Method for improving drifting of narrow-linewidth laser and narrow-linewidth laser assembly

Abstract

The invention relates to a method for improving drifting of a narrow-linewidth laser and a narrow-linewidth laser component, the narrow-linewidth laser component comprises the narrow-linewidth laser and a narrow-linewidth laser controller, and a gain chip component, a collimating lens, an etalon, an optical filter, a spectroscope and an isolator are packaged in a narrow-linewidth laser shell. An equivalent cavity length compensator is coupled between the gain chip assembly and the spectroscope; the narrow-linewidth laser controller comprises an environment temperature detection module and an equivalent cavity length compensator control module which is used for applying external voltage to the equivalent cavity length compensator to change the refractive index of the equivalent cavity length compensator; the narrow linewidth laser controller is internally provided with a table which records compensation voltages which should be applied to the equivalent cavity length compensator at different environment temperatures, so that the narrow linewidth laser controller can retrieve the compensation voltages at the corresponding environment temperatures in the table according to environment temperature values collected by the environment temperature detection module, and the compensation voltages can be applied to the equivalent cavity length compensator. And the equivalent cavity length compensator controller is controlled to send a corresponding voltage signal.

Description

Technical Field

[0001] The invention relates to a narrow-linewidth laser, belonging to the technical field of optical communications, and specifically provides a method for improving drift of a narrow-linewidth laser and a narrow-linewidth laser component. Background Art

[0002] A narrow-linewidth laser is a laser with an extremely narrow spectral linewidth of its output laser. It is highly monochromatic, with a linewidth typically as low as kilohertz (kHz) or even hertz (Hz), far superior to the megahertz (MHz) linewidth of ordinary lasers. It is widely used in laser communications, precision sensing, and other fields. High- and low-temperature mode drift of narrow-linewidth lasers refers to the phenomenon in which the output laser mode shifts compared to room temperature when the laser is exposed to high or low temperatures. This manifests as a shift in the center wavelength and tuning range, especially when the starting and ending points of the tuning range deviate at high and low temperatures. This affects the wavelength control accuracy, leading to a significant increase in the communication bit error rate and a significant decrease in sensing accuracy in high and low temperature environments.

[0003] The existing solution is called the three-temperature calibration method, which involves pre-calibrating the laser wavelength, laser current, TEC temperature, and other parameters at different ambient temperatures, storing them in a table, and then looking up the table for control during actual use. This method can temporarily solve the high and low temperature problem, but it requires temperature compensation in the driver circuit, which often leads to mode instability. At the same time, as aging and other problems such as driver circuit drift emerge, performance degradation is significant, posing a high challenge for products with long life cycles. Because the traditional three-temperature calibration method relies too much on calibration and direct temperature compensation, when the product environment undergoes significant changes, the calibration fails and the product is discarded, which is unacceptable. A method has been proposed to improve high and low temperature mode drift by adding negative thermo-optical coefficient materials, passively compensating by selecting suitable materials. However, in reality, the materials are packaged on the TEC, and the introduction of materials with thermo-optical effects will inevitably introduce additional heat into the laser. Using this method places extremely high demands on the packaging design and packaging process.

[0004] In response to this problem, we analyzed the root cause and found that the main reason for the problem was that the ambient temperature caused the change in the equivalent cavity length of the laser. The method to avoid temperature drift can also be started from controlling the equivalent cavity length of the laser. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the drift of a narrow-linewidth laser and a narrow-linewidth laser component, so that an equivalent cavity length compensator is added to the cavity of the laser and an electrical signal is applied to the equivalent cavity length compensator to control the refractive index of the equivalent cavity length compensator, thereby achieving the purpose of laser equivalent cavity length compensation.

[0006] The objectives of the present invention and the technical problems solved therein are achieved by adopting the following technical solutions. According to the present invention, a laser assembly for improving the drift of a narrow-linewidth laser comprises a narrow-linewidth laser and a narrow-linewidth laser controller, wherein a gain chip assembly 2, a collimating lens 3, an etalon 4, a filter 5, a beam splitter 7, and an isolator 8 are encapsulated in the narrow-linewidth laser housing in order from left to right, and an equivalent cavity length compensator 6 is coupled between the gain chip assembly 2 and the beam splitter 7; the narrow-linewidth laser controller comprises an ambient temperature detection module for collecting ambient temperature information and an equivalent cavity length compensator control module for applying an external voltage to the equivalent cavity length compensator to change its refractive index; the narrow-linewidth laser controller comprises a table recording compensation voltages to be applied to the equivalent cavity length compensator under different ambient temperatures, so that the narrow-linewidth laser controller can retrieve the compensation voltage corresponding to the ambient temperature in the table according to the ambient temperature value collected by the ambient temperature detection module, and control the equivalent cavity length compensator controller to send a corresponding voltage signal.

