A method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source

Abstract

The present application relates to a method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source. The method includes: obtaining a high-power linearly polarized supercontinuum laser source and output optical parameters of the high-power linearly polarized supercontinuum laser source; constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters; the extinction ratio test system includes a beam collimating and output instrument, a polarizer, an integrating sphere, a power meter, and a spectrometer; measuring the high-power linearly polarized supercontinuum laser source according to the extinction ratio test system, and rotating the polarizer to record the spectra at the maximum power and the minimum power measured by the power meter; calculating the extinction ratio of the spectra at the maximum power and the minimum power according to the extinction ratio definition formula to obtain the extinction ratio in the full spectral range. By using this method, the extinction ratio of a broadband spectral light source can be quickly measured and a high-power light source can be tested.

Description

Technical Field

[0001] This application relates to the field of optical measurement technologies, and particularly to a method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source. Background Art

[0002] A high-power linearly polarized supercontinuum laser source is a broadband linearly polarized light source, and the broadening of its spectrum is the result of the combined action of various effects such as optical power amplification, dispersion effects, and nonlinear effects. Due to the different correlations between different effects and polarization, the polarization states in different wavelength ranges of the linearly polarized supercontinuum light source may be different. Therefore, the measurement of the polarization state in the full spectral range is of great significance for the research of the linearly polarized supercontinuum light source. The polarization extinction ratio reflects the proportional relationship between two orthogonal components obtained by decomposing the measured light along the main vibration direction. When light is transmitted in a polarization-maintaining optical fiber, the extinction ratio is characterized by the ratio of the light intensities of the fast and slow axes. Traditional extinction ratio tests generally use the method of rotating an analyzer to measure the transmitted optical power. By rotating the analyzer and using a power meter to detect the change in the power of the light transmitted through the analyzer, the maximum power is detected when the main axis direction of the analyzer is parallel to the main vibration direction of the measured light. When the main axis direction of the analyzer is perpendicular to the main vibration direction of the measured light, the minimum power is detected. The result obtained using this measurement method is the superposition of the intensities of each wavelength in the entire band, and it cannot reflect the extinction ratio at a specific single wavelength position of a broadband light source. It is not suitable for the extinction ratio test of a supercontinuum laser source with a relatively wide spectrum.

[0003] However, currently, there is a method for measuring the extinction ratio that can reflect a single wavelength and is applicable to a broadband linearly polarized fiber laser: One end of a polarization-maintaining passive optical fiber is butt-welded at a 45-degree angle with the output pigtail of the linearly polarized fiber laser, and the other end is butt-welded at a 45-degree angle with a single-polarization optical fiber; the single-polarization optical fiber maintains the polarization state of the light transmitted along the slow axis direction; a single-mode jumper collects the output light of the single-polarization optical fiber into a spectrometer by means of spatial docking. Read the optical power value corresponding to a passing rate of 1 and a wavelength of λ from the spectrometer. After changing the length of the polarization-maintaining passive optical fiber, read the optical power value corresponding to a passing rate of 0 and a wavelength of λ from the spectrometer, and calculate the extinction ratio at a single wavelength. Using this method, only the extinction ratio at one wavelength can be obtained each time. When the extinction ratio values at multiple wavelengths are required, the measured light needs to be measured multiple times; when using this method to measure the extinction ratio of a broadband light source, when there is a situation where the power value perpendicular to the main vibration direction is higher than the power value in the main vibration direction within a certain wavelength range, the measured extinction ratio value is 0, and it cannot reflect the actual extinction ratio value within this wavelength range; in addition, a single-mode jumper cannot withstand high-power input and cannot test a high-power light source. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source, which can quickly measure the extinction ratio of a broadband light source and test a high-power light source.

