An automatic test method and system for extending the optimal working point of a swept source

Abstract

The present application belongs to the field of laser testing, and provides an automatic testing method and system for the optimal working point of an extended cavity swept source, wherein the maximum output power and the minimum driving current of the extended cavity swept source are determined by analyzing the tail fiber lasing power and the injected current distribution trajectory of the extended cavity swept source; the optimal working current point is determined by analyzing the tuning wavelength and the tolerance current distribution trajectory; the tuning wavelength and the control temperature partial trajectory are obtained by testing the resonant output wavelength distribution data under different control temperatures, and the optimal working control temperature point is determined by analyzing the tuning wavelength and the control temperature distribution trajectory; and the optimal working point of the extended cavity swept source is formed based on the optimal working current point and the optimal working control temperature point and is output. The present application solves the problem that the testing of the working parameters of the seed source by the traditional on-chip testing system cannot effectively represent the compatibility of the overall performance of the extended cavity resonant unit to the swept source system, thereby leading to a large difference in the output index performance of the swept source.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser testing, and particularly relates to an automatic testing method and system for an optimal working point of an extended cavity swept source. BACKGROUND

[0002] The statements in this section merely provide background information related to the application and do not necessarily constitute prior art.

[0003] The extended cavity swept source (also known as a free-space optical external cavity swept laser source, referred to as FS-ECSS for short) has been widely applied in high-speed coherent optical communication networks based on high-order optical modulation formats, optical fiber three-dimensional shape sensing decoupled in the correlation frequency domain, linear sweep trace gas detection, and automatic driving, etc. due to its outstanding advantages such as single longitudinal mode, narrow linewidth, continuous tunable output wavelength, full-waveband no mode hopping, and low phase noise. However, in the traditional spectral output process of the FS-ECSS, the realization of wide-range, no-mode hopping, and narrow-linewidth linear continuous swept laser output seriously depends on the accurate prediction of the optimal value of the running state of the extended cavity resonance unit.

[0004] The traditional on-chip test system often uses a probe and a tester to calibrate the characteristic parameters of the gain seed source after the gain seed source is processed and before it is diced. The calibration data of the characteristic parameters of each gain seed source under test are recorded by a storage module, a complex interactive analysis algorithm is used to invert the calibration data into a certain process parameter pattern that can be used to judge the electrical performance of the gain seed source, and the gain seed sources with incomplete structure and substandard electrical performance are removed by comparing with the standard value. However, the optical characteristic parameters of the gain seed source of the swept source cannot be effectively characterized. At present, the test of the optical characteristic parameters of the gain seed source is mainly through manual calibration of several parameters such as spectrum by optical coupling output. The calibration results are easily affected by subjective factors, which makes it difficult to make the overall performance parameters of the sample gain seed source compatible with the FS-ECSS. Obviously, the traditional on-chip test system as a test device can only calibrate the electrical characteristics of the sample gain seed source. For gain seed sources of different batches, different waveguide beam exit angles, and different lasing center wavelengths, the calibration process of the optical characteristic parameters of the sample gain seed source is complex, time-consuming, has large errors, and is not universal, which makes it difficult to meet the application requirements of the FS-ECSS in the field of high-speed coherent optical communication. At the same time, the non-targeted gain seed source characteristic parameter test system also leads to inefficient test process and increased cost.

[0005] In addition, the conventional hybrid integrated extension cavity feedback mode constructed sweep source system structure is relatively complex, usually adopts the method of obtaining mode jump trend monitoring by using a specific slope algorithm similar to the power spectrum of amplified spontaneous emission, and the phase compensation unit is adjusted online to fine tune, thereby reducing the probability of longitudinal mode jump. Obviously, the hybrid integrated extension cavity sweep source based on the online monitoring and adjustment technology needs to repeatedly construct a hybrid compensation algorithm model to calculate the fine tuning strategy of the phase compensation unit, resulting in low efficiency of the extension cavity continuous sweep source assembly and debugging process, complex system structure and self-feedback compensation algorithm, time-consuming and weak robustness. SUMMARY

[0006] In order to solve the above problems, the present application provides an automatic test method and system for the optimal working point of an extension cavity sweep source. The present application solves the problems of the traditional wafer test system, such as complicated calibration process of single-tube gain seed source characteristic working parameters, complex structure of the whole test system, and the fact that the test of seed source working parameters cannot effectively represent the compatibility of the overall performance of the extension cavity resonant unit to the sweep source system, resulting in large differences in the output performance of the sweep source.

[0007] According to some embodiments, the first aspect of the present application provides an automatic test method for the optimal working point of an extension cavity sweep source, which adopts the following technical solution:

[0008] An automatic test method for the optimal working point of an extension cavity sweep source, comprising:

[0009] By testing the distribution data of resonant output optical power under different driving currents, the tail fiber lasing power and the injection current distribution trajectory line of the extension cavity sweep source are obtained, and the maximum output power and the minimum driving current of the extension cavity sweep source are determined by analyzing the tail fiber lasing power and the injection current distribution trajectory line of the extension cavity sweep source;

[0010] Taking the maximum output power and the minimum driving current of the extension cavity sweep source as the limiting value, the tuning wavelength and the tolerance current distribution trajectory line are obtained by testing the resonant output wavelength distribution data under a single driving current, and the optimal working current point is determined by analyzing the tuning wavelength and the tolerance current distribution trajectory line;

[0011] By testing the resonant output wavelength distribution data under different control temperatures, the tuning wavelength and the control temperature partial trajectory line are obtained, and the optimal working control temperature point is determined by analyzing the tuning wavelength and the control temperature distribution trajectory line;

[0012] The optimal working point of the extension cavity sweep source is formed based on the optimal working current point and the optimal working control temperature point, and the optimal working point is output.

