Optical sensor

Abstract

The present application relates to the technical field of optics. Provided is an optical sensor, comprising a pump device used for outputting pump light, a resonant cavity used for absorbing the pump light and obtaining filtered laser light, a sensing device used for sensing an external factor, and a measurement device at least used for measuring the number of the longitudinal modes of the laser light, wherein the sensing device is connected to the resonant cavity, and the measurement device is provided on an output path of the resonant cavity. The sensing device is provided on the resonant cavity, and an environmental factor is sensed by means of the sensing device and affects the resonant cavity, such that the filtering range of the resonant cavity changes, then the number and / or positions of the longitudinal modes of the laser light outputted by the resonant cavity change, and the change in the number of the longitudinal modes of the laser light and / or the positions of the longitudinal modes is measured by means of the measurement module, so that the measurement and monitoring of an extremely small change in the external factor can be achieved, the measurement accuracy is high, and the application field is wide.

Description

Optical sensor TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, more particularly to an optical sensor. BACKGROUND

[0002] As one of the foundations of information technology, sensor technology plays a vital role in the development of the Internet of Things and information technology, and is highly concerned and researched by countries around the world.

[0003] With the complication and diversification of application scenarios, the market has increasingly high requirements for the detection accuracy of sensors. Traditional sensors based on electrical principles have large transmission loss and are easily disturbed by external electromagnetic fields, thus having great disadvantages, and their application is greatly limited in many special environments, and their accuracy is low, which cannot meet the use requirements.

[0004] The above shortcomings still need to be improved. SUMMARY

[0005] The present application aims to provide an optical sensor to solve the technical problem of low measurement accuracy of sensors in the prior art.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is to provide an optical sensor, comprising:

[0007] a pumping device for outputting pumping light;

[0008] a resonant cavity for absorbing pumping light and obtaining filtered laser light;

[0009] a sensing device connected to the resonant cavity for sensing external factors;

[0010] a measuring device provided on the output path of the resonant cavity, at least for measuring the number of longitudinal modes of the laser light.

[0011] In one embodiment, the resonant cavity comprises:

[0012] a first reflective filter unit for filtering and reflecting laser light in the resonant cavity;

[0013] a second reflective filter unit for filtering and reflecting laser light in the resonant cavity;

[0014] a gain medium for obtaining the laser light through excitation of the pumping light;

[0015] The first reflective filter unit and the second reflective filter unit at least constitute two ends of the resonant cavity, and the filtering ranges of the first reflective filter unit and the second reflective filter unit partially overlap.

[0016] The sensing device is connected with the first reflective filter unit and / or the second reflective filter unit.

[0017] In one embodiment, the first reflective filter unit is a partial reflective filter unit, which is configured to transmit the pump light, filter the laser light in the resonant cavity, partially reflect the light intensity, and output the laser light.

[0018] The second reflective filter unit is a total reflective filter unit, which is configured to filter the laser light in the resonant cavity and totally reflect the light intensity.

[0019] In one embodiment, the first reflective filter unit is a partial reflective filter unit, which is configured to transmit the pump light, filter the laser light in the resonant cavity, and partially reflect the light intensity.

[0020] The second reflective filter unit is a total reflective filter unit, which is configured to filter the laser light in the resonant cavity and totally reflect the light intensity.

[0021] The optical sensor further comprises a first output unit located in the resonant cavity, which is configured to output the laser light at the side end of the resonant cavity.

[0022] In one embodiment, the optical sensor further comprises a first coupling unit, which is configured to couple the pump light into the resonant cavity.

[0023] In one embodiment, the resonant cavity and the measuring device are further provided with a first isolation unit.

[0024] In one embodiment, the first reflective filter unit is an integrated structure capable of filtering and reflecting the pump light; or the first reflective filter unit comprises a first mirror and a first filter module arranged in the reflection direction of the first mirror.

[0025] The second reflective filter unit is an integrated structure capable of reflecting and filtering the pump light; or the second reflective filter unit comprises a second mirror and a second filter module arranged in the reflection direction of the second mirror.

[0026] In one embodiment, the resonant cavity is further provided with a cavity length control unit, which is configured to adjust the cavity length of the resonant cavity.

[0027] In one embodiment, the optical sensor further comprises:

[0028] A tuning device connected with the first reflective filter unit and / or the second reflective filter unit, which is configured to adjust the bandpass position and / or the bandpass width of the first reflective filter unit and / or the second reflective filter unit.

[0029] In one embodiment, the measuring device comprises:

[0030] a measuring device filtering module for filtering the laser, the laser outputted after passing through the measuring device filtering module being single longitudinal mode laser;

[0031] a measuring device tuning module connected with the measuring device filtering module, and used at least for adjusting the band-pass position of the measuring device filtering module;

[0032] a measuring device detecting module arranged on the output path of the measuring device filtering module, and used for detecting the laser.

[0033] In one embodiment, the measuring device filtering module comprises a measuring device first filtering unit and a measuring device second filtering unit for filtering the laser, and the measuring device tuning module is connected with the measuring device first filtering unit and / or the measuring device second filtering unit.

