Automatic testing method and system for volume grating diffraction efficiency based on a tunable laser

Abstract

The present invention provides an automatic test method and system for the diffraction efficiency of volume gratings based on a tunable laser. The method includes: setting the initial test parameters of the tunable laser, the constant temperature chamber, the optical power meter, and the optical wavelength meter; connecting the volume grating to be tested to the tunable laser, and obtaining the measurement data of the optical power meter and the optical wavelength meter at different spatial positions of the actuator; analyzing the obtained measurement data to obtain the change relationship curve between the output optical power of the light of multiple diffraction orders of the volume grating to be tested and the resonant output wavelength; analyzing the change relationship curve to obtain the relative diffraction efficiency distribution data of the volume gratings to be tested at different orders. The present invention can automatically test the relative diffraction efficiency of volume gratings of different batches, different wavelengths, and different diffraction orders of the same wavelength, and automatically analyze the test results of the output optical power obtained by the test, so as to achieve accurate and rapid testing of the characteristic parameters of the volume gratings.

Description

Technical Field

[0001] The present invention belongs to the technical field of automatic measurement of the diffraction efficiency of volume gratings, and particularly relates to a method and system for automatically measuring the diffraction efficiency of volume gratings based on a tunable laser. Background Technique

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] A wide-range free-space optical external cavity swept-frequency laser source (also known as a Littman-Metcalf type tunable laser, abbreviated as LM-TL) has been widely used in high-speed coherent optical communication networks based on high-order optical modulation formats, three-dimensional fiber shape frequency-domain sensing, linear swept-frequency trace gas detection, and autonomous driving due to its outstanding advantages such as single longitudinal mode, narrow linewidth, continuously tunable output wavelength, and low phase noise. However, in the operation and output process of traditional LM-TL, the realization of wide-range and narrow-linewidth linearly continuously tunable laser output highly depends on the accurate calibration of the relative diffraction efficiency of the volume grating.

[0004] At present, the volume grating relative diffraction efficiency test systems at home and abroad generally adopt the structure form of a monochromator. Since most monochromators need to adjust the incident slit and lens assembly to ensure the monochromaticity of the light beam incident on the surface of the volume grating to be measured, the scanning range of the test system is limited due to the limited fixed positions of the optical elements. At the same time, since a reference light is required to measure the incident light energy, the applicable spectral width is relatively narrow. In addition, using the monochromatic light generated by the monochromator as the test light source, there are differences between its optical characteristics and the resonant radiation light characteristics of LM-TL, and the projected light spot of the generated test light on the surface of the volume grating is often small, and there are large differences between the optical parameters of the test light and the actual working state of the volume grating. Obviously, the traditional volume grating relative diffraction efficiency test system cannot quickly, efficiently, and accurately characterize the applicability of the relative diffraction efficiency and other characteristic parameters of volume gratings of different batches, different wavelengths, and different diffraction orders of the same wavelength to LM-TL, and it is difficult to meet the application requirements of LM-TL in the field of high-speed coherent optical communication; at the same time, the non-targeted volume grating relative diffraction efficiency test method and system also lead to low efficiency and increased cost in the test process. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the present invention provides an automatic testing method and system for the diffraction efficiency of volume gratings based on a tunable laser. By using a wide-range free-space optical external cavity swept-frequency laser source (Littman-Metcalf type tunable laser, abbreviated as LM-TL) as the testing device, the relative diffraction efficiency of volume gratings of different batches, different wavelengths, and different diffraction orders at the same wavelength is automatically tested, and the test results of the output optical power are automatically analyzed, so as to obtain the relative diffraction efficiency spectrum of the volume grating to be tested and the test data of the optimal working wavelength range, realizing accurate and rapid testing of the characteristic parameters of the volume grating.

[0006] To achieve the above object, one or more embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present invention provides an automatic testing method for the diffraction efficiency of volume gratings based on a tunable laser, including:

[0008] Set the initial test parameters of the tunable laser, constant temperature box, optical power meter, and optical wavelength meter;

[0009] Connect the volume grating to be tested to the tunable laser, change the spatial position of the actuator, and obtain the measurement data of the optical power meter and optical wavelength meter at different spatial positions of the actuator;

[0010] Analyze the measurement data of the optical power meter and optical wavelength meter obtained to obtain the curve of the change relationship between the output optical power of multiple diffraction orders of light of the volume grating to be tested and the resonant output wavelength;

[0011] Combine the intrinsic parameters of the tunable laser and the intrinsic lasing intensity of multiple diffraction orders of light to analyze the change relationship curve, and obtain the relative diffraction efficiency distribution data of the volume grating to be tested at different orders.

