Laser longitudinal mode measurement device

Abstract

Provided in the present application is a laser longitudinal mode measurement device, comprising a filtering module (20) for filtering laser, a tuning module (30) for at least adjusting the bandpass position of the filtering module, and a detection module (40) for detecting laser. Laser from a laser device (10) is filtered by the filtering module and then output, and is transmitted to the detection module for measurement. A filtering module is provided, such that single-longitudinal-mode laser can be obtained after laser is filtered by the filtering module; a tuning module adjusts the bandpass position of the filtering module, such that the frequency range of the laser can be sequentially scanned; and by means of a detection module, the number of longitudinal modes can be obtained, thereby filling the gap where the number of longitudinal modes of laser cannot be measured, and thus making accurate measurement of the number of longitudinal modes of the laser possible.

Description

A laser longitudinal mode measuring device TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, more particularly to a laser longitudinal mode measuring device. BACKGROUND

[0002] With the birth of the first laser in the world in 1960, laser technology and application have developed rapidly and are widely used in application technology fields, such as optoelectronic technology, laser medical treatment and photon biology, laser processing technology, laser detection and measurement technology, laser holographic technology, laser spectral analysis technology, nonlinear optics, ultrafast laser optics, quantum optics, laser radar, laser controlled nuclear fusion, laser weapons, etc. The emergence of these applications has greatly promoted the development of traditional industries and new industries.

[0003] In laser transmission, in order to enable the laser in the laser resonant cavity to exist stably, the oscillation standing wave condition needs to 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 q finally meeting the above condition is the number of longitudinal modes of the laser output, so the frequency spectrum of the output laser is composed of multiple oscillation longitudinal modes (see FIG. 1), and the characteristics of these longitudinal modes are closely related to the output quality of the laser.

[0004] The existing laser spectrum measurement methods mainly include Fabry-Perot (F-P) etalon measurement method, beat frequency line width measurement method, delay heterodyne interference method, etc. These methods convert the optical signal into an electrical signal that can be measured through interference, so as to indirectly observe the output spectrum. However, when there are multiple longitudinal modes in the laser spectrum, the number of longitudinal modes can only be roughly inferred through the interference signal, and cannot be accurately measured.

[0005] The above deficiencies are to be improved. TECHNICAL PROBLEM

[0006] The purpose of the present application is to provide a laser longitudinal mode measuring device to solve the technical problem that the number of laser longitudinal modes cannot be measured in the prior art. TECHNICAL SOLUTION

[0007] To achieve the above purpose, the technical scheme adopted by the present application is to provide a laser longitudinal mode measuring device for measuring the laser longitudinal mode of a laser, comprising:

[0008] A filtering module for filtering the laser of the laser, the laser output after passing through the filtering module being single longitudinal mode laser;

[0009] A tuning module connected with the filtering module, at least for adjusting the bandpass position of the filtering module, the bandpass position of the filtering module covering the frequency domain range of the laser of the laser.

[0010] a detection module, disposed on an output path of the filtering module, configured to detect the single longitudinal mode laser.

[0011] In one embodiment, the filtering module comprises a first filtering unit and a second filtering unit for filtering the laser, and the tuning module is connected with the first filtering unit and / or the second filtering unit.

[0012] In one embodiment, the tuning module comprises a first tuning unit connected with the first filtering unit, and configured to at least adjust a band-pass position of the first filtering unit.

[0013] Alternatively,

[0014] the tuning module comprises a second tuning unit connected with the second filtering unit, and configured to at least adjust a band-pass position of the second filtering unit.

[0015] Alternatively,

[0016] the tuning module comprises a first tuning unit and a second tuning unit, the first tuning unit is connected with the first filtering unit, and the second tuning unit is connected with the second filtering unit.

[0017] In one embodiment, the first filtering unit is a transmission filtering unit, configured to be connected with the laser and to perform transmission filtering on the laser.

[0018] the second filtering unit is a transmission filtering unit, configured to perform transmission filtering on the laser and to output the laser.

[0019] In one embodiment, the first filtering unit is a transmission filtering unit, configured to perform transmission filtering on the laser.

[0020] the second filtering unit is a reflection filtering unit, configured to perform reflection filtering on the laser.

[0021] In one embodiment, the first filtering unit is further configured to be connected with the laser, and the laser is sequentially transmitted by the first filtering unit, reflected by the second filtering unit, and then emitted through the first filtering unit.

[0022] In one embodiment, the laser longitudinal mode measuring device further comprises an output unit, configured to output the laser at a side end of the filtering module.