[0005] A method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source, the method comprising:

[0006] Obtain the output optical parameters of a high-power linearly polarized supercontinuum laser source and the high-power linearly polarized supercontinuum laser source; the output optical parameters include the average power, the central wavelength, and the wavelength range to be measured;

[0007] Construct an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters; the extinction ratio test system includes a beam collimating output instrument, a polarizer, an integrating sphere, a power meter, and a spectrometer;

[0008] Measure the high-power linearly polarized supercontinuum laser source according to the extinction ratio test system, and rotate the polarizer to record the spectra at the maximum power and the minimum power measured by the power meter;

[0009] Calculate the extinction ratio of the spectra at the maximum power and the minimum power according to the extinction ratio definition formula to obtain the extinction ratio in the full spectral range.

[0010] In one embodiment, constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters includes:

[0011] Collimate the output light of the high-power linearly polarized supercontinuum laser source through a beam collimating output instrument, select a polarizer according to the central wavelength and the wavelength range to be measured, fix the polarizer on a rotary adjusting frame with specific rotation scales that can rotate 360 degrees, and make the polarizer and the collimating mirror have the same height and be coaxial;

[0012] Determine the integrating sphere according to the average power, the central wavelength, and the wavelength range to be measured; the integrating sphere, the collimating mirror, and the polarizer have the same height and are coaxial;

[0013] Select a suitable power meter probe according to the average power, the central wavelength, and the wavelength range to be measured, set the power range and the wavelength range of the power meter, select a spectrometer whose working wavelength includes the wavelength range to be measured according to the wavelength range to be measured, and connect the power meter and the spectrometer to different openings of the integrating sphere to form an extinction ratio test system.

[0014] In one embodiment, the beam collimating output instrument includes a collimating mirror and an optical fiber collimator; the beam collimating output instrument can completely receive the light source to be measured and the spot size of the output collimated light is smaller than the receiving surface sizes of the polarizer and the integrating sphere.

[0015] In one embodiment, the analyzer is any one of a Glan laser prism, a polarization beam splitter PBS, a Rochon prism, and a Glan-Taylor prism; the working wavelength range of the analyzer includes the wavelength range to be measured, and the power damage threshold of the analyzer is higher than the average power of the laser to be measured.

[0016] In one embodiment, the damage threshold of the receiving surface of the integrating sphere is greater than the average power and the working wavelength range includes the wavelength range to be measured; the number of openings of the integrating sphere is greater than 3.

[0017] In one embodiment, if the working wavelength range of a single spectrometer is not sufficient to cover the wavelength range to be measured, a multi-aperture integrating sphere is used to connect multiple spectrometers with different working wavelength ranges simultaneously to achieve spectral measurement.

[0018] In one embodiment, rotate the analyzer and record the spectra at the maximum power and minimum power measured by the power meter, including:

[0019] Rotate the analyzer to make the power meter measure the maximum power. At this time, the angle of the adjustment frame is θ, and use the spectrometer to record the spectrum at the maximum power. Continue to rotate the adjustment frame. When the angle of the adjustment frame is θ + 90 degrees, measure the minimum power, and use the spectrometer to record the spectrum at the minimum power.

[0020] The above method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source first obtains the high-power linearly polarized supercontinuum laser source and the output optical parameters of the high-power linearly polarized supercontinuum laser source; the output optical parameters include the average power, the central wavelength, and the wavelength range to be measured; construct an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters; the extinction ratio test system includes a beam collimation output instrument, an analyzer, an integrating sphere, a power meter, and a spectrometer; measure the high-power linearly polarized supercontinuum laser source according to the extinction ratio test system, and rotate the analyzer to record the spectra at the maximum power and minimum power measured by the power meter; calculate the extinction ratio of the spectra at the maximum power and minimum power to obtain the extinction ratio in the full spectral range. In this application, an extinction ratio test system is constructed according to the high-power linearly polarized supercontinuum laser source and the output optical parameters. An integrating sphere and a spectrometer are designed in the extinction ratio test system. Multiple openings are provided on the integrating sphere, and multiple spectrometers with different working wavelength ranges can be connected simultaneously to improve the spectral detection range, enabling the test system to detect the full spectral range. Furthermore, using the power meter and the spectrometer, the extinction ratio in the full spectral range can be obtained through a single measurement. The measurement result can accurately reflect the extinction ratio value at each single wavelength within the measured wavelength range. At the same time, the damage threshold of the integrating sphere is set to be greater than the average power of the light source to be measured, so that the damage threshold of the test system is high, and high-power laser sources can be tested. Description of the Drawings

