Optical sensor

Abstract

The utility model relates to the technical field of optics, and provides an optical sensor which comprises a pumping device used for outputting pumping light, a resonant cavity used for absorbing the pumping light and obtaining filtered laser, a sensing device used for sensing external factors and a measuring device at least used for measuring the number of longitudinal modes of the laser. The sensing device is connected with the resonant cavity, and the measuring device is arranged on an output path of the resonant cavity; a sensing device is arranged on a resonant cavity, environmental factors are sensed through the sensing device, the resonant cavity is influenced, the filtering range of the resonant cavity is changed, then the number and / or position of longitudinal modes of laser output by the resonant cavity are / is changed, and the change of the number and / or position of the longitudinal modes in the laser is measured through a measuring module. Therefore, measurement and monitoring of minimal changes of external factors can be realized, the measurement precision is high, and the application field is wide.

Description

Technical Field

[0001] The utility model relates to the field of optical technology, and more specifically, to an optical sensor. Background Art

[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 has received high attention and research from countries around the world.

[0003] As application scenarios become more complex and diverse, market demands for sensor detection accuracy are increasing. Traditional sensor technology based on electrical principles suffers from high transmission loss and susceptibility to interference from external electromagnetic fields, resulting in significant drawbacks. Its application is severely limited in many special environments, and its low accuracy cannot meet application requirements.

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

[0005] The purpose of the utility model is 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 invention is to provide an optical sensor, comprising:

[0007] A pump device, used for outputting pump light;

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

[0009] a sensing device connected to the resonant cavity and used to sense external factors;

[0010] The measuring device is arranged on the output path of the resonant cavity and is at least used to measure the number of longitudinal modes of the laser.

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

[0012] a first reflection filter unit, configured to filter and reflect the laser light in the resonant cavity;

[0013] a second reflection filter unit, configured to filter and reflect the laser light in the resonant cavity;

[0014] A gain medium, used for obtaining the laser through excitation of the pump light;

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

[0016] The sensor device is connected to the first reflection filter unit and / or the second reflection filter unit.

[0017] In one embodiment, the first reflection filter unit is a partial reflection filter unit, 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 reflection filter unit is a total reflection filter unit, which is used to filter the laser in the resonant cavity and perform total reflection on the light intensity.

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

[0020] The second reflection filter unit is a total reflection filter unit, which is used to filter the laser in the resonant cavity and fully reflect the light intensity;

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

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

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

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

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

[0026] In one embodiment, the resonant cavity is further provided with a cavity length control unit for adjusting the cavity length of the resonant cavity.

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

[0028] A tuning device is connected to the first reflection filtering unit and / or the second reflection filtering unit, and is used to adjust the bandpass position and / or bandpass width of the first reflection filtering unit and / or the second reflection filtering unit.

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

[0030] A measuring device filter module, used for filtering the laser light, wherein the laser light outputted after passing through the measuring device filter module is a single longitudinal mode laser light;

[0031] a measuring device tuning module, connected to the measuring device filtering module, and at least used to adjust the bandpass position of the measuring device filtering module;

[0032] The measuring device detection module is provided on the output path of the measuring device filter module and is used to detect the laser.

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

[0034] The beneficial effect of an optical sensor provided by this embodiment is that: a sensing device is arranged on the resonant cavity, and the environmental factors are sensed by the sensing device, which affects the resonant cavity, so that the filtering range of the resonant cavity changes, and the number and / or position of the longitudinal modes of the laser output through the resonant cavity changes. The change in the number and / or position of the longitudinal modes in the laser is measured by the measurement module, thereby realizing the measurement and monitoring of extremely small changes in external factors, with high measurement accuracy and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic diagram of the working principle of the filter module of the optical sensor provided by an embodiment of the present utility model;

[0037] Figure 2 A schematic diagram of the laser emission spectrum of the optical sensor provided in an embodiment of the present utility model;

[0038] Figure 3 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 1 ;

[0039] Figure 4 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 2 ;

[0040] Figure 5 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 3 ;

[0041] Figure 6 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 4 ;

[0042] Figure 7 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 5 ;

[0043] Figure 8 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 6 ;

[0044] Figure 9 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 7 ;

[0045] Figure 10 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 8 ;

[0046] Figure 11 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 9 ;

[0047] Figure 12 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 10 ;

[0048] Figure 13 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 10 one;

