Piezoelectric ceramic micro-displacement measurement method and device based on optical wavelength tuning

Abstract

The invention provides a piezoelectric ceramic micro-displacement measurement method and device based on optical wavelength tuning, and the method comprises the steps: a main control unit applies a driving pulse to a high-subdivision actuator, obtains the position information of the high-subdivision actuator corresponding to the driving pulse and the optical wavelength tuning information recognized by a wavelength recognition module, and carries out the fitting of a mapping relation curve Y; the main control unit applies driving voltage to the piezoelectric ceramic to be measured in a stepping manner, obtains optical wavelength tuning information caused by displacement of the piezoelectric ceramic to be measured under different driving voltages, and substitutes the optical wavelength tuning information caused by displacement of the piezoelectric ceramic to be measured into the fitting mapping relation curve to calculate corresponding micro-displacement information; the nanoscale displacement of the piezoelectric ceramic to be detected is detected in a non-no-load state, a numerical relationship between a wavelength tuning interval and a cavity length variation is mapped by using a high-subdivision actuator, and different micro-displacement information carried by collected optical wavelengths is analyzed through a main control unit; therefore, the real reachable telescopic length under the non-no-load condition can be effectively represented.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric ceramic performance measurement, and in particular to a piezoelectric ceramic micro-displacement measurement method and equipment based on light wavelength tuning. Background Art

[0002] With the ever-expanding commercial trend of silicon photonic chips and silicon photonic modules in the 800G and 1.6T era, low-cost and high-efficiency production and testing methods are the goals pursued by the industry. This requires that the determination of whether the wafer is qualified or not can be achieved in the front-end process as much as possible, and then accurate testing can be achieved to improve the product yield and reduce costs. This poses new challenges to the performance of tunable laser modules. Piezoelectric ceramics, nano-level driving devices with the characteristics of fast response speed, good repeatability and long service life, have been widely used as their core compensation devices. The micro-displacement reach of piezoelectric ceramics plays an important role in the dynamic compensation capability and fine tuning range of the internal and external cavity modes of the tunable laser module. This parameter even affects the absolute accuracy and line width of the wavelength of the tunable laser module. Due to the differences in preparation process and component ratio, the maximum strokes generated by different piezoelectric ceramics are different. Therefore, it is necessary to accurately measure the micro-displacement parameters of different piezoelectric ceramics, especially the micro-displacement parameters under non-no-load conditions.

[0003] In response to the demand for testing the micro-displacement of piezoelectric ceramics for dynamic compensation of tunable laser module mode mutations, the existing measurement methods usually include mechanical measurement, eddy current displacement meter, laser interferometer, etc. Among them, the mechanical measurement method has poor measurement accuracy, the eddy current displacement meter method is susceptible to electromagnetic interference, and the test structure of the laser interferometer method is complex. In addition, the micro-displacement test results of piezoelectric ceramics obtained by the above methods are all measured when the piezoelectric ceramics are in a no-load state, and the test scenarios are inconsistent with the actual application fields such as tunable laser modules and dynamic derivative test devices. Common methods can no longer meet the needs of nano-level displacement detection of piezoelectric ceramics for dynamic compensation under non-no-load conditions. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the first object of the present invention is to provide a piezoelectric ceramic micro-displacement measurement method based on light wavelength tuning in a non-no-load state, comprising:

[0005] The main control unit applies a driving pulse to the high-subdivision actuator, and obtains the position information P_grating[1~i] corresponding to the driving pulse received by the high-subdivision actuator every T_1 seconds and the optical wavelength tuning information W_tuning[0~ii] recognized by the wavelength recognition module, and fits the mapping relationship curve Y; the main control unit applies a driving voltage V[1~j] to the piezoelectric ceramic to be tested, and obtains the optical wavelength tuning information W_pzt[1~jj] caused by the displacement of the piezoelectric ceramic to be tested under different driving voltages V[1~j], and substitutes the optical wavelength tuning information W_pzt[1~jj] into the fitting mapping relationship curve Y to calculate the corresponding micro-displacement information P_pzt[1~jj].

[0006] Specifically, a corresponding relationship curve D_v between the micro-displacement information P_pzt[1~jj] and the driving voltage V[1~j] is established, and it is determined whether the fitting linearity and slope efficiency of the corresponding relationship curve D_v are both greater than the threshold value, so as to evaluate whether the piezoelectric ceramic to be tested meets the compensation requirements of the tunable laser module operation process.

[0007] Specifically, the threshold value of the fitting linearity is 95%, and the threshold value of the slope efficiency is 0.08 μm / V.