[0021] Figure 1Schematic flowchart of a method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source in an embodiment;

[0022] Figure 2 Schematic diagram of an extinction ratio test system in an embodiment;

[0023] Figure 3 Schematic diagram of the extinction ratio test results of the light source to be measured within the wavelength range of 1020 - 1280 nm in an embodiment. Detailed implementation manners

[0024] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application 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 only used to explain the present application and are not used to limit the present application.

[0025] In one embodiment, as Figure 1 shown, a method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source is provided, including the following steps:

[0026] Step 102, obtain a high-power linearly polarized supercontinuum laser source and the output optical parameters of the high-power linearly polarized supercontinuum laser source; the output optical parameters include the average power, the central wavelength, and the wavelength range to be measured.

[0027] Step 104, construct an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters; the extinction ratio test system includes a beam collimating and output instrument, a polarizer, an integrating sphere, a power meter, and a spectrometer.

[0028] Construct an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters, and connect each device to the supercontinuum laser source to be measured in the following order, as Figure 2As shown in the figure, there are a high-power linearly polarized supercontinuum laser source 1, a beam collimating output instrument 2, a polarizer 3, an integrating sphere 4, a power meter 5, and a spectrometer 6. Among them, fix the output pigtail of the high-power linearly polarized supercontinuum laser source on the output bracket, measure the height h between the output end and the experimental table, and adjust the output pigtail so that the output beam is parallel to the experimental table. Select a collimating mirror with an appropriate focal length and size so that the incident light to be measured can be completely received and the spot size of the output collimated light is smaller than the receiving surface sizes of the polarizer and the integrating sphere. Adjust the height of the collimating mirror to h and adjust the pitch, roll, and horizontal position of the collimating mirror so that the light to be measured is collimated and output. According to the central wavelength λ of the light to be measured and the wavelength range Δλ to be measured, select a polarizer whose working wavelength range can cover Δλ. The polarizer can be a Glan laser prism. Fix the polarizer on a rotary adjustment bracket with a specific rotation scale that can rotate 360 degrees, and adjust the height and position of the polarizer so that it is at the same height and coaxial with the collimating mirror, so that the light to be measured is perpendicularly incident on the incident surface of the polarizer. According to the average power P, central wavelength λ, and wavelength range Δλ to be measured of the light to be measured, select an integrating sphere with a high enough damage threshold and a working wavelength range that can cover Δλ. The number of openings of the integrating sphere should be greater than 3, including 1 receiving opening and more than 2 output openings, so that the integrating sphere can simultaneously input the information to be measured into the power meter and the spectrometer. Adjust the height and position of the integrating sphere so that it is at the same height and coaxial with the collimating mirror and the polarizer, so that the output light of the polarizer is perpendicularly incident on the receiving surface of the integrating sphere. The number of openings of the integrating sphere should be as many as possible, so that it can simultaneously connect multiple spectrometers with different working wavelength ranges to improve the spectral detection range. According to the average power P, central wavelength λ, and wavelength range Δλ to be measured of the light to be measured, set the power range and wavelength range of the power meter. According to the working wavelength range Δλ of the light to be measured, select a spectrometer whose working wavelength covers Δλ, and set an appropriate sampling resolution (i.e., sampling wavelength interval) and sampling sensitivity according to the test requirements. Set the power of the spectrometer to be expressed in dB, and dB = 10log().

[0029] If the working wavelength range of a single spectrometer is not sufficient to cover Δλ of the light to be measured, a multi-opening integrating sphere can be used to simultaneously connect multiple spectrometers with different working wavelength ranges, thereby improving the spectral measurement range.