[0012] The second aspect of the present invention provides an automatic testing system for the diffraction efficiency of volume gratings based on a tunable laser, including: a tunable laser, a coupler, a constant temperature box, an optical power meter, and an optical wavelength meter; the tunable laser, constant temperature box, optical power meter, and optical wavelength meter are respectively connected to a control computer;

[0013] The constant temperature box is arranged outside the tunable laser; the two output ends of the tunable laser are connected to the coupler, and the three output ends of the coupler are respectively connected to a first optical power meter, a second optical power meter, and an optical wavelength meter;

[0014] The control computer is used to provide instruction initialization and drive signals for the tunable laser and the thermostat, provide synchronous trigger acquisition signals for the optical power meter and the optical wavelength meter, and at the same time receive and process the resonant power and lasing wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter, so as to obtain the relative diffraction efficiency distribution data of the gratings of the objects to be measured at different levels.

[0015] The above one or more technical solutions have the following beneficial effects:

[0016] (1) The automatic test method and system for the diffraction efficiency of volume gratings proposed by the present invention are based on the characteristic that the resonant output optical power of the LM-TL is sensitive to the relative diffraction efficiency of the volume grating. By deeply analyzing the output optical power coupled by the single-mode fiber and the test traces of different wavelengths and different diffraction orders of the same wavelength, the automatic analysis of the relative diffraction efficiency of the sample volume grating is realized, and based on this, the precise screening of qualified volume gratings suitable for LM-TL assembly is realized, solving the problems that the traditional method depends on the monochromator structure form, the test process of the relative diffraction efficiency characteristic parameters of the volume grating is complex, the applicable spectral width is narrow, the mechanical stability of the test instrument is poor, the test efficiency is low, and the projected light spot of the test light on the surface of the volume grating is often small, and there are large differences between the optical parameters of the test light and the actual working state of the volume grating, and it cannot effectively characterize the compatibility of the overall performance of the volume grating with the LM-TL, and the accuracy is easily affected by the test light source factors, resulting in large differences in the output index performance of the LM-TL;

[0017] (2) The present invention realizes the efficient and high-accuracy automatic test of the relative diffraction efficiency parameters of the volume grating, provides advanced test instruments for fields such as intelligent high-speed coherent network reconfigurable transmission, fiber three-dimensional shape sensing with cross-correlation frequency domain decoupling, high-precision gas spectroscopy measurement, and autonomous driving, and at the same time further expands the application range of the Littman-Metcalf type tunable laser, increases application scenarios for the LM-TL, and promotes the rapid development of the wide-range free-space optical external cavity tunable laser industry.

[0018] The advantages of the additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0019] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0020] Figure 1 It is a flow chart of the automatic test method for the diffraction efficiency of volume gratings based on a tunable laser for the first embodiment.

[0021] Figure 2The curve of the variation relationship between the optical output power of the 0th diffraction order of the calibration volume grating and the resonant output wavelength in the first embodiment.

[0022] Figure 3 The flowchart of the calculation method of the intrinsic lasing intensity BL1 of the high diffraction order light in the first embodiment.

[0023] Figure 4 The flowchart of the calculation method of the relative diffraction efficiency of different diffraction orders of the volume grating to be measured in the first embodiment.

[0024] Figure 5 The structure diagram of the automatic test system for the diffraction efficiency of the volume grating based on the tunable laser in the second embodiment.

[0025] Figure 6 The schematic diagram of the structure of the Littman-Metcalf type tunable laser in the second embodiment. Detailed implementation manners

[0026] Embodiment 1

[0027] This embodiment discloses an automatic test method for the diffraction efficiency of a volume grating based on a tunable laser. The Littman-Metcalf type tunable laser is used as the test device to automatically test the relative diffraction efficiency of volume gratings of different batches, different wavelengths, and different diffraction orders of the same wavelength, and automatically analyze the test results of the output optical power obtained by the test, so as to obtain the relative diffraction efficiency spectrum of the volume grating to be measured and the test data of the optimal working wavelength range, and realize the accurate and rapid test of the characteristic parameters of the volume grating. The specific steps are as Figure 1 shown, including:

