Near-infrared super-wideband high-precision single-frequency wavelength measurement system for fiber laser

Abstract

The application discloses a near-infrared super-wideband high-precision single-frequency wavelength measurement system for fiber laser, and belongs to the field of laser wavelength measurement. A 1.5-micron single-frequency fiber laser is used as reference light, which is divided into reflected light and transmitted light by a beam splitter at a power ratio of 50:50. After the reflection of plane mirrors I, II and III, the two light paths are finally converged on the beam splitter I, and then irradiated on the detection surface of a point photodetector I through the transmission and reflection of the beam splitter I. The light signal collection is realized through the point photodetector I and a point photodetector II, and then the wavelength of the measured light is processed, analyzed and calculated by a high-speed signal acquisition and processing device. The application is suitable for the 0.8-2.4-micron waveband, and will play an important role in the fields of coherent optical communication, nonlinear optics, high-precision fiber sensing, coherent laser radar and space optical communication.

Description

Technical Field

[0001] This invention relates to a near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers, belonging to the field of laser wavelength measurement technology. Background Technology

[0002] Single-frequency fiber lasers play a vital role in coherent optical communication, nonlinear optics, high-precision fiber optic sensing, coherent lidar, and space optical communication. Currently, the main laser bands involved are 1μm ytterbium-doped fiber lasers, 1.55μm erbium-doped fiber lasers, and 2μm thulium-doped fiber lasers, as well as other nonlinear fiber lasers and random fiber lasers in adjacent bands. The overall wavelength coverage ranges from 0.8 to 2.4μm. Measurement systems capable of accurately measuring laser wavelengths within this range have high practical value. Summary of the Invention

[0003] This invention addresses the technical problems existing in the prior art, thereby providing a near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers.

[0004] A near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers includes the following steps:

[0005] Using a 1.5μm single-frequency fiber laser as the reference light, the beam is split into a reflected beam and a transmitted beam at a 50:50 power ratio by a beam splitter. After reflection by plane mirrors one, two, and three, the two beams are transmitted to hollow roof prisms one and two, which are moved by a servo motor stage. Hollow roof prism one reflects the light back to plane mirror one in a direction parallel to the incident direction, and hollow roof prism two reflects the light back to plane mirror three in the same direction. Finally, the light converges again at beam splitter one and, after transmission and reflection, illuminates the detection surface of point photodetector one. The optical path transmission method of the light under test is the same as that of the reference light. The light under test is split into a reflected light path and a transmitted light path by beam splitter two with a power ratio of 50:50. After being reflected by plane mirror four, plane mirror five and plane mirror six, the two light paths are transmitted to hollow roof reflecting prism three and hollow roof reflecting prism four carried by servo motor displacement stage. Hollow roof reflecting prism three reflects the light back to plane mirror four in a direction parallel to the incident direction. Hollow roof reflecting prism four reflects the light back to plane mirror five in a direction parallel to the incident direction. Finally, they are re-converged at beam splitter two and illuminate the detection surface of point photodetector two after transmission and reflection.

[0006] Generally speaking, wavelength measurement systems can accurately characterize the wavelength of the laser under test. Compared with common spectrometers that use diffraction gratings for wavelength measurement, they have advantages such as high measurement accuracy, low difficulty in manufacturing the main optical components, and simple and easy-to-build structure.

[0007] The advantage of this invention is that it uses the Michelson interferometric wavelength measurement method. By calculating the ratio of the number of periods between the interference signals generated by the unknown wavelength light to be measured and the built-in reference light of the measurement system with a known wavelength under the same time conditions, the wavelength value of the light to be measured can be obtained more accurately.

[0008] Wavelength systems based on this theory can achieve 10 -7 Wavelength resolution is a relatively mature wavelength measurement technology.

[0009] This invention uses a Michelson interferometer as the main optical structure of a wavelength measurement system. By employing optical components suitable for lasers in the 0.8–2.4 μm wavelength range and combining them with corresponding high-speed signal acquisition and processing equipment, a wavelength measurement system with high accuracy is ultimately achieved. This wavelength measurement system will play an important role in fields such as coherent optical communication, nonlinear optics, high-precision fiber optic sensing, coherent lidar, and space optical communication.

[0010] A high-precision single-frequency wavelength measurement system for near-infrared ultrawideband lasers is proposed. This wavelength measurement instrument employs the Michelson interferometric wavelength measurement method. By constructing a system structure with a Michelson interferometer as the main component, interference signals are acquired via a photodetector and processed for analysis to obtain precise values ​​for the wavelengths of the measured light over an ultrawide range in the near-infrared band. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. As shown in the figures:

[0012] Figure 1 This is a schematic diagram of a near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers.