[0007] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0008] The aforementioned laser assembly for improving the drift of a narrow-linewidth laser further comprises a thermoelectric cooler within the narrow-linewidth laser housing. The thermoelectric cooler is attached to the bottom of the narrow-linewidth laser housing, and the gain chip assembly 2, collimating lens 3, etalon 4, filter 5, equivalent cavity length compensator 6, beam splitter 7, and isolator 8 are arranged on the thermoelectric cooler via a ceramic substrate.

[0009] In the aforementioned laser assembly for improving narrow linewidth laser drift, the narrow linewidth laser housing is further provided with a backlight detector 1 , which is located on the left side of the gain chip assembly 2 .

[0010] The aforementioned laser assembly for improving narrow linewidth laser drift, the narrow linewidth laser controller also includes a TEC temperature control module, a gain chip current control module and a backlight current detection module. The table of the narrow linewidth laser controller also records the TEC temperature, backlight current and gain chip current values ​​under corresponding ambient temperature and compensation voltage.

[0011] In the aforementioned laser assembly for improving drift of a narrow-linewidth laser, the narrow-linewidth laser controller is fixed outside the narrow-linewidth laser housing.

[0012] The purpose of the present invention and the solution to its technical problems are also achieved by adopting the following technical solutions. According to a method for improving the drift of a narrow linewidth laser proposed by the present invention, the above-mentioned laser component is applied, and the method comprises: 1) calibrating the narrow linewidth laser component at an ambient temperature with a set step size, and during calibration, first detecting the cavity length that should be compensated by the equivalent cavity length compensator at the ambient temperature to be calibrated, and then calculating the compensation voltage that should be applied to compensate for the cavity length based on the relationship between the equivalent cavity length and the refractive index of the equivalent cavity length compensator, and the relationship between the refractive index and the applied external voltage; 2) testing the narrow linewidth laser component under the calibrated ambient temperature and compensation voltage, and detecting the central wavelength of the narrow linewidth laser and the compensating voltage. Whether the center wavelength is consistent at room temperature. If so, the ambient temperature and compensation voltage are recorded in the table of the narrow linewidth laser controller. If not, the compensation voltage is fine-tuned to make the center wavelength of the narrow linewidth laser consistent with the center wavelength at room temperature, and the ambient temperature and the adjusted compensation voltage are recorded in the table of the narrow linewidth laser controller; 3) The narrow linewidth laser controller detects the ambient temperature through the ambient temperature detection module, and then calls the compensation voltage corresponding to the ambient temperature recorded in the table according to the ambient temperature, and controls the equivalent cavity length compensation controller to apply the corresponding compensation voltage to the equivalent cavity length compensator.

[0013] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0014] In the aforementioned method for improving the drift of a narrow-linewidth laser, during calibration, the narrow-linewidth laser controller also detects the TEC temperature, backlight current, and gain chip current at the temperature to be calibrated. During the test, the TEC temperature, backlight current, and gain chip current information are input into the narrow-linewidth laser controller together with the ambient temperature and the compensation voltage. When the center wavelength of the narrow-linewidth laser is consistent with the center wavelength at room temperature, the above data are recorded in a table together with the ambient temperature and the compensation voltage.

[0015] The above-mentioned method for improving the drift of narrow linewidth laser is to compensate the cavity length ΔL = L*Δλ / λ, where L is the cavity length of the narrow linewidth laser at room temperature, and λ is the central wavelength of the narrow linewidth laser at room temperature; the original equivalent cavity length of the equivalent cavity length compensator is L d Compared with the original refractive index n, when the refractive index change of the effective cavity length compensator is Δn, ΔL=Δn*L d The compensation voltage required to compensate for the cavity length can be calculated by combining the above two equations with the relationship between the refractive index and the external voltage.

[0016] In the aforementioned method for improving narrow linewidth laser drift, the equivalent cavity length compensator is a silicon-based chip, and the equivalent cavity length compensator is made of silicon or silicon nitride material.

