Dual-wavelength tuning interference test method for tunable laser

Abstract

The invention discloses a dual-wavelength tuning interference test method for a tunable laser, and belongs to the technical field of computer communication, and the method comprises the following steps: 1, constructing a dual-wavelength interference measurement system which comprises a tunable laser, an optical splitter, a reference light path and a measurement light path, the optical splitter splits the initial laser beam into two light beams, and the two light beams enter the reference light path and the measurement light path respectively; the feedback control circuit monitors the wavelength of the laser output by the tunable laser in real time, and the automatic calibration module adjusts the light path of the interference device in real time while adjusting the working parameters, thereby ensuring that the light beam is correctly propagated in the reference arm and the measurement arm, and enabling the interference fringes to always keep high quality. The interference of the light path change on the measurement result is avoided; and parameters such as displacement and intensity of the interference fringes are analyzed and extracted through data processing software, so that the measurement efficiency and the data accuracy are greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical interference testing, and specifically relates to a dual-wavelength tuning interference testing method for a tunable laser. Background Technique

[0002] In the field of optical measurement, with the continuous improvement of the requirements for measurement accuracy, the application of tunable lasers is becoming increasingly widespread; tunable lasers can output lasers of different wavelengths, providing key light source support for various high-precision measurement technologies such as interference measurement and spectral analysis. However, currently, there is a problem of unstable laser wavelength in tunable lasers.

[0003] Subtle changes in environmental factors have a significant impact on the wavelength of tunable lasers. According to relevant research, for every 1°C change in environmental temperature, the laser wavelength may drift by 0.1nm - 0.5nm. In addition, fluctuations in the operating current of the laser will also cause wavelength instability. In actual working scenarios, a small fluctuation in current (such as ±0.01mA) may cause a change in wavelength. This instability of the wavelength will cause instability of interference fringes in interference measurement, which may lead to large errors in measurement results.

[0004] In existing interference measurement methods, although some attempt to correct the errors caused by wavelength instability through post-processing of data, for complex and variable wavelength fluctuation situations, the correction effect is limited; the overall measurement accuracy needs to be further improved. Summary of the Invention

[0005] Problems to be Solved

[0006] In view of the problems raised in the existing background technique, the present invention provides a dual-wavelength tuning interference testing method for a tunable laser.

[0007] Technical Solution

[0008] To solve the above problems, the present invention adopts the following technical solution.

[0009] A dual-wavelength tuning interference testing method for a tunable laser adopts the following steps: The steps are as follows:

[0010] Step 1: Construct a dual-wavelength interference measurement system. The measurement system includes a tunable laser, a beam splitter, a reference optical path, and a measurement optical path. The tunable laser is used to generate an initial laser beam, and the beam splitter divides the initial laser beam into two beams of light, which respectively enter the reference optical path and the measurement optical path.

[0011] Step 2: Perform wavelength pre-stabilization processing on the tunable laser. The feedback control circuit monitors the wavelength of the laser output by the tunable laser in real time. When it is detected that the wavelength deviates from the preset wavelength range, the feedback control circuit adjusts the operating parameters of the tunable laser;

[0012] Step 3: Interference devices are respectively arranged in the reference optical path and the measurement optical path. The interference device is used to make two beams of light interfere and generate interference fringes;

[0013] Step 4: During the measurement process, at preset time intervals or when the measurement conditions change, alternately change the two wavelengths output by the tunable laser, and record the changes in the interference fringes at different wavelengths;

[0014] Step 5: According to the change data of the interference fringes at different wavelengths, use a preset algorithm to calculate the relevant parameters of the measurement object. The algorithm can eliminate the measurement error caused by the instability of the laser wavelength and improve the measurement accuracy.

[0015] Preferably, the feedback control circuit includes a wavelength detection module, a comparison module, and a control signal generation module;

[0016] The wavelength detection module is used to detect the wavelength of the laser output by the tunable laser;

[0017] The comparison module compares the detected wavelength with the preset wavelength range;

[0018] The control signal generation module generates a control signal according to the comparison result to adjust the operating parameters of the tunable laser.