[0013] According to some embodiments, the second aspect of the present application provides an automatic test system for the optimal working point of an extension cavity sweep source, which adopts the following technical solution:

[0014] An automatic test system for extending the optimal working point of a swept cavity source, comprising:

[0015] The swept cavity source is composed of a single-tube gain seed source integrated unit, a shock-absorbing bearing unit, a control circuit and an optical interface.

[0016] The high-precision thermostat is used for simulating the working environment temperature that the swept cavity source may face.

[0017] The program-controlled attenuator is controlled by the control computer and is used for attenuating the resonant maser light power of the swept cavity source, so as to ensure that the optical wavelength meter is in a real-time working state below the damage threshold.

[0018] The optical switch is controlled by the control computer and switches the optical signal output channels of the optical power meter and the optical wavelength meter.

[0019] The optical power meter is used for extracting the resonant light power of the gain chip under different injection currents.

[0020] The optical wavelength meter is used for recording the maser wavelength.

[0021] The control computer provides the instruction initialization and driving signal of the control circuit, the temperature regulation signal of the high-precision thermostat, the attenuation gear initialization and attenuation gear switching of the program-controlled attenuator, the instruction initialization and test channel switching of the optical switch, the synchronous trigger acquisition signal of the optical power meter and the optical wavelength meter, and receives and processes the resonant power and the maser wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter.

[0022] Further, the single-tube gain seed source integrated unit is mainly composed of a gain chip, a thermistor, a thermal-electric cooler, an extended-range displacement mechanism and a gold wire bonding connection line.

[0023] The gain chip is used for generating a free-space optical external cavity strong feedback seed source.

[0024] The thermistor is used for monitoring and feeding back the junction temperature of the gain chip.

[0025] The thermal-electric cooler is used for temperature field adjustment.

[0026] The extended-range displacement mechanism is a stepping motor integrated with a piezoelectric ceramic and is used for controllable tuning of the cavity length of the swept cavity source.

[0027] The gold wire bonding connection line is used for electrical connection.

[0028] Further, the shock-absorbing bearing unit is used for bearing the swept cavity source and reducing damping.

[0029] The control circuit is controlled by a control computer and is used for driving current loading of the single-tube gain seed source integrated unit.

[0030] The optical interface is used for outputting the swept-frequency laser signal.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The present application solves the problems of the conventional on-chip test system, such as complicated calibration process of single-tube gain seed source characteristic working parameters, complex structure of the whole test system, and poor compatibility of the overall performance of the extended cavity resonant unit to the swept-frequency source system caused by the test of the working parameters of the seed source, which leads to large performance difference of the output indicators of the swept-frequency source.

[0033] The present application solves the problems of the conventional hybrid integrated extended cavity swept-frequency source, such as low efficiency of the whole machine assembly and debugging process, complex structure and algorithm caused by the dependence on cavity mode monitoring and phase hybrid compensation; and reduces the problems of the calibration process of the optical characteristic parameters of the gain seed source in the FS-ECSS system, such as complexity, time consumption, large error and non-universality.

[0034] The present application improves the efficiency of the whole machine assembly and debugging of the FS-ECSS by accurate prediction of the optimal value of the operating state of the extended cavity resonant unit, eliminates complicated monitoring algorithms and units, and reduces the cost; further expands the application range of the wide-range and mode-jump-free FS-ECSS, increases the application scenarios of the wide-range and mode-jump-free FS-ECSS, and promotes the rapid development of the wide-range and mode-jump-free FS-ECSS industry. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the present application, and do not constitute an improper limitation of the present application.

[0036] Figure 1 is the automatic test and analysis process schematic diagram of the optimal working point of the extended cavity swept-frequency source according to the embodiment of the present application Figure 1 ;

[0037] Figure 2 is the automatic test and analysis process schematic diagram of the optimal working point of the extended cavity swept-frequency source according to the embodiment of the present application Figure 2 ;

[0038] Figure 3 is the calculation method process schematic diagram of the minimum driving current according to the embodiment of the present application

[0039] Figure 4 is the calculation process schematic diagram of the optimal working current point DC_OP according to the embodiment of the present application

[0040] Figure 5 is the best working control temperature point T_OP calculation flowchart of the embodiment of the present application;

[0041] Figure 6 is the structure schematic diagram of the automatic test system of the best working point of the extended cavity swept source of the embodiment of the present application;

[0042] Figure 7 is the automatic test embodiment schematic diagram of the best working point of the extended cavity swept source of the embodiment of the present application;

[0043] Figure 8 is the structure schematic diagram of the single-tube gain seed source integrated unit of the embodiment of the present application. DETAILED DESCRIPTION

[0044] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0045] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as would be commonly understood by one of ordinary skill in the art to which the present application belongs.

[0046] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0047] The embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0048] Noun explanation:

[0049] Wafer test system: mainly composed of a probe station, a vector network analyzer, a semiconductor characteristic analyzer, an epitaxial wafer, etc. When the chip is not cut into independent bars, the detection system tests the electrical and other characteristics of the chip.

