A testing device and method for a laser communication filter

Abstract

The application relates to the technical field of laser communication, and discloses a testing device and method for an optical filter for laser communication, which comprises a laser, a to-be-tested optical filter provided with a multilayer film, a rotation control assembly used for adjusting the rotation angle of the to-be-tested optical filter relative to the transmission direction of a laser beam and connected with the to-be-tested optical filter, a monitoring assembly used for collecting a plurality of groups of laser beams when the laser beams are incident on the to-be-tested optical filter at different incident angles, and a main control module used for determining the performance parameters of the to-be-tested optical filter based on the filtering spectrum curve. The testing device and method provided by the application can realize the rapid testing and screening of batch optical filters by accurately positioning and dynamically adjusting the incident angle of the laser beam incident on the to-be-tested optical filter, and combining with synchronous spectrum data collection, and can provide all-round data support for the performance quantification and evaluation of the optical filter.

Description

Technical Field

[0001] This invention relates to the field of laser communication technology, and in particular to a testing device and method for laser communication filters. Background Technology

[0002] In existing laser communication systems, the filtering devices commonly employ a combination of spatial optical lenses and coatings. However, this method is limited by the inherent wavelength-locking characteristics of the coating process, making it difficult to meet the requirements of dynamically adjustable wavelengths in laser communication networking scenarios.

[0003] Currently, to achieve flexible control of transmit and receive wavelengths, complex film structures need to be designed to ensure that performance indicators meet the standards at different target wavelengths. However, such film filter elements often exhibit nonlinear characteristics in their performance. To accurately characterize and verify their optical performance, targeted film testing and modeling research is required. Traditional testing methods often focus on single-parameter measurements, making it difficult to achieve batch screening tests of film systems, resulting in low testing efficiency.

[0004] Therefore, the existing technology needs further improvement. Summary of the Invention

[0005] In view of the shortcomings of existing film-structured filters, which are all measured in a single operation and have low measurement efficiency, the present invention aims to provide a testing device and method for laser communication filters. This method can efficiently complete the modeling and analysis of film system performance parameters, laying a technical foundation for the realization of the dynamic adjustable wavelength function of laser communication.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, this application provides a testing apparatus for laser communication filters, comprising:

[0008] A laser is used to emit a laser beam with a tunable frequency.

[0009] The filter under test includes a multilayer thin film structure, the multilayer thin film structure including at least one Fabry-Perot resonant cavity unit, the filter under test is disposed in the optical path of the laser beam and the laser beam is obliquely incident on the filter under test;

[0010] A rotation control component, connected to the filter under test, is used to adjust the rotation angle of the filter under test relative to the transmission direction of the laser beam, so that the filter under test is located in the target space state;

[0011] A monitoring component is used to collect the filtered spectrum curves of the filter under test when multiple sets of laser beams are incident on the filter under test at different incident angles;

[0012] The main control module is connected to the laser, the rotation control component, and the monitoring component. It is used to adjust the emission wavelength of the laser, output control signals to the rotation control component and the monitoring component to control the rotation angle of the filter under test, and determine the performance parameters of the filter under test based on the filter spectral curves of the filter under test at different incident angles.

[0013] Optionally, the main control module is further configured to establish the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test as a function of the emission wavelength of the laser beam. Based on the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test as a function of the emission wavelength of the laser beam, the filter spectrum curve of the filter under test at different incident angles is obtained.

[0014] Optionally, the rotation control component includes: a drive component and an encoder;

[0015] The driving component is used to adjust the rotation angle of the filter under test according to the received control command;

[0016] The encoder is used to monitor the rotation angle of the filter under test and feed it back to the main control module.

[0017] Optionally, the monitoring components include a beam splitter, a photodetector, and a spectrometer;

[0018] The beam splitter is used to receive the filtered light beam output by the filter under test and split the filtered light beam into a first split beam and a second split beam.

[0019] The photodetector is located in the optical path of the first split beam, receives the first split beam, and detects the energy value of the first split beam;

[0020] The spectrometer is located in the optical path of the second beam splitter and is used to receive the second beam splitter and detect the curve of optical power corresponding to the second beam splitter as a function of optical wavelength.

[0021] Optionally, an optical fiber amplifier and an attenuator are also provided in the optical path of the laser beam output by the laser.

[0022] The fiber amplifier is used to amplify the received laser beam;

[0023] The attenuator is used to attenuate the light intensity of the received laser beam.

[0024] Optionally, the main control module is a data acquisition card.

[0025] Secondly, this application provides a testing method for a filter used in laser communication, wherein the testing is performed using the aforementioned testing apparatus, and the method includes:

[0026] The variation characteristics of the center wavelength of the filter under test with the incident angle were measured, and the curve of the center wavelength of the filter under test with the incident angle was established.