[0013] Figure 2 The results of 20 wavelength measurements were obtained for a single-frequency fiber laser with a standard wavelength of 2048.479 nm.

[0014] Figure 3The results of 20 wavelength measurements were obtained for a single-frequency fiber laser with a standard wavelength of 1569.410 nm. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1: As Figure 1 , Figure 2 and Figure 3 As shown, the technical problem solved by this invention is that many current spectrometers have a measurement accuracy of no more than 0.05 nm and a small measurable spectral range. The invention proposes a near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers.

[0017] like Figure 1 As shown, the near-infrared ultra-wideband high-precision single-frequency wavelength measurement system for fiber lasers includes a reference light 01, a light under test 02, a beam splitter 1 03, a beam splitter 2 04, a plane mirror 1 05, a plane mirror 2 06, a plane mirror 3 07, a plane mirror 4 08, a plane mirror 5 09, a plane mirror 6 10, a hollow roof reflecting prism 1 11, a hollow roof reflecting prism 2 12, a hollow roof reflecting prism 3 13, a hollow roof reflecting prism 4 14, a servo motor displacement stage 15, a point photodetector 1 16, a point photodetector 2 17, and a high-speed signal acquisition and processing device 18.

[0018] A near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers uses a 1.5μm single-frequency fiber laser as the reference light (01). The laser beam is split into a reflected light path and a transmitted light path at a 50:50 power ratio using a beam splitter (03). This 50:50 splitting ratio maximizes the signal-to-noise ratio of the final interference signal, facilitating subsequent filtering and extraction of key information.

[0019] After being reflected by plane mirror 105, plane mirror 206 and plane mirror 307, the two beams are transmitted to the hollow roof reflecting prism 11 and hollow roof reflecting prism 212 carried by the servo motor displacement stage 15.

[0020] Hollow ridge reflecting prism 11 reflects light back to plane mirror 05 in a direction parallel to the incident direction, and hollow ridge reflecting prism 22 reflects light back to plane mirror 307 in a direction parallel to the incident direction. Finally, the light is re-converged on beam splitter 03 and, after transmission and reflection, illuminates the detection surface of point photodetector 16.

[0021] The optical path transmission method of the light under test 02 is the same as that of the reference light 01.

[0022] The light to be measured, 02, is split into a reflected light path and a transmitted light path by beam splitter 2, 04, with a power ratio of 50:50. After being reflected by plane mirror 4, 08, 09, and 10, the two light paths are transmitted to the hollow roof reflecting prism 3, 13 and 4, which are carried by the servo motor displacement stage 15.

[0023] Hollow roof ridge reflecting prism three 13 reflects the light back to plane mirror four 08 in a direction parallel to the incident direction, and hollow roof ridge reflecting prism four 14 reflects the light back to plane mirror five 09 in a direction parallel to the incident direction. The light then converges again at beam splitter two 04 and, after transmission and reflection, illuminates the detection surface of point photodetector two 17. The interference signals collected by point photodetectors one 16 and two 17 are transmitted to high-speed signal acquisition and processing equipment 18. Using methods such as FFT and bandpass filtering, the signals are processed and analyzed to obtain the period values ​​of the two interference signals at equal time intervals and the proportional relationship between them.

[0024] During the measurement process, the high-speed signal acquisition and processing equipment 18 controls the servo motor displacement stage 15 to reciprocate in one dimension to provide the optical path difference change required to generate the interference signal for the reference light 01 and the light under test 02.

[0025] To evaluate the actual performance of the wavelength measurement system, two single-frequency fiber lasers with standard wavelengths of 2048.479 nm and 1569.410 nm were used for measurement, and the results are as follows: Figure 2 , Figure 3 As shown.

[0026] The measurement results showed errors of less than 0.015 nm compared to the standard wavelength values, indicating that the system's measurement accuracy can reach 0.015 nm, which is better than 0.05 nm.

[0027] Example 2: Figure 1 , Figure 2 and Figure 3 As shown, the near-infrared ultra-wideband high-precision single-frequency wavelength measurement system for fiber lasers includes the light under test, a reference light, beam splitter 1, beam splitter 2, plane mirror 1, plane mirror 2, plane mirror 3, plane mirror 4, plane mirror 5, plane mirror 6, hollow roof reflecting prism 1, hollow roof reflecting prism 2, hollow roof reflecting prism 3, hollow roof reflecting prism 4, servo motor displacement stage, point photodetector 1, point photodetector 2, and high-speed signal acquisition and processing equipment.

[0028] The system's optical path structure is divided into a reference light section and a test light section.

