WO2023272617A1

WO2023272617A1 - Cavity ring down electro-optical system and incident light path adjustment method

Info

Publication number: WO2023272617A1
Application number: PCT/CN2021/103721
Authority: WO
Inventors: 陈波; 杨志泉; 陈从干
Original assignee: 徐州旭海光电科技有限公司
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2023-01-05
Also published as: CN113646621A

Abstract

A cavity ring down electro-optical system (100, 200) and an incident light path adjustment method. The cavity ring down electro-optical system (100, 200) outputs a detection beam by means of a laser (1). The detection beam is attenuated to an emergent beam after same has been reflected back and forth by an optical resonant cavity (2). A first light detector (3) receives the emergent beam and converts same into a first electrical signal. An electro-optical control module (4) adjusts an operating parameter of the laser (1), so as to match the wavelength of the detection beam with a longitudinal mode of the optical resonant cavity (2); acquires the light intensity of the emergent beam according to the first electrical signal; and adjusts, when the light intensity of the emergent beam is greater than a preset threshold value, the operation parameter of the laser (1), so as to turn off the detection beam. A data processing module (5) acquires, according to the first electrical signal, a ring down time of the detection beam in the optical resonant cavity (2). The optical resonant cavity (2) is a plano-concave cavity, a fundamental transverse mode beam waist of which is located on a plane mirror; or the cavity ring down electro-optical system (100, 200) further comprises a single-mode output optical fiber (6) having a fundamental mode which matches a fundamental transverse mode of the emergent beam. A higher-order transverse mode can be effectively suppressed, so as to improve the system sensitivity.

Description

A cavity ring-down photoelectric system and its incident light path adjustment method

technical field

The application belongs to the technical field of cavity ring down (CRD), and in particular relates to a cavity ring down photoelectric system and an incident light path adjustment method thereof.

Background technique

Cavity ring down technology is mainly used in high reflectivity detection of mirrors, trace gas detection and other fields. Different from other detection technologies, cavity ring-down technology calculates the optical loss of the optical resonator by detecting the ring-down time of the light wave in the optical resonator, and then calculates the reflectivity of the mirror or the absorptivity of the gas.

technical problem

One of the purposes of the embodiments of the present application is to provide a cavity ring-down optoelectronic system and its incident light path adjustment method to solve the defects of the existing cavity ring-down optoelectronic system in terms of transverse mode matching and photodetector reception. There is a high-order transverse mode, and the optical detector receives the high-order transverse mode as well as the fundamental transverse mode, which will interfere with the optical ring-down signal and reduce the sensitivity of the system.

technical solution

In order to solve the above technical problems, the technical solution adopted in the embodiment of the present application is:

The first aspect of the embodiments of the present application provides a cavity ring-down optoelectronic system, including:

a laser for outputting a detection beam;

An optical resonant cavity, the detection beam is attenuated into an outgoing beam after being reflected back and forth by the optical resonant cavity;

a first light detector, configured to receive the outgoing light beam and convert it into a first electrical signal;

a photoelectric control module connected to the laser and the first photodetector, configured to adjust the working parameters of the laser so that the wavelength of the probe beam matches the longitudinal mode of the optical resonant cavity, according to the The first electrical signal obtains the light intensity of the outgoing light beam, and when the light intensity of the outgoing light beam is greater than a preset threshold, adjust the working parameters of the laser so that the wavelength of the detection light beam is the same as the longitudinal direction of the optical resonant cavity. mode mismatch to turn off the probe beam;

A data processing module connected to the first photodetector, configured to obtain the ring-down time of the probe beam in the optical resonant cavity according to the first electrical signal;

Wherein, the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector;

Alternatively, the cavity ring-down optoelectronic system further includes an output optical fiber connected to the first photodetector, the output optical fiber is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing light beam, and the outgoing optical fiber The light beam is transmitted to the first photodetector after being filtered by the output optical fiber to filter high-order transverse modes.