[0034] The optical sensor provided by the embodiment has the beneficial effect that the sensing device is arranged on the resonant cavity, the sensing device senses the environmental factors and has an influence on the resonant cavity, the filtering range of the resonant cavity changes, the number and / or position of the longitudinal modes of the laser outputted by the resonant cavity change, the measuring module measures the change of the number and / or position of the longitudinal modes of the laser, and thus the measurement and monitoring of the slight change of the external factors can be realized, the measurement precision is high, and the application field is wide. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. 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 effort on the basis of these drawings.

[0036] FIG. 1 is a working principle schematic diagram of a filtering module of an optical sensor provided by an embodiment of the present application;

[0037] FIG. 2 is a laser emission spectrum schematic diagram of an optical sensor provided by an embodiment of the present application;

[0038] FIG. 3 is a structure schematic diagram one of an optical sensor provided by an embodiment of the present application;

[0039] FIG. 4 is a structure schematic diagram two of an optical sensor provided by an embodiment of the present application;

[0040] FIG. 5 is a structure schematic diagram three of an optical sensor provided by an embodiment of the present application;

[0041] FIG. 6 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0042] FIG. 7 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0043] FIG. 8 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0044] FIG. 9 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0045] FIG. 10 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0046] FIG. 11 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0047] FIG. 12 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0048] FIG. 13 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0049] FIG. 14 is a structural schematic diagram of an optical sensor according to an embodiment of the present application;

[0050] FIG. 15 is a structural schematic diagram of a resonant cavity of an optical sensor according to an embodiment of the present application;

[0051] FIG. 16 is a working principle schematic diagram of a filter module of a measuring device of an optical sensor according to an embodiment of the present application;

[0052] FIG. 17 is a working principle schematic diagram of a filter module of a measuring device of an optical sensor according to an embodiment of the present application;

[0053] FIG. 18 is a working principle schematic diagram of a filter module of a measuring device of an optical sensor according to an embodiment of the present application;

[0054] FIG. 19 is a working principle schematic diagram of a band-pass position adjustment of a tuning module of a measuring device of an optical sensor according to an embodiment of the present application;

[0055] FIG. 20 is a working principle schematic diagram of a band-pass width adjustment of a tuning module of a measuring device of an optical sensor according to an embodiment of the present application;

[0056] FIG. 21 is a laser emission schematic diagram of a filter module of a measuring device of an optical sensor according to an embodiment of the present application;

[0057] FIG. 22 is a structural schematic diagram of a measuring device of an optical sensor according to an embodiment of the present application;

[0058] FIG. 23 is a structural schematic diagram of a measuring device of an optical sensor according to an embodiment of the present application;

[0059] Fig. 24 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0060] Fig. 25 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0061] Fig. 26 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0062] Fig. 27 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0063] Fig. 28 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0064] Fig. 29 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application;

[0065] Fig. 30 is a structural schematic diagram of a measurement device of an optical sensor according to an embodiment of the present application.

[0066] In the drawings, various elements are labeled with reference numerals, and the following is a list of the reference numerals:

[0067] 10 - pumping device; 20 - resonant cavity;

[0068] 201 - first reflective filter unit; 2011 - first mirror;

[0069] 2012 - first filter module; 202 - second reflective filter unit;

[0070] 2021 - second mirror; 2022 - second filter module;

[0071] 30 - sensing device; 40 - measurement device;

[0072] 50 - first coupling unit; 60 - first output unit;

[0073] 70 - first isolation unit; 80 - cavity length control unit;

[0074] 90 - tuning device; 901 - first tuning unit;

[0075] 902 - second tuning unit;

[0076] 401 - measurement device filtering module; 4011 - measurement device first filtering unit;

[0077] 4012 - measurement device second filtering unit; 402 - measurement device tuning module;

[0078] 4021 - measurement device first tuning unit; 4022 - measurement device second tuning unit;

[0079] 403 - measurement device detecting module; 404 - second coupling unit;

[0080] 405 - second output unit; 406 - second isolation unit. Embodiments of the present application

[0081] In order to make the technical problems to be solved, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0082] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly or indirectly on the other component. When a component is referred to as being "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", and the like indicate 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 convenience of 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.

[0083] FIGS. 1-30 are structural schematic diagrams of an optical sensor provided by the present embodiment.

[0084] Referring to FIG. 3, an optical sensor includes a pumping device 10 for outputting pumping light, a resonant cavity 20 for absorbing the pumping light and obtaining filtered laser light, a sensing device 30 for sensing external factors, and a measurement device 40 for measuring at least the number of longitudinal modes of the laser light, the sensing device 30 being connected to the resonant cavity 20, and the measurement device 40 being disposed on an output path of the resonant cavity 20.

[0085] The working principle of an optical sensor provided by the present embodiment is as follows:

[0086] The pump light generated by the pumping device 10 is transmitted into the resonant cavity 20, and the laser light is outputted after passing through the resonant cavity 20, and then the laser light continues to be transmitted into the measuring device 40 for measurement, so as to obtain the number of longitudinal modes in the laser light;

[0087] When the external factor (such as temperature, pressure, stress, etc.) changes, the sensing device 30 senses the change of the external factor and has an influence on the resonant cavity 20, so that the filtering range of the resonant cavity 20 changes, and thus the number and / or position of the longitudinal modes of the laser light outputted through the resonant cavity 20 changes, and the measuring device 40 measures the laser light, so as to obtain the number of longitudinal modes in the laser light;

[0088] Through the change of the number and / or position of the longitudinal modes in the laser light, the corresponding external factor can be obtained, so that the external factor can be monitored.

