External cavity laser and temperature control method

Abstract

The application provides an external cavity laser and a temperature control method, and relates to the technical field of lasers; the optical filtering feedback module and the laser chip of the external cavity laser are arranged in a packaging shell; the optical filtering feedback module is used for mode selection of an emission light signal emitted by the laser chip so that the laser chip performs mode locking on a feedback light signal output; a temperature controller controls a temperature adjusting unit to adjust the temperature in the packaging shell according to a monitoring result of a first temperature monitoring device on the temperature in the packaging shell; the temperature controller controls the temperature adjusting unit to adjust the temperature of the optical filtering feedback module according to a monitoring result of a second temperature monitoring device on the optical filtering feedback module, so that the temperature in the packaging shell and the temperature of the optical filtering feedback module both meet preset requirements and the device temperature difference of the optical filtering feedback module meets an expected temperature difference. The embodiment of the application can output more stable laser power and wavelength when the temperature difference between the inside and outside of the packaging shell is large.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of laser technology, and particularly to an external cavity laser and a temperature control method. Background Technology

[0002] External cavity lasers (ECLs) are widely used in lidar, spectral analysis, interferometric detection, frequency generation, coherent combining, high-precision satellite communication, atomic clock pumping, atmospheric absorption measurement, and fiber optic sensing due to their resistance to external environmental interference, small size, light weight, high conversion efficiency, and wide spectral range covering ITU channels. In practical applications, to ensure that the ECL provides a stable and high-quality narrow-linewidth beam, a temperature control system is often installed inside the package of the optical components. This temperature system includes a temperature adjustment unit and a temperature monitoring device. In related technologies, the temperature adjustment unit is typically located at the bottom of the optical component, and a temperature monitoring device is placed near the laser chip within the optical component to monitor temperature changes inside the package. However, when there is a large temperature difference between the inside and outside of the package, the stability of the beam quality emitted from the package is poor when the temperature adjustment unit is controlled based on the monitoring results of the temperature monitoring device. The wavelength and power are unstable. Therefore, there is an urgent need for an ECL that can output laser power and wavelength with greater stability even when there is a large temperature difference between the inside and outside of the package. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims. Embodiments of this application provide an external cavity laser and a temperature control method that, when there is a large temperature difference between the inside and outside of the package, results in more stable power and wavelength of the output laser.

[0004] In a first aspect, the external cavity laser according to the embodiments of this application includes:

[0005] Encapsulation shell;

[0006] Laser chip;

[0007] An optical filtering feedback module is provided, and the laser chip is disposed within the package housing. The optical filtering feedback module is used to perform mode selection on the emitted light signal emitted by the laser chip and output a feedback light signal so that the laser chip can perform mode locking on the feedback light signal.

[0008] A temperature control module includes a first temperature monitoring device, a second temperature monitoring device, a temperature controller, and a temperature adjustment unit. The first temperature monitoring device is positioned close to the laser chip. The first temperature monitoring device monitors the temperature inside the packaging shell, and the second temperature monitoring device monitors the temperature of the optical filter feedback module. The temperature controller is connected to both the first and second temperature monitoring devices. The temperature controller controls the temperature adjustment unit to adjust the temperature inside the packaging shell based on the monitoring results of the first temperature monitoring device, and also controls the temperature adjustment unit to adjust the temperature of the optical filter feedback module based on the monitoring results of the second temperature monitoring device, so that the temperature inside the packaging shell and the temperature of the optical filter feedback module both meet preset requirements, and the device temperature difference of the optical filter feedback module meets the desired temperature difference.

[0009] Secondly, according to the temperature control method for an external cavity laser proposed in the embodiments of this application, the external cavity laser includes a package shell, a laser chip, an optical filter feedback module, and a temperature control module. The optical filter feedback module and the laser chip are both disposed within the package shell. The optical filter feedback module is used to perform mode selection on the emitted light signal from the laser chip and output a feedback light signal, so that the laser chip performs mode locking on the feedback light signal. The temperature control module includes a first temperature monitoring device, a second temperature monitoring device, and a temperature adjustment unit. The first temperature monitoring device is disposed close to the laser chip. The method includes:

[0010] Based on the monitoring results of the first temperature monitoring device, the temperature adjustment unit is controlled to adjust the temperature inside the packaging shell so that the temperature inside the packaging shell meets the preset requirements.

