Laser longitudinal mode measuring device

Abstract

The utility model relates to the technical field of optics, and provides a laser longitudinal mode measuring device which is used for measuring a laser longitudinal mode of a laser and comprises a filtering module used for filtering laser, a tuning module at least used for adjusting the band-pass position of the filtering module and a detection module used for detecting the laser. Laser output after passing through the filtering module is single longitudinal mode laser, the tuning module is connected with the filtering module, and the detection module is arranged on an output path of the filtering module; the laser of the laser is output after being filtered by the filtering module, and is transmitted to the detection module for measurement; by arranging the filtering module, laser can obtain single-longitudinal-mode laser after being filtered by the filtering module, meanwhile, the band-pass position of the filtering module is adjusted through the tuning module, the frequency range of the laser can be scanned in sequence, the number of longitudinal modes can be obtained through the detection module, and the blank that the number of the laser longitudinal modes cannot be measured is filled up; accurate measurement of the number of laser longitudinal modes becomes possible.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and more specifically, to a laser longitudinal mode measurement device. Background Art

[0002] In laser transmission, in order to ensure the stability of the laser in the laser resonant cavity, the oscillation standing wave condition must be met: λ = 2nl / q, where λ is the wavelength, n is the refractive index, l is the resonant cavity length, and q is an integer. The number of qs that ultimately meet the above conditions is the number of longitudinal modes output by the laser, so the spectrum of the output laser is composed of multiple oscillating longitudinal modes (see Appendix Figure 1 ), the characteristics of these longitudinal modes are closely related to the output quality of the laser.

[0003] Existing research methods for laser spectrum measurement primarily include Fabry-Perot (FP) etalon measurement, beat-frequency linewidth measurement, and time-delayed heterodyne interferometry. These methods convert optical signals into measurable electrical signals through interference, thereby indirectly observing the output spectrum. However, when multiple longitudinal modes exist in the laser spectrum, the interference signal can only vaguely infer the number of longitudinal modes, and accurate measurement of the number of longitudinal modes is impossible.

[0004] The above shortcomings need to be improved. Utility Model Content

[0005] The purpose of this application is to provide a laser longitudinal mode measurement device to solve the technical problem in the prior art that the number of laser longitudinal modes cannot be measured.

[0006] To achieve the above-mentioned purpose, the technical solution adopted in this application is to provide a laser longitudinal mode measurement device for measuring the laser longitudinal mode of a laser, comprising:

[0007] A filter module is used to filter the laser light of the laser, and the laser light output after passing through the filter module is a single longitudinal mode laser light;

[0008] a tuning module connected to the filtering module and at least used to adjust a bandpass position of the filtering module, wherein the bandpass position of the filtering module covers a frequency domain range of the laser light of the laser;

[0009] The detection module is provided on the output path of the filtering module and is used for detecting the single longitudinal mode laser.

[0010] In one embodiment, the filtering module includes a first filtering unit and a second filtering unit for filtering the laser, and the tuning module is connected to the first filtering unit and / or the second filtering unit.

[0011] In one embodiment, the tuning module includes a first tuning unit connected to the first filtering unit and configured to adjust a passband position of the first filtering unit at least;

[0012] or,

[0013] The tuning module includes a second tuning unit connected to the second filtering unit and at least used to adjust the bandpass position of the second filtering unit;

[0014] or,

[0015] The tuning module includes a first tuning unit and a second tuning unit, wherein the first tuning unit is connected to the first filtering unit, and the second tuning unit is connected to the second filtering unit.

[0016] In one embodiment, the first filtering unit is a transmission filtering unit, which is used to connect to the laser and perform transmission filtering on the laser;

[0017] The second filtering unit is a transmission filtering unit, configured to perform transmission filtering on the laser and output the laser.

[0018] In one embodiment, the first filtering unit is a transmission filtering unit that performs transmission filtering on the laser;

[0019] The second filtering unit is a reflective filtering unit, configured to perform reflective filtering on the laser.

[0020] In one embodiment, the first filter unit is further configured to be connected to the laser, and the laser light is sequentially transmitted through the first filter unit, reflected by the second filter unit, and then emitted through the first filter unit.

[0021] In one embodiment, the laser longitudinal mode measurement device further includes an output unit, configured to output the laser at a side end of the filter module;

[0022] The first filter unit is further configured to be connected to the laser. The laser light is sequentially transmitted through the first filter unit, reflected by the second filter unit, and then emitted through the output unit.

[0023] In one embodiment, the laser longitudinal mode measurement device further comprises a coupling unit for coupling the laser light of the laser into the filtering module;

[0024] The laser is reflected by the coupling unit and the second filtering unit in sequence, transmitted by the first filtering unit, and then emitted through the first filtering unit.