[0089] In an embodiment, the external factor is temperature, which has an influence on the resonant cavity 20, so that the filtering range of the resonant cavity 20 changes. Through the change of the number and / or position of the longitudinal modes measured by the measuring device 40, the corresponding temperature and / or temperature change information can be obtained, so that the temperature can be monitored.

[0090] In an embodiment, the external factor is pressure, which has an influence on the resonant cavity 20, so that the filtering range of the resonant cavity 20 changes. Through the change of the number and / or position of the longitudinal modes measured by the measuring device 40, the corresponding pressure and / or pressure change information can be obtained, so that the pressure can be monitored.

[0091] In an embodiment, the external factor is stress, which has an influence on the resonant cavity 20, so that the filtering range of the resonant cavity 20 changes. Through the change of the number and / or position of the longitudinal modes measured by the measuring device 40, the corresponding stress and / or stress change information can be obtained, so that the stress can be monitored.

[0092] It should be understood that the external factor is not limited to the above-mentioned cases, but can also be other factors, which are not limited herein.

[0093] The optical sensor provided by the embodiment has the beneficial effect that the sensing device 30 is arranged on the resonant cavity 20, the environmental factor is sensed by the sensing device 30, and the resonant cavity 20 is influenced, so that the filtering range of the resonant cavity 20 changes, and then the number and / or position of the longitudinal modes of the laser light outputted through the resonant cavity 20 changes, and the change of the number and / or position of the longitudinal modes in the laser light is measured by the measuring module 40, so that the measurement and monitoring of the slight change of the external factor can be realized, the measurement precision is high, and the application field is wide.

[0094] Referring to FIG. 4, further, the resonant cavity 20 comprises a first reflective filtering unit 201 for filtering and reflecting laser light in the resonant cavity 20, a second reflective filtering unit 202 for filtering and reflecting laser light in the resonant cavity 20, and a gain medium 203 for obtaining laser light through excitation of pump light. The first reflective filtering unit 201 and the second reflective filtering unit 202 constitute the cavity of the laser resonant cavity 20, i.e. at least two ends of the resonant cavity 20, and also have filtering functions. The filtering ranges of the first reflective filtering unit 201 and the second reflective filtering unit 202 partially overlap (see FIG. 1, the first reflective filtering unit 201 and the second reflective filtering unit 202 have filtering bandwidths L1 and L2 respectively, the filtering bandwidths L1 and L2 have an overlapping frequency band L3, and the overlapping frequency band L3 is the filtering range; L1' is the filtering range of the first reflective filtering unit 201 after being affected by external factors through the sensing device 30, and L3' is the overlapping frequency band after being affected by external factors). The sensing device 30 is connected to the first reflective filtering unit 201 and / or the second reflective filtering unit 202, can affect the first reflective filtering unit 201 and / or the second reflective filtering unit 202 connected thereto, thereby affecting the filtering range of the resonant cavity 20, and further affecting the number and / or position of longitudinal modes of laser light output by the resonant cavity 20.

[0095] In the embodiment, the first reflective filtering unit 201 is at least used for filtering and reflecting light intensity of laser light in the resonant cavity 20. Specifically, the first reflective filtering unit 201 at least comprises a module capable of reflecting light intensity of laser light incident therein. The first reflective filtering unit 201 further comprises a module capable of "screening" (i.e. filtering) the frequency of laser light incident therein, thereby selectively reflecting or transmitting light of part of the frequency, and absorbing laser light of other frequencies. The laser light obtained after filtering is a necessary basis for forming output laser light. Of course, the two modules can be the same module structure capable of reflecting light intensity and filtering, or can be a combined structure of two independent modules for reflecting light intensity and filtering. Referring to FIG. 15, the combined structure specifically comprises: the first reflective filtering unit 201 comprises a first mirror 2011, and a first filtering module 2012 arranged in the reflection direction of the first mirror 2011.

[0096] The second reflective filter unit 202 is used for filtering and reflecting the light intensity in the resonant cavity 20. Specifically, the second reflective filter unit 202 comprises at least a module capable of reflecting the light intensity incident therein, which is used as the reflecting end of the resonant cavity 20, and a module capable of filtering the frequency of the light incident therein, thereby selectively reflecting or transmitting part of the frequency of the light and absorbing the light of other frequencies, and the filtered light is the necessary basis for forming the output laser. Of course, the two modules can also be an integrated structure or a combination of independent modules. Referring to FIG. 15, the combination structure is that the second reflective filter unit 202 comprises a second mirror 2021 and a second filter module 2022 arranged in the reflection direction of the second mirror 2021. According to the needs of total reflection and partial reflection, the first mirror 2021 or the second mirror 2022 is designed in the form of total reflection or partial reflection.