[0011] Based on the monitoring results of the second temperature monitoring device, the temperature adjustment unit is controlled to adjust the temperature of the optical filter feedback module so that the temperature of the optical filter feedback module meets the preset requirements and the device temperature difference of the optical filter feedback module meets the desired temperature difference.

[0012] Therefore, the above embodiments of this application have at least the following beneficial effects: by adding a second temperature monitoring device to monitor the temperature of the optical filter feedback module in real time, and by using a temperature adjustment unit to control the laser chip and the optical filter feedback module separately. When the temperature inside the packaged shell monitored by the first temperature monitoring device meets the preset requirements, the optical signal output by the laser chip is stable. At the same time, when the temperature of the optical filter feedback module monitored by the second temperature monitoring device meets the preset requirements, that is, when the temperature difference between the external ambient temperature and the temperature inside the packaged shell is large, the temperature difference of the entire device of the optical filter feedback module is also kept within a constant value. At this time, the feedback optical signal output by the optical filter feedback module is relatively stable. Therefore, by using the first temperature monitoring device, the second temperature monitoring device, the temperature controller, and the temperature adjustment unit, the optical signal output by the external cavity laser inside the packaged shell is stable. Therefore, compared with related technologies, the power and wavelength of the laser output by the external cavity laser in the embodiments of this application are more stable when the temperature difference between the inside and outside of the packaged shell is large. Attached Figure Description

[0013] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0014] Figure 1 This is a schematic diagram of the structure of an external cavity laser in the prior art;

[0015] Figure 2 This is a schematic diagram of the temperature of each region of the optical filtering feedback module of an external cavity laser in the prior art under the simulated state when the external temperature is -40 degrees Celsius.

[0016] Figure 3 This is a schematic diagram of the external cavity laser according to an embodiment of this application;

[0017] Figure 4 This is a schematic diagram showing the connection between the optical filtering feedback module and the second temperature monitoring device in an embodiment of this application;

[0018] Figure 5 This is a schematic diagram showing the connection between the optical filter feedback module and the second temperature monitoring device according to another embodiment of this application;

[0019] Figure 6 This is a schematic flowchart of the temperature control method according to an embodiment of this application.

[0020] Figure label:

[0021] Encapsulation housing 100

[0022] Laser chip 200

[0023] Optical filter feedback module 300

[0024] First temperature monitoring device 410, second temperature monitoring device 420, temperature adjustment unit 430

[0025] Collimating optical device 510, substrate 520, collimator 530,

[0026] First conductive adhesive heat dissipation layer 610, metal temperature shielding shell 620, and second conductive adhesive heat dissipation layer 630. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application. The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0029] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0030] External cavity lasers, with their characteristics of resistance to external environmental interference, small size, light weight, high conversion efficiency, and wide spectral range covering ITU channels, are widely used in lidar, spectral analysis, interferometric detection, frequency generation, coherent combining, high-precision satellite communication, atomic clock pumping, atmospheric absorption measurement, and fiber optic sensing. In practical applications, to ensure that the external cavity laser can provide a stable and high-quality narrow linewidth beam, a temperature control system is often installed within the package 100 of the encapsulated optical components. See also... Figure 1The schematic diagram shows that the external cavity laser includes a laser chip 200, an optical filter feedback module 300, and other optical components, as well as a package shell 100. The temperature control system includes a thermoelectric cooler (TEC) and a temperature monitoring device. The laser chip 200 and the optical filter feedback module 300 are the main heat sources, thus affecting the stability of the output laser power and wavelength. Therefore, the thermoelectric cooler, as a temperature adjustment unit 430, is usually located at the bottom of the laser chip 200 and the optical filter feedback module 300. The temperature monitoring device is located around the laser chip 200. In this case, the temperature monitoring device can monitor the bottom temperature of the laser chip 200 and the optical filter feedback module 300. However, due to the large temperature difference between the inside and outside of the package shell 100, the bottom temperature cannot accurately reflect the influence of the ambient temperature during the operation of the external cavity filter. Therefore, based on temperature adjustment using this temperature monitoring device, the beam emitted from the package shell 100 is unstable and of low quality. Therefore, there is an urgent need for an external cavity laser that can output laser power and wavelength with greater stability when the temperature difference between the inside and outside of the package shell 100 is large.