[0023] the first filtering unit is further configured to be connected with the laser, and the laser is sequentially transmitted by the first filtering unit, reflected by the second filtering unit, and then emitted through the output unit.

[0024] In one embodiment, the laser longitudinal mode measuring device further comprises a coupling unit, configured to couple the laser of the laser device into the filtering module.

[0025] The laser is emitted through the first filtering unit after being reflected by the coupling unit and the second filtering unit and being transmitted by the first filtering unit.

[0026] In one embodiment, the first filtering unit is a reflective filtering unit, configured to reflect filter the laser.

[0027] The second filtering unit is a reflective filtering unit, configured to reflect filter the laser.

[0028] The laser longitudinal mode measuring device further comprises:

[0029] a coupling unit, configured to couple the laser of the laser device into the filtering module;

[0030] an output unit, configured to output the laser at a side end of the filtering module.

[0031] In one embodiment, the laser longitudinal mode measuring device further comprises an isolation unit, arranged between the filtering module and the detecting module, configured to isolate the reverse laser.

[0032] In one embodiment, the tuning module is further configured to adjust the bandpass width of the filtering module.

[0033] 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. Advantages

[0034] The laser longitudinal mode measuring device provided by the present application has the following advantages: the filtering module is arranged to filter the laser, so that single longitudinal mode laser can be obtained; the tuning module is arranged to adjust the bandpass position of the filtering module, so that the frequency range of the laser can be scanned sequentially; the detecting module is arranged to detect the number of times of laser output, so that the number of longitudinal modes can be obtained, and the blank of being unable to measure the number of laser longitudinal modes is filled, and accurate measurement of the number of laser longitudinal modes is possible. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] FIG. 1 is a schematic diagram of a laser emission spectrum;

[0037] Fig. 2 is a schematic diagram of laser emission of a laser longitudinal mode measuring device provided by an embodiment of the present application;

[0038] Fig. 3 is a structural schematic diagram of a filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0039] Fig. 4 is a structural schematic diagram of the filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0040] Fig. 5 is a structural schematic diagram of the filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0041] Fig. 6 is a working principle schematic diagram of the filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0042] Fig. 7 is a working principle schematic diagram of the filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0043] Fig. 8 is a working principle schematic diagram of the filtering module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0044] Fig. 9 is a working principle schematic diagram of band-pass position adjustment of a tuning module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0045] Fig. 10 is a working principle schematic diagram of band-pass width adjustment of the tuning module of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0046] Fig. 11 is a working principle schematic diagram of an embodiment one of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0047] Fig. 12 is a working principle schematic diagram of the embodiment one of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0048] Fig. 13 is a working principle schematic diagram of an embodiment two of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0049] Fig. 14 is a working principle schematic diagram of the embodiment two of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0050] Fig. 15 is a working principle schematic diagram of an embodiment three of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0051] Fig. 16 is a working principle schematic diagram of the embodiment three of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0052] Fig. 17 is a working principle schematic diagram of the embodiment three of the laser longitudinal mode measuring device provided by an embodiment of the present application;

[0053] Fig. 18 is a schematic diagram of the working principle of the fourth embodiment of the laser longitudinal mode measuring device according to the present application;

[0054] Fig. 19 is a schematic diagram of the working principle of the fourth embodiment of the laser longitudinal mode measuring device according to the present application;

[0055] Fig. 20 is a schematic diagram of the working principle of the fourth embodiment of the laser longitudinal mode measuring device according to the present application;

[0056] Fig. 21 is a schematic diagram of the working principle of the fifth embodiment of the laser longitudinal mode measuring device according to the present application;

[0057] Fig. 22 is a schematic diagram of the working principle of the fifth embodiment of the laser longitudinal mode measuring device according to the present application;

[0058] Fig. 23 is a schematic diagram of the working principle of the fifth embodiment of the laser longitudinal mode measuring device according to the present application;

[0059] Fig. 24 is a schematic diagram of the working principle of the sixth embodiment of the laser longitudinal mode measuring device according to the present application;

[0060] Fig. 25 is a schematic diagram of the working principle of the sixth embodiment of the laser longitudinal mode measuring device according to the present application;

[0061] Fig. 26 is a schematic diagram of the working principle of the sixth embodiment of the laser longitudinal mode measuring device according to the present application.