[0027] Based on the curve of the center wavelength of the filter under test changing with the incident angle, the curve of the peak transmittance of the filter under test changing with the center wavelength is measured, and the filter spectrum curve of the filter under test at different incident angles is measured.

[0028] Based on the peak transmittance curve of the filter under test as a function of the center wavelength and the filter spectrum curve of the filter under test at different incident angles, the performance parameters of the filter under test are determined.

[0029] Optionally, an optical fiber amplifier and an attenuator are further provided in the optical path of the laser beam output by the laser; before the step of measuring the change characteristics of the center wavelength of the filter under test with the incident angle, the method further includes:

[0030] At the set emission wavelength of the laser, the output power value of the laser beam after passing through the fiber amplifier and attenuator and the detection power value of the photodetector are obtained;

[0031] The insertion loss of the system to be measured is determined based on the output power value and the detection power value.

[0032] Optionally, the step of measuring the variation characteristics of the center wavelength of the filter under test with the incident angle and establishing the variation curve of the center wavelength of the filter under test with the incident angle includes:

[0033] The laser executes the received wavelength adjustment command and emits a laser beam. At the same time, the rotation control component responds to the received angle deflection control command and adjusts the rotation angle of the filter under test so that the rotation angle of the filter under test is different in different time periods.

[0034] The monitoring component collects multiple sets of laser beams incident at different incident angles onto the filter under test, and records the center wavelength of the filter under test and the rotation angle of the rotation control component. It also records the actual rotation angle of the filter under test and establishes a curve showing the change of the center wavelength of the filter under test with the incident angle.

[0035] Optionally, the method further includes:

[0036] Based on the curve of the center wavelength of the filter under test changing with the incident angle, the curve of the peak transmittance of the filter under test changing with the center wavelength is measured, and the filter spectrum curve of the filter under test at different incident angles is measured, so as to establish the correlation between the center wavelength, the incident angle, and the spectral characteristic data.

[0037] Based on the correlation between the center wavelength, incident angle, and spectral characteristics, and the pre-established structural optimization function, an optimization algorithm is used to iteratively solve the problem and output the optimized film structure data of the filter under test.

[0038] Beneficial effects:

[0039] This invention proposes a testing device and method for laser communication filters. The device includes: a laser for emitting a frequency-tunable laser beam; a filter under test (DUT) composed of multiple thin films disposed in the optical path of the laser beam; a rotation control component connected to the DUT for adjusting the rotation angle of the DUT relative to the transmission direction of the laser beam; a monitoring component for acquiring the filtered spectral curves of the DUT when multiple sets of laser beams are incident on the DUT at different incident angles; and a main control module for determining the performance parameters of the DUT based on the filtered spectral curves. The testing device and method provided by this invention, through precise positioning and dynamic adjustment of the incident angle, combined with a synchronous data acquisition mechanism, avoids the human error and efficiency bottlenecks of traditional manual testing, enabling rapid screening and performance modeling of multiple batches of filters. This test modeling method not only provides a standardized technical solution for the performance verification of tunable wavelength filters, but also allows the wavelength-angle correlation model and spectral characteristic data it acquires to feed back into the optimized design of the filter film structure, providing key technical support for the engineering realization of the dynamic wavelength tunable function of laser communication systems, and significantly improving the adaptability and reliability of tunable wavelength laser communication systems. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of a testing device for laser communication filters provided by the present invention;

[0041] Figure 2 This is a schematic diagram of the test device structure for system insertion loss compensation provided by the present invention;

[0042] Figure 3 This is a flowchart of the steps of a testing method for a laser communication filter provided by the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0044] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0045] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0046] In laser communication systems, when the emitted laser light passes through optical components, reflection and scattering create back-interference light. This interference light couples to the receiving optical path and superimposes with the target signal light, leading to a deterioration in the optical signal-to-noise ratio at the receiver and an increase in the bit error rate, severely limiting the performance of the communication system. Therefore, the receiving optical path needs to be equipped with optical filters to suppress stray light and back-interference through spectral selective filtering, thereby improving the optical signal-to-noise ratio at the receiver and ensuring stable and reliable transmission of the communication system.

[0047] To meet the application requirements of dynamically tunable wavelengths in laser communication networking scenarios, existing technologies design complex film structures to ensure performance indicators meet standards at different target wavelengths. However, such film systems often exhibit nonlinear characteristics. To accurately characterize and verify their optical performance, it is necessary to test the film system. However, existing testing methods are all single-parameter, single-shot tests, which are inefficient.