[0028] Step 101: The control computer 7 remotely controls the startup of the Littman-Metcalf type tunable laser 1 and the high-precision constant temperature box 2, and proceeds to step 102;

[0029] Step 102: The control computer 7 reads the driving current and temperature field parameters of the semi-butterfly packaged seed source 101 driven by the control circuit 107 in the Littman-Metcalf type tunable laser 1, the spatial position parameters of the actuator 105, the temperature parameters of the support plate 106, and the temperature value of the high-precision constant temperature box 2 and other initial state parameters, and proceeds to step 103;

[0030] Step 103: Prompt the user to check the access situation of the volume grating whose relative diffraction efficiency has been calibrated, and proceed to step 104;

[0031] Step 104: The user inputs the holding temperature T0 of the high-precision thermostat 2, the sampling rate PS0 of the optical power meter 4, the wavelength resolution WR of the optical wavelength meter 5, the sampling rate PS1 of the optical power meter 6, the drive current IQ of the semi-butterfly packaged seed source 101, the holding temperature T1 of the support plate 106, and the drive step signal QS of the actuator 105, etc., and proceeds to Step 105;

[0032] Step 105: The control computer 7 communicates with the control circuit 107 to load the drive current IQ onto the semi-butterfly packaged seed source 101, set the holding temperatures to T0 and T1, and set the drive step signal to QS. Under these conditions, the optical power and optical wavelength are measured and the data is recorded at M spatial position parameters SL[1~M] of the actuator 105. The M positions of the actuator correspond to the M output wavelengths and powers of the tunable laser, and then proceed to Step 106;

[0033] Step 106: After the LM-TL calibration volume grating relative diffraction efficiency parameter automatic test system completes the optical power and optical wavelength tests, the control computer 7 reads the number of optical power data points A1, the number of optical wavelength points A11 at high diffraction orders, the number of optical power data points A0, the number of optical wavelength points A01 at the 0th diffraction order, the high diffraction order optical power distribution data P_A1[1~M][1~A1], the high diffraction order optical wavelength distribution data W_A11[1~M][1~A11], the 0th diffraction order optical power distribution data P_A0[1~M][1~A0], and the 0th diffraction order optical wavelength distribution data W_A01[1~M][1~A01] under the QS drive step signal, and then proceeds to Step 107;

[0034] Step 107: Analyze the high diffraction order optical wavelength distribution data W_A11[1~M][1~A11] and the high diffraction order optical power distribution data P_A1[1~M][1~A1] to obtain the variation relationship curve PW1 between the high diffraction order optical output power and the resonant output wavelength of the calibration volume grating, and then proceed to Step 108;

[0035] Step 108: Analyze the 0th diffraction order optical wavelength distribution data W_A01[1~M][1~A01] and the 0th diffraction order optical power distribution data P_A0[1~M][1~A0] to obtain the variation relationship curve PW0 between the 0th diffraction order optical output power and the resonant output wavelength of the calibration volume grating (as Figure 2 shown), and then proceed to Step 109;

[0036] Step 109: Analyze the distribution trace PW1 to obtain the intrinsic lasing intensity BL1 of the LM-TL for high diffraction order light. The specific steps are shown in Step 201, and then proceed to Step 110;

[0037] Step 110: Repeat step 201 to analyze the distributed trace PW0, obtain the intrinsic lasing intensity BL0 of the 0th diffraction order light of the LM-TL pair, and go to step 111;

[0038] Step 111: Prompt the user to replace the volume grating to be measured, and go to step 112;

[0039] Step 112: Repeat steps 104 to 108 to test and obtain the variation relationship curve PW1_1 between the output optical power of the high diffraction order light of the volume grating to be measured and the resonant output wavelength, and the variation relationship curve PW0_1 between the output optical power of the 0th diffraction order light of the volume grating to be measured and the resonant output wavelength, and go to step 113;

[0040] Step 113: Analyze PW1_1 and PW0_1 obtained in step 112 respectively to obtain the relative diffraction efficiency distribution data of the volume gratings of different orders of the sample to be measured. The specific steps are shown in step 301, and go to step 114;

[0041] Step 114: Output the diffraction efficiency test results of the volume grating to be measured, including: the relative diffraction efficiency MG[0] of the 0th diffraction order and the relative diffraction efficiency MG[1] of the high diffraction order, and end.