[0025] In one embodiment, the first filtering unit is a reflective filtering unit that performs reflective filtering on the laser;

[0026] The second filtering unit is a reflective filtering unit, configured to perform reflective filtering on the laser;

[0027] The laser longitudinal mode measuring device further comprises:

[0028] A coupling unit, configured to couple the laser light from the laser into the filtering module;

[0029] An output unit is used to output the laser at a side end of the filter module.

[0030] In one embodiment, the laser longitudinal mode measurement device further includes an isolation unit, which is provided between the filter module and the detection module and is used to isolate the reverse laser.

[0031] In one embodiment, the tuning module is further configured to adjust the passband width of the filtering module.

[0032] In one embodiment, the first filtering unit is a high-reflection fiber Bragg grating, and the second filtering unit is a high-reflection fiber Bragg grating.

[0033] The beneficial effect of the laser longitudinal mode measurement device provided in this embodiment is that: by setting a filtering module, a single longitudinal mode laser can be obtained after the laser is filtered by the filtering module. At the same time, the bandpass position of the filtering module is adjusted by the tuning module, the frequency range of the laser can be scanned in sequence, and the number of laser outputs is detected by the detection module, so that the number of longitudinal modes can be obtained, filling the gap in the inability to measure the number of laser longitudinal modes, making it possible to accurately measure the number of laser longitudinal modes. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 is a schematic diagram of the laser emission spectrum;

[0036] Figure 2 A schematic diagram of laser emission from a laser longitudinal mode measurement device provided in an embodiment of the present application;

[0037] Figure 3 Schematic diagram of the structure of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 1 ;

[0038] Figure 4Schematic diagram of the structure of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 2 ;

[0039] Figure 5 Schematic diagram of the structure of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 3 ;

[0040] Figure 6 Schematic diagram of the working principle of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 1 ;

[0041] Figure 7 Schematic diagram of the working principle of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 2 ;

[0042] Figure 8 Schematic diagram of the working principle of the filter module of the laser longitudinal mode measurement device provided in the embodiment of the present application Figure 3 ;

[0043] Figure 9 A schematic diagram of the working principle of the bandpass position adjustment of the tuning module of the laser longitudinal mode measurement device provided in an embodiment of the present application;

[0044] Figure 10 A schematic diagram of the working principle of the bandpass width adjustment of the tuning module of the laser longitudinal mode measurement device provided in an embodiment of the present application;

[0045] Figure 11 The working principle of the embodiment 1 of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown as follows: Figure 1 ;

[0046] Figure 12 The working principle of the embodiment 1 of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown as follows: Figure 2 ;

[0047] Figure 13 The working principle of the second embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0048] Figure 14 The working principle of the second embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0049] Figure 15 The working principle of the third embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown as follows: Figure 1 ;

[0050] Figure 16The working principle of the third embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown as follows: Figure 2 ;

[0051] Figure 17 The working principle of the third embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown as follows: Figure 3 ;

[0052] Figure 18 The working principle of the fourth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0053] Figure 19 The working principle of the fourth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0054] Figure 20 The working principle of the fourth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 3 ;

[0055] Figure 21 The working principle of the fifth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0056] Figure 22 The working principle of the fifth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0057] Figure 23 The working principle of the fifth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 3 ;

[0058] Figure 24 The working principle of the sixth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 1 ;

[0059] Figure 25 The working principle of the sixth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 2 ;

[0060] Figure 26 The working principle of the sixth embodiment of the laser longitudinal mode measurement device provided in the embodiment of the present application is shown in FIG. Figure 3 .

[0061] Among them, the reference numerals in the figures are:

[0062] 10-laser; 20-filter module;

[0063] 201-first filtering unit; 202-second filtering unit;

[0064] 30- tuning module; 301- first tuning unit;

[0065] 302-second tuning unit;

[0066] 40-detection module; 50-coupling unit;

[0067] 60-output unit; 70-isolation unit. DETAILED DESCRIPTION

[0068] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is 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 this application and are not intended to limit this application.

[0069] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be located directly or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on this technical solution. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0070] Figures 1 to 26 This is a schematic structural diagram of a laser longitudinal mode measurement device provided in this embodiment.

[0071] See also Figures 11 to 12 A laser longitudinal mode measurement device is used to measure the longitudinal mode of a laser 10. The device includes a filter module 20 for filtering the laser light, a tuning module 30 for at least adjusting the passband position of the filter module 20, and a detection module 40 for detecting the laser light. The laser light output after passing through the filter module 20 is a single longitudinal mode laser light. The tuning module 30 is connected to the filter module 20, and the detection module 40 is provided on the output path of the filter module 20. The passband position of the filter module 20 covers the frequency domain of the laser light of the laser. In this embodiment, the detection module 40 is used to detect whether there is laser output. During the detection process, the single longitudinal mode laser signal detected by the detection module 40 will exhibit a cycle of appearance and disappearance. By recording the number of times the single longitudinal mode laser signal appears, the number of longitudinal modes N is obtained.