[0050] Embodiment one

[0051] As shown in Figure 1 , Figure 2 , the present embodiment provides an automatic test method for the best working point of the extended cavity swept source. In the present embodiment, the method comprises the following steps:

[0052] The tail fiber lasing power of the extended cavity swept source and the injection current distribution trajectory are obtained by testing the distribution data of the resonance output optical power under different driving currents, and the maximum output power and the minimum driving current of the extended cavity swept source are determined by analyzing the tail fiber lasing power of the extended cavity swept source and the injection current distribution trajectory;

[0053] The maximum output power and the minimum driving current of the extended cavity swept source are used as the limiting values, the tuning wavelength and the tolerance current distribution trajectory are obtained by testing the distribution data of the resonance output wavelength under a single driving current, and the optimal working current point is determined by analyzing the tuning wavelength and the tolerance current distribution trajectory;

[0054] The tuning wavelength and the control temperature partial trajectory are obtained by testing the distribution data of the resonance output wavelength under different control temperatures, and the optimal working control temperature point is determined by analyzing the tuning wavelength and the control temperature distribution trajectory;

[0055] The optimal working point of the extended cavity swept source is formed based on the optimal working current point and the optimal working control temperature point, and the optimal working point is output.

[0056] The test and analysis process of the embodiment is shown in Figure 1 、 Figure 2 By deeply analyzing the test trajectories of the tail fiber lasing power of the extended cavity swept source and the injection current, the tuning wavelength and the tolerance current, and the tuning wavelength and the control temperature, the working point characteristic parameters of the extended cavity resonance unit are automatically analyzed, thereby obtaining the distribution data of the intrinsic working parameters of the single-tube gain seed source integrated unit of different batches and different packaging processes, and realizing efficient and high-accuracy testing of the optimal working point characteristic parameters of the extended cavity resonance unit. The specific steps are as follows:

[0057] Step 101: The control computer (7) remotely controls the start of the extended cavity swept source (1), and the process goes to step 102;

[0058] Step 102: The control computer (7) reads the initial state parameters of the driving current parameters of the gain chip (201) driven by the control circuit (103) in the extended cavity swept source (1), the control temperature parameters of the thermistor (202), the driving current parameters of the thermoelectric cooler (203), the spatial position parameters of the range extender displacement mechanism (204), the attenuation gear of the program-controlled attenuator (3), and the channel position CP[1~2] of the optical switch (4), and the process goes to step 103;

[0059] Step 103: The control computer (7) remotely controls the start of the high-precision thermostat (2) and reads the temperature value and other initial state parameters of the high-precision thermostat (2), and the process goes to step 104;

[0060] Step 104: the user inputs the set temperature ST of the high-precision thermostat (2), the sampling rate PS of the optical power meter (5) connected to the channel CP[1], the wavelength resolution WR of the optical wavelength meter (6) connected to the channel CP[2], the driving current DC[1~M] of the gain chip (201) in the single-tube gain seed source integrated unit (101), the control temperature RT of the thermistor (202), and the driving pulse signal QS[1~N] of the extended-range displacement mechanism (204), and the process goes to step 105.

[0061] Step 105: the control computer (7) adjusts the attenuation value introduced by the program-controlled attenuator (3) to the lowest gear ATT, remotely starts the optical switch (4) to be placed in the channel position CP[1], and loads the driving current DC[1~M] to the gain chip (201) in the single-tube gain seed source integrated unit (101) respectively by the control circuit (103). The resonant output optical power data generated by the M driving currents under the excitation of the N driving pulse signals of the extended-range displacement mechanism (204) are measured and recorded, and the process goes to step 106.

[0062] Step 106: after the resonant output optical power data is automatically tested, the control computer (7) reads the resonant output optical power distribution data P[1~N][1~M][1~M], and the process goes to step 107.

[0063] Step 107: the resonant output optical power distribution data P[1~N][1~M][1~M] is analyzed to obtain the extended-cavity swept source tail fiber lasing power and injection current distribution traces P[1][1~M][1~M], P[C][1~M][1~M], and P[N][1~M][1~M], where C=(N+1) / 2 when N is odd, and C=N / 2 when N is even. The process goes to step 108. It should be noted that the analysis of the resonant output optical power distribution data here refers to the construction of a two-dimensional plane curve of the corresponding position points of the injection current (horizontal axis) and optical power (vertical axis) of the extracted resonant output optical power distribution data when the extended-range displacement mechanism is loaded with different driving pulses (initial value [1], intermediate value [C], and final value [N]), to obtain the extended-cavity swept source tail fiber lasing power and injection current distribution traces.

[0064] Step 108: the extended-cavity swept source tail fiber lasing power and injection current distribution trace P[C][1~M][1~M] is analyzed to obtain the maximum output power Pmax of the extended-cavity swept source tail fiber, Pmax=P[C][M][M], and the process goes to step 109. It should be noted that due to the particularity of the extended-cavity swept source, the maximum output power basically appears at the middle position of the entire stroke of the extended-range displacement mechanism, i.e., when the driving pulse is the intermediate value [C] and the driving current is the maximum [M].

[0065] Step 109: Analyzing the tail fiber of the extended cavity swept source injection current distribution trace P[1][1~M][1~M] and P[N][1~M][1~M], the minimum drive current DCmin allowed for the extended cavity swept source full-band output is obtained, see step 201 for details, go to step 110;

[0066] Step 110: Control computer (7) reads the drive pulse signal number C corresponding to the maximum output power Pmax of the extended cavity swept source and the drive current number M, loads C and M into the gain chip (201) in the single-tube gain seed source integrated unit (101) and the range extender displacement mechanism (204) respectively, go to step 111;

[0067] Step 111: Control computer (7) adjusts the attenuation gear of the program-controlled attenuator (3) by 1, judges whether the resonant optical power PA collected by the optical power meter (5) is less than or equal to 9dBm, if yes, go to step 113, otherwise go to step 112;