[0042] Specifically, the calculation method process of the intrinsic lasing intensity BL1 of the high diffraction order light (i.e., the light intensity of the initial stimulated radiation field in the gain chip cavity) is as Figure 3 shown. By quickly analyzing the variation distribution data PW1 between the output optical power of the high diffraction order light of the calibrated volume grating and the resonant output wavelength, the intrinsic lasing intensity BL1 can be obtained. The specific steps are as follows:

[0043] Step 201: Read the distribution data PW1 between the output optical power of the high diffraction order light of the calibrated volume grating and the resonant output wavelength, and go to step 202;

[0044] Step 202: Input the intrinsic parameters of the LM-TL: the end face reflectivities R1 and R2 of the semi-butterfly packaged seed source 101, the single-pass gain G, the physical length Lic, the diffraction efficiency R3 of the calibrated volume grating, the reflectivity R4 of the actuating mirror, and the physical length Lec of the origin of the external cavity, and go to step 203;

[0045] Step 203: Calculate the output optical power Pic of the semi-butterfly packaged seed source 101 = (G * (1 - R2) * BL1) / (1 + A - B * C), where A = G 2*R1*R2, B = 2*G*sqrt(R1*R2)*C, C = cos(4*pi*Lic / (PW1[1~A11]) + 2*pi), where pi represents the ratio of the circumference of a circle to its diameter, i.e., π; Sqrt(...) represents taking the square root of the parameter inside the parentheses; PW1[1~A11] represents the resonant output wavelength of the high diffraction order of the volume grating; go to step 204;

[0046] Step 204: Calculate the external cavity output optical power Pec of LM-TL as Pec = (G*(1 - R2)*Pic) / (1 + A1 - 2*B1*cos(C1)), where, A1 = G 2 *(1 - R2) 2 *R1*R3, B1 = 2*G*(1 - R2)*sqrt(R1*R3), C1 = 4*pi*Lec / (PW1[1~A11]) + 2*pi, go to step 205;

[0047] Step 205: Calculate the intrinsic stimulated optical intensity BL1 of the high diffraction order light as BL1 = sqrt(PW1[1~A1] / E)*(1 / D), where, the calibrated output optical power PW1[1~A1] of the high diffraction order light of the volume grating is equal to the product of the output optical power Pic of the semi-butterfly package seed source 101 and the external cavity output optical power Pec, i.e., PW1[1~A1] = Pec*Pic; D = (G*(1 - R2)) / (1 + A - B*C), E = (G*(1 - R2)) / (1 + A1 - 2*B1*cos(C1)), go to step 206;

[0048] Step 206: Output the intrinsic stimulated optical intensity BL1 of the calibrated high diffraction order light of the volume grating.

[0049] Specifically, the calculation method process of the relative diffraction efficiency of different diffraction orders of the volume grating of the sample to be measured is as Figure 4 shown. By quickly analyzing the distribution data PW1_1 between the output optical power of the high diffraction order light of the original volume grating to be measured and the resonant output wavelength, and the distribution data PW0_1 between the output optical power of the 0th diffraction order light of the volume grating to be measured and the resonant output wavelength, the test results MG[0] and MG[1] of the volume grating of the sample to be measured are obtained. The specific steps are as follows:

[0050] Step 301: Read the distribution data PW1_1 between the output optical power of the high diffraction order light of the volume grating to be measured and the resonant output wavelength, the intrinsic stimulated optical intensity BL1 of the high diffraction order light, the distribution data PW0_1 between the output optical power of the 0th diffraction order light of the volume grating to be measured and the resonant output wavelength, the intrinsic stimulated optical intensity BL0 of the 0th diffraction order light, and the intrinsic parameters of LM-TL, and go to step 302;

[0051] Step 302: Calculate the output optical power Pic[0~1] of the half-butterfly packaged seed source 101, and go to Step 303;

[0052] Step 303: According to PW1_1[1~A1]=Pic[1]*Pec[1], D1 = G*(1 - R2)*Pic, D2 = G 2 *(1 - R2) 2 *R1, D3 = 2*G*(1 - R2)*sqrt(R1), D4 = D1*Pic[1] / PW1_1[1~A1], the test result MG[1] of the volume grating of the sample to be measured can be obtained as MG[1]=sqrt((D3 + sqrt(D3 2 - 4*D2*(1 - D4))) / 2*D2), and go to Step 304;

[0053] Step 304: Similarly, according to PW0_1[1~A0]=Pic[0]*Pec[0], the test result MG[0] of the volume grating of the sample to be measured can be obtained, and go to Step 305;