[0019] Further, the preset time interval is from 1 millisecond to 100 milliseconds.

[0020] Preferably, the preset algorithm in Step 5 is an error compensation algorithm based on the least squares method. By fitting the change data of the interference fringes at different wavelengths, the measurement error caused by wavelength instability is eliminated.

[0021] Further, the interference device is any one of a Michelson interferometer or a Mach-Zehnder interferometer.

[0022] Still further, the operating references in Step 2 include current parameters and temperature parameters.

[0023] Even further, when adjusting the operating parameters of the tunable laser in Step 2, the specific steps are to use an automatic calibration module to adjust the optical path of the interference device in real time to ensure that the light beam propagates correctly in the reference arm and the measurement arm.

[0024] Beneficial effects

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) The present invention uses a feedback control circuit to monitor the wavelength of the laser output by the tunable laser in real time. At the same time, while adjusting the working parameters, the automatic calibration module adjusts the optical path of the interference device in real time. By monitoring the clarity and stability of the interference fringes, the angles and positions of the mirrors in the interferometer are finely adjusted to ensure that the light beam propagates correctly in the reference arm and the measurement arm, so that the interference fringes always maintain high quality, avoiding interference with the measurement results due to changes in the optical path. The present invention also analyzes and extracts parameters such as the displacement and intensity of the interference fringes through data processing software, greatly improving the measurement efficiency and data accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments or exemplary examples of the present application, the following will briefly introduce the drawings required for use in the description of the embodiments or exemplary examples. Obviously, the drawings in the following description are only some embodiments of the present application, and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the drawings shown.

[0028] Figure 1 It is a flowchart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application to be protected, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0031] Embodiment 1

[0032] As Figure 1 shown, a dual-wavelength tuning interference test method for a tunable laser is as follows:

[0033] Step 1: Construct a dual-wavelength interference measurement system. The measurement system includes a tunable laser, a beam splitter, a reference optical path, and a measurement optical path. The tunable laser is used to generate an initial laser beam. The beam splitter divides the initial laser beam into two beams of light, which enter the reference optical path and the measurement optical path respectively;

[0034] Step 2: Perform wavelength pre-stabilization processing on the tunable laser. The feedback control circuit monitors the wavelength of the laser output by the tunable laser in real time. When it detects that the wavelength deviates from the preset wavelength range, the feedback control circuit adjusts the operating parameters of the tunable laser;

[0035] Step 3: Set interference devices in the reference optical path and the measurement optical path respectively. The interference devices are used to make the two beams of light interfere and generate interference fringes;

[0036] Step 4: During the measurement process, alternately change the two wavelengths output by the tunable laser according to the preset time interval or the change of measurement conditions, and record the changes of the interference fringes at different wavelengths;

[0037] Step 5: According to the change data of the interference fringes at different wavelengths, use a preset algorithm to calculate the relevant parameters of the measurement object. The algorithm can eliminate the measurement error caused by the instability of the laser wavelength and improve the measurement accuracy.

[0038] The feedback control circuit includes a wavelength detection module, a comparison module, and a control signal generation module;

[0039] The wavelength detection module is used to detect the wavelength of the laser output by the tunable laser;

[0040] The comparison module compares the detected wavelength with the preset wavelength range;

[0041] The control signal generation module generates a control signal according to the comparison result to adjust the operating parameters of the tunable laser.

[0042] The preset algorithm in Step 5 is an error compensation algorithm based on the least squares method. By fitting the change data of the interference fringes at different wavelengths, the measurement error caused by wavelength instability is eliminated.

[0043] When adjusting the operating parameters of the tuning laser in Step 2, the specific steps are to use the automatic calibration module to adjust the optical path of the interference device in real time to ensure that the light beam propagates correctly in the reference arm and the measurement arm.

[0044] Refer to Figure 1 , during the specific implementation and operation, the steps are as follows:

[0045] Implementation environment and equipment preparation:

[0046] In an optical laboratory, a dual-wavelength interference measurement system is constructed. A high-performance tunable laser is selected, with a wavelength tuning range of 1500nm - 1600nm, which can meet the requirements of common optical measurements. A beam splitter with a splitting ratio of 50:50 is equipped to ensure that the initial laser beam generated by the tunable laser is evenly divided into two beams of light, which are respectively introduced into the reference optical path and the measurement optical path.