[0068] Step 112: Control computer (7) adjusts the attenuation gear of the program-controlled attenuator (3) by 1 again, judges whether the resonant optical power PA collected by the optical power meter (5) is less than or equal to 9dBm, if yes, go to step 113, otherwise go to step 112;

[0069] Step 113: Control computer (7) sets optical switch (4) to channel position CP[2], control circuit (103) loads drive current DC[DCmin+100mA~M] into gain chip (201) in single-tube gain seed source integrated unit (101) respectively, measures and records resonant output wavelength data generated by M-(DCmin+100mA)+1 drive currents under the excitation of N drive pulse signals of range extender displacement mechanism (204), go to step 114;

[0070] Step 114: After the resonant output wavelength data is automatically tested, control computer (7) reads resonant output wavelength distribution data W[1~N][DCmin+100mA~M][DCmin+100mA~M], go to step 115;

[0071] Step 115: analyze the resonant output wavelength distribution data W[1~N][DCmin+100mA~M][DCmin+100mA~M] to obtain a tuning wavelength and tolerance current distribution trace WE, and analyze the distribution trace WE to obtain an optimal working current point DC_OP. For details, see step 301, and go to step 116. It should be noted that the analysis of the resonant output wavelength distribution data to obtain the tuning wavelength and tolerance current distribution trace refers to constructing a two-dimensional plane curve of the corresponding position points of the injection current (horizontal axis) and optical wavelength (vertical axis) on the extracted resonant output wavelength distribution data when the range extender displacement mechanism is loaded with different driving pulses, to obtain the tuning wavelength and tolerance current distribution trace.

[0072] Step 116: control the computer (7) to load the driving current DC_OP on the gain chip (201) in the single-tube gain seed source integrated unit (101) through the control circuit (103), control the control temperature T1=[RT-2℃~RT+2℃] of the thermistor (202), measure and record the resonant output wavelength data generated by the range extender displacement mechanism (204) under N driving pulse signal excitation conditions and ST different control temperature conditions, and go to step 117.

[0073] Step 117: after the resonant output wavelength data automatic test is completed, the control computer (7) reads the resonant output wavelength distribution data WT[1~N][T1][1~ST], and goes to step 118.

[0074] Step 118: analyze the resonant output wavelength distribution data WT[1~N][T1][1~ST] to obtain a tuning wavelength and control temperature distribution trace WTE, and analyze the distribution trace WTE to obtain an optimal working control temperature point T_OP. For details, see step 401, and go to step 119. It should be noted that the analysis of the resonant output wavelength distribution data to obtain the tuning wavelength and control temperature distribution trace refers to constructing a two-dimensional plane curve of the corresponding position points of the control temperature (horizontal axis) and optical wavelength (vertical axis) on the extracted resonant output wavelength distribution data when the range extender displacement mechanism is loaded with different driving pulses, to obtain the tuning wavelength and control temperature distribution trace.

[0075] Step 119: output the optimal working point W_OP[DC_OP, T_OP] of the extended cavity swept source.

[0076] The calculation process of the minimum driving current DCmin allowed to be loaded by the extended cavity swept source full-waveband output in this embodiment is as shown in Figure 3 By quickly analyzing the tail fiber lasing power and injection current distribution data of the extended cavity swept source, the distribution traces P[1][1~M][1~M] and P[N][1~M][1~M] are obtained. The specific steps are as follows:

[0077] Step 201: read the tail fiber of the extended cavity swept source injection current distribution trace P[1][1~M][1~M] and P[N][1~M][1~M], go to step 202;

[0078] Step 202: calculate P[1][i+1][i+1] / P[1][i][i] from the initial current and the first lasing power P[1][1][1] of the injection current distribution trace P[1][1~M][1~M] backward point by point, i=1~M, if the ratio of the nth0 point is greater than the determination threshold ThD0(typical threshold value is 3), stop operation, output the current value DC0, go to step 203;

[0079] Step 203: calculate P[1][j+1][j+1] / P[1][j][j] from the initial current and the first lasing power P[1][1][1] of the injection current distribution trace P[N][1~M][1~M] backward point by point, j=1~M, if the ratio of the nth1 point is greater than the determination threshold ThD1(typical threshold value is 3), stop operation, output the current value DC1, go to step 204;

[0080] Step 204: read the current values DC0 and DC1, calculate the difference DC01 of DC0-DC1, if DC01 is greater than or equal to 0, then the minimum drive current Dcmin allowed to be loaded for the full waveband output of the extended cavity swept source is DC0, otherwise, the minimum drive current Dcmin allowed to be loaded for the full waveband output of the extended cavity swept source is DC1, go to step 205;

[0081] Step 205: the minimum drive current Dcmin allowed to be loaded for the full waveband output of the extended cavity swept source.

[0082] In this embodiment, the original resonant output wavelength distribution data is automatically analyzed and the obtained tuning wavelength and tolerance current distribution trace is processed to obtain the best working current point DC_OP. The calculation process of the best working current point is as shown in the figure Figure 4 , and the specific steps are as follows:

[0083] Step 301: read the original resonant output wavelength distribution data W[1~N][DCmin+100mA~M][DCmin+100mA~M], go to step 302;

[0084] Step 302: convert the original resonant output wavelength distribution data to frequency domain data Fre=c / W[1~N][DCmin+100mA~M][DCmin+100mA~M], c is the speed of light in vacuum, go to step 303;

[0085] Step 303: Calculate the resonance frequency difference DF[ii] = Fre[k+1] - Fre[k] of the adjacent two points of the extended-range displacement mechanism (204) under the excitation of N driving pulse signals respectively, ii = 1 ~ N, k = DCmin + 100mA ~ M, turn to step 304;