[0008] Specifically, the device is preheated before measurement, and the stability of the short-time wavelength is judged. The method for judging the stability of the short-time wavelength is as follows: the main control unit collects N wavelength values ​​Wave_1[1~N] recognized by the wavelength recognition module every T_interaval seconds, collects T_end seconds in total, calculates the standard deviation STD of the wavelength value within T_end seconds, and judges whether the standard deviation STD of the wavelength value is within the threshold range.

[0009] Specifically, the driving voltage applied to the piezoelectric ceramic to be tested is V[j]=V[j-1]×step, where j is the number of applied voltages and step is the applied voltage step.

[0010] The second object of the present invention is to provide a piezoelectric ceramic micro-displacement measuring device based on optical wavelength tuning, comprising:

[0011] A main control unit, a tunable laser module and a wavelength recognition module. A high-subdivision actuator, a piezoelectric ceramic to be tested and a grating ruler are arranged in the resonant cavity of the tunable laser module. The high-subdivision actuator and the piezoelectric ceramic to be tested are used to adjust the cavity length of the resonant cavity. The grating ruler is used to measure the position information of the high-subdivision actuator. The main control unit provides a driving pulse for driving the high-subdivision actuator to extend and retract and a driving voltage for driving the piezoelectric ceramic to be tested to extend. The tunable laser module converts the driving pulse and driving voltage provided by the main control unit into an optical wavelength tuning signal carrying a micro-displacement. The wavelength recognition module recognizes the optical wavelength tuning signal of the tunable laser module. The main control unit collects and processes the optical wavelength tuning signal output by the wavelength recognition module.

[0012] Specifically, the high-subdivision actuator includes a high-subdivision stepper motor and a coupling connected to the output shaft of the high-subdivision actuator. The output shaft of the high-subdivision stepper motor can rotate and retract. The coupling is provided with a piezoelectric ceramic to be tested whose polarization direction is set in the same direction as the retraction direction of the output shaft.

[0013] Specifically, the output shaft of the high-subdivision stepper motor passes through the high-subdivision stepper motor, and the rear end of the output shaft extends from the rear side of the high-subdivision stepper motor. The grating ruler is arranged on the rear side of the high-subdivision stepper motor to read the position of the end of the output shaft.

[0014] Specifically, the tunable laser module adopts a Littman-Metcalf structure.

[0015] Specifically, the wavelength identification module is a Michelson interferometer, a Fizeau interferometer or a high-precision wavelength meter.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention proposes a method for measuring micro-displacement of piezoelectric ceramics based on optical wavelength tuning. The nanometer-level displacement of the piezoelectric ceramic to be tested is detected in a non-no-load state. The numerical relationship between the wavelength tuning range and the cavity length change is mapped using a high-resolution actuator. The driving signal provided by the main control unit is converted into an optical wavelength tuning signal carrying the micro-displacement through acquisition and analysis, thereby effectively characterizing the actual achievable telescopic length of the piezoelectric ceramic.

[0018] (2) Compared with conventional testing methods, the present invention not only improves measurement accuracy and reduces structural complexity, but also closely fits the actual application scenario and can more intuitively and accurately reflect the mapping between the micro-displacement parameters of the piezoelectric ceramic to be tested and the performance of the tunable laser module.

[0019] (3) The present invention measures the micro-displacement of piezoelectric ceramics through a tunable laser module, further expanding the application scope of the tunable laser module, adding application scenarios for the tunable laser module, and further promoting the rapid development of the tunable laser module industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the measuring device of the present invention;

[0021] Figure 2 It is a schematic diagram of the assembly of the high-subdivision actuator, the piezoelectric ceramic to be tested and the grating ruler in the resonant cavity of the tunable laser module of the present invention;

[0022] Figure 3 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The specific implementation of the present invention is described in detail below in combination with specific embodiments.

[0024] The present invention provides a piezoelectric ceramic micro-displacement measurement method and device based on optical wavelength tuning, which detects the nanometer-level displacement of the piezoelectric ceramic 22 to be tested in a non-no-load state, uses a high-resolution actuator to map the numerical relationship between the wavelength tuning range and the cavity length change, and uses a main control unit 1 to analyze the different micro-displacement information carried by the collected optical wavelength, thereby effectively characterizing the real achievable telescopic length under non-no-load conditions.

[0025] The measuring device comprises a main control unit 1 , a tunable laser module 2 , and a wavelength identification module 3 .

[0026] A high-subdivision actuator, a piezoelectric ceramic to be measured 22 and a grating ruler 25 are arranged in the resonant cavity of the tunable laser module 2. The high-subdivision actuator and the piezoelectric ceramic to be measured 22 are used to adjust the cavity length of the resonant cavity. The laser outputs different optical wavelength tuning signals through the resonant cavity with different cavity lengths. The grating ruler 25 is used to measure the position information of the high-subdivision actuator. Typical structures of the tunable laser module 2 include Littman-Metcalf and its improved version.