[0031] It should be noted that in practical applications, with Figure 1 Taking an external cavity laser as an example, when the desired operating temperature of the external cavity laser is 25℃, due to differences in the working environment, the external cavity laser may operate at temperatures ranging from -45℃ to 85℃. Although the temperature monitored by the temperature monitoring device can be controlled at around 25℃, actual verification revealed that the temperature distribution on the top and bottom surfaces and surrounding areas of the optical filter feedback module 300 is not uniform, resulting in device temperature differences. The greater the temperature difference between the inside and outside of the packaging shell 100, such as at -45℃ or 85℃, the greater the device temperature difference becomes (e.g., ...). Figure 2 As shown in the simulation at -40℃, the temperature variation at various points of the same optical filter feedback module 300 is large and the temperature difference with the laser chip 200 is significant. At this temperature, the optical filter feedback module 300 experiences wavelength drift due to the temperature difference, resulting in unstable power and wavelength of the laser output from the external cavity laser. When the temperature difference is small, the power and wavelength of the output laser are relatively stable. Based on this, this application proposes an external cavity laser and its control method, which can achieve more stable power and wavelength of the output laser when the temperature difference between the inside and outside of the packaging shell 100 is large.

[0032] It should be noted that the device temperature difference refers to the temperature of different surfaces of the same optical device.

[0033] Reference Figures 3 to 5 As shown, the external cavity laser includes:

[0034] Encapsulation housing 100;

[0035] Laser chip 200;

[0036] The optical filtering feedback module 300 and the laser chip 200 are both disposed inside the package housing 100. The optical filtering feedback module 300 is used to perform mode selection on the emitted light signal emitted by the laser chip 200 and output a feedback light signal so that the laser chip 200 performs mode locking on the feedback light signal.

[0037] The temperature control module includes a first temperature monitoring device 410, a second temperature monitoring device 420, a temperature controller, and a temperature adjustment unit 430. The first temperature monitoring device 410 is positioned close to the laser chip 200. The first temperature monitoring device 410 monitors the temperature inside the packaging shell 100, and the second temperature monitoring device 420 monitors the temperature of the optical filter feedback module 300. The temperature controller is connected to the first temperature monitoring device 410 and the second temperature monitoring device 420. The temperature controller controls the temperature adjustment unit 430 to adjust the temperature inside the packaging shell 100 based on the monitoring results of the first temperature monitoring device 410, and also controls the temperature adjustment unit 430 to adjust the temperature of the optical filter feedback module 300 based on the monitoring results of the second temperature monitoring device 420, so that the temperature inside the packaging shell 100 and the temperature of the optical filter feedback module 300 both meet preset requirements, and the device temperature difference of the optical filter feedback module 300 meets the desired temperature difference.