[0086] Step 304: Find the driving current point of DF[ii] > 0, and record the current DC[k] and DC[k+1] driving current points, turn to step 305;

[0087] Step 305: Set the current value outside the tolerance current FL_1[1~N] corresponding to the DC[k+1] and DC[k] two points in the DC[DCmin + 100mA ~ M] driving current of the extended-range displacement mechanism (204) under the excitation of N driving pulse signals respectively to 0, turn to step 306;

[0088] Step 306: Merge the tolerance current FL_1[1~N] distribution data into full-band tolerance current FL_Q, calculate the difference sequence DC_DF of DC[DCmin + 100mA ~ M] and FL_Q, and the maximum value max(DC_DF) in DC_DF is equal to the optimal working current point DC_OP, turn to step 307;

[0089] Step 307: Output the optimal working current point DC_OP.

[0090] In this embodiment, the original resonance output wavelength distribution data is automatically analyzed, and the obtained tuning wavelength and control temperature distribution trace are processed to obtain the optimal working control temperature point T_OP. The calculation process of the optimal working control temperature point is as shown in Figure 5 , and the specific steps are as follows:

[0091] Step 401: Read the original resonance output wavelength distribution data WT[1~N][T1][1~ST], turn to step 402;

[0092] Step 402: Convert the original resonance output wavelength distribution data into frequency domain data Fre1 = c / WT[1~N][T1][1~ST], c is the speed of light in vacuum, turn to step 403;

[0093] Step 403: Calculate the resonance frequency difference DF[iii] = Fre[kk+1] - Fre[kk] of the adjacent two points of the extended-range displacement mechanism (204) under the excitation of N driving pulse signals respectively, iii = 1 ~ N, kk = RT-2℃ ~ RT+2℃, turn to step 404;

[0094] Step 404: find the control temperature point of DF[iii]>0, and record the current DC[kk] and DC[kk+1] control temperature points, and go to step 405;

[0095] Step 405: set the control temperature value outside the tolerance temperature FL_2[1-N] corresponding to the DC[kk+1] and DC[kk] two points in the RT-2℃-RT+2℃ control temperature of the range extender displacement mechanism (204) under the condition of N driving pulse signal excitation to 0, and go to step 406;

[0096] Step 406: combine the tolerance temperature FL_2[1-N] distribution data into full-band tolerance temperature FL_Q1, calculate the difference sequence T1_DF of T1 and FL_Q1, and then the maximum value max(T1_DF) in T1_DF is equal to the optimal working temperature point T_OP, and go to step 407;

[0097] Step 407: output the optimal working temperature point T_OP.

[0098] The automatic test method for the optimal working point of the extended cavity swept source provided in the embodiment is based on the characteristics that the gain seed source used by the swept source is easily affected by the injection current and the environmental temperature fluctuation. Through in-depth analysis of the test traces of the tail fiber lasing power of the extended cavity swept source, the injection current, the tolerance current and the tuning wavelength, and the tuning wavelength and the control temperature, the automatic analysis of the working point characteristic parameters of the extended cavity resonant unit is realized, so as to obtain the distribution data of the intrinsic working parameters of the single-tube gain seed source of different batches and different packaging processes, realize the efficient and high-accuracy test of the optimal working point characteristic parameters of the extended cavity resonant unit, and obtain the wide-tuning extended cavity continuous laser output without mode jump suppression. On the one hand, the traditional on-chip test system is complicated in the process of calibrating the characteristic working parameters of the single-tube gain seed source, the whole test system structure is complex, and the test of the working parameters of the seed source cannot effectively represent the compatibility of the overall performance of the extended cavity resonant unit to the swept source system, which leads to large differences in the output index performance of the swept source. On the other hand, the traditional hybrid integrated extended cavity swept source relies on cavity mode monitoring and phase hybrid compensation, which leads to the problems of low efficiency, complex structure and algorithm in the process of assembling and debugging the extended cavity continuous swept source. The embodiment provides an advanced test instrument for the fields of intelligent high-speed coherent network reconfigurable transmission, optical fiber three-dimensional shape frequency domain sensing, high-precision gas spectrum measurement and automatic driving, and further expands the application range of the wide-range, non-jump-mode extended cavity continuous swept source, increases the application scenarios of the wide-range, non-jump-mode extended cavity continuous swept source, and promotes the rapid development of the wide-range, non-jump-mode extended cavity continuous swept source industry.

[0099] Embodiment two

[0100] As Figure 5 ,Figure 6 The embodiment provides an automatic test system for extending the optimal working point of a cavity swept source.

[0101] The cavity swept source is composed of a single-tube gain seed source integrated unit, a shock-absorbing bearing unit, a control circuit and an optical interface.

[0102] The high-precision thermostat is used for simulating the working environment temperature that the cavity swept source may face.

[0103] The program-controlled attenuator is controlled by the control computer and is used for attenuating the resonant maser light power of the cavity swept source, so that the optical wavelength meter is always in a working state below the damage threshold.

[0104] The optical switch is controlled by the control computer and switches the optical signal output channels of the optical power meter and the optical wavelength meter.

[0105] The optical power meter is used for extracting the resonant light power of the gain chip under different injection currents.

[0106] The optical wavelength meter is used for recording the maser wavelength.

[0107] The control computer provides the instruction initialization and driving signals of the control circuit, the temperature regulation signals of the high-precision thermostat, the attenuation gear initialization and attenuation gear switching of the program-controlled attenuator, the instruction initialization and test channel switching of the optical switch, the synchronous trigger collection signals of the optical power meter and the optical wavelength meter, and receives and processes the resonant power and the maser wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter.