[0048] To overcome the limitations of existing technologies that only allow for single-parameter, one-time testing of film-based filters, this application provides an automated testing device and method for tunable wavelength filters suitable for laser communication applications. This device and method can efficiently model and analyze film performance parameters, laying the technical foundation for realizing dynamically tunable wavelength functionality in laser communication.

[0049] The following example provides a more accurate explanation of the testing apparatus and method for laser communication filters provided by the present invention.

[0050] Firstly, this application provides a testing apparatus for filters used in laser communication, such as... Figure 1 It includes: laser 1, filter under test 4, rotation control component 12 and monitoring component 13.

[0051] Laser 1 is used to emit a frequency-tunable laser beam.

[0052] The filter under test 4 includes a multilayer thin film structure, the multilayer thin film structure including at least one Fabry-Perot resonator unit, the filter under test 4 is disposed in the optical path of the laser beam and the laser beam is obliquely incident on the filter under test 4.

[0053] The rotation control component 12 is connected to the filter under test 4 and is used to adjust the rotation angle of the filter under test relative to the transmission direction of the laser beam, so that the filter under test is located in the target space state.

[0054] The monitoring component 13 is used to collect the filtered spectrum curves of the filter under test 4 when multiple sets of laser beams are incident on the filter under test 4 at different incident angles.

[0055] Specifically, the laser is a frequency-tunable laser, which is a type of laser capable of actively changing the output laser wavelength. In this embodiment, by adjusting the wavelength of the output laser beam in the laser, a continuously tunable laser beam is obtained.

[0056] The filter under test is a narrowband filter based on the principle of a multilayer thin-film Fabry-Perot cavity (FP cavity). It is an optical element that utilizes the multi-beam interference effect to allow only a very narrow range of light near a specific wavelength to pass through. Typically, this type of narrowband filter consists of two parallel, highly reflective mirrors, with the region between the mirrors forming a resonant cavity. These highly reflective mirrors can be achieved by alternately depositing tens or even hundreds of nanometer-thick dielectric thin films on a glass substrate using vacuum deposition technology.

[0057] Furthermore, the core parameters of the filter under test include center wavelength, full width at half maximum (FWHM), peak transmittance, free spectral range, and cutoff depth. The center wavelength is the peak wavelength that the filter allows to pass through. The FWHM is the wavelength width at half the peak transmittance. Peak transmittance is the maximum transmittance at the center wavelength. The free spectral range is the wavelength interval between two adjacent interference orders. The cutoff depth is the ability to suppress non-transmittent wavelengths.

[0058] A rotation control component is used to precisely control the rotation angle of the filter under test so that the laser beam incident on the surface of the filter under test forms a controllable tilted incident angle.

[0059] In this embodiment, since the filter under test has a Fabry-Perot cavity (FP cavity), based on the wavelength-angle drift effect of the FP cavity, the center transmitted wavelength of the filter under test shifts regularly with the incident angle, thereby realizing the dynamic adjustment of the filtered wavelength.

[0060] The monitoring unit is used to collect the transmitted power and output spectrum of the filter under test, so as to determine the performance parameters of the filter under test based on the collected transmitted power and spectral data, and then determine whether the filter meets the filtering requirements of the current laser communication system.

[0061] Furthermore, such as Figure 1 As shown, the monitoring component 13 includes a beam splitter 8, a photodetector 9, and a spectrometer 10.

[0062] The beam splitter 8 is used to receive the filtered light beam output from the filter under test and split the filtered light beam into a first split beam and a second split beam. The splitting ratio of the beam splitter 8 is 1:1 to distribute the input light energy evenly to the photodetector and the spectrometer.

[0063] The photodetector 9 is located in the optical path of the first beam splitter, receives the first beam splitter, and detects the energy value of the first beam splitter.

[0064] The spectrometer 10 is located in the optical path of the second beam splitter and is used to receive the second beam splitter and detect the curve of the optical power of the second beam splitter as a function of optical wavelength.

[0065] Furthermore, in order to achieve automated batch testing of filters, the testing device also includes a main control module connected to the laser, the rotation control component, and the monitoring component.

[0066] The main control module is connected to the laser, the rotation control component, and the monitoring component. It is used to adjust the emission wavelength of the laser, output control signals to the rotation control component and the monitoring component to control the rotation angle of the filter under test, and determine the performance parameters of the filter under test based on the filter spectral curves of the filter under test at different incident angles.

[0067] Furthermore, the main control module is also used to establish the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test changing with the emission wavelength of the laser beam. Based on the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test changing with the emission wavelength of the laser beam, the filter spectrum curve of the filter under test at different incident angles is obtained.