[0038] Therefore, a second temperature monitoring device 420 is added to monitor the temperature of the optical filter feedback module 300 in real time, and the laser chip 200 and the optical filter feedback module 300 are controlled separately by the temperature adjustment unit 430. When the temperature inside the packaging shell 100 monitored by the first temperature monitoring device 410 meets the preset requirements, the optical signal output by the laser chip 200 is stable. Meanwhile, when the temperature of the optical filter feedback module 300 monitored by the second temperature monitoring device 420 meets the preset requirements, that is, when the temperature difference between the external ambient temperature and the temperature inside the package shell 100 is large, the temperature difference of the entire device of the optical filter feedback module 300 is also kept within a constant value. At this time, the feedback optical signal output by the optical filter feedback module 300 is relatively stable. Therefore, the optical signal output by the external cavity laser inside the package shell 100 is stable through the first temperature monitoring device 410, the second temperature monitoring device 420, the temperature controller, and the temperature adjustment unit 430. Therefore, compared with related technologies, the power and wavelength of the laser output by the external cavity laser in this embodiment are more stable when the temperature difference between the inside and outside of the package shell 100 is large.

[0039] It should be noted that in some embodiments, the optical filter feedback module 300 is configured as an optical filter feedback mirror, which is implemented using a grating (VBG VPG), etalon scheme, or thin-film optical filter feedback scheme to meet the technical requirements of the free space scheme for ultra-narrow linewidth lasers.

[0040] It should be noted that this application enables frequency stabilization control of ultra-narrow linewidth lasers in the field of semiconductor laser sensing technology. In related technologies, for industrial applications, ultra-narrow linewidth lasers are used in environments with wide temperature variations (-45℃ to 85℃), therefore improving the temperature stability of the laser's operating wavelength is crucial. Taking the optical filter feedback module 300 as an example, by setting a second temperature monitoring device 420 on the optical filter feedback mirror (such as a grating, etalon, or thin-film filter) to directly monitor the temperature of the optical filter feedback mirror, wavelength drift and power fluctuations in the feedback light signal output by the optical filter feedback module within the package housing 100 can be reduced, thereby ensuring high accuracy of the wavelength of the light signal ultimately output from the laser chip 200 to the package housing 100.

[0041] It should be noted that in some embodiments, the laser chip 200 can be configured as a gain laser chip.

[0042] For example, taking the optical filter feedback module 300 as an example of an optical filter feedback mirror, refer to... Figure 2 As shown, optical components such as the optical filter feedback module 300 and the laser chip 200 are all mounted on the substrate 520, and the temperature adjustment unit 430 is located below the substrate 520. The implementation principle of this embodiment is as follows:

[0043] The original light signal emitted by the laser chip 200 is collimated into parallel light by the collimating optics 510, enters the alignment optical filter feedback mirror, and is reflected back to excite the laser chip, thus oscillating back and forth to form a laser beam and outputting a corresponding signal. At this time, the wavelength of the original light signal emitted by the laser chip 200 is selected by the adjustment of the optical filter feedback mirror, and is thus selected and fed back to the laser chip 200. At this time, the laser chip 200 and the optical filter feedback mirror realize the oscillation and wave-locking of the laser array external cavity, and finally realize the output of the narrow linewidth beam through the collimator 530 to the outside of the package shell 100. During the beam generation and output process, the first temperature monitoring device 410, the second temperature monitoring device 420, the temperature adjustment unit 430, and the temperature controller can greatly ensure that the temperature on the path of the light signal transmission is kept as close as possible to the target temperature, thereby greatly improving the quality and stability of the output beam.

[0044] Understandably, the optical filter feedback module 300 is provided with a first conductive adhesive heat dissipation layer 610, and the second temperature monitoring device 420 is disposed on the first conductive adhesive heat dissipation layer 610. The second temperature monitoring device 420 is electrically connected to the temperature controller through the first conductive adhesive heat dissipation layer 610.

[0045] It should be noted that the first conductive adhesive heat dissipation layer 610 has a heat dissipation function, which can increase the temperature control and heat dissipation of the optical filter feedback module 300, thereby stabilizing the temperature inside the package shell 100 and further reducing the possibility of wavelength drift and power fluctuation inside the package shell 100, thus ensuring high wavelength accuracy.

[0046] Understandably, the external cavity laser also includes a metal temperature shield 620, which covers the optical filter feedback module 300. The second temperature monitoring device 420 is mounted on the metal temperature shield 620 and is electrically connected to the temperature controller through the metal temperature shield 620.