[0062] In the drawings, various reference numerals represent various objects;

[0063] 10 - laser; 20 - filtering module;

[0064] 201 - first filtering unit; 202 - second filtering unit;

[0065] 30 - tuning module; 301 - first tuning unit;

[0066] 302 - second tuning unit;

[0067] 40 - detecting module; 50 - coupling unit;

[0068] 60 - output unit; 70 - isolating unit. Embodiments of the present application

[0069] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0070] It should be noted that when a component is referred to as "fixed to" or "disposed on" another component, it can be directly or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or position based on the orientation or position shown in the drawings, and are only for the convenience of description, and cannot be understood as a limitation on the technical solutions. The terms "first", "second" are only for the purpose of convenient description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. The meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0071] Figures 1 to 26 are structural schematic diagrams of a laser longitudinal mode measuring device provided by the present embodiment.

[0072] Referring to Figures 11 to 12, a laser longitudinal mode measuring device is used to measure the laser longitudinal mode of a laser 10, which comprises a filtering module 20 for filtering laser, a tuning module 30 for adjusting the band-pass position of the filtering module 20, and a detection module 40 for detecting laser. The laser output after the filtering module 20 is single longitudinal mode laser. The tuning module 30 is connected with the filtering module 20. The detection module 40 is arranged on the output path of the filtering module 20. The band-pass position of the filtering module 20 covers the frequency range of the laser of the laser. In the present embodiment, the detection module 40 is used to detect whether there is laser output. In the detection process, the single longitudinal mode laser signal detected by the detection module 40 will present a cycle of appearance-disappearance. By recording the number of times of appearance of the single longitudinal mode laser signal, the number N of longitudinal modes is obtained.

[0073] The working principle of the laser longitudinal mode measuring device provided by the present embodiment is as follows:

[0074] First, the filtering module 20 is connected with the laser 10, so that the laser generated by the laser 10 can enter the filtering module 20. The filtering module 20 is tuned by the tuning module 30, so that the laser output after the filtering module 20 is single longitudinal mode laser.

[0075] When it is needed to measure the laser longitudinal modes of the laser 10, the band-pass position of the filter module 20 is first adjusted by the tuning module 30, so that the band-pass position of the filter module 20 is outside the laser frequency, at which time the detection module 40 cannot detect laser output.

[0076] The laser 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 band-pass position of the filter module 20, so that the band-pass position scans the frequency range of the laser in turn (the scanning order can be from low frequency to high frequency, or from high frequency to low frequency). When the laser longitudinal mode is located in the band-pass range of the filter module 20, the laser with the longitudinal mode is output to the detection module 40, and the detection module 40 detects that there is laser output. After the band-pass position of the filter module 20 scans the frequency range of the laser, the detection module 40 records the number of times of laser output, so that the number N of longitudinal modes can be obtained.

[0077] The laser longitudinal mode measuring device provided by the embodiment has the beneficial effects that: by arranging the filter module 20, the laser filtered by the filter module 20 can obtain single longitudinal mode laser, and by adjusting the band-pass position of the filter module 20 by the tuning module 30, the frequency range of the laser can be scanned in turn, and the number of times of laser output can be detected by the detection module 40, so that the number N of longitudinal modes can be obtained, and the blank of being unable to measure the number of laser longitudinal modes is filled, so that accurate measurement of the number of laser longitudinal modes becomes possible.

[0078] Referring to FIG. 2, further, the tuning module 30 is further used for adjusting the band-pass width L30 of the filter module 20, so that the band-pass width L30 is narrow enough, so that the band-pass width L30 is smaller than the width L31 between adjacent longitudinal modes in the multi-longitudinal mode laser, so that it can be ensured that the laser output after passing through the filter module 20 is single longitudinal mode laser.

[0079] Referring to FIGS. 3 to 5, in an embodiment, the filter module 20 includes a first filter unit 201 and a second filter unit 202 for filtering the laser, and the tuning module 30 is connected with the first filter unit 201 and / or the second filter unit 202, so that the band-pass position and / or the band-pass width of the first filter unit 201 and / or the second filter unit 202 can be adjusted. The filtering range of the first filter unit 201 and the filtering range of the second filter unit 202 partially overlap, and the laser is filtered by the first filter unit 201 and the second filter unit 202 to obtain single longitudinal mode laser and output to the detection module 40.

[0080] The adjustment mode of the tuning module 30 at least includes:

[0081] adjusting the passband position of the first filter unit 201 or the second filter unit 202;

[0082] adjusting the passband width of the first filter unit 201 or the second filter unit 202;

[0083] adjusting the passband position and the passband width of the first filter unit 201 or the second filter unit 202;

[0084] adjusting the passband position of the first filter unit 201 and the second filter unit 202;

[0085] adjusting the passband width of the first filter unit 201 and the second filter unit 202;

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

[0087] adjusting the passband position of the first filter unit 201 and adjusting the passband width of the second filter unit 202;

[0088] adjusting the passband width of the first filter unit 201 and adjusting the passband position of the second filter unit 202.