[0047] In the reference optical path and the measurement optical path, Michelson interferometers are respectively installed as interference devices. The structure of the Michelson interferometer is relatively simple and the interference effect is obvious. It can accurately make the two beams of light interfere and produce clear interference fringes, which is convenient for subsequent observation and data recording.

[0048] Wavelength pre-stabilization processing:

[0049] The wavelength detection module in the feedback control circuit uses a high-precision wavelength sensor to monitor the wavelength of the laser output by the tunable laser in real time. The accuracy of this wavelength sensor can reach 0.01nm, and it can sensitively capture the minute changes in wavelength.

[0050] The comparison module compares the wavelength detected by the wavelength detection module with a preset wavelength range (for example, 1549.9nm - 1550.1nm). In this implementation, the preset central wavelength is 1550nm, and the allowable fluctuation range is small to meet the requirements of high-precision measurement.

[0051] When the comparison module finds that the wavelength deviates from the preset range, the control signal generation module immediately generates a control signal according to the comparison result. For example, if the wavelength is lower than 1549.9nm, the control signal generation module will generate a control signal to increase the working current of the tunable laser; if the wavelength is higher than 1550.1nm, a control signal to decrease the current will be generated. At the same time, the control signal generation module will also adjust the temperature control device inside the tunable laser according to the influence characteristics of temperature on wavelength to stabilize the wavelength.

[0052] The working parameters of the tunable laser mainly include current parameters and temperature parameters. When adjusting the current parameters, the magnitude of the current flowing into the tunable laser is precisely changed through the control signal. For example, when the wavelength is on the low side, the current is gradually increased in steps of 0.1mA until the wavelength returns to the preset range. When adjusting the temperature parameters, the working temperature of the tunable laser is precisely controlled by the temperature control device. The accuracy of the temperature control device can reach 0.1°C. If the wavelength drifts due to the influence of temperature, the temperature control device will correspondingly increase or decrease the temperature to stabilize the wavelength.

[0053] While adjusting the working parameters, the optical path of the interference device is adjusted in real time using an automatic calibration module. The automatic calibration module monitors the clarity and stability of the interference fringes and finely tunes the angles and positions of the mirrors in the interferometer to ensure the correct propagation of the light beam in the reference arm and the measurement arm, thereby ensuring that the quality of the interference fringes is not affected by changes in the optical path.

[0054] Dual-wavelength tuning and data acquisition:

[0055] During the measurement process, the two wavelengths output by the tunable laser are alternately changed at a preset time interval of 10 milliseconds. For example, first output a laser with a wavelength of 1550 nm for 10 milliseconds, and record the change in the interference fringes generated by the Michelson interferometer at this time; then quickly switch to a laser with a wavelength of 1555 nm, also for 10 milliseconds, and record the corresponding change in the interference fringes. This fast and stable wavelength switching can obtain a large amount of measurement data at different wavelengths in a short time, improving the measurement efficiency.

[0056] A high-speed image acquisition device is used to capture and record the interference fringes in real time. The frame rate of the image acquisition device is 100 frames per second, which can clearly capture the dynamic changes of the interference fringes after each wavelength switch. The collected image data is transmitted to a computer, and a special data processing software is used to analyze and extract parameters such as the displacement and intensity of the interference fringes, providing accurate data support for the subsequent calculation of measurement parameters.

[0057] Calculation of measurement parameters:

[0058] Based on the change data of the interference fringes at different wavelengths, the relevant parameters of the measurement object are calculated using an error compensation algorithm based on the least squares method. Assume that the measurement object is a small-displacement object, and the displacement changes of the interference fringes at different wavelengths are used as the measurement parameter x i , and the actual displacement of the object is used as the relevant parameter y of the measurement object i .