[0027] The high-resolution actuator includes a high-resolution stepper motor 21 and a coupling 24 connected to the output shaft 23 of the high-resolution actuator. The output shaft 23 of the high-resolution stepper motor 21 can rotate and retract. When the high-resolution stepper motor 21 receives the driving pulse applied by the main control unit 1, the output shaft 23 rotates forward or reversely to adjust the position information of the high-resolution actuator. The piezoelectric ceramic 22 to be tested is arranged at the front side of the coupling 24. After the piezoelectric ceramic 22 to be tested is subjected to the driving voltage applied by the main control unit 1, its polarization direction is slightly extended, and the polarization direction of the piezoelectric ceramic 22 to be tested is arranged in the same direction as the extension direction of the output shaft 23. The output shaft 23 of the high-resolution stepper motor 21 passes through the high-resolution stepper motor 21, and the rear end of the output shaft 23 extends from the rear side of the high-resolution stepper motor 21. A grating ruler 25 and a reading head 26 are arranged at the rear side of the high-resolution stepper motor 21. By reading the end position of the output shaft 23 of the high-resolution stepper motor 21, the position information of the high-resolution actuator is obtained.

[0028] The main control unit 1 is used to provide a driving pulse for driving the high-resolution actuator to extend and retract, a driving voltage for driving the piezoelectric ceramic 22 to be tested to extend, and to collect and process the wavelength information output by the wavelength recognition module 3 .

[0029] The wavelength recognition module 3 is used to recognize that the tunable laser module 2 converts the driving signal provided by the main control unit 1 into an optical wavelength tuning signal carrying a micro-displacement. Its typical structure is a Michelson interferometer or a Fizeau interferometer, and its typical device is a high-precision wavelength meter.

[0030] The present invention provides a piezoelectric ceramic micro-displacement measurement method based on light wavelength tuning, and the specific steps are as follows.

[0031] S1: Turn on and preheat the tunable laser module and wavelength identification module through the main control unit.

[0032] S2: After preheating for T_warm minutes (e.g., 10 minutes), the main control unit reads the N wavelength values ​​Wave_1[1~N] identified by the wavelength identification module every T_interaval seconds (e.g., 1 second). After collecting the values ​​for a total of T_end minutes (e.g., 5 minutes), the standard deviation STD of the wavelength values ​​obtained within the T_end time is calculated, where Wave_1[1] is the first wavelength value collected at the T_warm+T_interaval time, and Wave_1[N] is the last wavelength value collected at the T_end time.

[0033] S3: Determine whether the standard deviation STD of the wavelength value is within the threshold interval Th_1 (typical value is -1pm / T_end to 1pm / T_end) to determine the stability of the short-time wavelength. If it is not within the threshold interval Th_1, go to S2. If it is, go to S4.

[0034] S4: Set the operating parameters of the tunable laser module, including scanning speed V_speed, starting wavelength W_start, ending wavelength W_end, step interval I_step, delay time T_delay and output power O_power (typical value: 8dBm);

[0035] S5: The main control unit applies a driving pulse to the high-resolution actuator in the tunable laser module every T_1 seconds, reads the position information P_grating[1~i] corresponding to the high-resolution actuator at the rising edge of each pulse of the grating ruler, i is the number of rising edges of the driving pulse, and reads the corresponding optical wavelength tuning information W_tuning[0~ii] identified by the wavelength recognition module, ii is the position of the actuator;

[0036] in: ;

[0037] .

[0038] S6: Use a quadratic equation to fit a mapping relationship curve Y between the position information P_grating[1~i] and the optical wavelength tuning information W_tuning[0~ii], where W_tuning[0]=W_start, and the corresponding grating ruler position is point 0.

[0039] S7: The main control unit applies a driving voltage V[1~j] to the piezoelectric ceramic to be tested in the tunable laser module, where V[j]=V[j-1]×step, where j is the number of applied voltages and step is the applied voltage step.

[0040] S8: The main control unit reads the optical wavelength tuning information W_pzt[1~jj] corresponding to different driving voltages V[1~j] identified by the wavelength recognition module, where jj represents the number of micro-displacements of the piezoelectric ceramic.

[0041] S9: Substitute the optical wavelength tuning information W_pzt[1~jj] into the mapping relationship curve Y, and calculate the micro-displacement information P_pzt[1]~P_pzt[jj] corresponding to the different optical wavelength tuning information W_pzt[1]~W_pzt[jj].