[0068] This main control module is used not only to control the emission wavelength of the laser, but also to control the rotation angle of the rotation control component to achieve the rotation of the filter under test, and to control the monitoring component to acquire spectral data of the filter under test, and establish the correlation between the spectral data and the incident angle. In one implementation, the main control module is a data acquisition card. This data acquisition card can not only acquire data, but also analyze and make decisions on the acquired data, and directly issue corresponding control commands to direct the various components to work together.

[0069] In this embodiment, a main control module is used to automate the testing process, enabling rapid screening of multiple batches of filters. This solves the problem of low efficiency in traditional manual testing and significantly improves the standardization level and reliability of the test results.

[0070] Furthermore, the rotation control component 12 includes a drive component and an encoder 7; the drive component includes a stepper motor 5 and a driver 6.

[0071] The drive assembly is used to adjust the rotation angle of the filter under test 4 according to the received control command; the stepper motor 5 and the driver 6 are responsible for adjusting the rotation angle of the filter under test.

[0072] The encoder 7 is used to monitor the rotation angle of the filter under test 4 and feed it back to the main control module. The encoder 7 is responsible for feeding back the current actual rotation angle of the filter under test 4.

[0073] In another implementation, the rotation control component can also electrically adjust the center wavelength offset based on cavity spacing or refractive index principles. This can be achieved by changing the refractive index using material characteristics or by precisely altering the physical dimensions of the cavity using microstructures.

[0074] Furthermore, an optical fiber amplifier and an attenuator are also provided in the optical path of the laser beam output by the laser.

[0075] The fiber amplifier is used to amplify the received laser beam; the attenuator is used to attenuate the light intensity of the received laser beam.

[0076] As the laser signal emitted by a laser travels through optical fiber, it may weaken due to fiber loss. When the laser signal weakens to a certain level, the receiver cannot correctly identify it, leading to an increase in the bit error rate. To overcome this laser signal attenuation problem, an optical fiber amplifier amplifies the received laser signal, thereby extending the transmission distance. In this embodiment, an erbium-doped optical fiber amplifier can be used to amplify the laser beam output from the laser.

[0077] Since excessively strong laser beam output from a laser may damage components in the optical path and cause signal distortion, an attenuator is installed in the output optical path of the fiber amplifier to attenuate the excessively strong laser signal, so that the signal strength of the attenuated laser beam is within the optimal power range for normal operation.

[0078] The testing device provided by this invention integrates the principle of tunable wavelength filtering of multilayer thin films with automated control. Based on the wavelength and angle drift effect of multilayer thin film FP cavity, it adopts a closed-loop control architecture of high-precision board and stepper motor. By precisely adjusting the rotation angle of the filter, the filtering wavelength can be dynamically adjusted. It deeply combines physical effects with automated control, breaking through the limitations of traditional fixed wavelength testing.

[0079] Furthermore, the testing device provided by this invention integrates a real-time monitoring component consisting of a photodetector and a spectrometer, accurately acquiring transmitted power and spectral measurements, and simultaneously acquiring multi-dimensional power and spectral data, which can solve the problem of incomplete data acquisition in traditional single detection methods.

[0080] The following describes the specific application steps of the testing device in this embodiment to further illustrate the testing device provided by the present invention.

[0081] The testing steps for the filter under test include: First, calibrating the system insertion loss to provide a compensation basis for accurately calculating the true transmittance of the narrowband filter at different wavelengths. Second, measuring the variation characteristics of the center wavelength of the narrowband filter with the incident angle to establish a quantitative correspondence between the center wavelength and the incident angle. Third, characterizing the evolution of the peak transmittance of the filter under test with the center wavelength to verify whether the transmittance of the filter at each center wavelength meets the practical application specifications. Finally, obtaining the filter spectrum curve of the filter under test for typical center wavelengths to achieve a comprehensive characterization of the overall optical performance of the filter under test.

[0082] The following section provides a more detailed explanation of the testing procedures for the filter under test.

[0083] Step H1: Measure the system insertion loss.

[0084] like Figure 2 The experimental setup required to measure the insertion loss of the system is shown, including a laser 1, an fiber amplifier 2, an attenuator 3, a photodetector 9, and a data acquisition card 11. The emission wavelength of the tunable laser 1 is continuously adjusted via the data acquisition card 11, within the 1530nm to 1570nm band, with an adjustment step size set to 2nm. After the laser signal is amplified by the fiber amplifier 2 and attenuated by the attenuator 3, the output power value P1 is measured and calculated. At each set emission wavelength, the detection power value of the photodetector 9 is simultaneously read and recorded as P2. By calculating the arithmetic mean of the differences between P2 and P1 at all wavelengths, the mean of the system insertion loss is finally obtained, and this mean is used as the system insertion loss.