[0030] Step 106: Measure the high-power linearly polarized supercontinuum laser source according to the extinction ratio test system, rotate the polarizer and record the spectra at the maximum power and minimum power measured by the power meter; calculate the extinction ratio of the spectra at the maximum power and minimum power according to the extinction ratio definition formula to obtain the extinction ratio in the full spectral range.

[0031] While rotating the analyzer, observe the power indicated by the power meter in real time, record the measured maximum power and the angle θ of the analyzer adjustment bracket, and measure the spectrum at the maximum power. The power measured by the power meter varies as a sine function with the rotation angle of the analyzer adjustment bracket. Due to certain errors in manually rotating the adjustment bracket, multiple measurements (more than 3 times) should be carried out during the specific implementation process, and the maximum value among multiple measurements should be recorded as the test result. Each time the analyzer is rotated, it should be adjusted clockwise (or counterclockwise) to avoid inaccurate measured angle θ values caused by backlash. Continue to rotate the analyzer, and at the 90-degree position of the maximum power angle θ, measure the minimum power and measure the spectrum at the minimum power. Use a light shield to block the reflected light of the analyzer, especially when the power meter measures the minimum power of the transmitted light of the analyzer. At this time, the reflected light power of the analyzer is the maximum. After obtaining the spectra of the maximum power and the minimum power, since the measured spectral power is represented by dB, calculating the difference between the two spectra can obtain the polarization extinction ratio in the full spectral range.

[0032] In the above method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source, first obtain the high-power linearly polarized supercontinuum laser source and the output optical parameters of the high-power linearly polarized supercontinuum laser source; the output optical parameters include the average power, the central wavelength, and the wavelength range to be measured; construct an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters; the extinction ratio test system includes a beam collimation output instrument, an analyzer, an integrating sphere, a power meter, and a spectrometer; measure the high-power linearly polarized supercontinuum laser source according to the extinction ratio test system, and rotate the analyzer to record the spectra at the maximum power and the minimum power measured by the power meter; calculate the extinction ratio for the spectra at the maximum power and the minimum power to obtain the extinction ratio in the full spectral range. In this application, by constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters, an integrating sphere and a spectrometer are designed in the extinction ratio test system. Multiple openings are provided on the integrating sphere, which can be connected to multiple spectrometers with different working wavelength ranges at the same time, improving the spectral detection range, enabling the test system to detect the full spectral range, and further enabling the extinction ratio in the full spectral range to be obtained through a single measurement using the power meter and the spectrometer. The measurement result can accurately reflect the extinction ratio value at each single wavelength within the measured wavelength range. At the same time, the damage threshold of the integrating sphere is set to be greater than the average power of the light source to be measured, so that the test system has a high damage threshold and can test high-power laser sources.

[0033] In one of the embodiments, constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser source and the output optical parameters includes:

[0034] The output light of a high-power linearly polarized supercontinuum laser source is collimated by a beam collimation output instrument. An analyzer is selected according to the central wavelength and the wavelength range to be measured. The analyzer is fixed on a rotating adjustment frame with a specific rotation scale that can rotate 360 degrees, so that the analyzer and the collimator are coaxial at the same height.

[0035] Determine the integrating sphere based on the average power, central wavelength and wavelength range to be measured; the integrating sphere, collimator and analyzer are all highly coaxial;

[0036] Select a suitable power meter probe according to the average power, center wavelength and wavelength range to be measured, and set the power range and wavelength range of the power meter. Select a spectrometer whose working wavelength includes the wavelength range to be measured according to the wavelength range to be measured, and connect the power meter and spectrometer to different openings of the integrating sphere to form an extinction ratio test system.

[0037] In a specific embodiment, the power meter consists of two parts: a probe and a power meter head. The probe of the power meter receives the output light of the laser. The material of the probe also determines the tolerable power threshold. The power meter head is used to display the measured power. The wavelength range and power range settings are both completed on the power meter head.