[0089] Since two filter units (the first filter unit 201 and the second filter unit 202) with partially overlapped filter ranges are arranged in the filter module 20, even if the filter range of each filter unit is wide, a laser with extremely narrow line width can be obtained by adjusting the first filter unit 201 and / or the second filter unit 202 through the tuning module 30, and thus single-longitudinal-mode filtering output can be realized. Since the filter range requirement of each filter unit is not high, a filter unit with lower parameters and wider filter range can be used, which greatly reduces the process difficulty.

[0090] Please refer to FIG. 4. In one embodiment, the tuning module 30 includes a first tuning unit 301 connected with the first filter unit 201, which is used to adjust the passband position and / or the passband width of the first filter unit 201. By adjusting the passband position of the first filter unit 201, the passband position of the overlapped part of the first filter unit 201 and the second filter unit 202 can be adjusted; by adjusting the passband width of the first filter unit 201, the passband width of the overlapped part of the first filter unit 201 and the second filter unit 202 can be adjusted.

[0091] Referring to FIG. 5, in an embodiment, the tuning module 30 comprises a second tuning unit 302 connected with the second filtering unit 202, for adjusting the band-pass position and / or the band-pass width of the second filtering unit 202. By adjusting the band-pass position of the second filtering unit 202, the band-pass position of the overlapping part of the first filtering unit 201 and the second filtering unit 202 can be adjusted; by adjusting the band-pass width of the second filtering unit 202, the band-pass width of the overlapping part of the first filtering unit 201 and the second filtering unit 202 can be adjusted.

[0092] Referring to FIG. 3, in an embodiment, the tuning module 30 comprises a first tuning unit 301 connected with the first filtering unit 201 and a second tuning unit 302 connected with the second filtering unit 202. By adjusting the band-pass position of the first filtering unit 201 and the second tuning unit 302, the band-pass position of the overlapping part of the first filtering unit 201 and the second filtering unit 202 can be adjusted (referring to FIG. 9, L30' is the band-pass position before adjustment, and L30 is the band-pass position after adjustment); by adjusting the band-pass width of the first filtering unit 201 and the second filtering unit 202, the band-pass width of the overlapping part of the first filtering unit 201 and the second filtering unit 202 can be adjusted (referring to FIG. 10, L30' is the band-pass width before adjustment, and L30 is the band-pass width after adjustment).

[0093] Referring to FIG. 6 and FIG. 13-14, in an embodiment, the first filtering unit 201 is a transmission filtering unit for transmitting filtering of laser, and the first filtering unit 201 is connected with the laser 10, so that part of the laser generated by the laser 10 can pass through the first filtering unit 201 into the filtering module 20; the second filtering unit 202 is a transmission filtering unit for transmitting filtering of laser, and part of the laser in the filtering module 20 is transmitted after passing through the second filtering unit, and then output to the detection module 40.

[0094] The laser generated by the laser 10 passes through the first filtering unit 201. Due to the reflectivity of the first filtering unit 201 in the frequency domain, the laser within the reflection range (i.e., the first reflection range L11) of the first filtering unit 201 is filtered and cannot pass through the first filtering unit 201, while the laser outside the first reflection range L11 passes 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. Due to the reflectivity of the second filtering unit 202 in the frequency domain, the laser within the reflection range (i.e., the second reflection range L21) of the second filtering unit 202 is filtered and cannot pass through the second filtering unit 202, while the laser outside the second reflection range L21 is output after passing through the second filtering unit 202. The part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second reflection range L21 overlaps, which 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 the single longitudinal mode laser of the filtering range L30.

[0095] It should be understood that the first filtering unit 201 can also transmit part of the laser, and 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 transmit part of the laser, and the part of the laser that cannot be transmitted will be absorbed by the second filtering unit 202.

[0096] In one embodiment, the first filtering unit 201 is a transmission filtering unit that transmits the laser, the reflection range of the first filtering unit 201 is the first reflection range L11, and the laser outside the first reflection range L11 passes through the first filtering unit 201 and enters or exits the filtering module 20; the second filtering unit 202 is a reflection filtering unit that reflects the laser, the transmission range of the second filtering unit 202 is the second transmission range L22, and the laser outside the second transmission range L22 is reflected at the second filtering unit 202; the part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 overlaps, which 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 filtering module 20 is the single longitudinal mode laser of the filtering range L30.