[0072] The working principle of the laser longitudinal mode measurement device provided in this embodiment is as follows:

[0073] First, the filter module 20 is connected to the laser 10 so that the laser light generated by the laser 10 can enter the filter module 20. The filter module 20 is tuned by the tuning module 30 so that the laser light outputted from the filter module 20 is a single longitudinal mode laser light.

[0074] When the laser longitudinal mode of the laser 10 needs to be read for measurement, the bandpass position of the filter module 20 is first adjusted by the tuning module 30 so that the bandpass position of the filter module 20 is outside the laser frequency. At this time, the detection module 40 cannot detect any laser output.

[0075] The laser light generated by the laser 10 enters the filter module 20, is filtered by the filter module 20, and is output and transmitted to the detection module 40. The detection module 40 detects whether there is laser output. During the detection process, the tuning module 30 adjusts the bandpass position of the filter module 20 so that the bandpass position sweeps through the frequency range of the laser in sequence (the scanning sequence can be from low frequency to high frequency, or from high frequency to low frequency). When the laser longitudinal mode is within the bandpass range of the filter module 20, the laser light with the longitudinal mode is output to the detection module 40, and the detection module 40 detects the laser output. After the bandpass position of the filter module 20 sweeps through the frequency range of the laser, the detection module 40 records the number of times the laser is output, thereby obtaining the number N of longitudinal modes.

[0076] The beneficial effect of a laser longitudinal mode measurement device provided in this embodiment is that: by setting a filter module 20, a single longitudinal mode laser can be obtained after the laser is filtered by the filter module 20, and at the same time, the bandpass position of the filter module 20 is adjusted by the tuning module 30, the frequency range of the laser can be scanned in sequence, and the number of laser outputs is detected by the detection module 40, so that the number of longitudinal modes N can be obtained, filling the gap of being unable to measure the number of laser longitudinal modes, making it possible to accurately measure the number of laser longitudinal modes.

[0077] See also Figure 2 Furthermore, the tuning module 30 is also used to adjust the bandpass width L30 of the filter module 20, so that the bandpass width L30 can be narrow enough, so that the bandpass width L30 is smaller than the width L31 between adjacent longitudinal modes in the multi-longitudinal mode laser, thereby ensuring that the laser output after passing through the filter module 20 is a single longitudinal mode laser.

[0078] See also Figures 3 to 5In one embodiment, the filtering module 20 includes a first filtering unit 201 and a second filtering unit 202 for filtering laser light. The tuning module 30 is connected to the first filtering unit 201 and / or the second filtering unit 202, thereby adjusting the passband position and / or passband width of the first filtering unit 201 and / or the second filtering unit 202. The filtering range of the first filtering unit 201 partially overlaps with the filtering range of the second filtering unit 202. After filtering by the first filtering unit 201 and the second filtering unit 202, the laser light is converted into a single longitudinal mode laser light and output to the detection module 40.

[0079] The adjustment method of the tuning module 30 includes at least:

[0080] Adjusting the passband position of the first filtering unit 201 or the second filtering unit 202;

[0081] Adjusting the passband width of the first filtering unit 201 or the second filtering unit 202;

[0082] Adjusting the passband position and passband width of the first filtering unit 201 or the second filtering unit 202;

[0083] Adjusting the passband positions of the first filtering unit 201 and the second filtering unit 202;

[0084] Adjusting the passband widths of the first filtering unit 201 and the second filtering unit 202;

[0085] Adjusting the passband position and passband width of the first filtering unit 201 and the second filtering unit 202;

[0086] Adjust the passband position of the first filter unit 201 and adjust the passband width of the second filter unit 202;

[0087] The passband width of the first filtering unit 201 is adjusted, and the passband position of the second filtering unit 202 is adjusted.

[0088] Because the filter module 20 includes two filter units (a first filter unit 201 and a second filter unit 202) with partially overlapping filtering ranges, even if each filter unit has a relatively wide filtering range, by adjusting the first filter unit 201 and / or the second filter unit 202 via the tuning module 30, a laser with an extremely narrow linewidth can be obtained, thereby achieving single longitudinal mode filtering output. Since the filtering range requirements for each filter unit are not high, filter units with lower parameters and a wider filtering range can be used, greatly reducing the process difficulty.