[0054] Step 305: Output the relative diffraction efficiency test results MG[0~1] of different diffraction orders of the volume grating to be measured, and go to Step 306;

[0055] Step 306: Find the wavelength range SW_1 = PW1_1[St1~En1] corresponding to the output optical power PW1_1[1~A1]>THR_1(10dBm) recorded in the original distribution data PW1_1 automatically tested under the driving current IQ condition, and go to Step 307;

[0056] Step 307: Find the wavelength range SW_0 = PW0_1[St0~En0] corresponding to the output optical power PW0_1[1~A0]>THR_0(13dBm) recorded in the original distribution data PW0_1 automatically tested under the driving current IQ condition, and go to Step 308;

[0057] Step 308: Calculate the intersection SW of SW_1 and SW_0, and go to Step 309;

[0058] Step 309: Judge whether SW>THR_2(THR_2 = 110nm) holds. If it holds, go to Step 310; if not, go to Step 311;

[0059] Step 310: Output the best working wavelength range SW of the volume grating, prompt the user that the volume grating to be measured is applicable to the LM-TL system, and end;

[0060] Step 311: Prompt the user that the volume grating to be measured is not applicable to the LM-TL system, and end.

[0061] Example 2

[0062] As Figure 5 shown, this embodiment discloses an automatic test system for the diffraction efficiency of a volume grating based on a tunable laser, including: a Littman-Metcalf type tunable laser, a coupler, a thermostat, an optical power meter, and an optical wavelength meter; the Littman-Metcalf type tunable laser, the thermostat, the optical power meter, and the optical wavelength meter are respectively connected to a control computer;

[0063] The thermostat is arranged outside the Littman-Metcalf type tunable laser; two output ends of the Littman-Metcalf type tunable laser are connected to the coupler, and three output ends of the coupler are respectively connected to a first optical power meter, a second optical power meter, and the optical wavelength meter;

[0064] Among them, the control computer is used to provide instruction initialization and drive signals for the Littman-Metcalf type tunable laser and the thermostat, provide synchronous trigger acquisition signals for the optical power meter and the optical wavelength meter, and at the same time receive and process the resonant power and lasing wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter, so as to obtain the relative diffraction efficiency distribution data of the volume gratings to be measured at different orders;

[0065] The high-precision thermostat is used to reduce the output deviation of the LM-TL caused by the change of the external environmental temperature, and the typical temperature regulation accuracy is ±0.5°C.

[0066] The coupler is a 2×3 fiber coupler, which is used to transmit the equivalent optical power of the resonant output of the calibrated volume grating and the volume grating to be measured, and the resonant wavelength corresponding to the relative equivalent optical power.

[0067] The first optical power meter is used to collect the resonant optical power of high diffraction orders with different batches and different wavelengths, and the typical order is -1 order.

[0068] The second optical power meter is used to collect the resonant optical power of the 0th order with different batches and different wavelengths.

[0069] The optical wavelength meter is used to record the resonant output wavelength of the LM-TL at different positions of the actuator.

[0070] As Figure 6 shown, the Littman-Metcalf type tunable laser mainly consists of a semi-butterfly packaged seed source 101, a beam shaping lens 102, a volume grating 103, a tunable mirror 104, an actuator 105, a support plate 106, and a control circuit 107, etc.

[0071] Specifically, the semi-butterfly packaged seed source 101 is typically an InP-based single-facet semiconductor gain chip with a semi-butterfly package. The typical value of the single-facet reflectivity is 0.005%, and the typical value of the 3dB bandwidth is better than 80nm. A thermistor and a thermoelectric cooler are integrated inside for the stable generation of a free-space optical external cavity strong feedback seed source.

[0072] The beam shaping lens 102 is used for beam expansion and collimation of the laser beam output by the semi-butterfly packaged seed source 101, and is typically a molded aspheric lens with a large numerical aperture.

[0073] The volume grating 103 is typically a blazed grating with a high groove density, and the typical value of the groove density is greater than 900 lines / mm, which is used for the selection of resonant modes.

[0074] The tunable mirror 104 is used to realize the oscillation of photons with a specific frequency selected by the volume grating 103 in the external cavity, and is typically a gold-plated mirror.