[0049] Figure 14 Schematic diagram of the structure of the optical sensor provided in the embodiment of the utility model Figure 10 two;

[0050] Figure 15 A schematic structural diagram of a resonant cavity of an optical sensor provided in an embodiment of the present utility model;

[0051] Figure 16 Schematic diagram of the working principle of the filter module of the optical sensor measurement device provided by the embodiment of the utility model Figure 1 ;

[0052] Figure 17 Schematic diagram of the working principle of the filter module of the optical sensor measurement device provided by the embodiment of the utility model Figure 2 ;

[0053] Figure 18 Schematic diagram of the working principle of the filter module of the optical sensor measurement device provided by the embodiment of the utility model Figure 3 ;

[0054] Figure 19 A schematic diagram of the working principle of the bandpass position adjustment of the tuning module of the measuring device of the optical sensor provided by the embodiment of the utility model;

[0055] Figure 20 A schematic diagram of the working principle of the bandpass width adjustment of the tuning module of the measuring device of the optical sensor provided by the embodiment of the utility model;

[0056] Figure 21 A schematic diagram of laser emission from a filter module of a measuring device of an optical sensor provided by an embodiment of the present utility model;

[0057] Figure 22 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 1 ;

[0058] Figure 23 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 2 ;

[0059] Figure 24 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 3 ;

[0060] Figure 25 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 4 ;

[0061] Figure 26 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 5 ;

[0062] Figure 27 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 6 ;

[0063] Figure 28 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 7 ;

[0064] Figure 29 Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 8 ;

[0065] Figure 30Schematic diagram of the structure of the measuring device of the optical sensor provided in the embodiment of the utility model Figure 9 .

[0066] Among them, the reference numerals in the figures are:

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

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

[0069] 2012-first filtering module; 202-second reflection filtering unit;

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

[0071] 30-sensing device; 40-measuring 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-measuring device filtering module; 4011-measuring device first filtering unit;

[0077] 4012 - second filter unit of the measuring device; 402 - tuning module of the measuring device;

[0078] 4021 - first tuning unit of the measuring device; 4022 - second tuning unit of the measuring device;

[0079] 403 - measuring device detection module; 404 - second coupling unit;

[0080] 405 - second output unit; 406 - second isolation unit. DETAILED DESCRIPTION

[0081] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0082] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be located directly or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on this technical solution. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0083] Figures 1 to 30 This is a schematic structural diagram of an optical sensor provided in this embodiment.

[0084] See also Figure 3 An optical sensor includes a pump device 10 for outputting pump light, a resonant cavity 20 for absorbing the pump light and obtaining filtered laser light, a sensing device 30 for sensing external factors, and a measuring device 40 for at least measuring the number of longitudinal modes of the laser. The sensing device 30 is connected to the resonant cavity 20, and the measuring device 40 is arranged on the output path of the resonant cavity 20.

[0085] The working principle of the optical sensor provided in this embodiment is as follows:

[0086] The pump light generated by the pump device 10 is transmitted to the resonant cavity 20 and outputs laser light after passing through the resonant cavity 20. The laser light is then transmitted to the measuring device 40 for measurement, thereby obtaining the number of longitudinal modes in the laser light.

[0087] When external factors (such as temperature, pressure, and stress) change, the sensor device 30 senses the change in the external factor and affects the resonant cavity 20, causing the filtering range of the resonant cavity 20 to change, thereby changing the number and / or position of the longitudinal modes of the laser output from the resonant cavity 20. The measuring device 40 measures the laser to obtain the number of longitudinal modes in the laser.

[0088] By changing the number and / or position of longitudinal modes in the laser, the corresponding external factors can be known, thereby monitoring the external factors.

[0089] In one embodiment, the external factor is temperature, which affects the resonant cavity 20, thereby changing the filtering range of the resonant cavity 20. By measuring the changes in the number and / or position of longitudinal modes by the measuring device 40, the corresponding temperature and / or temperature change information can be obtained, thereby monitoring the temperature.

[0090] In one embodiment, the external factor is pressure, which affects the resonant cavity 20, thereby changing the filtering range of the resonant cavity 20. By measuring the changes in the number and / or position of longitudinal modes by the measuring device 40, the corresponding pressure and / or pressure change information can be obtained, thereby monitoring the pressure.