[0017] In the aforementioned method for improving drift of a narrow linewidth laser, when the ambient temperature detected in step 3) is an uncalibrated ambient temperature, the compensation voltage at the ambient temperature is calculated based on the fitting interpolation expansion.

[0018] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technological advancement and practicality, and has wide industrial application value. It has at least the following advantages:

[0019] The present invention provides a narrow-linewidth laser component and method for improving the high- and low-temperature mode drift of a narrow-linewidth laser, thereby solving the existing problem of high- and low-temperature mode drift of the narrow-linewidth laser caused by high and low temperatures and improving the stability and accuracy of a system using a narrow-linewidth laser.

[0020] The present invention reduces the impact of ambient temperature on the narrow-linewidth laser mode, thereby improving the stability and accuracy of the system using the narrow-linewidth laser. The present invention can compensate for the product tuning range and improve the product qualification rate.

[0021] One of the core technologies of the present invention is to add an equivalent cavity length compensator inside the existing narrow linewidth laser cavity. The equivalent length of the optical path inside the laser oscillating inside the cavity can be controlled by applying an electrical signal to this material. The present invention uses an equivalent cavity length compensator in conjunction with an external circuit to calibrate the compensation voltage required for different temperatures during the manufacturing stage. Under actual working conditions, the external temperature is detected and the corresponding voltage is applied by looking up the table. For temperature points that cannot be calibrated, an electrical signal is applied through algorithm calculation. The present invention does not require complex design and high-precision technology. It only requires ordinary equipment of narrow linewidth laser manufacturers to achieve compensation for high and low temperature mode drift at a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the composition of the narrow linewidth laser of the present invention;

[0023] Figure 2 This is a control schematic diagram of the narrow linewidth laser assembly of the present invention.

[0024]

Main component symbol description

[0025] 1: Backlight detector

[0026] 2: Gain chip components

[0027] 3: Collimating lens

[0028] 4: Etalon

[0029] 5: Filter

[0030] 6: Equivalent cavity length compensator

[0031] 7: Spectroscope

[0032] 8: Isolator

[0033] 9: Fiber collimator DETAILED DESCRIPTION

[0034] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation method, structure, characteristics and effects of the narrow linewidth laser assembly proposed in accordance with the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0035] See also Figure 1 and Figure 2 , which is a schematic diagram of the various components of the narrow-linewidth laser assembly of the present invention. The narrow-linewidth laser assembly includes a narrow-linewidth laser and a narrow-linewidth laser controller. The narrow-linewidth laser includes a laser housing, which is equipped with a ceramic substrate and a thermoelectric cooler (TEC) to achieve heat dissipation of the heat-generating components within the laser and maintain the stability of the operating temperature of each component within the laser. The laser housing also contains a gain chip assembly 2, a collimating lens 3, an etalon 4, a filter 5, an equivalent cavity length compensator 6, a beamsplitter 7, an isolator 8, and a fiber collimator 9.

[0036] The gain chip assembly 2 includes a gain chip for providing gain, a thin-film circuit substrate, and a thermistor. A collimating lens 3, an etalon 4, a filter 5, a beam splitter 7, an isolator 8, and a fiber collimator 9 are sequentially arranged on the right side of the gain chip assembly 2. The equivalent cavity length compensator 6 is located anywhere between the gain chip assembly 2 and the beam splitter 7, into which the coupled light enters. In this embodiment, the equivalent cavity length compensator 6 is located between the filter 5 and the beam splitter 7. However, in other embodiments of the present invention, the equivalent cavity length compensator 6 may also be located between the gain chip assembly 2 and the collimating lens 3, or between the collimating lens 3 and the etalon 4.

[0037] In the embodiment of the present invention, a backlight detector 1 is further provided on the left side of the gain chip assembly 2 .

[0038] In this embodiment of the present invention, the equivalent cavity length compensator 6 couples light using a direct coupling method, eliminating the need for additional lenses. The equivalent cavity length compensator 6 can change its refractive index by applying an external electrical signal, thereby affecting the equivalent cavity length. The equivalent cavity length compensator 6 is connected to a narrow-linewidth laser controller via a pin, and can thus influence the equivalent cavity length by changing the refractive index under the control of the narrow-linewidth laser controller.