[0075] The output end of the actuator 105 is connected to the tunable mirror 104 for precisely adjusting the spatial position of the tunable mirror 104. The actuator 105 is driven by the control circuit 107 and is typically a stepper motor;

[0076] The support plate 107 is integrated with a semiconductor cooler and a temperature sensor for stabilizing the operating temperature of the Littman-Metcalf type tunable laser 1 and is controlled by the control circuit 107.

[0077] The control circuit 107 is controlled by the control computer 7 to achieve the loading of the drive current of the semi-butterfly packaged seed source 101, the loading of the actuation voltage of the actuator 105, and the precise regulation of the temperature field of the support plate 106.

[0078] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. An automatic test method for the diffraction efficiency of a volume grating based on a tunable laser, characterized in that, Including: Setting the initial test parameters of a tunable laser, a thermostat, an optical power meter, and an optical wavelength meter; Connecting the grating under test to the tunable laser, changing the spatial position of the actuator, and obtaining the measurement data of the optical power meter and the optical wavelength meter at different spatial positions of the actuator; Analyzing the measurement data of the optical power meter and the optical wavelength meter obtained to obtain a curve of the variation relationship between the output optical power and the resonant output wavelength of light of multiple diffraction orders of the grating under test; Combining the intrinsic parameters of the tunable laser and the intrinsic lasing intensities of light of multiple diffraction orders to analyze the variation relationship curve to obtain the relative diffraction efficiency distribution data of gratings under test of different orders; The obtaining the measurement data of the optical power meter and the optical wavelength meter at different spatial positions of the actuator includes: Obtaining the number of high diffraction order optical power data points, the number of optical wavelength points, the high diffraction order optical power distribution data, and the high diffraction order optical wavelength distribution data; Obtaining the number of optical power data points, the number of optical wavelength points, the 0th order diffraction order optical power distribution data, and the 0th order diffraction order optical wavelength distribution data at the 0th diffraction order; The analyzing the measurement data of the optical power meter and the optical wavelength meter obtained to respectively obtain a curve of the variation relationship between the output optical power and the resonant output wavelength of light of multiple diffraction orders of the grating under test includes: Analyzing the high diffraction order optical wavelength distribution data and the high diffraction order optical power distribution data to obtain a curve of the variation relationship between the output optical power and the resonant output wavelength of high diffraction order light of the calibration volume grating; Analyzing the 0th order diffraction order optical wavelength distribution data and the 0th order diffraction order optical power distribution data to obtain a curve of the variation relationship between the output optical power and the resonant output wavelength of 0th order diffraction order light of the calibration volume grating.

2. The automatic test method for the diffraction efficiency of a volume grating based on a tunable laser according to claim 1, wherein The setting the initial test parameters of the tunable laser includes: setting the drive current of the semi-butterfly packaged seed source, the holding temperature of the support plate, and the drive step signal of the actuator; The setting the initial test parameters of the thermostat includes: setting the holding temperature of the thermostat; The setting the initial test parameters of the optical power meter and the optical wavelength meter includes: setting the sampling rate of the optical power meter and the wavelength resolution of the optical wavelength meter.

3. The automatic test method for the diffraction efficiency of a volume grating based on a tunable laser according to claim 1, characterized in that, The combining the intrinsic parameters of the tunable laser and the intrinsic lasing intensities of light of multiple diffraction orders to analyze the variation relationship curve to obtain the relative diffraction efficiency distribution data of gratings under test of different orders specifically includes: Calculating the output optical power of the semi-butterfly packaged seed source and the external cavity output optical power of the tunable laser according to the distribution data between the output optical power and the resonant output wavelength of high diffraction order light of the grating under test, the intrinsic lasing intensity of high diffraction order light, the distribution data between the output optical power and the resonant output wavelength of 0th order diffraction order light of the grating under test, the intrinsic lasing intensity of 0th order diffraction order light, and the intrinsic parameters of the Littman-Metcalf type tunable laser; According to the relationship between the output optical power of the semi-butterfly packaged seed source, the output optical power of the external cavity of the tunable laser, the output optical power of the high diffraction order light of the object grating to be measured, and the output optical power of the 0th order diffraction order light, calculate the relative diffraction efficiency of the high diffraction order and the relative diffraction efficiency of the 0th order diffraction order of the object grating to be measured respectively.