[0047] It should be noted that the metal temperature shield 620 can isolate some of the heat from the optical filter feedback module 300, thereby ensuring the temperature stability of the optical filter feedback module 300.

[0048] Understandably, a second conductive adhesive heat dissipation layer 630 is provided on the metal temperature shield 620, and a second temperature monitoring device 420 is provided on the second conductive adhesive heat dissipation layer 630; the second temperature monitoring device 420 is electrically connected to the temperature controller through the second conductive adhesive heat dissipation layer 630 and the metal temperature shield 620.

[0049] It should be noted that the second conductive adhesive heat dissipation layer 630 has a heat dissipation function. By setting the second conductive heat dissipation layer on the metal temperature shield 620, the temperature control and heat dissipation of the optical filter feedback module 300 can be increased, thereby stabilizing the temperature inside the package 100 and further reducing the possibility of wavelength drift and power fluctuation inside the package 100, thereby ensuring high wavelength accuracy.

[0050] It should be noted that both the first conductive adhesive heat dissipation layer 610 and the second conductive adhesive heat dissipation layer 630 can be silver paste coatings. For example, silver powder and adhesive are uniformly mixed to form silver paste, which is then applied to the surface of the optical filter feedback module 300 to provide conductivity and auxiliary heat dissipation. This forms a silver paste coating on the surface of the optical filter feedback module 300, allowing the second temperature monitoring device 420 to be adhered to for feedback temperature control. Because silver paste has adhesive and good thermal conductivity, it provides better conductivity for the second temperature monitoring device 420. When the second temperature monitoring device 420 is set as a thermistor, the silver paste coating enables the thermistor to provide better feedback, resulting in better temperature control.

[0051] It should be noted that in some embodiments, the silver coating may also be a coating containing copper powder.

[0052] It should be noted that, in some embodiments, the metal temperature shield 620 may be made of materials such as copper or aluminum to make it conductive.

[0053] Understandably, the temperature adjustment unit 430 includes a first semiconductor cooler and a second semiconductor cooler. The first semiconductor cooler is used to adjust the temperature inside the package housing 100 according to the monitoring results of the first temperature monitoring device 410, and the second semiconductor cooler is used to adjust the temperature of the optical filter feedback module 300 according to the monitoring results of the second temperature monitoring device 420.

[0054] It should be noted that both the first and second semiconductor coolers can be used for cooling or heating. The first semiconductor cooler can be located on the left, right, front, or rear side of the bottom of the laser chip 200. The second semiconductor cooler can be located on the left, right, front, or rear side of the bottom of the optical feedback module. This application does not impose many restrictions on the relative bottom positions of the first and second semiconductor coolers.

[0055] Understandably, the second temperature monitoring device 420 is located in the middle area of ​​the top of the optical filter feedback module 300 or on the side of the optical filter feedback module 300.

[0056] It should be noted that when a metal temperature shield 620 is provided, the volume of the metal temperature shield 620 matches that of the optical filter feedback module 300. Therefore, the second temperature monitoring device 420 is located in the middle area of ​​the top of the metal temperature shield 620 or on the side of the metal temperature shield 620.

[0057] It should be noted that when the temperature is set in the middle of the top area, since this position is far from the packaging shell 100 of the temperature adjustment unit 430, the temperature determined by its monitoring is more accurate in reflecting the temperature of the optical filter feedback module 300. The side of the optical filter feedback module 300 refers to the surfaces other than the top and bottom. When set on the side of the optical filter feedback module 300, the first temperature of the optical filter feedback module 300 determined by the second temperature monitoring device 420 is more accurate than the second temperature determined by the first temperature monitoring device 410. Therefore, when adjusting the temperature based on this position, the temperature difference of the optical filter feedback module 300 can be reduced, thereby improving the stability of the feedback light signal output by the optical filter feedback module 300.

[0058] Understandably, both the first temperature monitoring device 410 and the second temperature monitoring device 420 are configured as thermistors.