[0085] Step H2: Measure the curve of the center wavelength of the filter under test as a function of the incident angle ( ).

[0086] Based on the propagation characteristics of the filter under test, changes in the angle of the incident light will cause a shift in its center wavelength. Therefore, it is necessary to establish a correspondence between the center wavelength and the incident angle beforehand. Initially, the incident direction of the light is perpendicular to the surface of the filter under test, and its center wavelength is... The experimental setup diagram for this step is as follows: Figure 1 Similarly, data acquisition card 11 sends a wavelength tuning command to laser 1, including the starting wavelength. ( ), End wavelength , sweep frequency step size The sweep interval n (i.e., the change in wavelength of the laser during each emission) is ) and length of stay Simultaneously, the emission power of laser 1, the output power of fiber amplifier 2, and the attenuation value of attenuator 3 are set; angle deflection control commands, including the starting angle, are simultaneously sent to stepper motor 5 via driver 6. ( (Take 0°, corresponding to the case where the incident light is perpendicular to the filter under test), end angle Rotation step size Rotation interval m (i.e., the change in angle of the stepper motor with each rotation) ) and length of stay During system operation, each time laser 1 is adjusted to a new wavelength, the dwell time at that wavelength is recorded. Inside, the stepper motor 5 drives the filter 4 under test to complete one full angular frequency sweep. To ensure that the target wavelength is within the scanning range, the angular change of the stepper motor 5 in each rotation must be within a preset small range. Simultaneously, the data acquisition card 11 monitors the peak power of the laser signal and its corresponding wavelength in real time using a spectrometer. When the peak power reaches its maximum value, the wavelength at this time is recorded simultaneously. Rotation angle of stepper motor The encoder 7 records the actual rotation angle of the filter under test at this time. Repeat the above process to establish the wavelength. Rotation angle of stepper motor and the rotation angle of the filter under test The correspondence.

[0087] Step H3: Measure the peak transmittance of the filter under test as a function of wavelength (T~ ).

[0088] Based on the test results of steps 1 and 2, the insertion loss characteristics of the system and the center wavelength of filter 4 under test have been determined. Rotation angle with stepper motor 5 The corresponding relationship. To further obtain the transmittance of the center wavelength of the filter under test at different incident angles, the following test procedure was designed: The experimental setup diagram for this step is shown in the figure. Figure 1 Similarly, data acquisition card 11 sends a frequency sweep command to laser 1; at the same time, stepper motor 5 performs a frequency sweep according to a preset schedule. The corresponding relationship is directly used to adjust the incident angle of the filter under test 4 to match the current emission wavelength. The laser transmission power at this time is recorded by the photodetector 9. After compensating for the system insertion loss, the peak power Pmax corresponding to the current wavelength can be obtained; further calculations can be performed to solve for the peak transmittance Tmax. By repeating the above test steps, the relationship between peak transmittance Tmax and wavelength can be established. The correspondence.

[0089] The calculation steps for peak transmittance Tmax are as follows: Since the emission power P0 of each wavelength is known, if the power after passing through the filter to be tested is Pmax, then the peak transmittance Tmax = Pmax / P0 × 100%.

[0090] Step H4: Measure the filtered spectrum of the filter under test at different incident angles.

[0091] The core performance indicators of optical filters typically include peak transmittance, full width at half maximum (FWHM), rectangularity, and waviness. Quantitative characterization of these indicators requires analysis based on the filter's filtered spectrum. The experimental setup diagram for this step is shown below. Figure 1 Similarly, the specific testing procedure is as follows: First, select several representative typical wavelength values ​​(e.g., 532nm green light, 635nm red light, 850nm infrared light, etc.), based on the filter center wavelength established in step 1 above. With the rotation angle of the motor The corresponding relationship is determined by the motor driving the filter to precisely rotate to the target incident angle corresponding to each typical wavelength. After the filter angle is fixed, the data acquisition card 11 sends a frequency sweep command to the tunable laser 1, setting a large frequency sweep range and a reasonable scanning step size to ensure the integrity and accuracy of the spectral data. While the laser 1 performs frequency sweep according to the preset parameters, the spectrometer 10 collects and records the laser wavelength and corresponding peak power at each moment in real time, and finally obtains multiple sets of peak power-wavelength correlation data. Based on this data, the filtered spectrum curves of the filter under different incident angles are plotted, and then the performance indicators such as peak transmittance, half width at half maximum, rectangularity and waviness are quantitatively calculated and comprehensively evaluated.

[0092] The testing device provided by this invention supports comprehensive performance characterization of tunable wavelength filters. It can measure and acquire core parameters such as peak transmittance and full width at half maximum (FWHM) of the filter under test, as well as complete data such as wavelength-angle variation curves and spectral parameters. This provides comprehensive data support for the quantitative evaluation of filter performance and avoids the limitations of single-parameter testing.