[0039] The narrow-linewidth laser controller primarily consists of four components: a TEC temperature control module, a gain chip current control module, a backlight current detection module, and an equivalent cavity length compensator control module. The TEC temperature control module includes a TEC temperature detection module and a TEC control module. The TEC temperature detection module is used to detect the temperature of the thermistor in the gain chip assembly 2, while the TEC control module is used to control the temperature of the thermoelectric cooler. The backlight current detection module is used to detect the current of the backlight detector 1, while the gain chip current control module is used to control the current of the gain chip in the gain chip assembly 2. The equivalent cavity length compensator control module is used to control the refractive index of the equivalent cavity length compensator, thereby controlling its equivalent cavity length.

[0040] The narrow-linewidth laser controller also includes necessary components such as a power supply, a processor, and a memory. This component is connected to the TEC temperature control module, the gain chip current control module, the backlight current detection module, and the equivalent cavity length compensator control module to provide power to the above modules, receive, store, and process the information collected by them. The narrow-linewidth laser also includes an ambient temperature detection module for collecting ambient temperature information. The equivalent cavity length compensator transmits an electrical signal to the equivalent cavity length compensator based on the temperature information collected by the ambient temperature detection module to control its refractive index change and thereby control its equivalent cavity length.

[0041] After the narrow linewidth laser assembly of the present invention is packaged, it is first calibrated, and then the calibration data is tested. The calibration data is fine-tuned during the test so that each set of calibration data meets the purpose of eliminating temperature drift. The data that has been actually tested and meets the requirement of eliminating temperature drift is saved in a table of the narrow linewidth laser controller.

[0042] During the calibration phase, the ambient temperature, the cavity length to be compensated by the equivalent cavity length compensator 6 at that ambient temperature (the compensated cavity length), and the external voltage to be applied to achieve this compensated cavity length (the compensation voltage) are calibrated using a set step size. Specifically, during the calibration phase, pattern analysis is performed on the wavelength data corresponding to the ambient temperature, TEC temperature, and laser (LD) current tested at different ambient temperatures to calculate the cavity length to be changed, i.e., the compensated cavity length. The magnitude of the electrical signal to be applied is then calculated based on the relationship between the compensated cavity length, the refractive index data of the equivalent cavity length compensator used, and the electrical signal.

[0043] That is, during the calibration phase, the controller voltage signal (compensation voltage) is calculated based on the compensation cavity length. The compensation cavity length ΔL = L*Δλ / λ, where L is the distance between the center wavelength and the end wavelength or the starting wavelength at room temperature, that is, the cavity length at room temperature, and λ is the center wavelength at room temperature. Δλ is the difference between the center wavelength at ambient temperature and the center wavelength at room temperature. The original equivalent cavity length of the equivalent cavity length compensator 6 (equivalent cavity length when there is no external electrical signal) is L dThe original refractive index (refractive index without external electrical signal) is n. When the equivalent cavity length compensator control module applies an electrical signal to the equivalent cavity length compensator 6, the refractive index change of the equivalent cavity length compensator is Δn. The equivalent cavity length change of the equivalent cavity length compensator ΔL=Δn*L d , thus the refractive index change Δn can be obtained according to the equivalent cavity length change ΔL, and the refractive index change Δn is related to the external voltage U. The external voltage under the corresponding refractive index change can be calculated based on the relationship between the refractive index and the external voltage.

[0044] In order to improve the stability and accuracy of the system using narrow linewidth lasers, the narrow linewidth laser assembly of the present invention is also tested after calibration is completed. The ambient temperature, TEC temperature, LD current and controller voltage calibrated during the calibration phase are tested to detect whether the center wavelength of the laser under the calibration ambient temperature, TEC temperature, LD current and controller voltage is the center wavelength at room temperature. If the measured center wavelength deviates, the controller voltage signal is fine-tuned until the center wavelength returns to the center wavelength value at room temperature. This set of calibration data meets the requirements and is stored in the corresponding table in the narrow linewidth laser controller.

[0045] The narrow linewidth laser assembly of the present invention can be put into use after calibration and testing. In actual use, the data in the table inside the narrow linewidth laser controller is queried according to the ambient temperature, and an appropriate control signal is applied according to the data in the table.