[0091] In one embodiment, the external factor is stress, which affects the resonant cavity 20, thereby changing the filtering range of the resonant cavity 20. By measuring the changes in the number and / or position of longitudinal modes by the measuring device 40, information such as the corresponding stress and / or stress change can be obtained, thereby monitoring the stress.

[0092] It should be understood that external factors are not limited to the above-mentioned situations, and may also be other factors, which are not limited here.

[0093] The beneficial effect of an optical sensor provided by this embodiment is that: a sensing device 30 is set on the resonant cavity 20, and the sensing device 30 senses environmental factors and affects the resonant cavity 20, 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 output through the resonant cavity 20 changes. The change in the number and / or position of the longitudinal modes in the laser is measured by the measurement module 40, thereby realizing the measurement and monitoring of extremely small changes in external factors, with high measurement accuracy and a wide range of applications.

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

[0095] In this embodiment, the first reflection filter unit 201 is at least used to filter the laser light in the resonant cavity 20 and reflect the light intensity. Specifically, the first reflection filter unit 201 means that the unit at least includes a module that can reflect the laser light intensity incident therein. The first reflection filter unit 201 also includes a module that can "screen" (i.e., filter) the frequency of the laser light incident therein, thereby selectively reflecting or transmitting light of certain frequencies and absorbing laser light of other frequencies. The laser light obtained after filtering is the necessary basis for forming the output laser. Of course, the two modules can be the same module structure that can perform the dual functions of reflecting light intensity and filtering, or they can be a combination structure of two independent modules used for reflecting light intensity and filtering respectively. Please refer to Figure 15 The combined structure is specifically as follows: the first reflection filtering unit 201 includes a first reflection mirror 2011 and a first filtering module 2012 arranged in the reflection direction of the first reflection mirror 2011.

[0096] The second reflection filter unit 202 is used to filter the laser light in the resonant cavity 20 and reflect the light intensity. Specifically, the second reflection filter unit 202 includes at least a module capable of reflecting the laser light intensity incident therein, which serves as the reflection end of the resonant cavity 20. It also includes a module capable of frequency "screening" (i.e., filtering) the laser light incident therein, thereby selectively reflecting or transmitting laser light of certain frequencies while absorbing laser light of other frequencies. The laser light obtained after filtering is the necessary basis for forming the output laser. Of course, these two modules can also be an integrated structure or a combination of independent modules. Please refer to Figure 15 The combined structure is specifically as follows: the second reflection filter unit 202 includes a second reflector 2021 and a second filter module 2022 arranged in the reflection direction of the second reflector 2021. According to the requirements of total reflection and partial reflection, the first reflector 2021 or the second reflector 2022 can be designed to be fully reflective or partially reflective.

[0097] Furthermore, the filtering ranges of the first reflection filter unit 201 and the second reflection filter unit 202 partially overlap. Pump light is incident on the resonant cavity 20, exciting the gain medium 203 to generate laser light. The laser light is reflected between the first reflection filter unit 201 and the second reflection filter unit 202, and after being filtered by the first reflection filter unit 201 and the second reflection filter unit 202, the generated laser light frequency band is located in the overlapping filtering range. By selecting an appropriate filtering range, the desired laser light can be obtained (see Figure 2 The laser light may be output from the resonant cavity 20 through the first reflection filter unit 201 or the second reflection filter unit 202 or the side end of the resonant cavity.

[0098] In this embodiment, there are various forms of input of pump light and output of laser light.

[0099] See also Figure 4 In one embodiment, the first reflection filter unit 201 is a partial reflection filter unit, configured to transmit the pump light, filter the laser light within the resonant cavity 20, partially reflect the light intensity, and output the laser light. The second reflection filter unit 202 is a total reflection filter unit, configured to filter the laser light within the resonant cavity 20 and fully reflect the light intensity. The pump light enters the resonant cavity 20 through the first reflection filter unit 201, and the laser light exits the resonant cavity 20 through the first reflection filter unit 201. The laser light output after passing through the first reflection filter unit 201 is laser light in the overlapping frequency band L3.