[0042] S10: Establish the corresponding relationship D_v between the micro-displacement information P_pzt[1~jj] and V[1~j], perform linear fitting on D_v, and evaluate whether the piezoelectric ceramic to be tested meets the compensation of the tunable laser module operation process. If the fitting linearity is greater than 95% and the slope efficiency is greater than the threshold (the threshold can be set to 0.08 microns / volt), the piezoelectric ceramic can be used for compensation of the normal operation process of the tunable laser module.

[0043] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning, characterized in that: include: The main control unit applies a driving pulse to the high-resolution actuator, obtains the position information P_grating[1~i] corresponding to the driving pulse received by the high-resolution actuator every T_1 seconds and the optical wavelength tuning information W_tuning[0~ii] recognized by the wavelength recognition module, and fits the mapping relationship curve Y; The main control unit applies a driving voltage V[1~j] to the piezoelectric ceramic to be tested, and obtains the optical wavelength tuning information W_pzt[1~jj] caused by the displacement of the piezoelectric ceramic to be tested under different driving voltages V[1~j], and substitutes the optical wavelength tuning information W_pzt[1~jj] into the fitting mapping relationship curve Y to calculate the corresponding micro-displacement information P_pzt[1~jj].

2. The piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning according to claim 1 is characterized in that: Establish the corresponding relationship curve D_v between the micro-displacement information P_pzt[1~jj] and the driving voltage V[1~j], judge whether the fitting linearity and slope efficiency of the corresponding relationship curve D_v are both greater than the threshold, and evaluate whether the piezoelectric ceramic to be tested meets the compensation requirements of the tunable laser module operation process.

3. The piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning according to claim 2 is characterized in that: The threshold value of the fitting linearity is 95%, and the threshold value of the slope efficiency is 0.08 μm / V.

4. The piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning according to claim 1 is characterized in that: Before measurement, the device is preheated and the short-time wavelength stability is determined. The method for determining the short-time wavelength stability is as follows: the main control unit collects N wavelength values ​​Wave_1[1~N] every T_interaval seconds, reads the wavelength value Wave_1[1~N] identified by the wavelength recognition module, collects T_end seconds in total, calculates the standard deviation STD of the wavelength value within T_end seconds, and determines whether the standard deviation STD of the wavelength value is within the threshold range.

5. The piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning according to claim 1 is characterized in that: The driving voltage applied to the piezoelectric ceramic to be tested is V[j]=V[j-1]×step, where j is the number of applied voltages and step is the applied voltage step.

6. A piezoelectric ceramic micro-displacement measurement device based on optical wavelength tuning, characterized in that: The piezoelectric ceramic micro-displacement measurement method based on optical wavelength tuning as described in any one of claims 1 to 5 comprises: a main control unit, a tunable laser module and a wavelength recognition module, a high-subdivision actuator, a piezoelectric ceramic to be measured and a grating ruler are arranged in the resonant cavity of the tunable laser module, the high-subdivision actuator and the piezoelectric ceramic to be measured are used to adjust the cavity length of the resonant cavity, the grating ruler is used to measure the position information of the high-subdivision actuator, the main control unit provides a driving pulse for driving the high-subdivision actuator to extend and retract and a driving voltage for driving the piezoelectric ceramic to be measured to extend, the tunable laser module converts the driving pulse and driving voltage provided by the main control unit into an optical wavelength tuning signal carrying a micro-displacement, the wavelength recognition module recognizes the optical wavelength tuning signal of the tunable laser module, and the main control unit collects and processes the optical wavelength tuning signal output by the wavelength recognition module.

7. The piezoelectric ceramic micro-displacement measuring device based on optical wavelength tuning according to claim 6 is characterized in that: The high-subdivision actuator includes a high-subdivision stepper motor and a coupling connected to the output shaft of the high-subdivision actuator. The output shaft of the high-subdivision stepper motor can rotate and retract. The coupling is provided with a piezoelectric ceramic to be tested whose polarization direction is set in the same direction as the retraction direction of the output shaft.

8. The piezoelectric ceramic micro-displacement measuring device based on optical wavelength tuning according to claim 7 is characterized in that: The output shaft of the high-subdivision stepper motor passes through the high-subdivision stepper motor, and the rear end of the output shaft extends from the rear side of the high-subdivision stepper motor. The grating ruler is arranged on the rear side of the high-subdivision stepper motor to read the position of the end of the output shaft.

9. The piezoelectric ceramic micro-displacement measuring device based on optical wavelength tuning according to claim 6, characterized in that: The tunable laser module adopts a Littman-Metcalf structure.

10. The piezoelectric ceramic micro-displacement measuring device based on optical wavelength tuning according to claim 6, characterized in that: The wavelength identification module is a Michelson interferometer, a Fizeau interferometer or a high-precision wavelength meter.

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