The second aspect of the embodiments of the present application provides a cavity ring-down optoelectronic system, including:

a laser for outputting a detection beam;

light switch;

The piezoelectric ceramic actuator is arranged on the outer cavity wall of the optical resonant cavity;

A photoelectric control module connected with the optical switch, the piezoelectric ceramic actuator and the first photodetector, used to control the piezoelectric ceramic actuator to adjust the cavity length of the optical resonant cavity, so that The wavelength of the detection beam matches the longitudinal mode of the optical resonant cavity, the light intensity of the outgoing light beam is obtained according to the first electrical signal, and when the light intensity of the outgoing light beam is greater than a preset threshold, the control The optical switch changes the transmission direction of the detection beam or reduces the light intensity of the detection beam to turn off the detection beam;

The third aspect implemented in the present application provides a method for adjusting the incident light path, which is implemented based on the cavity ring-down optoelectronic system provided in the first aspect or the second aspect of the embodiments of the present application. The method includes:

During the process of adjusting the beam waist position and incident angle of the probe beam, the probe beam is transmitted to the optical resonant cavity through a circulator, and the circulator is connected to the laser;

converting the reflected light beam reflected by the plane reflector into a second electrical signal through a second photodetector, the second photodetector is connected to the circulator and the photoelectric control module;

Obtain the light intensity of the reflected light beam through the photoelectric control module according to the second electrical signal, so as to monitor the coupling degree of the detection beam and the fundamental transverse mode of the optical resonator until the coupling degree is greater than the coupling degree Up to a threshold value, the light intensity of the reflected light beam is positively correlated with the coupling degree.

Beneficial effect

In the cavity ring-down optoelectronic system provided in the first aspect of the embodiment of the present application, the laser outputs the detection beam, the optical resonant cavity reflects the detection beam back and forth and attenuates it into an outgoing beam, and the first photodetector receives the outgoing beam and converts it into a first electrical signal , the photoelectric control module adjusts the working parameters of the laser so that the wavelength of the probe beam matches the longitudinal mode of the optical resonator, obtains the light intensity of the outgoing beam according to the first electrical signal, and adjusts when the light intensity of the outgoing beam is greater than a preset threshold The working parameters of the laser are such that the wavelength of the probe beam does not match the longitudinal mode of the optical resonator to turn off the probe beam, and the data processing module obtains the ring-down time of the probe beam in the optical resonator according to the first electrical signal; wherein, the optical The resonant cavity is the fundamental transverse mode beam waist located in the flat concave cavity of the plane mirror; or, the cavity ring-down optoelectronic system also includes a single-mode output fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, which can effectively suppress high-order transverse modes , to improve system sensitivity.

In the cavity ring-down optoelectronic system provided by the second aspect of the embodiment of the present application, the laser outputs the detection beam, the optical resonant cavity reflects the detection beam back and forth and attenuates it into an outgoing beam, and the first photodetector receives the outgoing beam and converts it into a first electrical signal , the photoelectric control module controls the piezoelectric ceramic actuator to adjust the cavity length of the optical resonant cavity, so that the wavelength of the detection beam matches the longitudinal mode of the optical resonant cavity, and the light intensity of the outgoing beam is obtained according to the first electrical signal. When the light intensity is greater than the preset threshold, control the optical switch to change the transmission direction of the detection beam or reduce the light intensity of the detection beam to turn off the detection beam, and the data processing module obtains the ringdown of the detection beam in the optical resonant cavity according to the first electrical signal time; wherein, the optical resonant cavity is a flat concave cavity where the beam waist of the fundamental transverse mode is located in a plane mirror; or, the cavity ring-down optoelectronic system also includes a single-mode output fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, which can effectively Higher-order transverse modes are suppressed to improve system sensitivity.

In the incident light path adjustment method provided by the third aspect of the embodiment of the present application, in the process of adjusting the beam waist position and incident angle of the probe beam, the probe beam is transmitted to the optical resonator through a circulator, and the circulator is connected to the laser; through the first The second light detector converts the reflected light beam reflected by the plane reflector into a second electrical signal, and the second light detector is connected with the circulator and the photoelectric control module; the light intensity of the reflected light beam is obtained by the photoelectric control module according to the second electric signal, so as to Monitor the coupling degree of the probe beam and the fundamental transverse mode of the optical resonator until the coupling degree is greater than the threshold value of the coupling degree. coupling.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings that need to be used in the descriptions of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only for the present application For some embodiments, those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a first structural schematic diagram of a cavity ring-down optoelectronic system provided by an embodiment of the present application;

Fig. 2 is a second structural schematic diagram of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 3 is a third structural schematic diagram of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 4 is a schematic diagram of the fourth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

FIG. 5 is a schematic diagram of a fifth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 6 is a schematic diagram of the sixth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 7 is a schematic diagram of the seventh structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 8 is a schematic diagram of the eighth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

FIG. 9 is a schematic diagram of the ninth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application;

Fig. 10 is a schematic diagram of a tenth structure of the cavity ring-down optoelectronic system provided by the embodiment of the present application.