[0100] See also Figure 5 and Figure 6 In one embodiment, the first reflection filter unit 201 is a partial reflection filter unit, configured to transmit the pump light, filter the laser light within the resonant cavity 20, partially reflect the light intensity, and output the laser light. The second reflection filter unit 202 is a total reflection filter unit, configured to filter the laser light within the resonant cavity 20 and fully reflect the light intensity. A first coupling unit 50 is further provided between the pump device 10 and the resonant cavity 20 to couple the pump light into the resonant cavity 20. After passing through the first coupling unit 50, the pump light enters the resonant cavity 20 from the first reflection filter unit 201. The laser light then exits the resonant cavity 20 through the first reflection filter unit 201, or is output from the first reflection filter unit 201 to the coupling unit 50 and then emitted to the measurement device 40. The laser light output after passing through the first reflection filter unit 201 is laser light in the overlapping frequency band L3.

[0101] See also Figure 7In one embodiment, the first reflection filter unit 201 is a partial reflection filter unit, configured to transmit the pump light, filter the laser light within the resonant cavity 20, partially reflect the light intensity, and output the laser light. The second reflection filter unit 202 is a total reflection filter unit, configured to filter the laser light within the resonant cavity 20 and fully reflect the light intensity. The first coupling unit 50 is disposed within the resonant cavity 20 and connected to the pump device 10, thereby coupling the pump light into the resonant cavity 20. After passing through the first coupling unit 50, the pump light enters the resonant cavity 20, and the laser light exits the resonant cavity 20 through the first reflection filter unit 201. The laser light output after passing through the first reflection filter unit 201 is laser light in the overlapping frequency band L3.

[0102] See also Figure 8 In one embodiment, the first reflection filter unit 201 is a partial reflection filter unit, which is used to transmit the pump light, filter the laser light in the resonant cavity 20, partially reflect the light intensity, and output the laser light. The second reflection filter unit 202 is a total reflection filter unit, which is used to filter the laser light in the resonant cavity 20 and fully reflect the light intensity. The resonant cavity 20 is provided with a first output unit 60, which is used to output the laser light from the side of the resonant cavity 20. The pump light enters the resonant cavity 20 through the first reflection filter unit 201, and the laser light is output from the resonant cavity 20 through the first output unit 60. The laser light output by the first output unit 60 is the laser light of the overlapping frequency band L3. Please refer to Figure 9 It should be understood that, at this time, a first coupling unit 50 may be further provided between the pump device 10 and the resonant cavity 20 .

[0103] See also Figure 10 In one embodiment, the first reflection filter unit 201 and the second reflection filter unit 202 are both total reflection filter units, which are used to filter the laser in the resonant cavity 20 and fully reflect 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 to couple the pump light into the resonant cavity 20, and the first output unit 60 is used to output the laser from the side end of the resonant cavity 20.

[0104] See also Figure 11 Furthermore, a first isolation unit 70 is provided between the resonant cavity 20 and the measuring device 40 for isolating the reverse laser and protecting the optical sensor.

[0105] See also Figure 12 Furthermore, the resonant cavity 20 is further provided with a cavity length control unit 80 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. This can be set as needed to meet the requirements of different application scenarios, effectively expanding the scope of application.

[0106] See also Figure 13and Figure 14 Furthermore, the optical sensor also includes a tuning device 90 connected to the first reflection filter unit 201 and / or the second reflection filter unit 202, and configured to adjust the bandpass position and / or bandpass width of the first reflection filter unit 201 and / or the second reflection filter unit 202, thereby adjusting the bandpass position and / or bandpass width of the overlapping portion of the first reflection filter unit 201 and / or the second reflection filter unit 202. The tuning device 90 may include a first tuning unit 901 connected to the first reflection filter unit 201, may include a second tuning unit 902 connected to the second reflection filter unit 202, or may include the first tuning unit 901 connected to the first reflection filter unit 201 and the second tuning unit 902 connected to the second reflection filter unit 202, without limitation herein.

[0107] Furthermore, a first circulator may be provided between the resonant cavity 20 and the measuring device 40 , which may be used to output the laser light and transmit the laser light back to the resonant cavity 20 on the other hand.

[0108] Furthermore, the first filter unit 201 can be a partially reflective fiber Bragg grating, and the second filter unit 202 can be a highly reflective fiber Bragg grating. Due to its frequency-domain reflectivity, the highly reflective fiber Bragg grating filters light within its frequency range. External factors can affect the highly reflective fiber Bragg grating or the partially reflective fiber Bragg grating through the sensor device 30, causing the reflection center wavelength of the highly reflective fiber Bragg grating or the partially reflective fiber Bragg grating to shift, thereby causing a change in the output wavelength and the number of longitudinal modes of the output laser light.