[0059] Through the data processing software, a large number of data points (x i , y i ) Assuming there are 100 data points, that is, (n = 100) are analyzed and calculated according to the following formula:

[0060]

[0061] After solving the equation, the values of a and b are calculated to construct an accurate measurement model, thereby eliminating the measurement error caused by the instability of the laser wavelength and accurately calculating the relevant parameters such as the displacement of the object. For example, after calculation, the displacement of the object is 0.01 mm, and the measurement accuracy is improved by an order of magnitude compared with that without using this algorithm, reaching the nanometer level.

[0062] The present invention monitors the wavelength of the laser output by the tunable laser in real time through a feedback control circuit. Meanwhile, while adjusting the working parameters, the automatic calibration module adjusts the optical path of the interference device in real time. By monitoring the clarity and stability of the interference fringes, the angles and positions of the mirrors in the interferometer are finely adjusted to ensure that the light beam propagates correctly in the reference arm and the measurement arm, so that the interference fringes always maintain high quality, avoiding interference with the measurement results due to changes in the optical path. The present invention also analyzes and extracts parameters such as the displacement and intensity of the interference fringes through data processing software, greatly improving the measurement efficiency and data accuracy.

[0063] The above-described embodiments only represent the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations, improvements and substitutions can be made, and these all belong to the protection scope of the present invention.

Claims

1. A dual-wavelength tuning interference test method for a tunable laser, characterized in that, The steps are as follows: Step 1: Construct a dual-wavelength interferometric measurement system. The measurement system includes a tunable laser, a beam splitter, a reference optical path, and a measurement optical path. The tunable laser is used to generate an initial laser beam. The beam splitter divides the initial laser beam into two beams of light, which respectively enter the reference optical path and the measurement optical path; Step 2: Perform wavelength pre-stabilization processing on the tunable laser. The feedback control circuit monitors the wavelength of the laser output by the tunable laser in real time. When it is detected that the wavelength deviates from the preset wavelength range, the feedback control circuit adjusts the operating parameters of the tunable laser; Step 3: Interference devices are respectively arranged in the reference optical path and the measurement optical path. The interference device is used to make the two beams of light interfere and generate interference fringes; Step 4: During the measurement process, at preset time intervals or when the measurement conditions change, alternately change the two wavelengths output by the tunable laser, and record the changes in the interference fringes at different wavelengths; Step 5: According to the change data of the interference fringes at different wavelengths, use a preset algorithm to calculate the relevant parameters of the measurement object. The algorithm can eliminate the measurement error caused by the instability of the laser wavelength and improve the measurement accuracy.

2. The dual-wavelength tuning interference test method for a tunable laser according to claim 1, characterized in that: The feedback control circuit includes a wavelength detection module, a comparison module, and a control signal generation module; The wavelength detection module is used to detect the wavelength of the laser output by the tunable laser; The comparison module compares the detected wavelength with the preset wavelength range; The control signal generation module generates a control signal according to the comparison result to adjust the operating parameters of the tunable laser.

3. The dual-wavelength tuning interference test method for a tunable laser according to claim 2, characterized in that: The preset time interval is from 1 millisecond to 100 milliseconds.

4. A dual-wavelength tuning interference test method for a tunable laser according to claim 1, characterized in that: The preset algorithm in Step 5 is an error compensation algorithm based on the least squares method. By fitting the change data of the interference fringes at different wavelengths, the measurement error caused by wavelength instability is eliminated.

5. The dual-wavelength tuning interference test method for a tunable laser according to claim 1, characterized in that: The interference device is any one of a Michelson interferometer or a Mach-Zehnder interferometer.

6. A dual-wavelength tuning interference test method for a tunable laser according to claim 4, characterized in that: The formula of the error compensation algorithm is as follows: x i represents the measurement parameters at different wavelengths, y i corresponds to the relevant parameters of the measurement object, and n represents the number of data points.

7. A dual-wavelength tuning interference test method for a tunable laser according to claim 5, characterized in that, The operating references in Step 2 include current parameters and temperature parameters.

8. A dual-wavelength tuning interference test method for a tunable laser according to claim 7, characterized in that: When adjusting the operating parameters of the tunable laser in Step 2, the specific steps are to use an automatic calibration module to adjust the optical path of the interference device in real time to ensure that the light beam propagates correctly in the reference arm and the measurement arm.

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