[0108] The single-tube gain seed source integrated unit is mainly composed of a gain chip, a thermistor, a thermo-electric cooler, an extended-range displacement mechanism and a gold wire bonding connection line.

[0109] The gain chip is used for generating a free-space optical external cavity strong feedback seed source.

[0110] The thermistor is used for monitoring and feeding back the junction temperature of the gain chip.

[0111] The thermo-electric cooler is used for temperature field adjustment.

[0112] The extended-range displacement mechanism is a stepping motor integrated with a piezoelectric ceramic and is used for controllable tuning of the cavity length of the cavity swept source.

[0113] The gold wire bonding connection line is used for electrical connection.

[0114] The shock-absorbing bearing unit is used for bearing the cavity swept source and reducing damping.

[0115] The control circuit is controlled by a control computer and is used for driving current loading of the single-tube gain seed source integrated unit.

[0116] The optical interface is used for output of the swept-frequency laser signal.

[0117] The present application provides an automatic test method for an optimal working point of an extended cavity swept-frequency source. Through in-depth analysis of test traces of tail fiber lasing power of the extended cavity swept-frequency source, injection current, tuning wavelength and tolerance current, and tuning wavelength and control temperature, automatic analysis of working point characteristic parameters of the extended cavity resonance unit is realized, so that distribution data of intrinsic working parameters of single-tube gain seed source integrated units of different batches and different packaging processes are obtained, efficient and high-accuracy test of the optimal working point characteristic parameters of the extended cavity resonance unit is realized, and wide-tuning extended cavity continuous laser output without mode jump suppression is obtained on the basis. A structure of an automatic test system for the optimal working point of the typical extended cavity swept-frequency source is shown in Figure 6 , and comprises the following components.

[0118] (1) The extended cavity swept-frequency source mainly comprises a single-tube gain seed source integrated unit (101), a shock-absorbing bearing unit (102), a control circuit (103), and an optical interface (104), and details are shown in Figure 2 .

[0119] (2) The high-precision thermostat is used for simulating the working environment temperature that the extended cavity swept-frequency source may face, and the typical temperature regulation accuracy is ±1℃, and the typical temperature setting range is 10℃-35℃.

[0120] (3) The program-controlled attenuator is controlled by the control computer (7) and is used for attenuation of the resonance lasing light power of the extended cavity swept-frequency source (1), so as to ensure that the optical wavelength meter (6) is always in a working state below the damage threshold.

[0121] (4) The 1×2 optical switch is controlled by the control computer (7) and switches the optical signal output channels of the optical power meter (5) and the optical wavelength meter (6).

[0122] (5) The optical power meter is used for extraction of resonance light power of the gain chip under different injection currents.

[0123] (6) The optical wavelength meter is used for recording of the lasing wavelength.

[0124] (7) Control computer, providing instruction initialization and driving signal of control circuit (103) in extended cavity swept source, temperature control signal of high-precision thermostat (2), attenuation gear initialization and attenuation gear switching of program-controlled attenuator (3), instruction initialization and test channel switching of optical switch (4), synchronous trigger acquisition signal of optical power meter (5) and optical wavelength meter (6), receiving and processing of resonant power and lasing wavelength distribution data information recorded in real time in optical power meter (5) and optical wavelength meter (6).

[0125] The typical implementation of the automatic test of the optimal working point of the extended cavity swept source is as shown in the figure. Figure 7 As shown in the figure, through in-depth analysis of the test traces of the tail fiber lasing power of the extended cavity swept source, the injection current, the tuning wavelength and the tolerance current, and the tuning wavelength and the control temperature, the automatic analysis of the working point characteristic parameters of the extended cavity resonant unit is realized, so that the distribution data of the intrinsic working parameters of the single-tube gain seed source integrated unit of different batches and different packaging processes are obtained, the efficient and high-accuracy test of the optimal working point characteristic parameters of the extended cavity resonant unit is realized, and the specific composition is as follows:

[0126] As shown in the figure, Figure 8 The single-tube gain seed source integrated unit (101) is mainly composed of a gain chip (201), a thermistor (202), a thermo-electric cooler (203), an extended-range displacement mechanism (204), and a gold wire bonding connection line (205). The gain chip (201) is typically an InP-based single-angle semiconductor gain chip, the typical value of the single-angle reflectivity is 0.005%, and the typical value of the 3dB bandwidth is better than 80nm, which is used for the generation of a free-space optical external cavity strong feedback seed source; the thermistor (202) is typically controlled at a temperature of 25℃ (10kΩ), which is used for the monitoring and feedback of the junction temperature of the gain chip; the thermo-electric cooler (203) is used for temperature field adjustment; the extended-range displacement mechanism (204) is typically a stepping motor integrated with a piezoelectric ceramic, which is used for controllable tuning of the cavity length of the extended cavity swept source; and the gold wire bonding connection line (205) is used for electrical connection.

[0127] (102) Shock absorption and bearing unit, used for bearing the extended cavity swept source and reducing damping.

[0128] (103) Control circuit, controlled by the control computer (7), used for driving current loading of the single-tube gain seed source integrated unit (101).

[0129] (104) Optical interface, generally an FC / APC interface, used for output of the swept laser signal.