[0109] In one embodiment, gain medium 203, serving as the medium for beam inversion, is preferably a full-gain fiber, with its two ends connected to first reflection filter unit 201 and second reflection filter unit 202, respectively. First coupling unit 50 couples pump light into resonant cavity 20, achieving full-gain fiber beam inversion within resonant cavity 20 to generate laser light. Laser light in overlapping frequency band L3 is emitted through filtering by first reflection filter unit 201 and second reflection filter unit 202.

[0110] In other embodiments, the gain medium 203 may also be a block-shaped gain crystal. The gain crystal may be independently disposed in the resonant cavity 20 or connected to the first reflection filter unit 201 and the second reflection filter unit 202 via a non-gain optical fiber.

[0111] See also Figure 22Furthermore, the measuring device 40 includes a measuring device filtering module 401 for filtering laser light, a measuring device tuning module 402 for adjusting the passband position and passband width of the measuring device filtering module 401, and a measuring device detection module 403 for detecting laser longitudinal modes. The laser light output after passing through the measuring device filtering module 401 is single longitudinal mode laser light. The measuring device tuning module 402 is connected to the measuring device filtering module 401, and the measuring device detection module 403 is located on the output path of the measuring device filtering module 401. Laser light from the filtering module 20 is filtered by the measuring device filtering module 401 and then output and transmitted to the measuring device detection module 403 for measurement. In this embodiment, the measuring device detection module 403 is used to detect whether laser light is being output. During the detection process, the single longitudinal mode laser signal detected by the measuring device detection module 403 will exhibit a cycle of appearance and disappearance. By recording the number of appearances of the single longitudinal mode laser signal, the number of longitudinal modes can be obtained.

[0112] When it is necessary to measure the laser longitudinal mode, the measurement device tuning module 402 first adjusts the bandpass position of the measurement device filter module 401 so that the bandpass position of the measurement device filter module 401 is outside the laser frequency. At this time, the measurement device detection module 403 cannot detect any laser output. The laser light from the filter module 20 enters the measurement device filter module 401, is filtered by the measurement device filter module 401, and is output and transmitted to the measurement device detection module 403. The measurement device detection module 403 detects whether there is laser output. During the detection process, the measurement device tuning module 402 adjusts the bandpass position of the measurement device filter module 401 so that the bandpass position sequentially sweeps across the laser frequency range (the scanning sequence can be from low frequency to high frequency or from high frequency to low frequency). When the laser longitudinal mode is within the bandpass range of the measurement device filter module 401, the laser light having this longitudinal mode is output to the measurement device detection module 403, and the measurement device detection module 403 detects the laser output. After the bandpass position of the filter module 401 of the measuring device sweeps through the frequency range of the laser, the detection module 403 of the measuring device records the number of times the laser is output, thereby obtaining the number of longitudinal modes.

[0113] By setting up a measuring device filter module 401, a single longitudinal mode laser can be obtained after the laser is filtered by the measuring device filter module 401. At the same time, the bandpass position of the measuring device filter module 401 is adjusted by the measuring device tuning module 402, and the frequency range of the laser can be scanned in sequence. The number of laser outputs is detected by the measuring device detection module 403, so that the number of longitudinal modes can be obtained; when external factors change, the number and / or longitudinal mode positions in the laser will change, so that the number and / or longitudinal mode positions detected by the measuring device detection module 403 will change, which can realize the measurement and monitoring of extremely small changes in external factors, with high measurement accuracy and a wide range of applications.

[0114] See also Figure 21 Furthermore, the measuring device tuning module 402 is also used to adjust the measuring device bandpass width L60 of the measuring device filter module 401, so that the bandpass width L60 of the measuring device filter module 401 can be adjusted to be narrow enough to be smaller than the width L61 between adjacent longitudinal modes in the multi-longitudinal mode laser, thereby ensuring that the laser output after passing through the measuring device filter module 401 is a single longitudinal mode laser.

[0115] See also Figure 23 In one embodiment, the measurement device filtering module 401 includes a first measurement device filtering unit 4011 and a second measurement device filtering unit 4012 for filtering laser light. The measurement device tuning module 402 is connected to the first measurement device filtering unit 4011 and / or the second measurement device filtering unit 4012, thereby adjusting the passband position and / or passband width of the first measurement device filtering unit 4011 and / or the second measurement device filtering unit 4012. The filtering range of the first measurement device filtering unit 4011 partially overlaps with the filtering range of the second measurement device filtering unit 4012. After filtering by the first measurement device filtering unit 4011 and the second measurement device filtering unit 4012, the laser light is converted into a single longitudinal mode laser and output to the measurement device detection module 403.