Embodiments of the present invention

In order to enable those skilled in the art to better understand the solution of the application, the technical solution in the embodiment of the application will be clearly described below in conjunction with the drawings in the embodiment of the application. Obviously, the described embodiment is the Some examples, but not all examples. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

The terms "comprising" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. For example, a process, method or system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units not listed, or optionally further includes Other steps or units inherent in these processes, methods, products or apparatus. In addition, the terms "first", "second", and "third", etc. are used to distinguish different objects, not to describe a specific order.

As shown in Figure 1, Figure 2 or Figure 3, the first cavity ring-down optoelectronic system 100 provided in the embodiment of the present application includes:

Laser 1, for outputting a detection beam;

An optical resonant cavity 2, the detection beam is reflected back and forth by the optical resonant cavity 2 and attenuated into an outgoing beam;

The first light detector 3 is used to receive the outgoing light beam and convert it into a first electrical signal;

The photoelectric control module 4 connected to the laser 1 and the first photodetector 3 is used to adjust the working parameters of the laser 1, so that the wavelength of the detection beam matches the longitudinal mode of the optical resonator 2, and obtains the outgoing beam according to the first electrical signal When the light intensity of the outgoing beam is greater than the preset threshold, the working parameters of the laser 1 are adjusted so that the wavelength of the detection beam does not match the longitudinal mode of the optical resonator 2, so as to turn off the detection beam;

The data processing module 5 connected to the first photodetector 3 is used to obtain the ring down time of the probe beam in the optical resonant cavity 2 according to the first electrical signal.

Fig. 1 exemplarily shows that the optical resonant cavity 2 is a flat concave cavity composed of a plane reflector and a concave reflector;

Fig. 2 exemplarily shows that the optical resonant cavity 2 is a confocal cavity composed of two concave mirrors, and the fundamental transverse mode beam waist of the confocal cavity is located between the two concave mirrors; the cavity ring-down optoelectronic system 100 is also It includes an output optical fiber 6 connected to the first photodetector 3, the output optical fiber 6 is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, and the outgoing beam is transmitted to the first light detector 3;

Fig. 3 exemplarily shows that the optical resonant cavity 2 is a flat concave cavity composed of a plane reflector and a concave reflector, and the fundamental transverse mode beam waist of the flat concave cavity is located at the plane reflector; the cavity ring-down optoelectronic system 100 also includes and The output optical fiber 6 connected to the first photodetector 3 is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, and the outgoing beam is transmitted to the first optical detector after the high-order transverse mode is filtered by the output optical fiber. Device 3.

In the application, the optical resonant cavity can be a flat-concave cavity composed of a plane reflector and a concave reflector, or the cavity ring-down optoelectronic system can also include an output optical fiber connected to the first photodetector, and the output optical fiber is a fundamental mode and A single-mode optical fiber whose fundamental transverse mode of the outgoing light beam matches, and the outgoing light beam is transmitted to the first photodetector after the high-order transverse mode is filtered by the output optical fiber. The optical resonant cavity is a flat concave cavity and the cavity ring-down optoelectronic system also includes the output optical fiber. These two conditions can exist at the same time.

In applications, the optical resonator can be an open cavity or a closed cavity. When the optical resonant cavity is an open cavity, it can be used to detect the absorption rate of the gas (for example, the atmosphere) in any space where it is located; when the optical resonant cavity is a closed cavity, it can be used to detect the gas filling the closed cavity The absorption rate of any gas (for example, trace gas) in the body needs to make the absorption peak wavelength of the gas in the optical cavity within the central wavelength range of the probe beam; no matter whether the optical cavity is airtight, it can be used to detect its The reflectivity of the inner wall (that is, the reflectivity of the plane mirror or concave mirror used to form the optical resonant cavity) needs to make the absorption peak wavelength of the gas in the optical resonant cavity not within the central wavelength range of the probe beam; when the optical When the resonant cavity is airtight and vacuum, since there is no gas interference, it can be used to accurately detect the reflectivity of its inner wall.