4. The automatic test method for the diffraction efficiency of a volume grating based on a tunable laser according to claim 3, wherein The calculation methods for the intrinsic stimulated optical intensity of the 0th order diffraction order light and the intrinsic stimulated optical intensity of the high diffraction order light include: Connect the calibrated volume grating to the tunable laser to obtain the change relationship curve between the output optical power of the 0th order diffraction order light and the high diffraction order light of the calibrated volume grating and the resonant output wavelength; Combined with the intrinsic parameters of the tunable laser, analyze the change relationship curve respectively to obtain the intrinsic stimulated optical intensity of the tunable laser for the 0th order diffraction order light and the high diffraction order light.

5. The automatic test method for the diffraction efficiency of a volume grating based on a tunable laser according to claim 4, characterized in that, The specific steps of combining the intrinsic parameters of the tunable laser and analyzing the change relationship curve respectively include: According to the intrinsic parameters of the tunable laser and the distribution data of the output optical power of the high diffraction order and the 0th order diffraction order light of the calibrated volume grating and the resonant output wavelength, calculate the output optical power of the semi-butterfly packaged seed source and the output optical power of the external cavity of the tunable laser; The intrinsic parameters of the tunable laser include: the end face reflectivity of the semi-butterfly packaged seed source, the single-pass gain and the physical length, the diffraction efficiency of the calibrated volume grating, the reflectivity of the actuating mirror, and the physical length of the external cavity origin. According to the output optical power of the semi-butterfly packaged seed source and the output optical power of the external cavity, calculate the intrinsic stimulated optical intensity of the high diffraction order light and the 0th order diffraction order light respectively.

6. A method for automatically testing the diffraction efficiency of a volume grating based on a tunable laser according to claim 1, characterized in that The described test method further includes: calculating the optimal working wavelength range of the object grating to be measured and judging whether the object grating to be measured is suitable for the tunable laser, including: Using the obtained change relationship curve between the output optical power of the high diffraction order light of the object grating to be measured and the resonant output wavelength, find the wavelength range one corresponding to when the output optical power of the high diffraction order light is greater than the set value; Using the obtained change relationship curve between the output optical power of the 0th order diffraction order light of the object grating to be measured and the resonant output wavelength, find the wavelength range two corresponding to when the output optical power of the 0th order diffraction order light is greater than another set value; Calculate the intersection of wavelength range one and wavelength range two; Judge whether it is true that the wavelength value in the wavelength intersection is greater than the set wavelength value; If it holds, output the optimal working wavelength range of the object grating to be measured and prompt the user that the object grating to be measured is suitable for the tunable laser; otherwise, prompt the user that the object grating to be measured is not suitable for the tunable laser.

7. An automatic test system for the diffraction efficiency of volume gratings based on a tunable laser, characterized in that, Adopt the automatic test method for the diffraction efficiency of the volume grating based on the tunable laser according to any one of claims 1-6, including: a tunable laser, a coupler, a constant temperature box, an optical power meter, and an optical wavelength meter; the tunable laser, the constant temperature box, the optical power meter, and the optical wavelength meter are respectively connected to a control computer; The constant temperature box is arranged outside the tunable laser; the two output ends of the tunable laser are connected to the coupler, and the three output ends of the coupler are respectively connected to a first optical power meter, a second optical power meter, and an optical wavelength meter; The control computer is used to provide command initialization and drive signals for the tunable laser and the constant temperature box, provide synchronous trigger acquisition signals for the optical power meter and the optical wavelength meter, and simultaneously receive and process the resonant power and laser wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter to obtain relative diffraction efficiency distribution data of different orders of the volume grating to be measured.

8. An automatic test system for the diffraction efficiency of a volume grating based on a tunable laser according to claim 7, characterized in that, The tunable laser comprises a half-butterfly packaged seed source, a beam shaping lens, a volume grating, a tunable mirror, an actuator, a support plate and a control circuit; The half-butterfly packaged seed source is used for the stable generation of a strong feedback seed source in a free-space optical external cavity; the beam shaping lens is used for beam expansion and collimation of a laser beam output by the half-butterfly packaged seed source; the volume grating is used for the selection of a resonance mode; the tunable mirror is used for realizing the oscillation of photons of a specific frequency selected by the volume grating in the external cavity; the actuator is driven by a control circuit and is used for precisely adjusting the spatial position of the tunable mirror; a semiconductor cooler and a temperature sensor are integrated on the support plate and are used for realizing the stabilization of the operating temperature of the tunable laser; the control circuit is controlled by a control computer and is used for realizing the loading of a driving current of the half-butterfly packaged seed source, the loading of an actuator actuation voltage, and the precise adjustment of the temperature field of the support plate.

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