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

[0117] Adjusting the passband positions of the first filter unit 4011 and the second filter unit 4012 of the measuring device;

[0118] Adjusting the passband widths of the first filter unit 4011 and the second filter unit 4012 of the measuring device;

[0119] Adjust the passband position of the first filter unit 4011 of the measuring device, and adjust the passband width of the second filter unit 4012 of the measuring device;

[0120] The passband width of the first filter unit 4011 of the measuring device is adjusted, and the passband position of the second filter unit 4012 of the measuring device is adjusted.

[0121] Because the measurement device filter module 401 includes two filter units (a first measurement device filter unit 4011 and a second measurement device filter unit 4012) with partially overlapping filtering ranges, even if each filter unit has a relatively wide filtering range, by adjusting the first measurement device filter unit 4011 and / or the second measurement device filter unit 4012 via the measurement device tuning module 402, a laser with an extremely narrow linewidth can be obtained, thereby achieving single longitudinal mode filtering output. Because the filtering range requirements for each filter unit are relatively low, filter units with lower parameters and wider filtering ranges can be utilized, significantly reducing process complexity.

[0122] In one embodiment, the measuring device tuning module 402 includes a first measuring device tuning unit 4021, which is connected to the first measuring device filtering unit 4011 and is configured to adjust the passband position and / or passband width of the first measuring device filtering unit 4011. By adjusting the passband position of the first measuring device filtering unit 4011, the passband position of the overlapping portion of the first measuring device filtering unit 4011 and the second measuring device filtering unit 4012 can be adjusted; by adjusting the passband width of the first measuring device filtering unit 4011, the passband width of the overlapping portion of the first measuring device filtering unit 4011 and the second measuring device filtering unit 4012 can be adjusted.

[0123] In one embodiment, the measuring device tuning module 402 includes a measuring device second tuning unit 4022, which is connected to the measuring device second filtering unit 4012 and is configured to adjust the passband position and / or passband width of the measuring device second filtering unit 4012. By adjusting the passband position of the measuring device second filtering unit 4012, the passband position of the overlapping portion of the measuring device first filtering unit 4011 and the measuring device second filtering unit 4012 can be adjusted; by adjusting the passband width of the measuring device second filtering unit 4012, the passband width of the overlapping portion of the measuring device first filtering unit 4011 and the measuring device second filtering unit 4012 can be adjusted.

[0124] See also Figure 23In one embodiment, the measuring device tuning module 402 includes a first measuring device tuning unit 4021 and a second measuring device tuning unit 4022. The first measuring device tuning unit 4021 is connected to the first measuring device filtering unit 4011, and the second measuring device tuning unit 4022 is connected to the second measuring device filtering unit 4012. By adjusting the passband positions of the first measuring device filtering unit 4011 and the second measuring device tuning unit 4022, the passband position of the overlapping portion of the first measuring device filtering unit 4011 and the second measuring device filtering unit 4012 can be adjusted (see Figure 18 , L60' is the bandpass position before adjustment, L60 is the bandpass position after adjustment); by adjusting the bandpass width of the first filter unit 4011 of the measuring device and the second filter unit 4012 of the measuring device, the bandpass width of the overlapping portion of the first filter unit 4011 and the second filter unit 4012 of the measuring device can be adjusted (see Figure 19 , L60' is the bandpass width before adjustment, and L60 is the bandpass width after adjustment).

[0125] See also Figure 16 and Figure 23 In one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit that performs transmission filtering on the laser. A portion of the laser from the filter module 20 enters the filter module 401 of the measuring device through the first filter unit 4011 of the measuring device; the second filter unit 4012 of the measuring device is a transmission filter unit that performs transmission filtering on the laser. After passing through the second filter unit, a portion of the laser in the filter module 401 of the measuring device is transmitted, and thus output to the detection module 403 of the measuring device.