[0097] Further, the filtering ranges of the first reflective filter unit 201 and the second reflective filter unit 202 partially overlap. The pump light is incident in the resonant cavity 20, the gain medium 203 is excited to generate laser light, the laser light is reflected between the first reflective filter unit 201 and the second reflective filter unit 202, and after being filtered by the first reflective filter unit 201 and the second reflective filter unit 202, the generated laser light frequency band is located in the overlapping area of the filtering ranges, and by selecting a suitable filtering range, the required laser light can be obtained (see the filtering range L30 in FIG. 2). The laser light can be output from the resonant cavity 20 through the first reflective filter unit 201 or the second reflective filter unit 202 or the side end of the resonant cavity.

[0098] In the present embodiment, the input of the pump light and the output of the laser light have various forms.

[0099] Referring to FIG. 4, in one embodiment, the first reflective filter unit 201 is a partial reflective filter unit, which is used for transmitting the pump light, filtering the laser light in the resonant cavity 20, partially reflecting the light intensity, and outputting the laser light; and the second reflective filter unit 202 is a total reflective filter unit, which is used for filtering the laser light in the resonant cavity 20 and totally reflecting the light intensity. The pump light enters the resonant cavity 20 through the first reflective filter unit 201, the laser light is output from the resonant cavity 20 through the first reflective filter unit 201, and the laser light output after passing through the first reflective filter unit 201 is the laser light of the overlapping frequency band L3.

[0100] Please refer to FIG. 5 and FIG. 6, in an embodiment, the first reflective filter unit 201 is a partial reflective filter unit, which is used for transmitting the pump light, filtering the laser in the resonant cavity 20, partially reflecting the light intensity, and outputting the laser; the second reflective filter unit 202 is a total reflective filter unit, which is used for filtering the laser in the resonant cavity 20 and totally reflecting the light intensity; and the first coupling unit 50 is arranged between the pump device 10 and the resonant cavity 20, so as to couple the pump light into the resonant cavity 20. The pump light enters the resonant cavity 20 after passing through the first coupling unit 50, and the laser is output from the resonant cavity 20 through the first reflective filter unit 201 or is output from the resonant cavity 20 to the coupling unit 50 and then is output to the measuring device 40 through the first reflective filter unit 201. The laser output through the first reflective filter unit 201 is the laser of the overlapping frequency band L3.

[0101] Please refer to FIG. 7, in an embodiment, the first reflective filter unit 201 is a partial reflective filter unit, which is used for transmitting the pump light, filtering the laser in the resonant cavity 20, partially reflecting the light intensity, and outputting the laser; the second reflective filter unit 202 is a total reflective filter unit, which is used for filtering the laser in the resonant cavity 20 and totally reflecting the light intensity; and the first coupling unit 50 is arranged in the resonant cavity 20 and is connected with the pump device 10, so as to couple the pump light into the resonant cavity 20. The pump light enters the resonant cavity 20 after passing through the first coupling unit 50, and the laser is output from the resonant cavity 20 through the first reflective filter unit 201. The laser output through the first reflective filter unit 201 is the laser of the overlapping frequency band L3.

[0102] Please refer to FIG. 8, in an embodiment, the first reflective filter unit 201 is a partial reflective filter unit, which is used for transmitting the pump light, filtering the laser in the resonant cavity 20, partially reflecting the light intensity, and outputting the laser; the second reflective filter unit 202 is a total reflective filter unit, which is used for filtering the laser in the resonant cavity 20 and totally reflecting the light intensity; and the first output unit 60 is arranged in the resonant cavity 20, which is used for outputting the laser from the side end of the resonant cavity 20. The pump light enters the resonant cavity 20 through the first reflective filter unit 201, and the laser is output from the resonant cavity 20 through the first output unit 60. The laser output through the first output unit 60 is the laser of the overlapping frequency band L3. Please refer to FIG. 9, it should be understood that the first coupling unit 50 can also be arranged between the pump device 10 and the resonant cavity 20 at this time.

[0103] Referring to FIG. 10, in an embodiment, the first reflective filter unit 201 and the second reflective filter unit 202 are both full reflective filter units, which are used for filtering the laser in the resonant cavity 20 and fully reflecting the light intensity; the resonant cavity 20 is provided with a first coupling unit 50 and a first output unit 60, the first coupling unit 50 is used for coupling the pump light into the resonant cavity 20, and the first output unit 60 is used for outputting the laser from the side end of the resonant cavity 20.

[0104] Referring to FIG. 11, further, a first isolation unit 70 is further provided between the resonant cavity 20 and the measuring device 40, which is used for isolating the reverse laser and protecting the optical sensor.

[0105] Referring to FIG. 12, further, the resonant cavity 20 is further provided with a cavity length control unit 80, which is used for adjusting the cavity length of the resonant cavity 20. By adjusting the cavity length of the resonant cavity 20, the number and position of the longitudinal modes of the laser can be adjusted, which can be set according to the needs to meet the use requirements of different application scenarios, effectively expanding the application range.

[0106] Referring to FIG. 13 and FIG. 14, further, the optical sensor further includes a tuning device 90 connected with the first reflective filter unit 201 and / or the second reflective filter unit 202, which is used for adjusting the bandpass position and / or the bandpass width of the first reflective filter unit 201 and / or the second reflective filter unit 202, so as to adjust the bandpass position and / or the bandpass width of the overlapping part of the first reflective filter unit 201 and / or the second reflective filter unit 202. The tuning device 90 can include a first tuning unit 901 connected with the first reflective filter unit 201, can include a second tuning unit 902 connected with the second reflective filter unit 202, or can include the first tuning unit 901 connected with the first reflective filter unit 201 and the second tuning unit 902 connected with the second reflective filter unit 202, which is not limited here.