[0130] The above describes the specific embodiments of the present application in combination with the drawings, but is not a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. An automatic test method for extending the optimal operating point of a swept source cavity, characterized by, The application relates to a method for determining an optimal working point of an extended cavity swept source. The method comprises the following steps: obtaining tail fiber lasing power and injection current distribution trajectory lines of the extended cavity swept source by testing distribution data of resonant output optical power under different driving currents, and determining maximum output power and minimum driving current of the extended cavity swept source by analyzing the tail fiber lasing power and injection current distribution trajectory lines; obtaining tuning wavelength and tolerance current distribution trajectory lines by testing resonant output wavelength distribution data under different control temperatures, and determining an optimal working current point by analyzing the tuning wavelength and tolerance current distribution trajectory lines, with the maximum output power and the minimum driving current of the extended cavity swept source as limiting values; obtaining tuning wavelength and control temperature partial trajectory lines by testing resonant output wavelength distribution data under different control temperatures, and determining an optimal working control temperature point by analyzing the tuning wavelength and control temperature distribution trajectory lines; 2. The automatic testing method for the optimal operating point of an extended cavity sweep frequency source as described in claim 1, characterized in that, and outputting an optimal working point of the extended cavity swept source based on the optimal working current point and the optimal working control temperature point. The method for obtaining the tail fiber lasing power and injection current distribution trajectory lines by testing the distribution data of resonant output optical power under different driving currents comprises the following steps: loading driving currents DC[1~M] respectively into gain chips in a single-tube gain seed source integrated unit in the extended cavity swept source, measuring and recording resonant output optical power data generated by the M driving currents under the excitation of N driving pulse signals respectively in the extended cavity swept source; after the resonant output optical power data are automatically tested, reading resonant output optical power distribution data P[1~N][1~M][1~M]; 3. The automatic testing method for the optimal operating point of an extended cavity sweep frequency source as described in claim 1, characterized in that, analyzing the resonant output optical power distribution data P[1~N][1~M][1~M] to obtain tail fiber lasing power and injection current distribution trajectory lines P[1][1~M][1~M], P[C][1~M][1~M] and P[N][1~M][1~M], wherein C=(N+1) / 2 when N is odd, and C=N / 2 when N is even. The method for determining the maximum output power and the minimum driving current of the extended cavity swept source by analyzing the tail fiber lasing power and injection current distribution trajectory lines comprises the following steps: analyzing the tail fiber lasing power and injection current distribution trajectory line P[C][1~M][1~M] to obtain the maximum output power Pmax of the extended cavity swept source, Pmax=P[C][M][M]; 4. The automatic testing method for the optimal operating point of an extended cavity sweep frequency source as described in claim 3, characterized in that, analyzing the tail fiber lasing power and injection current distribution trajectory lines P[1][1~M][1~M] and P[N][1~M][1~M] to obtain the minimum driving current DCmin allowed to be loaded for full-band output of the extended cavity swept source. The method for obtaining the minimum driving current DCmin allowed to be loaded for full-band output of the extended cavity swept source by analyzing the tail fiber lasing power and injection current distribution trajectory lines P[1][1~M][1~M] and P[N][1~M][1~M] comprises the following steps: reading the tail fiber lasing power and injection current distribution trajectory lines P[1][1~M][1~M] and P[N][1~M][1~M]; The initial current and the first lasing power P[1][1][1] of the self-lasing power and the injected current distribution trace P[1][1~M][1~M] are calculated point by point backward to obtain P[1][i+1][i+1] / P[1][i][i], i=1~M, if the ratio at the nth0 point is greater than the determination threshold ThD0, the operation is stopped, and the current value DC0 is output; The initial current and the first lasing power P[1][1][1] of the self-lasing power and the injected current distribution trace P[N][1~M][1~M] are calculated point by point backward to obtain P[1][j+1][j+1] / P[1][j][j], j=1~M, if the ratio at the nth1 point is greater than the determination threshold ThD1, the operation is stopped, and the current value DC1 is output; The current values DC0 and DC1 are read, the difference DC01 of DC0-DC1 is calculated, if DC01 is greater than or equal to 0, the minimum drive current DCmin=DC0 allowed to be loaded for the full-band output of the extended cavity swept source is extended, otherwise, the minimum drive current DCmin=DC1 allowed to be loaded for the full-band output of the extended cavity swept source is extended. The minimum drive current DCmin allowed to be loaded for the full-band output of the extended cavity swept source is extended.

5. The automatic testing method for the optimal operating point of an extended cavity sweep frequency source as described in claim 1, characterized in that, The maximum output power and the minimum drive current of the extended cavity swept source are taken as the limiting values, the tuning wavelength and the tolerance current distribution trace are obtained by testing the resonant output wavelength distribution data under a single drive current, and specifically: Step a: reading the drive pulse signal number C corresponding to the maximum output power Pmax of the extended cavity swept source and the drive current number M, and loading C and M into the range extender displacement mechanism in the extended cavity swept source and the gain chip in the single-tube gain seed source integrated unit in the extended cavity swept source; Step b: controlling the computer to adjust the attenuation gear of the program-controlled attenuator by 1, and judging whether the resonant optical power PA collected by the optical power meter is less than or equal to the set threshold, if yes, turning to step d, otherwise, turning to step c; Step c: controlling the computer to adjust the attenuation gear of the program-controlled attenuator by 1 again, and judging whether the resonant optical power PA collected by the optical power meter is less than or equal to the set threshold, if yes, turning to step d, otherwise, turning to step c again; Step d: controlling the computer to place the optical switch at the channel position CP[2], loading the drive current DC[DCmin+100mA~M] in the single-tube gain seed source integrated unit in the extended cavity swept source into the gain chip in the extended cavity swept source by the control circuit in the extended cavity swept source, measuring and recording the resonant output wavelength data generated by M-(DCmin+100mA)+1 drive currents under the excitation of N drive pulse signals of the range extender displacement mechanism in the extended cavity swept source, and turning to step e; Step e: after the resonant output wavelength data is automatically tested, reading the resonant output wavelength distribution data W[1~N][DCmin+100mA~M][DCmin+100mA~M], and turning to step f; Step f: analyzing the resonant output wavelength distribution data to obtain the tuning wavelength and the tolerance current distribution trace WE.