[0038] In one embodiment, the beam collimation output instrument includes a collimating mirror and a fiber collimator; the beam collimation output instrument can completely receive the light source to be measured and output the collimated light with a spot size smaller than the receiving surface size of the analyzer and the integrating sphere.

[0039] In one embodiment, the polarizer is one of a Glan laser prism, a polarization beam splitter (PBS), a Rochon prism, and a Glan-Taylor prism; the operating wavelength range of the polarizer includes the wavelength range to be measured, and the power damage threshold of the polarizer is higher than the average power of the laser to be measured.

[0040] In a specific embodiment, the differences between the Glan laser prism, polarization beam splitter PBS, Rochon prism and Glan-Taylor prism mainly lie in the operating wavelength range, receiving surface material and polarization splitting method. When used in specific applications, it is necessary to select according to the wavelength range to be measured and the average power of the laser to be measured.

[0041] In one embodiment, the receiving surface damage threshold of the integrating sphere is greater than the average power and the operating wavelength range includes the wavelength range to be measured; the number of openings of the integrating sphere is greater than 3.

[0042] In one embodiment, if the operating wavelength range of a single spectrometer is insufficient to cover the wavelength range to be measured, a multi-aperture integrating sphere is used to simultaneously connect multiple spectrometers with different operating wavelength ranges to achieve spectral measurement.

[0043] In one embodiment, the rotating analyzer records spectra at maximum power and minimum power measured by a power meter, comprising:

[0044] Rotate the analyzer to make the power meter measure the maximum power. At this time, the angle of the adjustment frame is θ. Use a spectrometer to record the spectrum at the maximum power. Continue to rotate the adjustment frame. When the angle of the adjustment frame is θ + 90 degrees, measure the minimum power and use a spectrometer to record the spectrum at the minimum power.

[0045] In one of the embodiments, calculate the extinction ratio of the spectra at the maximum power and the minimum power to obtain the extinction ratio in the full spectral range.

[0046] In a specific embodiment, calculate the extinction ratio of the spectra at the maximum power and the minimum power. Finally, what this application obtains is a spectrogram with the wavelength on the abscissa and the extinction ratio on the ordinate. The abscissa of the spectrogram is the wavelength and the ordinate is the extinction ratio, indicating that a specific extinction ratio value is measured at each wavelength.

[0047] First, determine the output parameters of the high-power linearly polarized supercontinuum laser source to be measured. The central operating wavelength of the object to be measured is 1064 nm, the wavelength range to be measured is 1020 - 1280 nm, and the average power is 200 W.

[0048] Construct an extinction ratio test system. The height h of the output pigtail from the experimental bench is 11.7 cm. Select a plano-convex lens with a focal length of 3 cm as the collimating lens. The diameter of the collimated light spot after collimation is 8 mm. Adjust the collimating lens so that the output collimated light is perpendicularly incident on a polarization beam splitter with a working wavelength of 900 - 1300 nm. The transmitted light of the polarization beam splitter is perpendicularly incident on the receiving surface of the integrating sphere. The two openings of the integrating sphere are respectively connected to a power meter and a spectrometer with a working wavelength range of 600 - 1700 nm.

[0049] Use the constructed extinction ratio test system to measure the extinction ratio. Rotate the polarization beam splitter to make the power meter measure the maximum power. At this time, the angle of the adjustment frame is θ. Use a spectrometer to record the spectrum at the maximum power. Continue to rotate the adjustment frame. When the angle of the adjustment frame is θ + 90 degrees, measure the minimum power and use a spectrometer to record the spectrum at the minimum power. Calculate the difference between the spectrum at the maximum power and the spectrum at the minimum power. As Figure 3 shown, obtain the extinction ratio of the light source to be measured in the wavelength range of 1020 - 1280 nm. Specific extinction ratio values can be obtained at each single wavelength in the range of 1020 - 1280 nm. In the wavelength range of 1020 - 1050 nm, the extinction ratio is negative, indicating that the power value perpendicular to the main vibration direction is higher than the power value in the main vibration direction.