[0107] Further, a first circulator can be further provided between the resonant cavity 20 and the measuring device 40, which can be used for outputting the laser and returning the laser to the resonant cavity 20.

[0108] Further, the first filter unit 201 can be a partially reflective fiber Bragg grating, and the second filter unit 202 can be a high reflective fiber Bragg grating. Because of the reflection of the high reflective fiber Bragg grating in the frequency domain, the light in the reflection range of the high reflective fiber Bragg grating is filtered. External factors affect the high reflective fiber Bragg grating or the partially reflective fiber Bragg grating through the sensing device 30, causing the reflection center wavelength of the high reflective fiber Bragg grating or the partially reflective fiber Bragg grating to shift, thereby causing the output wavelength to change, and the number of longitudinal modes of the output laser also changes.

[0109] In one embodiment, the gain medium 203 is a full gain fiber as a medium for realizing the particle beam inversion, and is connected to the first reflective filter unit 201 and the second reflective filter unit 202 at two ends, respectively. The first coupling unit 50 couples the pump light into the resonant cavity 20, realizes the particle beam inversion of the full gain fiber in the resonant cavity 20, and obtains the laser. The laser of the overlapping frequency band L3 is outputted through the filtering effect of the first reflective filter unit 201 and the second reflective filter unit 202.

[0110] In other embodiments, the gain medium 203 can also be a block gain crystal. The gain crystal can be independently arranged in the resonant cavity 20 or connected to the first reflective filter unit 201 and the second reflective filter unit 202 through a non-gain fiber.

[0111] Referring to FIG. 22, further, the measuring device 40 includes a measuring device filtering module 401 for filtering the laser, a measuring device tuning module 402 for adjusting the band-pass position and the band-pass width of the measuring device filtering module 401, and a measuring device detecting module 403 for detecting the longitudinal modes of the laser. The laser outputted after passing through the measuring device filtering module 401 is single longitudinal mode laser. The measuring device tuning module 402 is connected to the measuring device filtering module 401, and the measuring device detecting module 403 is arranged on the output path of the measuring device filtering module 401. The laser from the filtering module 20 is filtered by the measuring device filtering module 401 and outputted, and is transmitted to the measuring device detecting module 403 for measurement. In this embodiment, the measuring device detecting module 403 is used for detecting whether there is laser output. In the detection process, the single longitudinal mode laser signal detected by the measuring device detecting module 403 presents a cycle of appearing and disappearing. By recording the number of times of appearing of the single longitudinal mode laser signal, the number of longitudinal modes is obtained.

[0112] When the laser longitudinal mode needs to be measured, first, the band-pass position of the measuring device filtering module 401 is adjusted by the measuring device tuning module 402, so that the band-pass position of the measuring device filtering module 401 is outside the laser frequency, at this time, the measuring device detection module 403 cannot detect the laser output. The laser from the filtering module 20 enters the measuring device filtering module 401, is filtered by the measuring device filtering module 401, and is output and transmitted to the measuring device detection module 403. The measuring device detection module 403 detects whether there is laser output. During the detection process, the measuring device tuning module 402 adjusts the band-pass position of the measuring device filtering module 401, 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 in the band-pass range of the measuring device filtering module 401, the laser with the longitudinal mode is output to the measuring device detection module 403, and the measuring device detection module 403 detects the laser output. After the band-pass position of the measuring device filtering module 401 scans the frequency range of the laser, the measuring device detection module 403 records the number of times of laser output, so that the number of longitudinal modes can be obtained.

[0113] By setting the measuring device filtering module 401, the laser filtered by the measuring device filtering module 401 can obtain single longitudinal mode laser, and by adjusting the band-pass position of the measuring device filtering module 401 by the measuring device tuning module 402, the frequency range of the laser can be scanned in turn, and the number of times of laser output can be detected by the measuring device detection module 403, so that the number of longitudinal modes can be obtained; when the external factors change, the number and / or position of the longitudinal modes in the laser will change, so that the number and / or position of the longitudinal modes detected by the measuring device detection module 403 will change, and the measurement and monitoring of the small change of the external factors can be realized, the measurement accuracy is high, and the application field is wide.

[0114] Please refer to FIG. 21, further, the measuring device tuning module 402 is also used for adjusting the measuring device band-pass width L60 of the measuring device filtering module 401, which can make the band-pass width L60 of the measuring device filtering module 401 narrow enough, so that it is smaller than the width L61 between adjacent longitudinal modes in the multi-longitudinal mode laser, so that the laser output after passing through the measuring device filtering module 401 is single longitudinal mode laser.

[0115] Referring to FIG. 23, in one embodiment, the measurement device filtering module 401 comprises a measurement device first filtering unit 4011 and a measurement device second filtering unit 4012 for filtering the laser, and the measurement device tuning module 402 is connected to the measurement device first filtering unit 4011 and / or the measurement device second filtering unit 4012, so that the passband position and / or the passband width of the measurement device first filtering unit 4011 and / or the measurement device second filtering unit 4012 can be adjusted. The filtering range of the measurement device first filtering unit 4011 and the filtering range of the measurement device second filtering unit 4012 partially overlap, and the laser is filtered by the measurement device first filtering unit 4011 and the measurement device second filtering unit 4012 to obtain a single longitudinal mode laser and output to the measurement device detection module 403.