6. The method of claim 1, wherein the step of automatically testing the optimum operating point of the extended cavity swept source is characterized by, The analysis of the tuning wavelength and the tolerance current distribution trajectory line determines the optimal working current point, specifically: Read the original resonant output wavelength distribution data W[1~N][DCmin+100mA~M][DCmin+100mA~M]; Convert the original resonant output wavelength distribution data into frequency domain data Fre=c / W[1~N][DCmin+100mA~M][DCmin+100mA~M], c is the speed of light in vacuum; Calculate the resonant frequency difference DF[ii]=Fre[k+1]-Fre[k] of the adjacent two points of the extended cavity swept source internal range extender displacement mechanism under the excitation of N driving pulse signals, ii=1~N, k=DCmin+100mA~M; Find the driving current point where DF[ii]>0, and record the current DC[k] and DC[k+1] driving current points; Set the current values outside the tolerance current FL_1[1~N] corresponding to the DC[k+1] and DC[k] points in the DC[DCmin+100mA~M] driving current of the extended cavity swept source internal range extender displacement mechanism under the excitation of N driving pulse signals to 0; Merge the tolerance current FL_1[1~N] distribution data into full-band tolerance current FL_Q, calculate the difference sequence DC_DF of DC[DCmin+100mA~M] and FL_Q, then the maximum value max(DC_DF) in DC_DF is equal to the optimal working current point DC_OP; Output the optimal working current point DC_OP.

7. The automatic testing method for the optimal operating point of an extended cavity sweep frequency source as described in claim 1, characterized in that, The analysis of the tuning wavelength and the control temperature distribution trajectory line determines the optimal working control temperature point, specifically: Read the original resonant output wavelength distribution data WT[1~N][T1][1~ST]; Convert the original resonant output wavelength distribution data into frequency domain data Fre1=c / WT[1~N][T1][1~ST], c is the speed of light in vacuum; Calculate the resonant frequency difference DF[iii]=Fre[kk+1]-Fre[kk] of the adjacent two points of the extended cavity swept source internal range extender displacement mechanism under the excitation of N driving pulse signals, iii=1~N, kk=RT-2℃~RT+2℃; Find the control temperature point where DF[iii]>0, and record the current DC[kk] and DC[kk+1] control temperature points; Set the control temperature values outside the tolerance temperature FL_2[1~N] corresponding to the DC[kk+1] and DC[kk] points in the RT-2℃~RT+2℃ control temperature of the extended cavity swept source internal range extender displacement mechanism under the excitation of N driving pulse signals to 0; Merge the tolerance temperature FL_2[1~N] distribution data into full-band tolerance temperature FL_Q1, calculate the difference sequence T1_DF of T1 and FL_Q1, then the maximum value max(T1_DF) in T1_DF is equal to the optimal working temperature point T_OP; Output the optimal working temperature point T_OP.

8. An automatic test system for extending the optimum operating point of a swept source cavity, characterized by, The automatic test method for realizing the optimal working point of the extended cavity swept source based on claim 1, comprising: The extended cavity swept source is composed of a single-tube gain seed source integrated unit, a damping bearing unit, a control circuit and an optical interface; The high-precision thermostat is used for simulating the working environment temperature that the extended cavity swept source may face; The program-controlled attenuator is controlled by the control computer and is used for attenuating the resonant laser power of the extended cavity swept source, so as to ensure that the optical wavelength meter is in a real-time damage threshold working state; The optical switch is controlled by the control computer and switches the optical signal output channel of the optical power meter and the optical wavelength meter; The optical power meter is used for extracting the resonant optical power of the gain chip under different injection currents; The optical wavelength meter is used for recording the lasing wavelength; The control computer provides the instruction initialization and driving signal of the control circuit, the temperature regulation signal of the high-precision thermostat, the attenuation gear initialization and attenuation gear switching of the program-controlled attenuator, the instruction initialization and test channel switching of the optical switch, and the synchronous trigger acquisition signal of the optical power meter and the optical wavelength meter, and receives and processes the resonant power and the lasing wavelength distribution data information recorded in real time by the optical power meter and the optical wavelength meter.

9. An automatic test system for optimizing the operating point of a swept-cavity source as recited in claim 8, wherein, The single-tube gain seed source integrated unit is mainly composed of a gain chip, a thermistor, a thermo-electric cooler, an extended-range displacement mechanism and a gold wire bonding connection line; The gain chip is used for generating a free-space optical external cavity strong feedback seed source; The thermistor is used for monitoring and feeding back the junction temperature of the gain chip; The thermo-electric cooler is used for temperature field adjustment; The extended-range displacement mechanism is a stepping motor integrated with a piezoelectric ceramic and is used for controllable tuning of the cavity length of the extended cavity swept source; The gold wire bonding connection line is used for electrical connection.

10. The automatic test system for optimizing the operating point of a swept-cavity source as recited in claim 8, wherein, The damping bearing unit is used for bearing the extended cavity swept source and reducing the damping; The control circuit is controlled by the control computer and is used for driving current loading of the single-tube gain seed source integrated unit; The optical interface is used for outputting the swept laser signal.

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