[0097] Please refer to FIG. 7, FIG. 15 to FIG. 16, in an embodiment, the first filter unit 201 is a transmission filter unit, and the second filter unit 202 is a reflection filter unit. The first filter unit 201 is connected with the laser 10, so that the laser of the laser 10 can enter the filter module 20 through the first filter unit 201. The laser entering the filter module 20 continues to transmit to the second filter unit 202 and is reflected. The part of the laser being reflected returns to the first filter unit 201 and is output after being filtered by the first filter unit 201. The output laser is the laser of the filtering range L30.

[0098] It should be understood that the first filter unit 201 can also make part of the laser be transmitted, and the part of the laser which cannot be transmitted is 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 in the range is absorbed by the second filter unit 202.

[0099] Please refer to FIG. 17 to FIG. 20, in an 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 measuring device further comprises a coupling unit 50. The coupling unit 50 is connected with the first filter unit 201, and the coupling unit 50 is connected with the laser 10, so that the laser of the laser 10 is coupled into the filter module 20. At this time, the laser transmitted by the first filter unit 201 can be directly output through the first filter unit 201 or transmitted to the coupling unit 50 and then output. Please refer to FIG. 21 to FIG. 22, the coupling unit 50 can also be located in the filter module 20, and the coupling unit 50 is connected with 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 first transmits to the second filter unit 202 and is reflected. The part of the laser being reflected returns to the first filter unit 201 and is output after being filtered by the first filter unit 201. The output laser is the laser of the filtering range L30.

[0100] Please refer to FIG. 23 to FIG. 24, in one embodiment, the first filter unit 201 is a transmission filter unit, the first filter unit 201 is connected with the laser 10, the second filter unit 202 is a reflection filter unit, the laser longitudinal mode measuring device further comprises an output unit 60 for outputting laser at the side end of the filter module 20, the laser is transmitted to the detection module 40 after being emitted by the output unit 60. The laser of the laser 10 is transmitted by the first filter unit 201 and reflected by the second filter unit 202 in turn, and then is emitted by the output unit 60, and the output laser is the laser of the filter range L30. The output unit 60 can also be located outside the filter module 20 and connected with the first filter unit 201, so that the laser is transmitted by the first filter unit 201, reflected by the second filter unit 202, and then transmitted by the first filter unit 201 in turn, and then is emitted by the output unit 60 to the detection module 40.

[0101] Please refer to FIG. 8, FIG. 25 to FIG. 26, in one embodiment, the first filter unit 201 is a reflection filter unit for reflecting and filtering laser, the transmission range of the first filter unit 201 is the first transmission range L12, and the laser outside the first transmission range L12 is reflected at the first filter unit 201; the second filter unit 202 is a reflection filter unit for reflecting and filtering laser, the transmission range of the second filter unit 202 is the second transmission range L22, and the laser outside the second transmission range L22 is reflected at the second filter unit 202; the part of the frequency domain outside the first transmission range L12 and the frequency domain outside the second transmission range L22 which overlap 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 output laser after passing through the filter module 20 is the laser of the filter range L30.

[0102] The laser longitudinal mode measuring device further comprises a coupling unit 50 and an output unit 60, the coupling unit 50 is located in the filter module 20, and the coupling unit 50 is connected with the laser 10, so as to couple the laser of the laser 10 into the filter module 20; the output unit 60 is used for outputting laser to the detection module 40 at the side end of the filter module 20. The laser of the laser 10 enters the filter module 20 through the coupling unit 50, and is output to the detection module 40 through the output unit 60 after being reflected by the first filter unit 201 and the second filter unit 202, and the output laser is the laser of the filter range L30.

[0103] 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 in the range is 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 in the range is absorbed by the second filter unit 202.

[0104] Further, the laser longitudinal mode measuring device provided by the embodiment can further comprise an isolation unit 70 arranged on the output path of the filtering module 20, the isolation unit 70 is arranged between the filtering module 20 and the detection module 40, and is used for isolating the reverse laser, thereby protecting the laser longitudinal mode measuring device.

[0105] Further, the first filtering unit 201 can be a high-reflection fiber Bragg grating, and the second filtering unit 202 can also be a high-reflection fiber Bragg grating. Because of the reflection in the frequency domain of the high-reflection fiber Bragg grating, the light (including laser) in the reflection range of the high-reflection fiber Bragg grating is filtered. The first tuning unit 301 is connected with the first filtering unit 201, and the second tuning unit 302 is connected with the second filtering unit 202. By affecting the physical and chemical properties of the grating (including temperature, stress, pressure, etc.), the bandpass position and the bandpass width are adjusted to meet the specific use requirements.