[0126] When the laser light passes through the first filter unit 4011 of the measuring device, due to the frequency domain reflectivity of the first filter unit 4011, the laser light within the reflection range of the first filter unit 4011 (i.e., the first reflection range L41 of the measuring device) is filtered out and cannot pass through the first filter unit 4011. However, the laser light outside the first reflection range L41 of the measuring device passes through the first filter unit 4011 and enters the filter module 401 of the measuring device. The laser light entering the filter module 401 of the measuring device continues to propagate to the second filter unit 4012 of the measuring device. Due to the frequency domain reflectivity of the second filter unit 4012, the laser light within the reflection range of the second filter unit 4012 (i.e., the second reflection range L51 of the measuring device) is filtered out and cannot pass through the second filter unit 4012. However, the laser light outside the second reflection range L51 of the measuring device passes through the second filter unit 4012 and exits. The overlapping 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 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 filtering 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 allow part of the laser to be transmitted, while 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 allow part of the laser to be transmitted, while 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 that performs transmission filtering on the laser. The reflection range of the first filter unit 4011 of the measuring device is the first reflection range L41 of the measuring device. Laser light outside the first reflection range L41 of the measuring device passes through the first filter unit 4011 and enters the filter module 401 of the measuring device or is emitted from the filter module 401 of the measuring device. The second filter unit 4012 of the measuring device is a reflection filter unit that performs reflection filtering on 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. 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 overlapping portion of the frequency domain outside the first reflection range L41 of the measuring device and the frequency domain outside the second transmission range L52 of the measuring device is the filter range L60 of the measuring device (the filter range L60 of the measuring device is less than the width between adjacent longitudinal modes in a multi-longitudinal mode laser). The laser light output after passing through the filter module 401 of the measuring device is a single longitudinal mode laser light within the filter range L60 of the measuring device.

[0129] See also Figure 17 and Figure 24 In one embodiment, the first filter unit 4011 of the measuring device is a transmissive filter unit, and the second filter unit 4012 of the measuring device is a reflective filter unit. Laser light passes through the first filter unit 4011 and enters the filter module 401 of the measuring device. The laser light that enters the filter module 401 is then transmitted to the second filter unit 4012, where it is reflected. The reflected portion of the laser light then returns to the first filter unit 4011, where it is filtered by the first filter unit 4011 before being emitted. The output laser light then falls within the filter range L60 of the measuring device.

[0130] It should be understood that the first filtering unit 4011 of the measuring device can also allow part of the laser to be transmitted, while the part of the laser that cannot be transmitted will be absorbed by the first filtering unit 4011 of the measuring device; the second transmission range L52 of the measuring device second filtering unit 4012 of the measuring device can also be an absorption range, that is, the laser within this range will be absorbed by the second filtering unit 4012 of the measuring device.

[0131] See also Figure 17 、 Figures 25 to 26 In one embodiment, the first filter unit 4011 of the measuring device is a transmission filter unit, and the second filter unit 4012 of the measuring device is a reflection filter unit. The optical sensor further includes a second coupling unit 404, which is connected to the first filter unit 4011 of the measuring device and couples the laser light into the filter module 401 of the measuring device. In this case, the laser light transmitted through the first filter unit 4011 of the measuring device can be directly emitted through the first filter unit 4011 of the measuring device, or can be transmitted to the second coupling unit 404 before being emitted. Figure 27 The second coupling unit 404 may also be located in the filter module 401 of the measuring device, and the second coupling unit couples the laser into the filter module 401 of the measuring device. After the laser enters the filter module 401 of the measuring device, it is first transmitted to the second filter unit 4012 of the measuring device and reflected. 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 before being emitted. The output laser is the laser within the filter range L60 of the measuring device.

[0132] See also Figure 17 and Figure 28In one embodiment, the first filter unit 4011 of the measuring device is a transmissive filter unit, and the second filter unit 4012 of the measuring device is a reflective filter unit. The optical sensor further includes a second output unit 405 for outputting laser light at a side end of the measuring device filter module 401. The laser light is emitted from the second output unit 405 and then transmitted to the measuring device detection module 403. The laser light is sequentially transmitted through the first filter unit 4011, reflected from the second filter unit 4012, and then emitted through the second output unit 405. The output laser light is within the measuring device's filtering range L60. The second output unit 405 can also be located outside the measuring device filter module 401 and connected to the first filter unit 4011. The laser light is then sequentially transmitted through the first filter unit 4011, reflected from the second filter unit 4012, and then transmitted through the first filter unit 4011, before being emitted through the second output unit 405 to the measuring device detection module 403.