[0046] During calibration, the present invention adjusts the ambient temperature every 5 to 20°C to achieve the desired function, depending on the required model accuracy. In actual use, if the ambient temperature is uncalibrated, the cavity length that needs to be compensated at the corresponding ambient temperature is calculated through fitting, interpolation, and expansion based on the calibrated and tested data in the table, thereby calculating the corresponding compensation voltage.

[0047] The present invention is further described below by taking a narrow linewidth laser assembly consisting of a narrow linewidth laser in a 14PIN butterfly package and a narrow linewidth laser combination as an example:

[0048] In this embodiment, the laser housing is butterfly-shaped, with a thermoelectric cooler attached to the bottom of the housing. A ceramic substrate is placed on the thermoelectric cooler. The optical resonant cavity, consisting of a backlight detector 1, a gain chip assembly 2, a collimating lens 3, an etalon 4, a filter 5, an equivalent cavity length compensator 6, a beam splitter 7, and an isolator 8, is located entirely on the ceramic substrate. The fiber collimator 9 is located within the tail pipe of the butterfly-shaped laser housing. In this embodiment of the present invention, the device packaging for the narrow-linewidth laser is identical to that of a conventional narrow-linewidth laser. The process steps for coupling the equivalent cavity length compensator are performed after coupling the beam splitter, while the remaining coupling methods remain unchanged.

[0049] In this embodiment, the narrow-linewidth laser controller uses a microcontroller chip as its core control. Control of the equivalent cavity length compensator is achieved through the controller chip's built-in analog-to-digital converter. An op amp chip is added after the analog-to-digital converter to enhance driving capability. After device packaging, the narrow-linewidth laser and narrow-linewidth laser controller are assembled and combined, and calibration and testing begin.

[0050] When tested at room temperature, the center wavelength of the laser's non-mode-hopping tuning range was 1550.00nm@25.0°C, the starting wavelength was 1549.92nm@22.1°C, and the end wavelength was 1550.10nm@28.2°C. When tested at 50°C, the center wavelength shifted by 0.98nm, requiring compensation.

[0051] First, calculate the cavity length ΔL that should be compensated at 50°C:

[0052] ΔL=L*Δλ / λ=10mm*0.98nm / 1550nm=0.00632mm, L is the cavity length of the laser at room temperature, λ is the center wavelength of the laser at room temperature, and Δλ is the offset of the center wavelength relative to the center wavelength at room temperature when 50℃;

[0053] The equivalent cavity length compensator of the present invention is made of silicon or silicon nitride material. The material of the equivalent cavity length compensator used in this embodiment is a silicon-based chip, and its effective cavity length is L d =1mm, the relationship between the refractive index n and the voltage U can be simplified as follows:

[0054] n=1.5+0.005*U;

[0055] The equivalent cavity length ΔL of the equivalent cavity length compensator satisfies

[0056] ΔL=Δn*L d =(0.005*U)*1mm=0.00632mm

[0057] The magnitude of the electrical signal that should be applied is:

[0058] U=1.26V

[0059] After actual testing, it was found that applying a voltage of 1.26V resulted in a slight deviation. When a voltage of 1.31V was applied, the center wavelength returned from 1550.1nm to 1550.0nm, proving that the calculated deviation was small. The actual tested voltage of 1.31V was saved in the table along with an ambient temperature of 50°C, a TEC temperature of 25°C, an LD current of 180mA, a PD current of 50uA, and a compensation voltage of 1.31V. The compensation operation for mode drift at other ambient temperatures is similar and will not be detailed here. In actual operating conditions, when the controller's ambient temperature detection module detects that the ambient temperature has reached 50°C, it automatically retrieves the required TEC temperature, LD current, and compensation voltage, and sets them accordingly. This compensates for the mode drift caused by the ambient temperature change and keeps the mode consistent with that at normal temperature.

[0060] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A laser assembly for improving narrow linewidth laser drift, characterized by: The invention comprises a narrow-linewidth laser and a narrow-linewidth laser controller, wherein a gain chip assembly, a collimating lens, an etalon, a filter, a spectroscope and an isolator are sequentially encapsulated in the narrow-linewidth laser housing from left to right, and an equivalent cavity length compensator is also coupled between the gain chip assembly and the spectroscope; the narrow-linewidth laser controller comprises an ambient temperature detection module for collecting ambient temperature information and an equivalent cavity length compensator control module for applying an external voltage to the equivalent cavity length compensator to change its refractive index; the narrow-linewidth laser controller has a table recording the compensation voltage that the equivalent cavity length compensator should apply to the equivalent cavity length compensator under different ambient temperatures, so that the narrow-linewidth laser controller can call the compensation voltage corresponding to the ambient temperature in the table according to the ambient temperature value collected by the ambient temperature detection module, and control the equivalent cavity length compensator controller to send a corresponding voltage signal.