In one embodiment, when the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector, the distance from the plane reflector to the concave reflector is 1/2 of the radius of curvature of the concave reflector, and the distance of the flat concave cavity The fundamental transverse mode beam waist is located on the flat mirror.

In application, depending on the structure of the optical resonant cavity, the cavity ring-down optoelectronic system has three structures as shown in Figure 1 to Figure 3, and its effects are as follows:

In the first structure shown in Figure 1, the optical resonant cavity is a flat concave cavity and does not include an output fiber composed of a single-mode fiber. By adopting a flat concave cavity whose fundamental transverse mode beam waist is located in a plane mirror, it is beneficial to the output beam Matches the fundamental transverse mode of the flat concave cavity, reducing the excitation of high-order transverse modes;

In the second structure shown in Figure 2, the optical resonant cavity is a double concave cavity and includes an output fiber composed of a single-mode fiber. By using a single-mode fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, it can effectively filtering out the high-order transverse modes in the outgoing light beam, so that the high-order transverse modes in the outgoing light beam finally received by the first photodetector approach to 0;

In the third structure shown in Figure 3, the optical resonant cavity is a flat concave cavity and includes an output fiber composed of a single-mode fiber. The single-mode fiber whose fundamental transverse mode of the outgoing beam matches can realize the superposition of the two effects of reducing the excitation of the high-order transverse mode and filtering the high-order transverse mode in the outgoing beam, so that it is finally received by the first photodetector The higher-order transverse modes in the outgoing beam of , tend to zero.

In the application, the modulation type of the laser can be current modulation type or voltage modulation type. The laser can be any type of tunable laser, for example, Fabry-Perot laser, Distributed Feedback semiconductor laser, Distributed Bragg reflector laser, vertical cavity surface Tunable semiconductor lasers such as vertical-cavity surface-emitting lasers and external cavity tuned semiconductor lasers. The operating parameters of the laser can be operating temperature, bias current or bias voltage. The wavelength of the probe beam output by the laser can be adjusted by changing the working temperature, bias current or bias voltage of the laser chip of the laser.

In applications, the first photodetector may be a photoelectric conversion device such as a photodiode or a photomultiplier tube.

In the application, the photoelectric control module and the data processing module can be a central processing unit (Central Processing Unit, CPU), or other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application-specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general purpose processor may be a microprocessor or any conventional processor or the like.

In the application, the working principle of the photoelectric control module and the data processing module is:

The photoelectric control module adjusts the working parameters of the laser to change the wavelength of the detection beam, so that the wavelength of the detection beam matches the longitudinal mode of the optical resonator and can be received by the first photodetector;

The photoelectric control module acquires the light intensity of the outgoing beam according to the first electrical signal. When the light intensity of the outgoing light beam is greater than the preset threshold, it indicates that the wavelength of the outgoing light beam matches the longitudinal mode of the optical resonator to a high degree. At this time, the laser is adjusted working parameters to change the wavelength of the detection beam, so that the wavelength of the detection beam does not match the longitudinal mode of the optical resonator and cannot be received by the first photodetector, so as to realize the indirect shutdown of the detection beam and trigger the first photodetector at the same time fast sampling;

The data processing module can obtain the ring-down time of the detection beam in the optical resonant cavity according to the first electrical signal obtained by fast sampling by the first photodetector.

As shown in Fig. 4, an embodiment of the present application also provides a kind of optical cavity ring-down optoelectronic system 100 when the optical resonant cavity 2 is a flat-concave cavity composed of a plane reflector and a concave reflector. The structure for implementing the incident light path adjustment method, the structure also includes a circulator 7 connected to the laser 1 and a second photodetector 8 connected to the circulator 7 and the photoelectric control module 4 on the basis of the cavity ring-down optoelectronic system 100, Incident light path adjustment methods include:

During the process of adjusting the beam waist position and incident angle of the probe beam, the probe beam is transmitted to the optical resonant cavity 2 through the circulator 7;

Convert the reflected light beam reflected by the plane reflector into a second electrical signal through the second photodetector 8;

Obtain the light intensity of the reflected light beam through the photoelectric control module 4 according to the second electrical signal, to monitor the coupling degree of the probe light beam and the fundamental transverse mode of the optical resonant cavity 2, until the coupling degree is greater than the coupling degree threshold value, the light intensity of the reflected light beam and The degree of coupling is positively correlated.