[0093] Furthermore, by selecting high-quality filters through precise performance modeling, the accuracy of dynamic wavelength adjustment in laser communication systems can be effectively ensured. Simultaneously, stray light suppression is enhanced, and the system's optical signal-to-noise ratio is improved, thereby significantly enhancing the adaptability and transmission reliability of tunable wavelength laser communication systems. The filter provided by this invention precisely adapts to the core requirement of dynamically adjustable wavelengths in laser communication networking, breaking through the application limitations of traditional fixed-wavelength filters and providing key technical support for multi-frequency, flexible networking laser communication scenarios.

[0094] Secondly, this application provides a testing method for filters used in laser communication, such as... Figure 3 As shown, the test is performed using the aforementioned testing apparatus, and the method includes:

[0095] Step S1: Measure the variation characteristics of the center wavelength of the filter under test with the incident angle, and establish the variation curve of the center wavelength of the filter under test with the incident angle.

[0096] This step is implemented using the testing apparatus and testing steps disclosed in the above embodiments. Specifically, the emission power of the laser is set through a data acquisition card, and an angle deflection control command is sent synchronously to control the rotation of the filter under test within a predetermined rotation interval. The peak power and corresponding wavelength of the laser signal monitored by the spectrometer are acquired, and the wavelength and stepper motor rotation angle when the peak power reaches its maximum value are recorded, and the actual rotation angle of the filter under test is recorded. This process is repeated multiple times to obtain multiple sets of data between the wavelength, the stepper motor rotation angle, and the actual rotation angle of the filter under test. Based on these multiple sets of data, the correspondence between the wavelength, the stepper motor rotation angle, and the actual rotation angle of the filter under test is obtained.

[0097] Step S2: Based on the curve of the center wavelength of the filter under test changing with the incident angle, measure the curve of the peak transmittance of the filter under test changing with the center wavelength and measure the filter spectrum curve of the filter under test at different incident angles.

[0098] Based on the established correspondence between wavelength, stepper motor rotation angle, and the actual rotation angle of the filter under test, the stepper motor is controlled to directly drive the filter under test to adjust to the incident angle matching the current emission wavelength. The laser transmission power is recorded using photoelectric detection to obtain the peak power corresponding to the current wavelength. A correspondence between peak transmittance and wavelength is established based on the peak power.

[0099] Step S3: Based on the curve of the peak transmittance of the filter under test as a function of the center wavelength and the filter spectrum curve of the filter under test at different incident angles, determine the performance parameters of the filter under test.

[0100] Based on the curve of peak transmittance of the filter under test as a function of center wavelength, a fixed angle of the filter under test is determined. Laser wavelength and corresponding peak power are collected at different fixed angles to obtain multiple sets of peak power and wavelength correlation data. Based on the peak power and wavelength correlation data, the filter spectrum curve of the filter under test at different incident angles is obtained. Then, the performance indicators such as peak transmittance, half width at half maximum (FWHM), rectangularity, and waviness are quantitatively calculated and comprehensively evaluated.

[0101] Furthermore, to obtain more accurate power and spectral data, an optical fiber amplifier and an attenuator are also provided in the optical path of the laser beam output by the laser; before the step of measuring the change characteristics of the center wavelength of the filter under test with the incident angle, the method further includes:

[0102] At the set emission wavelength of the laser, the output power value of the laser beam after passing through the fiber amplifier and attenuator and the detection power value of the photodetector are obtained; the insertion loss of the system to be measured is determined based on the output power value and the detection power value.

[0103] The insertion loss of this system is the loss value when no filter under test is set in the test device. Therefore, when calculating the system insertion loss, only the laser emits a laser beam, which is then sequentially input to the fiber amplifier and attenuator to obtain the output power value. The detection power value of the photodetector is then read synchronously, and the difference between the output power value and the detection power value is calculated to obtain the system insertion loss.

[0104] like Figure 3 The diagram shows a test setup for measuring the insertion loss of a system, including a laser 1, an fiber amplifier 2, an attenuator 3, a photodetector 9, and a data acquisition card 11. The emission wavelength of the laser 1 is continuously adjusted via the data acquisition card 11, within the 1530nm to 1570nm band, with an adjustment step size of 2nm. After the laser signal is amplified by the fiber amplifier 2 and attenuated by the attenuator 3, the output power value P1 is measured and calculated. At each set emission wavelength, the detection power value of the photodetector 9 is simultaneously read and recorded as P2. By calculating the arithmetic mean of the differences between P2 and P1 at all wavelengths, the average insertion loss of the system is finally obtained.