[0059] Understandably, the first temperature monitoring device 410 is configured as a single thermistor, and the second temperature monitoring device 420 is configured as a dual thermistor.

[0060] It should be noted that thermistors are more sensitive to temperature changes, which allows for better adjustment.

[0061] It should be noted that the dual thermistors have two temperature monitoring points. Therefore, the temperature obtained from these two monitoring points can more accurately reflect the temperature difference of the devices other than the optical filter feedback module 300. Thus, precise temperature control can be achieved based on this temperature, thereby improving the quality of the output beam.

[0062] Understandably, referring to Figure 6 As shown, according to the temperature control method for an external cavity laser provided in this application embodiment, the external cavity laser includes a package shell 100, a laser chip 200, an optical filter feedback module 300, and a temperature control module. The optical filter feedback module 300 and the laser chip 200 are both disposed within the package shell 100. The optical filter feedback module 300 is used to perform mode selection on the emitted light signal from the laser chip 200 and output a feedback light signal, so that the laser chip 200 performs mode locking on the feedback light signal. The temperature control module includes a first temperature monitoring device 410, a second temperature monitoring device 420, and a temperature adjustment unit 430. The first temperature monitoring device 410 is disposed close to the laser chip 200. The method includes:

[0063] Step S100: Based on the monitoring results of the first temperature monitoring device 410, control the temperature adjustment unit 430 to adjust the temperature inside the packaging shell 100 so that the temperature inside the packaging shell 100 meets the preset requirements.

[0064] Step S200: Based on the monitoring results of the second temperature monitoring device 420, control the temperature adjustment unit 430 to adjust the temperature of the optical filter feedback module 300 so that the temperature of the optical filter feedback module 300 meets the preset requirements and the device temperature difference of the optical filter feedback module 300 meets the expected temperature difference.

[0065] It should be noted that the temperature adjustment is a constant decrease and a constant increase, so that the temperature inside the package 100 will not change abruptly, thereby improving the stability of the output laser power and wavelength.

[0066] Understandably, step S200, which controls the temperature adjustment unit 430 to adjust the temperature of the optical filter feedback module 300 based on the monitoring results of the second temperature monitoring device 420, includes:

[0067] Obtain the target temperature;

[0068] In each control cycle, the monitoring results of the second temperature monitoring device 420 are acquired in real time to determine the first temperature;

[0069] Based on the first temperature and the target temperature, the temperature adjustment unit 430 is controlled to perform temperature control by a first increment or a first decrement.

[0070] When the difference between the first temperature and the target temperature within the current control cycle is within a preset threshold, the temperature adjustment unit 430 continuously fine-tunes to keep the difference stable within the preset threshold.

[0071] It should be noted that when the second temperature monitoring device 420 is set as a dual-sensitive resistor, it will determine the first temperature of the optical filter feedback module 300 based on the two temperature monitoring points, and then make adjustments based on the first temperature. The temperature adjustment of the first temperature monitoring device 410 can be kept constant with reference to the first temperature.

[0072] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An external cavity laser, characterized in that, include: Encapsulation shell; Laser chip; An optical filtering feedback module is provided, and the laser chip is disposed within the package housing. The optical filtering feedback module is used to perform mode selection on the emitted light signal emitted by the laser chip and output a feedback light signal so that the laser chip can perform mode locking on the feedback light signal. A temperature control module includes a first temperature monitoring device, a second temperature monitoring device, a temperature controller, and a temperature adjustment unit. The first temperature monitoring device is positioned close to the laser chip. The first temperature monitoring device monitors the temperature inside the packaging shell, and the second temperature monitoring device monitors the temperature of the optical filter feedback module. The temperature controller is connected to both the first and second temperature monitoring devices. The temperature controller controls the temperature adjustment unit to adjust the temperature inside the packaging shell based on the monitoring results of the first temperature monitoring device, and also controls the temperature adjustment unit to adjust the temperature of the optical filter feedback module based on the monitoring results of the second temperature monitoring device. This ensures that both the temperature inside the packaging shell and the temperature of the optical filter feedback module meet preset requirements, and that the device temperature difference of the optical filter feedback module meets a desired temperature difference. The device temperature difference characterizes the magnitude of temperature change on different surfaces of the optical filter feedback module. A metal temperature shielding shell is provided, which covers the optical filter feedback module. A second temperature monitoring device is disposed on the metal temperature shielding shell and is electrically connected to the temperature controller through the metal temperature shielding shell. The second temperature monitoring device is configured as a dual thermistor.