[0089] See also Figure 4In one embodiment, the tuning module 30 includes a first tuning unit 301, which is connected to the first filtering unit 201 and is configured to adjust the passband position and / or passband width of the first filtering unit 201. By adjusting the passband position of the first filtering unit 201, the passband position of the overlapping portion of the first filtering unit 201 and the second filtering unit 202 can be adjusted; by adjusting the passband width of the first filtering unit 201, the passband width of the overlapping portion of the first filtering unit 201 and the second filtering unit 202 can be adjusted.

[0090] See also Figure 5 In one embodiment, the tuning module 30 includes a second tuning unit 302, which is connected to the second filtering unit 202 and is configured to adjust the passband position and / or passband width of the second filtering unit 202. By adjusting the passband position of the second filtering unit 202, the passband position of the overlapping portion of the first filtering unit 201 and the second filtering unit 202 can be adjusted; by adjusting the passband width of the second filtering unit 202, the passband width of the overlapping portion of the first filtering unit 201 and the second filtering unit 202 can be adjusted.

[0091] See also Figure 3 In one embodiment, the tuning module 30 includes a first tuning unit 301 and a second tuning unit 302. The first tuning unit 301 is connected to the first filtering unit 201, and the second tuning unit 302 is connected to the second filtering unit 202. By adjusting the passband positions of the first filtering unit 201 and the second tuning unit 302, the passband positions of the overlapping portions of the first filtering unit 201 and the second filtering unit 202 can be adjusted (see Figure 9 , L30' is the bandpass position before adjustment, L30 is the bandpass position after adjustment); by adjusting the bandpass width of the first filtering unit 201 and the second filtering unit 202, the bandpass width of the overlapping portion of the first filtering unit 201 and the second filtering unit 202 can be adjusted (see Figure 10 , L30' is the bandpass width before adjustment, and L30 is the bandpass width after adjustment).

[0092] See also Figure 6 、 Figures 13 and 14 In one embodiment, the first filter unit 201 is a transmission filter unit that performs transmission filtering on the laser. The first filter unit 201 is connected to the laser 10, so that a portion of the laser generated by the laser 10 can enter the filter module 20 through the first filter unit 201; the second filter unit 202 is a transmission filter unit that performs transmission filtering on the laser. After passing through the second filter unit, the laser in the filter module 20 is partially transmitted and output to the detection module 40.

[0093] When the laser light generated by the laser 10 passes through the first filter unit 201, due to the reflectivity of the first filter unit 201 in the frequency domain, the laser light within the reflection range of the first filter unit 201 (i.e., the first reflection range L11) is filtered and cannot pass through the first filter unit 201. However, the laser light outside the first reflection range L11 passes through the first filter unit 201 and enters the filter module 20. The laser light entering the filter module 20 continues to propagate to the second filter unit 202. Due to the reflectivity of the second filter unit 202 in the frequency domain, the laser light within the reflection range of the second filter unit 202 (i.e., the second reflection range L21) is filtered and cannot pass through the second filter unit 202. However, the laser light outside the second reflection range L21 passes through the second filter unit 202 and is emitted. The overlapping part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second reflection range L21 is the filtering range L30 (the filtering range L30 is smaller than the width between adjacent longitudinal modes in the multi-longitudinal mode laser), and the laser output after passing through the second filtering unit 202 is a single longitudinal mode laser in the filtering range L30.

[0094] It should be understood that the first filtering unit 201 can also allow part of the laser to be transmitted, while the part of the laser that cannot be transmitted will be absorbed by the first filtering unit 201; the second filtering unit 202 can also allow part of the laser to be transmitted, while the part of the laser that cannot be transmitted will be absorbed by the second filtering unit 202.

[0095] In one embodiment, the first filter unit 201 is a transmission filter unit that performs transmission filtering on the laser, and the reflection range of the first filter unit 201 is the first reflection range L11, and the laser outside the first reflection range L11 passes through the first filter unit 201 to enter the filter module 20 or is emitted from the filter module 20; the second filter unit 202 is a reflection filter unit that performs reflection filtering on the laser, and the transmission range of the second filter unit 202 is the second transmission range L22, and the laser outside the second transmission range L22 will be reflected at the second filter unit 202; the overlapping part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 is the filter range L30 (the filter range L30 is smaller than the width between adjacent longitudinal modes in the multi-longitudinal mode laser), and the laser output after passing through the filter module 20 is a single longitudinal mode laser in the filter range L30.