[0105] Furthermore, the step of measuring the variation characteristics of the center wavelength of the filter under test with the incident angle and establishing the variation curve of the center wavelength of the filter under test with the incident angle includes:

[0106] The laser executes the received wavelength adjustment command and emits a laser beam. At the same time, the rotation control component responds to the received angle deflection control command and adjusts the rotation angle of the filter under test so that the rotation angle of the filter under test is different in different time periods.

[0107] The monitoring component collects multiple sets of laser beams incident at different incident angles onto the filter under test, and records the center wavelength of the filter under test and the rotation angle of the rotation control component. It also records the actual rotation angle of the filter under test and establishes a curve showing the change of the center wavelength of the filter under test with the incident angle.

[0108] Furthermore, the method also includes:

[0109] Step S4: Based on the curve of the center wavelength of the filter under test changing with the incident angle, measure the curve of the peak transmittance of the filter under test changing with the center wavelength and measure the filter spectrum curve of the filter under test at different incident angles, and establish the correlation between the center wavelength, the incident angle and the spectral characteristic data.

[0110] When the testing device and the testing method given in the above embodiments are used, the curves of the center wavelength of the filter under test changing with the incident angle and the curves of the center wavelength of the filter under test changing with the incident angle can be obtained respectively. Based on the above data, the correlation between the center wavelength, the incident angle and the spectral characteristic data can be established.

[0111] Step S5: Based on the correlation between the center wavelength, incident angle, and spectral characteristic data, and the pre-established structural optimization function, an optimization algorithm is used to iteratively solve the problem and output the optimized film structure data of the filter under test.

[0112] Once the correlation between the center wavelength of the filter and the incident angle and spectral characteristics of the laser beam are obtained, the structure of the filter under test can be optimized according to the pre-established structure optimization function, and the optimized structure data of the filter under test can be output.

[0113] In detail, a structural optimization function is pre-constructed, which is a mathematical model describing the mapping relationship between filter structural parameters and optical performance. Based on this mathematical model, an objective function is constructed to evaluate the advantages of the current filter spectral structural parameters. The error is judged based on the objective function, and then the structural parameters of the filter are adjusted based on the error.

[0114] In detail, once the performance parameters of the filter are obtained, the established structural optimization function is invoked. This function outputs the spectral characteristics of the filter under the current structural parameters and the change of the center wavelength with the incident angle. Based on the objective function value, the optimization algorithm adjusts the film thickness to reduce the objective function value. After multiple iterative optimization calculations, the final optimized structural parameters of the filter under test are obtained.

[0115] The testing apparatus and method disclosed in this application overcome the limitations of traditional manual testing. Through a fully automated design encompassing board-driven operation, angle closed-loop control, and synchronous data acquisition, it enables rapid screening of multiple batches of filters, overcoming the bottlenecks of low efficiency and poor batch adaptability inherent in traditional methods. Furthermore, the testing method provided in this application not only achieves quantitative evaluation of filter performance but also uses the acquired wavelength-angle correlation model and spectral characteristic data to feed back into the optimized design of the filter film structure, forming a closed-loop technology of "testing-modeling-optimization," rather than simply performance verification.

[0116] This invention proposes a testing device and method for laser communication filters. The device includes: a laser for emitting a frequency-tunable laser beam; a filter under test (DUT), composed of multiple thin films, disposed in the optical path of the laser beam with the laser beam incident at an angle onto the DUT; a rotation control component connected to the DUT for adjusting the rotation angle of the DUT relative to the transmission direction of the laser beam, so that the DUT is positioned in a target space; a monitoring component for acquiring power data and spectral curves of multiple sets of laser beams incident on the DUT at different incident angles; and a main control module for determining the performance parameters of the DUT based on the power data and spectral curves. The testing device and method provided by this invention, through precise positioning and dynamic adjustment of the incident angle, combined with a synchronous data acquisition mechanism, avoids the human error and efficiency bottlenecks of traditional manual testing, enabling rapid screening and performance modeling of multiple batches of filters. This test modeling method not only provides a standardized technical solution for the performance verification of tunable wavelength filters, but also allows the wavelength-angle correlation model and spectral characteristic data it acquires to feed back into the optimized design of the filter film structure, providing key technical support for the engineering realization of the dynamic wavelength tunable function of laser communication systems, and significantly improving the adaptability and reliability of tunable wavelength laser communication systems.

[0117] It should be noted that the above application scenarios are shown only for the purpose of understanding the present invention, and the embodiments of the present invention are not limited in any way. On the contrary, the embodiments of the present invention can be applied to any applicable scenario.