2. The external cavity laser according to claim 1, characterized in that, The optical filter feedback module is provided with a first conductive adhesive heat dissipation layer, and the second temperature monitoring device is disposed on the first conductive adhesive heat dissipation layer. The second temperature monitoring device is electrically connected to the temperature controller through the first conductive adhesive heat dissipation layer.

3. The external cavity laser according to claim 1, characterized in that, A second conductive adhesive heat dissipation layer is provided on the metal temperature shielding shell, and the second temperature monitoring device is disposed on the second conductive adhesive heat dissipation layer; the second temperature monitoring device is electrically connected to the temperature controller through the second conductive adhesive heat dissipation layer and the metal temperature shielding shell.

4. The external cavity laser according to claim 1, characterized in that, The temperature adjustment unit includes a first semiconductor cooler and a second semiconductor cooler. The first semiconductor cooler is used to adjust the temperature inside the package shell according to the monitoring results of the first temperature monitoring device, and the second semiconductor cooler is used to adjust the temperature of the optical filter feedback module according to the monitoring results of the second temperature monitoring device.

5. The external cavity laser according to claim 4, characterized in that, The second temperature monitoring device is located in the middle area of ​​the top of the optical filter feedback module or on the side of the optical filter feedback module.

6. The external cavity laser according to claim 1, characterized in that, Both the first temperature monitoring device and the second temperature monitoring device are configured as thermistors.

7. The external cavity laser according to claim 1, characterized in that, The first temperature monitoring device is configured as a single thermistor.

8. A temperature control method for an external cavity laser, characterized in that, The external cavity laser includes a package shell, a laser chip, an optical filtering feedback module, a temperature control module, and a metal temperature shield. The optical filtering feedback module and the laser chip are both housed within the package shell. The optical filtering feedback module performs mode selection on the emitted light signal from the laser chip and outputs a feedback light signal, enabling the laser chip to perform mode locking on the feedback light signal. The temperature control module includes a first temperature monitoring device, a second temperature monitoring device, and a temperature adjustment unit. The first temperature monitoring device is positioned close to the laser chip. The metal temperature shield covers the optical filtering feedback module, and the second temperature monitoring device is mounted on the metal temperature shield. The second temperature monitoring device is configured as a dual thermistor. The method includes: Based on the monitoring results of the first temperature monitoring device, the temperature adjustment unit is controlled to adjust the temperature inside the packaging shell so that the temperature inside the packaging shell meets the preset requirements. Based on the monitoring results of the second temperature monitoring device, the temperature adjustment unit is controlled to adjust the temperature of the optical filter feedback module so that the temperature of the optical filter feedback module meets the preset requirements and the device temperature difference of the optical filter feedback module meets the expected temperature difference. The device temperature difference characterizes the magnitude of temperature change on different surfaces of the optical filter feedback module device.

9. The temperature control method for an external cavity laser according to claim 8, characterized in that, The step of controlling the temperature adjustment unit to adjust the temperature of the optical filter feedback module based on the monitoring results of the second temperature monitoring device includes: Obtain the target temperature; In each control cycle, the monitoring results of the second temperature monitoring device are acquired in real time to determine the first temperature; Based on the first temperature and the target temperature, the temperature adjustment unit is controlled to perform temperature control with a first increment or a first decrement. When the difference between the first temperature and the target temperature is within a preset threshold during the current control cycle, the temperature adjustment unit is controlled to continuously fine-tune so that the difference is stabilized within the preset threshold.

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