[0106] The following provides several specific embodiments, but is not limited to the following embodiments. In the following embodiments, the tuning module 30 can comprise a first tuning unit 301 connected with the first filtering unit 201, and used for adjusting the bandpass position and / or the bandpass width of the first filtering unit 201; the tuning module 30 can comprise a second tuning unit 302 connected with the second filtering unit 202, and used for adjusting the bandpass position and / or the bandpass width of the second filtering unit 202; the tuning module 30 can also comprise the first tuning unit 301 and the second tuning unit 302, the first tuning unit 301 is connected with the first filtering unit 201, and the second tuning unit 302 is connected with the second filtering unit 202. Thus, the bandpass position and the bandpass width of the first filtering unit 201 and the second filtering unit 202 can be adjusted by the tuning module 30.

[0107] Please refer to FIGS. 11-12, embodiment one:

[0108] The laser longitudinal mode measuring device comprises a filtering module 20, a tuning module 30 and a detection module 40. The tuning module 30 is connected with the filtering module 20, and the detection module 40 is arranged on the output path of the filtering module 20. The tuning module 30 can adjust the bandpass width and the bandpass position of the filtering module 20, so that the laser output after the filtering module 20 is single longitudinal mode laser.

[0109] The laser of the laser device 10 is filtered by the filtering module 20 and then output, and is transmitted to the detection module 40 for measurement. In the detection process, the single longitudinal mode laser signal detected by the detection module 40 will present a cycle of appearance-disappearance. By recording the number of times of appearance of the single longitudinal mode laser signal, the number N of longitudinal modes is obtained.

[0110] Please refer to FIGS. 6, 13-14, embodiment two:

[0111] On the basis of the above embodiment one, the filtering module 20 comprises a first filtering unit 201 and a second filtering unit 202, the first filtering unit 201 is a transmissive filtering unit, and the second filtering unit 202 is a transmissive filtering unit; the first filtering unit 201 is connected with the laser 10, and the laser in the filtering module 20 is output from the second filtering unit 202. Due to the reflectivity of the first filtering unit 201 in the frequency domain, the laser in the first reflection range L11 of the first filtering unit 201 is filtered and cannot pass through the first filtering unit 201, and the laser outside the first reflection range L11 passes through the first filtering unit 201; due to the reflectivity of the second filtering unit 202 in the frequency domain, the laser in the second reflection range L21 of the second filtering unit 202 is filtered and cannot pass through the second filtering unit 202, and the laser outside the second reflection range L21 passes through the second filtering unit 202; the part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second reflection range L21 that overlaps is the filtering range L30.

[0112] 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 by 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, the laser outside the second reflection range L21 is transmitted by the second filtering unit 202 and exits to the detection module 40, and the exited laser is the laser of the filtering range L30.

[0113] It should be understood that the laser in the first reflection range L11 can be reflected at the first filtering unit 201 or be absorbed by the first filtering unit 201; the laser in the second reflection range L21 can be reflected at the second filtering unit 202 or be absorbed by the second filtering unit 202.

[0114] Embodiment three:

[0115] Please refer to FIG. 7, FIG. 15 to FIG. 16, on the basis of the above embodiment one, the filtering module 20 comprises a first filtering unit 201 and a second filtering unit 202, the first filtering unit 201 is a transmissive filtering unit, the reflection range of the first filtering unit 201 is the first reflection range L11, and the laser outside the first reflection range L11 can pass through the first filtering unit 201; the second filtering unit 202 is a reflective filtering unit, the transmission range of the second filtering unit 202 is the second transmission range L22, and the laser outside the second transmission range L22 is reflected at the second filtering unit 202; the part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 that overlaps is the filtering range L30; the first filtering unit 201 is connected with the laser 10, and the laser in the filtering module 20 is output to the detection module 40 through the first filtering unit 201.

[0116] The laser of the laser 10 enters the filtering module 20 through the first filtering unit 201, the laser entering the filtering module 20 continues to transmit to the second filtering unit 202 to reflect, the part of the laser reflecting returns to the first filtering unit 201, and then transmits to the detection module 40 through the first filtering unit 201, and the output laser is the laser of the filtering range L30.

[0117] It should be understood that the laser in the first reflection range L11 can be reflected at the first filtering unit 201 or be absorbed by the first filtering unit 201; the laser in the second transmission range L22 can be transmitted at the second filtering unit 202 or be absorbed by the second filtering unit 202.