[0096] See also Figure 7 、 Figures 15 and 16In one embodiment, the first filter unit 201 is a transmissive filter unit, and the second filter unit 202 is a reflective filter unit. The first filter unit 201 is connected to the laser 10, so that the laser light from the laser 10 can pass through the first filter unit 201 and enter the filter module 20. The laser light entering the filter module 20 is further transmitted to the second filter unit 202 and reflected. The reflected portion of the laser light returns to the first filter unit 201 and is filtered by the first filter unit 201 before being emitted. The output laser light is the laser light within the filtering range L30.

[0097] It should be understood that the first filtering unit 201 can also allow part of the laser to be transmitted, while the part of the laser that cannot be transmitted will be absorbed by the first filtering unit 201; the second transmission range L22 of the second filtering unit 202 can also be an absorption range, that is, the laser within this range will be absorbed by the second filtering unit 202.

[0098] See also Figures 17 to 20 In one embodiment, the first filter unit 201 is a transmission filter unit, and the second filter unit 202 is a reflection filter unit. The laser longitudinal mode measurement device further includes a coupling unit 50, which is connected to the first filter unit 201 and the laser 10, thereby coupling the laser light from the laser 10 into the filter module 20. At this time, the laser light transmitted by the first filter unit 201 can be directly emitted through the first filter unit 201, or transmitted to the coupling unit 50 before being emitted. Figures 21 to 22 The coupling unit 50 can also be located in the filter module 20, and the coupling unit 50 is connected to the laser 10, so that the laser of the laser 10 is coupled into the filter module 20. After the laser enters the filter module 20, it is first transmitted to the second filter unit 202 for reflection. The reflected part of the laser returns to the first filter unit 201 and is filtered by the first filter unit 201 before being emitted. The output laser is the laser within the filter range L30.

[0099] See also Figures 23 to 24In one embodiment, the first filter unit 201 is a transmissive filter unit connected to the laser 10, and the second filter unit 202 is a reflective filter unit. The laser longitudinal mode measurement device further includes an output unit 60 for outputting laser light at a side end of the filter module 20. The laser light is emitted from the output unit 60 and then transmitted to the detection module 40. The laser light from the laser 10 is sequentially transmitted through the first filter unit 201, reflected from the second filter unit 202, and then emitted through the output unit 60. The output laser light is within the filtering range L30. The output unit 60 can also be located outside the filter module 20 and connected to the first filter unit 201, so that the laser light is sequentially transmitted through the first filter unit 201, reflected from the second filter unit 202, and then transmitted through the first filter unit 201, then emitted through the output unit 60 to the detection module 40.

[0100] See also Figure 8 、 Figures 25 to 26 In one embodiment, the first filter unit 201 is a reflective filter unit that performs reflection filtering on the laser. The transmission range of the first filter unit 201 is a first transmission range L12, and the laser outside the first transmission range L12 will be reflected at the first filter unit 201; the second filter unit 202 is a reflective filter unit that performs reflection filtering on the laser. The transmission range of the second filter unit 202 is a second transmission range L22, and the laser outside the second transmission range L22 will be reflected at the second filter unit 202; the overlapping part of the frequency domain outside the first transmission range L12 and the frequency domain outside the second transmission range L22 is the filter range L30, and the filter range L30 is smaller than the width between adjacent longitudinal modes in the multi-longitudinal mode laser. The laser output after passing through the filter module 20 is the laser within the filter range L30.

[0101] The laser longitudinal mode measurement device also includes a coupling unit 50 and an output unit 60. The coupling unit 50 is located within the filter module 20 and is connected to the laser 10, thereby coupling the laser light from the laser 10 into the filter module 20. The output unit 60 is used to output the laser light to the detection module 40 at the side of the filter module 20. The laser light from the laser 10 enters the filter module 20 through the coupling unit 50, is reflected by the first filter unit 201 and the second filter unit 202, and is output to the detection module 40 through the output unit 60. The output laser light is the laser light within the filter range L30.

[0102] It should be understood that the first transmission range L12 of the first filter unit 201 can also be an absorption range, that is, the laser within this range will be absorbed by the first filter unit 201; the second transmission range L22 of the second filter unit 202 can also be an absorption range, that is, the laser within this range will be absorbed by the second filter unit 202.

[0103] Furthermore, the laser longitudinal mode measurement device provided in this embodiment may include an isolation unit 70 arranged on the output path of the filter module 20. The isolation unit 70 is arranged between the filter module 20 and the detection module 40 to isolate the reverse laser, thereby protecting the laser longitudinal mode measurement device.

[0104] Furthermore, the first filter unit 201 can be a highly reflective fiber Bragg grating, and the second filter unit 202 can be a highly reflective fiber Bragg grating. Due to its frequency domain reflectivity, the highly reflective fiber Bragg grating filters light (including laser light) within its frequency domain reflection range. The first tuning unit 301 is connected to the first filter unit 201, and the second tuning unit 302 is connected to the second filter unit 202. By influencing the physical and chemical properties of the grating (including temperature, stress, pressure, etc.), the bandpass position and bandpass width can be adjusted to meet specific usage requirements.