[0050] The most advantageous aspect of this application compared with other methods Figure 3Shown is a spectrogram with wavelength as the abscissa and extinction ratio as the ordinate. It can be understood that a specific extinction ratio value is measured at each wavelength, while using other methods to measure the extinction ratio, only the extinction ratio at one wavelength can be obtained through a single measurement. The introduction of the integrating sphere and the spectrometer enables the measurement of the power value at each specific wavelength.

[0051] It should be understood that although Figure 1 the steps in the flowchart of Figure 1 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover,

[0052] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0053] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for directly measuring the polarization extinction ratio of a linearly polarized supercontinuum laser source, characterized in that The method includes: Obtaining a high-power linearly polarized supercontinuum laser light source and output optical parameters of the high-power linearly polarized supercontinuum laser light source; the output optical parameters include average power, central wavelength, and a wavelength range to be measured; Constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser light source and the output optical parameters; the extinction ratio test system includes a beam collimating and output instrument, a polarizer, an integrating sphere, a power meter, and a spectrometer; the beam collimating and output instrument includes a collimating mirror and an optical fiber collimator; collimating the output light of the high-power linearly polarized supercontinuum laser light source through the beam collimating and output instrument, selecting a polarizer according to the central wavelength and the wavelength range to be measured, fixing the polarizer on a rotating adjustment frame with specific rotation scales that can rotate 360 degrees, so that the polarizer and the collimating mirror are at the same height and coaxial; the integrating sphere is at the same height and coaxial with the collimating mirror and the polarizer; the number of openings of the integrating sphere is greater than 3, including 1 receiving opening and more than 2 output openings, so that the integrating sphere can input the measured information into the power meter and the spectrometer simultaneously; Measuring the high-power linearly polarized supercontinuum laser light source according to the extinction ratio test system, and rotating the polarizer to record the spectra at the maximum power and minimum power measured by the power meter; Calculating the extinction ratio of the spectra at the maximum power and minimum power according to the extinction ratio definition formula to obtain the extinction ratio in the full spectral range.

2. The method according to claim 1, wherein Constructing an extinction ratio test system according to the high-power linearly polarized supercontinuum laser light source and the output optical parameters, including: Determining an integrating sphere according to the average power, central wavelength, and wavelength range to be measured; Selecting a suitable power meter probe according to the average power, central wavelength, and wavelength range to be measured and setting the power range and wavelength range of the power meter, selecting a spectrometer with a working wavelength range covering the wavelength range to be measured according to the wavelength range to be measured, and connecting the power meter and the spectrometer to different openings of the integrating sphere to form an extinction ratio test system.

3. The method according to claim 1, wherein The spot size of the collimated light output by the beam collimating and output instrument that can completely receive the light source to be measured is smaller than the receiving surface sizes of the polarizer and the integrating sphere.

4. The method according to claim 2, wherein The polarizer is any one of a Glan laser prism, a polarization beam splitter PBS, a Rochon prism, and a Glan-Taylor prism; the working wavelength range of the polarizer covers the wavelength range to be measured, and the power damage threshold of the polarizer is higher than the average power of the laser to be measured.

5. The method according to claim 2, wherein The damage threshold of the receiving surface of the integrating sphere is greater than the average power and the working wavelength range covers the wavelength range to be measured.

6. The method according to claim 5, characterized in that, The method further includes: If the working wavelength range of a single spectrometer is not sufficient to cover the wavelength range to be measured, using an integrating sphere with multiple openings to connect multiple spectrometers with different working wavelength ranges simultaneously to achieve spectral measurement.

7. The method according to claim 1, wherein Rotating the polarizer to record the spectra at the maximum power and minimum power measured by the power meter, including: Rotating the polarizer to make the power meter measure the maximum power. At this time, the angle of the adjustment frame is θ. Use the spectrometer to record the spectrum at the maximum power. Continue to rotate the adjustment frame. When the angle of the adjustment frame is θ + 90 degrees, measure the minimum power, and use the spectrometer to record the spectrum at the minimum power.

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