[0116] The adjustment mode of the measurement device tuning module 402 at least includes:

[0117] adjusting the passband position of the measurement device first filtering unit 4011 and the measurement device second filtering unit 4012;

[0118] adjusting the passband width of the measurement device first filtering unit 4011 and the measurement device second filtering unit 4012;

[0119] adjusting the passband position of the measurement device first filtering unit 4011 and the passband width of the measurement device second filtering unit 4012;

[0120] adjusting the passband width of the measurement device first filtering unit 4011 and the passband position of the measurement device second filtering unit 4012.

[0121] Since the measurement device filtering module 401 is provided with two filtering units (the measurement device first filtering unit 4011 and the measurement device second filtering unit 4012) with partially overlapping filtering ranges, even if the filtering range of each filtering unit is wide, as long as the measurement device first filtering unit 4011 and / or the measurement device second filtering unit 4012 is adjusted by the measurement device tuning module 402, a laser with extremely narrow linewidth can be obtained, and single longitudinal mode filtering output is realized. Since the filtering range requirement of each filtering unit is not high, a filtering unit with lower parameters and wider filtering range can be used, which greatly reduces the process difficulty.

[0122] In one embodiment, the measurement device tuning module 402 comprises a measurement device first tuning unit 4021 connected with the measurement device first filter unit 4011, for adjusting the bandpass position and / or the bandpass width of the measurement device first filter unit 4011. By adjusting the bandpass position of the measurement device first filter unit 4011, the bandpass position of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted. By adjusting the bandpass width of the measurement device first filter unit 4011, the bandpass width of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted.

[0123] In one embodiment, the measurement device tuning module 402 comprises a measurement device second tuning unit 4022 connected with the measurement device second filter unit 4012, for adjusting the bandpass position and / or the bandpass width of the measurement device second filter unit 4012. By adjusting the bandpass position of the measurement device second filter unit 4012, the bandpass position of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted. By adjusting the bandpass width of the measurement device second filter unit 4012, the bandpass width of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted.

[0124] Referring to FIG. 23, in one embodiment, the measurement device tuning module 402 comprises a measurement device first tuning unit 4021 connected with the measurement device first filter unit 4011 and a measurement device second tuning unit 4022 connected with the measurement device second filter unit 4012. By adjusting the bandpass position of the measurement device first filter unit 4011 and the measurement device second tuning unit 4022, the bandpass position of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted (referring to FIG. 18, L60’ is the bandpass position before adjustment, and L60 is the bandpass position after adjustment). By adjusting the bandpass width of the measurement device first filter unit 4011 and the measurement device second filter unit 4012, the bandpass width of the overlapping part of the measurement device first filter unit 4011 and the measurement device second filter unit 4012 can be adjusted (referring to FIG. 19, L60’ is the bandpass width before adjustment, and L60 is the bandpass width after adjustment).

[0125] Please refer to FIG. 16 and FIG. 23, in one embodiment, the first filter unit 4011 of the measuring device is a transmissive filter unit for transmitting the laser, and a part of the laser from the filter module 20 enters the measuring device filter module 401 through the first filter unit 4011 of the measuring device; the second filter unit 4012 of the measuring device is a transmissive filter unit for transmitting the laser, and a part of the laser in the measuring device filter module 401 is transmitted after passing through the second filter unit, thereby outputting to the measuring device detection module 403.

[0126] When the laser passes through the first filter unit 4011 of the measuring device, due to the reflectivity of the frequency domain of the first filter unit 4011 of the measuring device, the laser in the reflection range of the first filter unit 4011 of the measuring device (i.e. the first reflection range L41 of the measuring device) is filtered and cannot pass through the first filter unit 4011 of the measuring device, and the laser outside the first reflection range L41 of the measuring device passes through the first filter unit 4011 of the measuring device and enters the measuring device filter module 401. The laser entering the measuring device filter module 401 continues to propagate to the second filter unit 4012 of the measuring device, and due to the reflectivity of the frequency domain of the second filter unit 4012 of the measuring device, the laser in the reflection range of the second filter unit 4012 of the measuring device (i.e. the second reflection range L51 of the measuring device) is filtered and cannot pass through the second filter unit 4012 of the measuring device, and the laser outside the second reflection range L51 of the measuring device exits after passing through the second filter unit 4012 of the measuring device. The part of the frequency domain outside the first reflection range L41 of the measuring device and the frequency domain outside the second reflection range L51 of the measuring device overlap, which is the filtering range L60 of the measuring device (the filtering range L60 of the measuring device is smaller than the width between adjacent longitudinal modes in the multi-longitudinal-mode laser), and the laser output after passing through the second filter unit 4012 of the measuring device is the single-longitudinal-mode laser of the filtering range L60 of the measuring device.

[0127] It should be understood that the first filter unit 4011 of the measuring device can also transmit part of the laser, and the part of the laser that cannot be transmitted will be absorbed by the first filter unit 4011 of the measuring device; the second filter unit 4012 of the measuring device can also transmit part of the laser, and the part of the laser that cannot be transmitted will be absorbed by the second filter unit 4012 of the measuring device.