[0118] Please refer to FIG. 7, FIG. 17 to FIG. 18, embodiment four:

[0119] On the basis of the above-mentioned embodiment three, the laser longitudinal mode measuring device further comprises a coupling unit 50, the coupling unit 50 is connected with the first filtering unit 201, and the coupling unit 50 is connected with the laser 10; the laser of the laser 10 enters the filtering module in turn through the coupling unit 50 and the first filtering unit 201, the laser entering the filtering module 20 continues to transmit to the second filtering unit 202 to reflect, the part of the laser reflecting returns to the first filtering unit 201, and then transmits to the detection module 40 through the first filtering unit 201, and the output laser is the laser of the filtering range L30.

[0120] Please refer to FIG. 7, FIG. 19 to FIG. 20, embodiment five:

[0121] On the basis of the above-mentioned embodiment four, the laser in the filtering module 20 transmits to the detection module 40 through the coupling unit 50 after transmitting to the coupling unit 50 through the first filtering unit 201, and the output laser is the laser of the filtering range L30.

[0122] Embodiment six:

[0123] Please refer to FIG. 7, FIG. 21 to FIG. 22, on the basis of the above-mentioned embodiment one, the filtering module 20 comprises a first filtering unit 201 and a second filtering unit 202, the first filtering unit 201 is a transmission type filtering unit, the reflection range of the first filtering unit 201 is the first reflection range L11; the second filtering unit 202 is a reflection type filtering unit, the transmission range of the second filtering unit 202 is the second transmission range L22; the part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 which overlaps is the filtering range L30; the laser longitudinal mode measuring device further comprises a coupling unit 50, the coupling unit 50 is located in the filtering module 20 and connected with the laser 10; the laser in the filtering module 20 transmits to the detection module 40 through the first filtering unit 201.

[0124] The laser of the laser 10 enters the filter module 20 through the coupling unit 50, and the laser entering the filter module 20 continues to transmit to the second filter unit 202 to be reflected, and the reflected part of the laser continues to transmit to the first filter unit 201 and is emitted to the detection module 40 after being transmitted through the first filter unit 201, and the output laser is the laser of the filter range L30.

[0125] Please refer to FIG. 7, FIG. 23 to FIG. 24, embodiment seven:

[0126] On the basis of the above-mentioned embodiment one, the filter module 20 comprises a first filter unit 201 and a second filter unit 202, the first filter unit 201 is a transmission filter unit, the reflection range of the first filter unit 201 is a first reflection range L11; the second filter unit 202 is a reflection filter unit, the transmission range of the second filter unit 202 is a second transmission range L22; the part of the frequency domain outside the first reflection range L11 and the frequency domain outside the second transmission range L22 which overlap is a filter range L30; the first filter unit 201 is connected with the laser 10; the laser longitudinal mode measuring device further comprises an output unit 60 for outputting laser at the side end of the filter module 20, and the output unit 60 is arranged between the filter module 20 and the detection module 40.

[0127] The laser of the laser 10 enters the filter module 20 through the first filter unit 201, and the laser entering the filter module 20 continues to transmit to the second filter unit 202 to be reflected, and 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 of the filter range L30.

[0128] It should be understood that the output unit 60 can also be located outside the filter module 20 and connected with the first filter unit 201, and the laser is emitted to the detection module 40 through the output unit 60 after being transmitted through the first filter unit 201, reflected by the second filter unit 202 and transmitted through the first filter unit 201 in turn.

[0129] Please refer to FIG. 8, FIG. 25 to FIG. 26, embodiment eight:

[0130] On the basis of the above embodiment one, the filtering module 20 comprises a first filtering unit 201 and a second filtering unit 202, the first filtering unit 201 is a reflective filtering unit, the transmission range of the first filtering unit 201 is a first transmission range L12, and the laser outside the first transmission range L12 is reflected at the first filtering unit 201; the second filtering unit 202 is a reflective filtering unit, the transmission range of the second filtering unit 202 is a second transmission range L22; the part of the frequency domain outside the first transmission range L12 and the frequency domain outside the second transmission range L22 is overlapped, which is a filtering range L30. The laser longitudinal mode measuring device further comprises a coupling unit 50 and an output unit 60, the coupling unit 50 is located in the filtering module 20, and the coupling unit 50 is connected with the laser 10, so as to couple the laser of the laser 10 into the filtering module 20; the output unit 60 is used for outputting the laser to the detection module 40 at the side end of the filtering module 20.