FIG. 4 exemplarily shows a structure implemented on the basis of the cavity ring-down optoelectronic system 100 shown in FIG. 3 for implementing a method for adjusting an incident light path.

In the application, in the process of adjusting the beam waist position and incident angle of the detection beam, the detection beam reflected by the plane mirror (that is, the reflected beam) can be reversely transmitted to the second photodetector by setting a circulator, The reflected light beam is received by the second photodetector and converted into a second electrical signal, so that the photoelectric control module can obtain the light intensity of the reflected light beam according to the second electric signal, and then monitor the relationship between the detection light beam and the optical resonant cavity according to the light intensity of the reflected light beam The coupling degree of the fundamental transverse mode, when the coupling degree does not reach the coupling degree threshold, repeatedly adjust the beam waist position and incident angle of the probe beam until the coupling degree is greater than the coupling degree threshold, and finally realize the fundamental of the probe beam and the optical resonator. Efficient coupling of transverse modes. Theoretically, the higher the coupling degree, the more reflected beams and the higher the light intensity. When the beam waist of the fundamental transverse mode of the probe beam is located on the plane mirror and parallel to the normal of the plane mirror, it is reflected back to the second beam through the optical circulator. The light beam of the photodetector has the strongest light intensity. The coupling degree threshold should be set to a value corresponding to the strongest light intensity of the reflected light beam obtained by the photoelectric control module according to the actual situation.

In an application, the second photodetector may be a photoelectric conversion device such as a photodiode or a photomultiplier tube, that is, the implementation manner of the first photodetector may be the same.

In one embodiment, based on the embodiment corresponding to any one of Figures 1 to 3, the cavity ring-down optoelectronic system further includes:

The incident light shaping unit is arranged on the optical path between the laser and the optical resonant cavity, and the detection beam is spatially modulated by the incident light shaping unit and then transmitted to the optical resonant cavity;

Alternatively, the outgoing light shaping unit is arranged on the optical path between the optical resonant cavity and the first photodetector, and the outgoing light beam is spatially modulated by the outgoing light shaping unit and then transmitted to the first photodetector or the output optical fiber.

In the application, the cavity ring down optoelectronic system can include an incident light shaping unit, so that the detection beam can be better coupled to the optical resonant cavity; it can also include an outgoing light shaping unit, so that the outgoing light beam can be better coupled to the first photodetector or output fiber.

As shown in Figure 5, in one embodiment, the incident light shaping unit includes:

An optical isolator 9 connected to the laser 1 is used to isolate the reverse beam whose propagation direction is opposite to that of the detection beam;

Input optical fiber 10 connected with optical isolator 9;

A collimating lens 11, the detection beam is transmitted to the optical resonant cavity 2 through the optical isolator 9, the input optical fiber 10 and the collimating lens 11 in sequence;

The outgoing light shaping unit includes a first focusing lens 12 , and the outgoing light beam is focused by the first focusing lens 12 and transmitted to the first light detector 3 .

Figure 5 exemplarily shows on the basis of Figure 3 that an optical isolator 9, an input fiber 10 and a collimating lens 11 are arranged between the laser 1 and the optical resonator 2, and the first focusing lens 12 is arranged between the optical resonator 2 and the output between 6 fibers.

As shown in FIG. 6, FIG. 7 or FIG. 8, the second cavity ring-down optoelectronic system 200 provided by the embodiment of the present application includes:

Laser 1, for outputting a detection beam;

Optical switch 13;

The piezoelectric ceramic actuator 14 is arranged on the outer cavity wall of the optical resonant cavity;

The photoelectric control module 4 connected with the optical switch 13, the piezoelectric ceramic actuator 14 and the first photodetector 3 is used to control the piezoelectric ceramic actuator 14 to adjust the cavity length of the optical resonant cavity, so that the wavelength of the detection beam and The longitudinal modes of the optical resonant cavity are matched, and the light intensity of the outgoing beam is obtained according to the first electrical signal. When the light intensity of the outgoing light beam is greater than a preset threshold, the optical switch 13 is controlled to change the transmission direction of the detection beam or reduce the light intensity of the detection light beam. , to turn off the detection beam;

