fiber phase-shift grating is adjusted to C21+0.4nm. The whole process realizes the tuning of the wavelength of the laser system from 1552.93nm to 1561.41nm. The opposite direction controls the sequential gating of the optical switch and the temperature change direction of the erbium-doped fiber phase shift grating, that is, the wavelength change direction, and can realize the tuning from the long wavelength 1561.41nm to the short wavelength 1552.93nm.

When the number of channels of the optical switch increases, the number of erbium-doped fiber phase-shift gratings increases, and the corresponding wavelength expands accordingly, so that a wider range of wavelength tuning can be realized. In this laser system, there is only one pump and one set of optical path system, which reduces the system cost.

If the phase shift grating is written on other gain fibers, and the laser system replaces the corresponding pump, wavelength division multiplexer, isolator, amplifier and other components, it can achieve a certain range of wavelengths in other bands such as 1.0μm or 2.0μm. tuning.

In addition, the temperature control and temperature adjustment of the phase-shift grating resonator can adopt the TEC control scheme, or other temperature control schemes, as long as the scheme can change the temperature (can realize heating and cooling).

Finally, it is noted that the above embodiments are only used to illustrate the technical solution of the present invention without limitation, other modifications or equivalent replacements made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and spirit of the technical solution of the present invention All should be included in the scope of the claims of the present invention.

Claims (5)

1. A multichannel fast selection and tunable single-frequency fiber laser comprises a 980nm pump (1), and is characterized in that:

the output port of the 980nm pump (1) is connected with a 980nm port of the WDM (wavelength division multiplexer) (2), a COM common port of the WDM (2) is connected with a COM common port of a 1*N optical switch (3), wherein each channel port of the optical switch with the N being more than or equal to 2,1 × N is respectively connected with erbium-doped fiber phase-shift gratings (4) of N different ITU channels, each erbium-doped fiber phase-shift grating (4) is packaged and subjected to temperature control through a TEC temperature control unit (5) to change the wavelength within a certain range, the 1550nm port of the WDM (2) is connected with an isolator (6), the output end of the isolator (6) is connected with the input end of an optical amplifier (7), and finally laser is output from the output end of the optical amplifier (7).

2. The multi-channel fast selection and tunable single-frequency fiber laser of claim 1, wherein:

the 980nm pump (1) is a single-mode semiconductor laser with the wavelength of 980nm wave band;

the WDM wavelength division multiplexer (2) is a 980nm/1550nm wavelength division multiplexer;

the isolator (6) is a 1550nm isolator;

the 1*N optical switch (3) and the TEC temperature control unit (5) are controlled in a linkage mode through a driving control unit (8);

the erbium-doped fiber phase shift grating (4) is a fiber grating with pi phase shift, which is inscribed on a section of erbium-doped fiber, and the phase shift is arranged at the center of the grating or slightly deviated from the center.

3. A method for implementing a multi-channel fast selection function based on the multi-channel fast selection and tunable single-frequency fiber laser of any one of claims 1-2, characterized in that:

the laser output by the erbium-doped fiber phase shift grating (4) is generally lower than 1mW, and the final output power of the laser through the optical amplifier (7) is more than 10 mW;

the drive control unit (8) controls the 1*N optical switch (3) to gate only one channel at a certain moment, and at the moment, the erbium-doped fiber phase shift grating (4) of the corresponding channel is pumped and excited to output single-frequency laser with the wavelength of the corresponding channel.

4. A method for implementing a wavelength wide-range tunable function of a multichannel fast selection and tunable single-frequency fiber laser based on any one of claims 1 to 2, characterized in that:

the 1*N optical switch (3) and the TEC temperature control unit (5) of the erbium-doped fiber phase shift grating (4) work in a linkage and matching mode, the 1*N optical switch (3) needs to sequentially communicate with the next channel from a certain channel to a target channel, and the method comprises the following specific steps:

s1, when tuning from the shortest wave direction to the longest wave direction is required, sequentially communicating a channel 2, a channel 3 and a channel N from the channel 1;

s2, when the 1*N optical switch (3) is positioned on a certain channel, the TEC temperature control unit (5) of the erbium-doped fiber phase shift grating (4) controls the temperature of the optical switch from low to high, so that the wavelength of the optical switch moves from the lower boundary to the upper boundary of the channel;

s3, when the laser wavelength of the erbium-doped fiber phase-shift grating (4) reaches the upper boundary of the channel, the 1*N optical switch (3) is communicated with the next channel, and the TEC temperature control unit (5) of the erbium-doped fiber phase-shift grating (4) of the next channel also enables the wavelength of the erbium-doped fiber phase-shift grating to be shifted from the lower boundary of the channel to the upper boundary;

s4, the residual channels are similar, so that the wavelength of the whole laser system is shifted from short wave to long wave;

s5, if the long wave needs to be shifted to the short wave, the 1*N optical switches (3) are downwards gated in sequence, and the corresponding erbium-doped fiber phase shift grating (4) of each channel controls the temperature to enable the wavelength of the erbium-doped fiber phase shift grating to be shifted from the upper boundary to the lower boundary of the channel.

5. The method for realizing the wavelength large-range tunable function of the multi-channel fast selection and tunable single-frequency fiber laser as claimed in claim 4, is characterized in that:

the range of the upper boundary and the lower boundary of the channel is 0.8nm, and the temperature change rate of each channel is the same.

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