[0128] In one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit for transmitting the laser light, the reflection range of the first filter unit 4011 of the measuring device is the first reflection range L41 of the measuring device, and the laser light outside the first reflection range L41 of the measuring device can enter or exit the filter module 401 of the measuring device; the second filter unit 4012 of the measuring device is a reflection filter unit for reflecting the laser light, the transmission range of the second filter unit 4012 of the measuring device is the second transmission range L52 of the measuring device, and the laser light outside the second transmission range L52 of the measuring device is reflected at the second filter unit 4012 of the measuring device; the part of the frequency range outside the first reflection range L41 of the measuring device and the frequency range outside the second transmission range L52 of the measuring device that overlap each other is the filter range L60 of the measuring device (the filter range L60 of the measuring device is smaller than the width between adjacent longitudinal modes in the multi-longitudinal-mode laser light), and the laser light output after passing through the filter module 401 of the measuring device is single-longitudinal-mode laser light in the filter range L60 of the measuring device.

[0129] Referring to FIGS. 17 and 24, in one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit, the second filter unit 4012 of the measuring device is a reflection filter unit, and the laser light enters the filter module 401 of the measuring device through the first filter unit 4011 of the measuring device. The laser light entering the filter module 401 of the measuring device continues to be transmitted to the second filter unit 4012 of the measuring device and is reflected there. The reflected part of the laser light returns to the first filter unit 4011 of the measuring device and is output after being filtered by the first filter unit 4011 of the measuring device. The output laser light is laser light in the filter range L60 of the measuring device.

[0130] It should be understood that the first filter unit 4011 of the measuring device can also transmit part of the laser light, and the part of the laser light that cannot be transmitted is absorbed by the first filter unit 4011 of the measuring device; the second transmission range L52 of the second filter unit 4012 of the measuring device can also be an absorption range, i.e., the laser light in the range is absorbed by the second filter unit 4012 of the measuring device.

[0131] Please refer to FIG. 17, FIG. 25 to FIG. 26, in one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit, the second filter unit 4012 of the measuring device is a reflection filter unit, and the optical sensor further comprises a second coupling unit 404, which is connected with the first filter unit 4011 of the measuring device and couples the laser into the measuring device filter module 401, at this time, the laser transmitted by the first filter unit 4011 of the measuring device can be directly emitted out of the first filter unit 4011 of the measuring device or transmitted to the second coupling unit 404 and then emitted out. Please refer to FIG. 27, the second coupling unit 404 can also be located in the measuring device filter module 401, and the second coupling unit couples the laser into the measuring device filter module 401, the laser enters the measuring device filter module 401, is reflected at the second filter unit 4012 of the measuring device, and then the reflected part of the laser returns to the first filter unit 4011 of the measuring device and is filtered by the first filter unit 4011 of the measuring device and then emitted out, and the output laser is the laser of the measuring device filter range L60.

[0132] Please refer to FIG. 17 and FIG. 28, in one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit, the second filter unit 4012 of the measuring device is a reflection filter unit, and the optical sensor further comprises a second output unit 405 for outputting the laser at the side end of the measuring device filter module 401, the laser is transmitted to the measuring device detection module 403 after being emitted out of the second output unit 405. The laser is transmitted by the first filter unit 4011 of the measuring device, reflected by the second filter unit 4012 of the measuring device, and then emitted out of the second output unit 405, and the output laser is the laser of the measuring device filter range L60. The second output unit 405 can also be located outside the measuring device filter module 401 and connected with the first filter unit 4011 of the measuring device, so that the laser is transmitted by the first filter unit 4011 of the measuring device, reflected by the second filter unit 4012 of the measuring device, transmitted by the first filter unit 4011 of the measuring device, and then emitted out of the second output unit 405 to the measuring device detection module 403.

[0133] Please refer to FIG. 18 and FIG. 29, in one embodiment, the first filter unit 4011 of the measuring device is a reflective filter unit that reflects the laser, the transmission range of the first filter unit 4011 of the measuring device is the first transmission range L42 of the measuring device, and the laser outside the first transmission range L42 of the measuring device is reflected at the first filter unit 4011 of the measuring device; the second filter unit 4012 of the measuring device is a reflective filter unit that reflects the laser, the transmission range of the second filter unit 4012 of the measuring device is the second transmission range L52 of the measuring device, and the laser outside the second transmission range L52 of the measuring device is reflected at the second filter unit 4012 of the measuring device; the part of the frequency domain outside the first transmission range L42 of the measuring device and the frequency domain outside the second transmission range L52 of the measuring device that overlap is the filter range L60, the filter range L60 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 401 of the measuring device is the laser of the filter range L60 of the measuring device.

[0134] The optical sensor further comprises a second coupling unit 404 and a second output unit 405, the second coupling unit 404 is located in the filter module 401 of the measuring device and couples the laser into the filter module 401 of the measuring device; the second output unit 405 is used to output the laser to the detection module 403 of the measuring device at the side end of the filter module 401 of the measuring device. The laser from the filter module 401 enters the filter module 401 of the measuring device through the second coupling unit 404, is reflected by the first filter unit 4011 and the second filter unit 4012 of the measuring device, and is output to the detection module 403 of the measuring device through the second output unit 405, and the output laser is the laser of the filter range L60 of the measuring device.