[0105] Several specific embodiments are provided below, but are not limited to the following embodiments. In the following embodiments, the tuning module 30 may include a first tuning unit 301, the first tuning unit 301 being connected to the first filtering unit 201 and configured to adjust the passband position and / or passband width of the first filtering unit 201; the tuning module 30 may include a second tuning unit 302, the second tuning unit 302 being connected to the second filtering unit 202 and configured to adjust the passband position and / or passband width of the second filtering unit 202; the tuning module 30 may also include a first tuning unit 301 and a second tuning unit 302, the first tuning unit 301 being connected to the first filtering unit 201 and the second tuning unit 302 being connected to the second filtering unit 202. Thus, the passband position and passband width of the first filtering unit 201 and the second filtering unit 202 can be adjusted by the tuning module 30.

[0106] See also Figures 11 to 12 , Example 1:

[0107] The laser longitudinal mode measurement device includes a filter module 20, a tuning module 30 and a detection module 40. The tuning module 30 is connected to the filter module 20, and the detection module 40 is arranged on the output path of the filter module 20. The tuning module 30 can adjust the bandpass width and bandpass position of the filter module 20 so that the laser output after passing through the filter module 20 is a single longitudinal mode laser.

[0108] The laser light from the laser 10 is filtered by the filter module 20 and then transmitted to the detection module 40 for measurement. During the detection process, the single longitudinal mode laser signal detected by the detection module 40 will show a cycle of appearance and disappearance. By recording the number of occurrences of the single longitudinal mode laser signal, the number of longitudinal modes N is obtained.

[0109] See also Figure 6 、 Figures 13 and 14 , Example 2:

[0110] Based on the above-described first embodiment, the filter module 20 includes a first filter unit 201 and a second filter unit 202. The first filter unit 201 is a transmissive filter unit, and the second filter unit 202 is a transmissive filter unit. The first filter unit 201 is connected to the laser 10, and the laser light in the filter module 20 is output from the second filter unit 202. Due to the frequency domain reflectivity of the first filter unit 201, laser light within a first reflection range L11 of the first filter unit 201 is filtered and cannot pass through the first filter unit 201, while laser light outside the first reflection range L11 passes through the first filter unit 201. Due to the frequency domain reflectivity of the second filter unit 202, laser light within a second reflection range L21 of the second filter unit 202 is filtered and cannot pass through the second filter unit 202, while laser light outside the second reflection range L21 passes through the second filter unit 202. The overlapping portion of the frequency domain outside the first reflection range L11 and the second reflection range L21 constitutes the filter range L30.

[0111] When the laser generated by the laser 10 passes through the first filtering unit 201, the laser outside the first reflection range L11 is transmitted through the first filtering unit 201 and enters the filtering module 20; the laser entering the filtering module 20 continues to propagate to the second filtering unit 202, and the laser outside the second reflection range L21 is transmitted through the second filtering unit 202 and emitted to the detection module 40. The emitted laser is the laser in the filtering range L30.

[0112] It should be understood that the laser within the first reflection range L11 can be reflected at the first filtering unit 201 or absorbed by the first filtering unit 201; the laser within the second reflection range L21 can be reflected at the second filtering unit 202 or absorbed by the second filtering unit 202.

[0113] Example 3:

[0114] See also Figure 7 、 Figures 15 and 16Based on the above-mentioned embodiment 1, the filtering module 20 includes a first filtering unit 201 and a second filtering unit 202. The first filtering unit 201 is a transmission filtering unit. The reflection range of the first filtering unit 201 is a first reflection range L11. Laser light outside the first reflection range L11 can pass through the first filtering unit 201; the second filtering unit 202 is a reflection filtering unit. The transmission range of the second filtering unit 202 is a second transmission range L22. Laser light outside the second transmission range L22 will be reflected at the second filtering unit 202; the overlapping portion of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 is the filtering range L30; the first filtering unit 201 is connected to the laser 10, and the laser light in the filtering module 20 is emitted to the detection module 40 through the first filtering unit 201.

[0115] The laser of the laser 10 enters the filter module 20 through the first filter unit 201. The laser entering the filter module 20 continues to be transmitted to the second filter unit 202 and reflected. The reflected part of the laser returns to the first filter unit 201 and is transmitted through the first filter unit 201 and then emitted to the detection module 40. The output laser is the laser in the filter range L30.

[0116] It should be understood that the laser within the first reflection range L11 can be reflected at the first filter unit 201 or absorbed by the first filter unit 201; the laser within the second transmission range L22 can be transmitted at the second filter unit 202 or absorbed by the second filter unit 202.