[0118] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A testing device for laser communication filters, characterized in that, include: A laser is used to emit a laser beam with a tunable frequency. The filter under test includes a multilayer thin film structure, the multilayer thin film structure including at least one Fabry-Perot resonant cavity unit, the filter under test is disposed in the optical path of the laser beam and the laser beam is obliquely incident on the filter under test; A rotation control component, connected to the filter under test, is used to adjust the rotation angle of the filter under test relative to the transmission direction of the laser beam, so that the filter under test is located in the target space state; The monitoring components include a beam splitter, a photodetector, and a spectrometer; The beam splitter is used to receive the filtered light beam output by the filter under test and split the filtered light beam into a first split beam and a second split beam. The photodetector is located in the optical path of the first split beam and is used to receive the first split beam and detect the energy value of the first split beam. The spectrometer is located in the optical path of the second beam splitter and is used to receive the second beam splitter and detect the curve of optical power corresponding to the second beam splitter as a function of optical wavelength. The main control module is connected to the laser, the rotation control component, and the monitoring component. It is used to adjust the emission wavelength of the laser, output control signals to the rotation control component and the monitoring component to control the rotation angle of the filter under test, and determine the performance parameters of the filter under test based on the filter spectral curves of the filter under test at different incident angles. The main control module is also used to establish the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test changing with the emission wavelength of the laser beam. Based on the correspondence between the center wavelength of the filter under test and the rotation angle of the rotation control component and the actual rotation angle of the filter under test, as well as the curve of the peak transmittance of the filter under test changing with the emission wavelength of the laser beam, the filter spectrum curve of the filter under test under different incident angles is obtained.

2. The testing apparatus for laser communication filters according to claim 1, characterized in that, The rotation control component includes: a drive component and an encoder; The driving component is used to adjust the rotation angle of the filter under test according to the received control command; The encoder is used to monitor the rotation angle of the filter under test and feed the rotation angle back to the main control module.

3. The testing apparatus for laser communication filters according to claim 1, characterized in that, The laser output beam is also equipped with an optical fiber amplifier and an attenuator. The fiber amplifier is used to amplify the received laser beam; The attenuator is used to attenuate the light intensity of the received laser beam.

4. The testing apparatus for laser communication filters according to claim 2, characterized in that, The main control module is a data acquisition card.

5. A test method for a filter used in laser communication, characterized in that, The method of performing a test using the test apparatus as described in any one of claims 1-4 includes: The variation characteristics of the center wavelength of the filter under test with the incident angle were measured, and the curve of the center wavelength of the filter under test with the incident angle was established. Based on the curve of the center wavelength of the filter under test changing with the incident angle, the curve of the peak transmittance of the filter under test changing with the center wavelength is measured, and the filter spectrum curve of the filter under test at different incident angles is measured. Based on the peak transmittance curve of the filter under test as a function of the center wavelength and the filter spectrum curve of the filter under test at different incident angles, the performance parameters of the filter under test are determined.

6. The test method for laser communication filters according to claim 5, characterized in that, The optical path of the laser beam output by the laser is further provided with an optical fiber amplifier and an attenuator; before the step of measuring the change characteristics of the center wavelength of the filter under test with the incident angle, the method further includes: At the set emission wavelength of the laser, the output power value of the laser beam after passing through the fiber amplifier and attenuator and the detection power value of the photodetector are obtained; The system insertion loss is determined based on the output power value and the detection power value.

7. The test method for laser communication filters according to claim 5, characterized in that, The steps of measuring the variation characteristics of the center wavelength of the filter under test with the incident angle and establishing the variation curve of the center wavelength of the filter under test with the incident angle include: The laser executes the received wavelength adjustment command and emits a laser beam. At the same time, the rotation control component responds to the received angle deflection control command and adjusts the rotation angle of the filter under test so that the rotation angle of the filter under test is different in different time periods. The monitoring component collects multiple sets of laser beams incident at different incident angles onto the filter under test, and records the center wavelength of the filter under test and the rotation angle of the rotation control component. It also records the actual rotation angle of the filter under test and establishes a curve showing the change of the center wavelength of the filter under test with the incident angle.

8. The test method for laser communication filters according to claim 7, characterized in that, The method further includes: Based on the curve of the center wavelength of the filter under test changing with the incident angle, the curve of the peak transmittance of the filter under test changing with the center wavelength is measured, and the filter spectrum curve of the filter under test at different incident angles is measured, so as to establish the correlation between the center wavelength, the incident angle, and the spectral characteristic data. Based on the correlation between the center wavelength, incident angle, and spectral characteristics, and the pre-established structural optimization function, an optimization algorithm is used to iteratively solve the problem and output the optimized film structure data of the filter under test.

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