[0133] See also Figure 18 and Figure 29 In one embodiment, the first filter unit 4011 of the measuring device is a reflective filter unit that performs reflection filtering on 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 light outside the first transmission range L42 of the measuring device will be 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 performs reflection filtering on 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 will be reflected at the second filter unit 4012 of the measuring device. The overlapping portion 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 is the filter range L60. The filter range L60 is smaller than the width between adjacent longitudinal modes in the multi-longitudinal mode laser. The laser light output after passing through the filter module 401 of the measuring device is the laser light within the filter range L60 of the measuring device.

[0134] The optical sensor also includes a second coupling unit 404 and a second output unit 405. The second coupling unit 404 is located within the measuring device filter module 401 and couples laser light into the measuring device filter module 401. The second output unit 405 is configured to output laser light from the side of the measuring device filter module 401 to the measuring device detection module 403. Laser light from the filter module 20 enters the measuring device filter module 401 through the second coupling unit 404, is reflected by the first and second filter units 4011, 4012, and is then output to the measuring device detection module 403 through the second output unit 405. The output laser light is within the measuring device filter range L60.

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

[0136] See also Figure 30 Furthermore, the optical sensor provided in this embodiment may include a second isolation unit 406 arranged on the output path of the measuring device filter module 401, and the second isolation unit 406 is arranged between the measuring device filter module 401 and the measuring device detection module 403, and is used to isolate the reverse laser, thereby protecting the optical sensor.

[0137] Furthermore, the first filter unit 4011 of the measuring device can be a highly reflective fiber Bragg grating, and the second filter unit 4012 of the measuring device can be a highly reflective fiber Bragg grating. Due to its frequency domain reflectivity, the highly reflective fiber Bragg grating filters light (including laser light) within its frequency domain reflection range. The first tuning unit 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 influencing the physical and chemical properties of the grating (including temperature, stress, pressure, etc.), the bandpass position and bandpass width can be adjusted to meet specific usage requirements.

[0138] Furthermore, the pump device 10, the resonant cavity 20, the measuring device 40 and other devices can be connected by optical fibers to realize an all-fiber optical filter with higher sensitivity, larger dynamic range, faster response speed, etc.; some devices can also be connected by optical fibers to realize a partial fiber optical filter; and light can also be transmitted through free space, which is not limited here.

[0139] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An optical sensor, characterized in that: include A pump device, used for outputting pump light; a resonant cavity for absorbing the pump light and obtaining filtered laser light; a sensing device connected to the resonant cavity and used to sense external factors; The measuring device is arranged on the output path of the resonant cavity and is at least used to measure the number of longitudinal modes of the laser.

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

3. The optical sensor according to claim 2, wherein: The first reflection filter unit is a partial reflection filter unit, which is used to transmit the pump light, filter the laser light in the resonant cavity, partially reflect the light intensity, and output the laser light; The second reflection filter unit is a total reflection filter unit, which is used to filter the laser in the resonant cavity and perform total reflection on the light intensity.

4. The optical sensor according to claim 2, wherein: The first reflection filter unit is a partial reflection filter unit, which is used to transmit the pump light, filter the laser in the resonant cavity and partially reflect the light intensity; The second reflection filter unit is a total reflection filter unit, which is used to filter the laser in the resonant cavity and fully reflect the light intensity; The optical sensor further includes a first output unit located in the resonant cavity, configured to output the laser light at a side end of the resonant cavity.

5. The optical sensor according to claim 2, wherein: The optical sensor further includes a first coupling unit configured to couple the pump light into the resonant cavity.

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

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

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

9. The optical sensor according to any one of claims 2 to 7, wherein: The optical sensor further comprises: A tuning device is connected to the first reflection filtering unit and / or the second reflection filtering unit, and is used to adjust the bandpass position and / or bandpass width of the first reflection filtering unit and / or the second reflection filtering unit.

10. The optical sensor according to claim 8, wherein: The measuring device comprises: A measuring device filter module, used for filtering the laser light, wherein the laser light outputted after passing through the measuring device filter module is a single longitudinal mode laser light; a measuring device tuning module, connected to the measuring device filtering module, and at least used to adjust the bandpass position of the measuring device filtering module; The measuring device detection module is provided on the output path of the measuring device filter module and is used to detect the laser.

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

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