[0029] A near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers, comprising the following reference light section: A 1.5μm single-frequency fiber laser is used as the reference light, which is split into a reflected light path and a transmitted light path by a beam splitter with a 50:50 power ratio. The two beams are reflected by plane mirrors one, two, and three, and then transmitted to hollow roof prisms one and two, which are moved by a servo motor stage. Hollow roof prism one reflects the light back to plane mirror one in a direction parallel to the incident direction, and hollow roof prism two reflects the light back to plane mirror three in a direction parallel to the incident direction. Finally, the light converges again at beam splitter one and, after transmission and reflection, illuminates the detection surface of point photodetector one.

[0030] The light under test is split into a reflected light path and a transmitted light path by beam splitter two with a 50:50 power ratio. After reflection by plane mirrors four, five, and six, the two beams are transmitted to hollow roof prisms three and four, which are moved by a servo motor stage. Hollow roof prism three reflects the light back to plane mirror four in a direction parallel to the incident direction, and hollow roof prism four reflects the light back to plane mirror five in a direction parallel to the incident direction. Finally, the light converges again at beam splitter two and, after transmission and reflection, illuminates the detection surface of point photodetector two.

[0031] The interference signals collected by point photodetector one and point photodetector two are transmitted to a high-speed signal acquisition and processing device. Combined with filtering and analysis, the period values ​​of the two interference signals under equal time conditions and the proportional relationship between them are obtained.

[0032] During the measurement process, the high-speed signal acquisition and processing equipment controls the servo motor displacement stage to move back and forth in one dimension to provide the optical path difference change required to generate the interference signal between the reference light and the light under test.

[0033] The optical path transmission method of the light under test is the same as that of the reference light.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A near-infrared ultrawideband high-precision single-frequency wavelength measurement system for fiber lasers, characterized in that, Includes the following steps: Using a 1.5μm single-frequency fiber laser as the reference light, the beam is split into a reflected light path and a transmitted light path with a 50:50 power ratio by a beam splitter. After being reflected by plane mirror one, plane mirror two, and plane mirror three, the two beams of light are transmitted to hollow roof reflecting prism one and hollow roof reflecting prism two, which are carried by a servo motor displacement stage. Hollow roof ridge reflecting prism one reflects the light back to plane mirror one in a direction parallel to the incident direction, and hollow roof ridge reflecting prism two reflects the light back to plane mirror three in a direction parallel to the incident direction. Finally, the light re-converges at beam splitter one and, after transmission and reflection, illuminates the detection surface of point photodetector one. The optical path transmission mode of the light under test is the same as that of the reference light. The light to be measured is split into a reflected light path and a transmitted light path by beam splitter II with a power ratio of 50:

50. After being reflected by plane mirrors four, five, and six, the two beams of light are transmitted to hollow roof reflecting prisms three and four, which are carried by a servo motor displacement stage. Hollow roof ridge reflecting prism three reflects the light rays back to plane mirror four in a direction parallel to the incident direction. Hollow roof ridge reflecting prism four reflects the light rays back to plane mirror five in a direction parallel to the incident direction. Finally, the light rays converge again at beam splitter two and, after transmission and reflection, illuminate the detection surface of point photodetector two. High-precision wavelength measurement is performed on lasers in the ultra-wide near-infrared band of 0.8–2.4 μm. Beam splitters 1 and 2 have a 50:50 power splitting ratio suitable for lasers in the 0.8–2.4 μm band. Plane mirrors 1, 2, 3, 4, 5, and 6, as well as hollow roof prisms 1, 2, 3, and 4, all have high reflectivity coatings suitable for lasers in the 0.8–2.4 μm band. Point photodetectors 1 and 2 are both suitable for the 0.8–2.4 μm band, are made of indium gallium arsenide, and have a detector bandwidth of 10 MHz. The reference light uses a 1549.367 nm single-frequency fiber laser with a maximum stable power of 10 mW and a wavelength stability of ±1 pm.

2. The near-infrared ultra-wideband high-precision single-frequency wavelength measurement system for fiber lasers according to claim 1, characterized in that, The interference signals collected by point photodetector one and point photodetector two are transmitted to a high-speed signal acquisition and processing device. Combined with filtering and analysis, the period values ​​of the two interference signals under equal time conditions and the proportional relationship between them are obtained.

3. The near-infrared ultra-wideband high-precision single-frequency wavelength measurement system for fiber lasers according to claim 2, characterized in that, During the measurement process, the high-speed signal acquisition and processing equipment controls the servo motor displacement stage to move back and forth in one dimension to provide the optical path difference change required to generate the interference signal between the reference light and the light under test.

4. The near-infrared ultra-wideband high-precision single-frequency wavelength measurement system for fiber lasers according to claim 1, characterized in that, The filtering process for interference signals involves first using FFT to quickly analyze the approximate frequency range of the signal, then performing bandpass filtering to remove noise interference, and finally calculating the number of periods to achieve rapid and accurate wavelength measurement.

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