[0117] See also Figure 7 、 Figures 17 and 18 , Example 4:

[0118] On the basis of the above-mentioned embodiment three, the laser longitudinal mode measurement device also includes a coupling unit 50, which is connected to the first filtering unit 201, and the coupling unit 50 is connected to the laser 10. The laser light of the laser 10 passes through the coupling unit 50 and the first filtering unit 201 in sequence and enters the filtering module. The laser light entering the filtering module 20 continues to be transmitted to the second filtering unit 202 and reflected. The reflected part of the laser light returns to the first filtering unit 201 and is transmitted through the first filtering unit 201 and then emitted to the detection module 40. The output laser light is the laser light in the filtering range L30.

[0119] See also Figure 7 、 Figures 19 to 20 , Example 5:

[0120] Based on the above fourth embodiment, the laser in the filter module 20 is emitted after being transmitted through the first filter unit 201, and is transmitted to the coupling unit 50 and then emitted to the detection module 40 through the coupling unit 50. The output laser is the laser in the filtering range L30.

[0121] Example 6:

[0122] See also Figure 7 、 Figures 21 to 22 Based on the above-mentioned embodiment 1, the filtering module 20 includes a first filtering unit 201 and a second filtering unit 202. The first filtering unit 201 is a transmission filtering unit, and the reflection range of the first filtering unit 201 is a first reflection range L11; the second filtering unit 202 is a reflection filtering unit, and the transmission range of the second filtering unit 202 is a second transmission range L22; the overlapping portion of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 is the filtering range L30; the laser longitudinal mode measurement device also includes a coupling unit 50, which is located in the filtering module 20 and connected to the laser 10; the laser in the filtering module 20 is emitted to the detection module 40 through the first filtering unit 201.

[0123] The laser from the laser 10 enters the filter module 20 through the coupling unit 50. The laser that enters the filter module 20 continues to be transmitted to the second filter unit 202 and is reflected. The reflected part of the laser continues to be transmitted to the first filter unit 201, and is transmitted through the first filter unit 201 and then emitted to the detection module 40. The output laser is the laser within the filter range L30.

[0124] See also Figure 7 、 Figures 23 to 24 , embodiment seven:

[0125] Based on the above-mentioned embodiment 1, the filtering module 20 includes a first filtering unit 201 and a second filtering unit 202. The first filtering unit 201 is a transmission filtering unit, and the reflection range of the first filtering unit 201 is a first reflection range L11; the second filtering unit 202 is a reflection filtering unit, and the transmission range of the second filtering unit 202 is a second transmission range L22; the overlapping part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 is the filtering range L30; the first filtering unit 201 is connected to the laser 10; the laser longitudinal mode measurement device also includes an output unit 60 for outputting laser light at the side end of the filtering module 20, and the output unit 60 is arranged between the filtering module 20 and the detection module 40.

[0126] The laser of the laser 10 enters the filter module 20 through the first filter unit 201. The laser entering the filter module 20 continues to be transmitted to the second filter unit 202 and reflected. The reflected part of the laser is emitted to the detection module 40 through the output unit 60, and the output laser is the laser in the filter range L30.

[0127] It should be understood that the output unit 60 can also be located outside the filter module 20 and connected to the first filter unit 201. The laser is transmitted through the first filter unit 201, reflected by the second filter unit 202, and transmitted through the first filter unit 201 before being emitted to the detection module 40 through the output unit 60.

[0128] See also Figure 8 、 Figures 25 to 26 , embodiment eight:

[0129] Based on the above-described first embodiment, the filter module 20 includes a first filter unit 201 and a second filter unit 202. The first filter unit 201 is a reflective filter unit, and the transmission range of the first filter unit 201 is a first transmission range L12. Laser light outside the first transmission range L12 will be reflected at the first filter unit 201. The second filter unit 202 is a reflective filter unit, and the transmission range of the second filter unit 202 is a second transmission range L22. The overlapping portion of the frequency domain outside the first transmission range L12 and the frequency domain outside the second transmission range L22 is the filter range L30. The laser longitudinal mode measurement device also includes a coupling unit 50 and an output unit 60. The coupling unit 50 is located within the filter module 20 and is connected to the laser 10, thereby coupling the laser light from the laser 10 into the filter module 20. The output unit 60 is used to output the laser light to the detection module 40 at the side end of the filter module 20.

[0130] The laser light from the laser 10 enters the filter module 20 through the coupling unit 50, and is reflected by the first filter unit 201 and the second filter unit 202 before being output to the detection module 40 through the output unit 60. The output laser light is within the filtering range L30. The laser light entering the filter module 20 may first be transmitted to the first filter unit 201 for reflection and then to the second filter unit 202 for reflection, or may first be transmitted to the second filter unit 202 for reflection and then to the first filter unit 201 for reflection.