[0135] It should be understood that the first transmission range L42 of the first filter unit 4011 of the measuring device can also be an absorption range, that is, the laser in the range is absorbed by the first filter unit 4011 of the measuring device; the second transmission range L52 of the second filter unit 4012 of the measuring device can also be an absorption range, that is, the laser in the range is absorbed by the second filter unit 4012 of the measuring device.

[0136] Please refer to FIG. 30, further, the optical sensor provided by the embodiment can comprise a second isolation unit 406 arranged on the output path of the filter module 401 of the measuring device, the second isolation unit 406 is arranged between the filter module 401 of the measuring device and the detection module 403 of the measuring device, and is used to isolate the reverse laser, thereby protecting the optical sensor.

[0137] Further, the first filter unit 4011 of the measuring device can be a high-reflection fiber Bragg grating, and the second filter unit 4012 of the measuring device can 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 light) in the reflection range of the high-reflection fiber Bragg grating is filtered. The first tuning unit 4021 of the measuring device is connected to the first filter unit 4011 of the measuring device, and the second tuning unit 4022 of the measuring device is connected to the second filter unit 4012 of the measuring device. By affecting the physical and chemical properties (including temperature, stress, pressure, etc.) of the grating, the tuning of the bandpass position and the bandpass width is realized, and the specific use requirements are met.

[0138] Further, the devices such as the pumping device 10, the resonant cavity 20, and the measuring device 40 can be connected by optical fibers, so as to realize an all-fiber optical filter, which has higher sensitivity, larger dynamic range, faster response speed, etc. Some devices can be connected by optical fibers, so as to realize a partial-fiber optical filter. The optical transmission can also be performed by free space, which is not limited here.

[0139] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An optical sensor, characterized by: The optical sensor comprises: a pumping device for outputting pumping light; a resonant cavity for absorbing the pumping light and obtaining filtered laser light; a sensing device connected to the resonant cavity for sensing external factors; a measuring device arranged on an output path of the resonant cavity for measuring at least the number of longitudinal modes of the laser light.

2. The optical sensor of claim 1, wherein: The resonant cavity comprises: a first reflective filter unit for filtering and reflecting the laser light in the resonant cavity; a second reflective filter unit for filtering and reflecting the laser light in the resonant cavity; a gain medium for obtaining the laser light through excitation of the pumping light; the first reflective filter unit and the second reflective filter unit at least constitute two ends of the resonant cavity, and the filtering ranges of the first reflective filter unit and the second reflective filter unit partially overlap; the sensing device is connected to the first reflective filter unit and / or the second reflective filter unit.

3. The optical sensor of claim 2, wherein: the first reflective filter unit is a partially reflective filter unit for transmitting the pumping light, filtering the laser light in the resonant cavity, partially reflecting light intensity, and outputting the laser light; the second reflective filter unit is a fully reflective filter unit for filtering the laser light in the resonant cavity and fully reflecting light intensity.

4. The optical sensor of claim 2, wherein: the first reflective filter unit is a partially reflective filter unit for transmitting the pumping light, filtering the laser light in the resonant cavity, and partially reflecting light intensity; the second reflective filter unit is a fully reflective filter unit for filtering the laser light in the resonant cavity and fully reflecting light intensity; the optical sensor further comprises a first output unit arranged in the resonant cavity for outputting the laser light at a side end of the resonant cavity.

5. The optical sensor of claim 2, wherein: The optical sensor further comprises a first coupling unit for coupling the pumping light into the resonant cavity.

6. The optical sensor of claim 2, wherein: A first isolation unit is further arranged between the resonant cavity and the measuring device.

7. The optical sensor of claim 2, wherein: the first reflective filter unit is an integrated structure capable of filtering and reflecting the pumping light; or the first reflective filter unit comprises a first mirror and a first filter module arranged in a reflection direction of the first mirror; the second reflective filter unit is an integrated structure capable of reflecting and filtering the pumping light; or the second reflective filter unit comprises a second mirror and a second filter module arranged in a reflection direction of the second mirror.

8. The optical sensor according to any one of claims 1 to 7, wherein: The resonant cavity further comprises a cavity length control unit for adjusting the cavity length of the resonant cavity.

9. An optical sensor as claimed in any one of claims 2 to 7, characterized in that: The optical sensor further comprises: a tuning device connected to the first reflective filter unit and / or the second reflective filter unit for adjusting the passband position and / or the passband width of the first reflective filter unit and / or the second reflective filter unit.

10. The optical sensor of claim 8, wherein: The measuring device comprises: a measuring device filter module for filtering the laser light, and the laser light outputted after passing through the measuring device filter module is single longitudinal mode laser light; The measuring device tuning module is connected with the measuring device filtering module and is used at least for adjusting the band-pass position of the measuring device filtering module. The measuring device detection module is arranged on the output path of the measuring device filtering module and is used for detecting the laser.

11. The optical sensor of claim 10, wherein: The measuring device filtering module comprises a measuring device first filtering unit and a measuring device second filtering unit for filtering the laser, and the measuring device tuning module is connected with the measuring device first filtering unit and / or the measuring device second filtering unit.

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