2. The laser assembly for improving narrow linewidth laser drift according to claim 1, characterized in that: A thermoelectric cooler is also provided in the narrow linewidth laser housing. The thermoelectric cooler is attached to the bottom of the narrow linewidth laser housing. The gain chip assembly, collimating lens, etalon, filter, equivalent cavity length compensator, spectrometer and isolator are arranged on the thermoelectric cooler through a ceramic substrate.

3. The laser assembly for improving narrow linewidth laser drift according to claim 1 or 2, characterized in that: The narrow linewidth laser housing is further provided with a backlight detector, which is located on the left side of the gain chip assembly.

4. The laser assembly for improving narrow linewidth laser drift according to claim 3, wherein: The narrow linewidth laser controller also includes a TEC temperature control module, a gain chip current control module and a backlight current detection module. The table of the narrow linewidth laser controller also records the TEC temperature, backlight current and gain chip current values ​​under corresponding ambient temperature and compensation voltage.

5. The laser assembly for improving narrow linewidth laser drift according to claim 4, characterized in that: The narrow linewidth laser controller is fixed outside the narrow linewidth laser housing.

6. A method for improving narrow linewidth laser drift, characterized by: Applying the laser assembly of claim 4, the method comprises: 1) Calibrate the narrow linewidth laser assembly at a set ambient temperature step. During calibration, first detect the cavity length that should be compensated by the equivalent cavity length compensator at the ambient temperature to be calibrated. Then, calculate the compensation voltage to be applied to compensate for the cavity length based on the relationship between the equivalent cavity length and the refractive index of the equivalent cavity length compensator, and the relationship between the refractive index and the applied external voltage. 2) Testing the narrow linewidth laser assembly at the calibrated ambient temperature and compensation voltage to detect whether the center wavelength of the narrow linewidth laser is consistent with the center wavelength at room temperature. If they are consistent, the ambient temperature and compensation voltage are recorded in the table of the narrow linewidth laser controller. If they are inconsistent, the compensation voltage is fine-tuned to make the center wavelength of the narrow linewidth laser consistent with the center wavelength at room temperature, and the ambient temperature and the adjusted compensation voltage are recorded in the table of the narrow linewidth laser controller; 3) The narrow linewidth laser controller detects the ambient temperature through the ambient temperature detection module, and then calls the compensation voltage corresponding to the ambient temperature recorded in the table according to the ambient temperature, and controls the equivalent cavity length compensation controller to apply the corresponding compensation voltage to the equivalent cavity length compensator.

7. The method for improving narrow linewidth laser drift according to claim 6, wherein: During calibration, the narrow linewidth laser controller also detects the TEC temperature, backlight current, and gain chip current at the temperature to be calibrated. During the test, the TEC temperature, backlight current, and gain chip current information are input into the narrow linewidth laser controller together with the ambient temperature and compensation voltage. When the center wavelength of the narrow linewidth laser is consistent with the center wavelength at room temperature, the above data are recorded in the table together with the ambient temperature and compensation voltage.

8. The method for improving narrow linewidth laser drift according to claim 6, wherein: Compensated cavity length ΔL = L*Δλ / λ, L is the cavity length of the narrow linewidth laser at room temperature, λ is the central wavelength of the narrow linewidth laser at room temperature; the original equivalent cavity length of the equivalent cavity length compensator is L d Compared with the original refractive index n, when the refractive index change of the effective cavity length compensator is Δn, ΔL=Δn*L d The compensation voltage required to compensate for the cavity length can be calculated by combining the above two equations with the relationship between the refractive index and the external voltage.

9. The method for improving narrow linewidth laser drift according to claim 8, characterized in that: The equivalent cavity length compensator is made of silicon or silicon nitride material.

10. The method for improving narrow linewidth laser drift according to claim 6, wherein: When the ambient temperature detected in step 3) is an uncalibrated ambient temperature, the compensation voltage at the ambient temperature is calculated based on the fitting interpolation expansion.

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