[0131] It should be understood that the laser within the first transmission range L12 can be transmitted through the first filter unit 201 or absorbed by the first filter unit 201; the laser within the second transmission range L22 can be transmitted through the second filter unit 202 or absorbed by the second filter unit 202.

[0132] Furthermore, the laser longitudinal mode measurement device in the above-mentioned embodiments 1 to 8 may also include an isolation unit 70, which is arranged on the output path of the filter module 20 and between the filter module 20 and the detection module 40, and is used to isolate the reverse laser, thereby protecting the laser longitudinal mode measurement device.

[0133] In the above embodiments, the laser 10, the filter module 20, the detection module 40, the coupling unit 50, the output unit 60 and the isolation unit 70 can be connected by optical fibers to realize an all-fiber laser longitudinal mode measurement device; some components can also be connected by optical fibers to realize a partial fiber laser longitudinal mode measurement device; and light can also be transmitted through free space, which is not limited here.

[0134] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A laser longitudinal mode measuring device for measuring the laser longitudinal mode of a laser, characterized in that: include A filter module is used to filter the laser light of the laser, and the laser light output after passing through the filter module is a single longitudinal mode laser light; a tuning module connected to the filter module and at least used to adjust the bandpass position of the filter module, wherein the bandpass position of the filter module covers the frequency domain range of the laser of the laser; The detection module is provided on the output path of the filtering module and is used for detecting the single longitudinal mode laser.

2. The laser longitudinal mode measurement device according to claim 1, wherein: The filtering module includes a first filtering unit and a second filtering unit for filtering the laser light, and the tuning module is connected to the first filtering unit and / or the second filtering unit.

3. The laser longitudinal mode measurement device according to claim 2, wherein: The tuning module includes a first tuning unit connected to the first filtering unit and at least used to adjust the bandpass position of the first filtering unit; or, The tuning module includes a second tuning unit connected to the second filtering unit and at least used to adjust the bandpass position of the second filtering unit; or, The tuning module includes a first tuning unit and a second tuning unit, wherein the first tuning unit is connected to the first filtering unit, and the second tuning unit is connected to the second filtering unit.

4. The laser longitudinal mode measurement device according to claim 2, wherein: The first filtering unit is a transmission filtering unit, which is used to connect to the laser and perform transmission filtering on the laser; The second filtering unit is a transmission filtering unit, configured to perform transmission filtering on the laser and output the laser.

5. The laser longitudinal mode measurement device according to claim 2, wherein: The first filtering unit is a transmission filtering unit that performs transmission filtering on the laser; The second filtering unit is a reflective filtering unit, configured to perform reflective filtering on the laser.

6. The laser longitudinal mode measurement device according to claim 5, characterized in that: The first filter unit is further configured to be connected to the laser. The laser light is sequentially transmitted through the first filter unit, reflected by the second filter unit, and then emitted through the first filter unit.

7. The laser longitudinal mode measurement device according to claim 5, wherein: The laser longitudinal mode measurement device further includes an output unit, configured to output the laser at a side end of the filter module; The first filter unit is further configured to be connected to the laser. The laser light is sequentially transmitted through the first filter unit, reflected by the second filter unit, and then emitted through the output unit.

8. The laser longitudinal mode measurement device according to claim 5, wherein: The laser longitudinal mode measurement device further includes a coupling unit for coupling the laser light of the laser into the filtering module; The laser is reflected by the coupling unit and the second filtering unit in sequence, transmitted by the first filtering unit, and then emitted through the first filtering unit.

9. The laser longitudinal mode measurement device according to claim 2, wherein: The first filtering unit is a reflective filtering unit that performs reflective filtering on the laser; The second filtering unit is a reflective filtering unit, configured to perform reflective filtering on the laser; The laser longitudinal mode measuring device further comprises: A coupling unit, configured to couple the laser light from the laser into the filtering module; An output unit is used to output the laser at a side end of the filter module.

10. The laser longitudinal mode measurement device according to any one of claims 1 to 9, characterized in that: The laser longitudinal mode measurement device further includes an isolation unit, which is provided between the filter module and the detection module and is used to isolate the reverse laser.

11. The laser longitudinal mode measurement device according to any one of claims 1 to 9, characterized in that: The tuning module is further used to adjust the passband width of the filtering module.

12. The laser longitudinal mode measurement device according to claim 4, wherein: The first filtering unit is a high-reflection fiber Bragg grating, and the second filtering unit is a high-reflection fiber Bragg grating.

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