Figure 6 exemplarily shows that the optical resonant cavity 2 is a flat concave cavity composed of a plane reflector and a concave reflector;

Fig. 7 exemplarily shows that the optical resonant cavity 2 is a confocal cavity composed of two concave mirrors, and the fundamental transverse mode beam waist of the confocal cavity is located between the two concave mirrors; the cavity ring-down optoelectronic system 100 is also It includes an output optical fiber 6 connected to the first photodetector 3, the output optical fiber 6 is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, and the outgoing beam is transmitted to the first light detector 3;

Figure 8 exemplarily shows that the optical resonant cavity 2 is a flat concave cavity composed of a plane reflector and a concave reflector, and the fundamental transverse mode beam waist of the flat concave cavity is located at the plane reflector; the cavity ring-down optoelectronic system 100 also includes a The output optical fiber 6 connected to the first photodetector 3 is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing beam, and the outgoing beam is transmitted to the first optical detector after the high-order transverse mode is filtered by the output optical fiber. Device 3.

In application, the optical switch can be an acousto-optic switch (AOM) or an electro-optic switch (EOM).

In application, the piezoelectric ceramic actuator can be arranged on any outer cavity wall of the optical resonant cavity in the direction of the optical path, that is, the outer wall of the reflector or the concave reflector. The piezoelectric ceramic actuator can move under the control of the photoelectric control module, thereby driving any cavity wall of the optical resonant cavity to move in the direction of the optical path, so as to realize the adjustment of the cavity length of the optical resonant cavity, and then by adjusting the cavity length, To change the matching degree between the wavelength of the probe beam and the longitudinal mode of the optical cavity.

The photoelectric control module analyzes the wavelength and light intensity of the outgoing beam according to the first electrical signal, and controls the piezoelectric ceramic actuator to adjust the cavity length of the optical resonant cavity according to the wavelength of the outgoing beam, so as to change the wavelength of the detection beam, so that the wavelength of the detection beam is consistent with the optical The longitudinal modes of the resonant cavity are matched and can be received by the first photodetector;

When the light intensity of the outgoing beam is greater than the preset threshold, it indicates that the wavelength of the outgoing beam matches the longitudinal mode of the optical resonator to a high degree. At this time, the acousto-optic modulator is controlled to change the transmission direction of the detection beam so that the detection beam cannot be transmitted. to the optical resonant cavity, or control the electro-optic modulator to change the light intensity of the detection beam, so that the light intensity is reduced and cannot be received by the first photodetector, so as to directly turn off the detection beam and trigger the first photodetector to quickly sample ;

As shown in Fig. 9, an embodiment of the present application also provides an optical resonant cavity 2 which is a flat-concave cavity composed of a plane reflector and a concave reflector, on the basis of the cavity ring-down optoelectronic system 200 The structure for implementing the incident light path adjustment method, the structure also includes a circulator 7 connected to the laser 1 and a second photodetector 8 connected to the circulator 7 and the photoelectric control module 4 on the basis of the cavity ring-down optoelectronic system 100, For the method of adjusting the incident light path, refer to the embodiment corresponding to FIG. 4 , which will not be repeated here.

FIG. 9 exemplarily shows a structure implemented on the basis of the cavity ring-down optoelectronic system 200 shown in FIG. 8 for implementing a method for adjusting an incident light path.

In one embodiment, based on the embodiment corresponding to any one of Fig. 6 to Fig. 9, the cavity ring-down optoelectronic system further includes:

The incident light shaping unit is arranged on the optical path between the optical switch and the optical resonant cavity, and the detection beam passes through the optical switch to the incident light shaping unit for spatial light modulation and then is transmitted to the optical resonant cavity;

Alternatively, the outgoing light shaping unit is arranged on the optical path between the optical resonant cavity and the first photodetector, and the outgoing light beam is spatially modulated by the outgoing light shaping unit and then transmitted to the first photodetector.