[0131] The laser of the laser 10 enters the filtering module 20 through the coupling unit 50, and is reflected by the first filtering unit 201 and the second filtering unit 202 and then output to the detection module 40 through the output unit 60, and the output laser is the laser of the filtering range L30. Wherein, the laser entering the filtering module 20 can be transmitted to the first filtering unit 201 to be reflected first, and then transmitted to the second filtering unit 202 to be reflected; or the laser entering the filtering module 20 can be transmitted to the second filtering unit 202 to be reflected first, and then transmitted to the first filtering unit 201 to be reflected.

[0132] It should be understood that the laser in the first transmission range L12 can be transmitted at the first filtering unit 201, or can be absorbed by the first filtering unit 201; the laser in the second transmission range L22 can be transmitted at the second filtering unit 202, or can be absorbed by the second filtering unit 202.

[0133] Further, the laser longitudinal mode measuring device in the above embodiments one to eight can further comprise an isolation unit 70, the isolation unit 70 is arranged on the output path of the filtering module 20 and between the filtering module 20 and the detection module 40, and is used for isolating the reverse laser, so as to protect the laser longitudinal mode measuring device.

[0134] In the above embodiments, the laser 10, the filtering module 20, the detection module 40, the coupling unit 50, the output unit 60 and the isolation unit 70 can be connected through optical fibers, so as to realize a full-fiber laser longitudinal mode measuring device; or some devices can be connected through optical fibers, so as to realize a partial-fiber laser longitudinal mode measuring device; or all the optical transmission can be through free space, which is not limited here.

[0135] The above only describes preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A laser longitudinal mode measuring device for measuring a laser longitudinal mode of a laser, characterized by: The application relates to a laser longitudinal mode measuring device. The filter module is used for filtering laser of the laser device, and the output laser after the filter module is single longitudinal mode laser. The tuning module is connected with the filter module and is used for adjusting at least the band-pass position of the filter module. The filter module comprises a first filter unit and a second filter unit.

2. The laser longitudinal mode measuring apparatus of claim 1, wherein: The tuning module comprises a first tuning unit connected with the first filter unit and used for adjusting at least the band-pass position of the first filter unit.

3. The laser longitudinal mode measuring apparatus of claim 2, wherein: The tuning module comprises a second tuning unit connected with the second filter unit and used for adjusting at least the band-pass position of the second filter unit. The first filter unit is a transmission filter unit used for connecting with the laser device and transmitting filtering the laser. The second filter unit is a transmission filter unit used for transmitting filtering the laser and outputting the laser. The first filter unit is a transmission filter unit used for transmitting filtering the laser. The second filter unit is a reflection filter unit used for reflecting filtering the laser.

4. The laser longitudinal mode measuring apparatus of claim 2, wherein: The first filter unit is also used for connecting with the laser device, and the laser is transmitted by the first filter unit, reflected by the second filter unit and then emitted by the first filter unit. The laser longitudinal mode measuring device further comprises an output unit used for outputting the laser at the side end of the filter module.

5. The laser longitudinal mode measuring apparatus of claim 2, wherein: The first filter unit is also used for connecting with the laser device, and the laser is transmitted by the first filter unit, reflected by the second filter unit and then emitted by the output unit. The laser longitudinal mode measuring device further comprises a coupling unit used for coupling the laser of the laser device into the filter module.

6. The laser longitudinal mode measuring apparatus of claim 5, wherein: The laser is transmitted by the first filter unit, reflected by the second filter unit and then emitted by the first filter unit.

7. The laser longitudinal mode measuring apparatus of claim 5, wherein: The first filter unit is a reflection filter unit used for reflecting filtering the laser. The second filter unit is a reflection filter unit used for reflecting filtering the laser.

8. The laser longitudinal mode measuring apparatus of claim 5, wherein: The laser longitudinal mode measuring device further comprises: A coupling unit used for coupling the laser of the laser device into the filter module.

9. The laser longitudinal mode measuring apparatus of claim 2, wherein: An output unit used for outputting the laser at the side end of the filter module. The laser longitudinal mode measuring device further comprises an isolation unit arranged between the filter module and the detection module and used for isolating reverse laser. The tuning module is also used for adjusting the band-pass width of the filter module. The first filter unit is a high-reflection fiber Bragg grating, and the second filter unit is a high-reflection fiber Bragg grating. ​ 10. The laser longitudinal mode measuring apparatus according to any one of claims 1 to 9, wherein: ​ 11. The laser longitudinal mode measuring apparatus according to any one of claims 1 to 9, wherein: ​ 12. The laser longitudinal mode measuring apparatus of claim 4, wherein: ​

Images