As shown in Figure 10, in one embodiment, the incident light shaping unit includes:

An input optical fiber 10 connected to an optical switch 13;

A collimating lens 11, the detection beam is transmitted to the optical resonant cavity 2 through the optical isolator 9, the optical switch 13, the input optical fiber 10 and the collimating lens 11 in sequence;

Figure 10 schematically shows that the optical isolator 9, the input fiber 10 and the collimating lens 11 are arranged between the laser 1 and the optical resonant cavity 2 on the basis of Figure 8, and the first focusing lens 12 is arranged between the optical resonant cavity 2 and the output between 6 fibers.

In application, for the implementation, working principles and effects of components not described in detail in FIGS. 6 to 10 , refer to the corresponding embodiments in FIGS. 1 to 5 , and details will not be repeated here.

In application, the cavity ring down optoelectronic system may include but not limited to the above components. Those skilled in the art can understand that the illustration is only an example of the cavity ring-down optoelectronic system, and does not constitute a limitation to the cavity ring-down optoelectronic system, and may include more or less components than those shown in the figure, or combine certain components, Or different components, for example, may also include storage, input and output devices, network access devices, and the like.

In application, the memory may be an internal storage unit of the cavity ring-down optoelectronic system in some embodiments, for example, a hard disk or memory of the cavity ring-down optoelectronic system, specifically, the memory of the optoelectronic control module or the data processing module. In other embodiments, the memory may also be an external storage device of the cavity ring-down optoelectronic system, for example, a plug-in hard disk equipped on the cavity ring-down optoelectronic system, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, flash memory card (Flash Card), etc. Further, the memory may also include both an internal storage unit of the cavity ring-down optoelectronic system and an external storage device. The memory is used to store operating systems, application programs, boot loaders (BootLoader), data, and other programs, such as program codes of computer programs. The memory can also be used to temporarily store data that has been output or will be output. The photoelectric control module and the data processing module can be integrated into one processing unit, or each unit can exist separately physically. In addition, the specific names of the photoelectric control module and the data processing module are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application.

The embodiment of the present application also provides an application method of the above-mentioned cavity ring-down optoelectronic system, including the following steps:

Obtaining the reflectivity of the inner sidewall of the optical resonant cavity according to the ring-down time obtained when there is no gas in the optical resonant cavity;

Alternatively, the absorptivity of the gas is obtained based on the ring-down time obtained when there is no gas in the optical resonant cavity and the ring-down time obtained when there is gas in the optical resonant cavity.

In one embodiment, the relationship between the light intensity of the outgoing light beam and the ring-down time is as follows:

I=I ₀ exp(-t/τ) (Relationship 1)

Among them, I is the light intensity of the outgoing beam acquired at the moment when the outgoing light beam is stopped to be converted into the first electrical signal, I ₀ is the initial light intensity of the outgoing light beam, and t is from the moment when the detection beam is turned off to the time when the outgoing light beam is stopped. is the measurement time between the moments of the first electric signal, and τ is the ring-down time.

In application, the initial light intensity of the outgoing light beam is the light intensity of the outgoing light beam acquired according to the first electrical signal when the light intensity of the outgoing light beam is greater than a preset threshold.

In one embodiment, the relationship between the ring-down time and the parameters of the optical resonant cavity is as follows:

τ=2L/C[-ln(R ₁ R ₂ )+2δ+2β] (Relationship 2)

Among them, L is the cavity length of the optical resonant cavity, C is the speed of light, R ₁ and R ₂ are the reflectivity of the two inner walls of the optical resonant cavity, δ is the optical path of the probe beam in the optical resonant cavity equal to the single cavity length , the optical loss (for example, diffraction loss) caused by the optical resonator to the probe beam, β is the absorption rate of the gas in the optical resonator to the probe beam when the optical path of the probe beam in the optical resonator is equal to the single cavity length .

In the application, the reflectivity of the two inner walls of the optical resonator can be regarded as equal, that is, R ₁ =R ₂ =R, therefore, the second relation can be simplified as the following relation:

τ=L/C(1- R+δ+β] (Relationship 3).

Based on the third relation, when there is no gas in the optical cavity, the third relation can be simplified to the following relation:

τ ₁ =L/C(1- R+δ] (Relationship 4)

Among them, τ1 is the ring-down time obtained according to relational formula ₁ when there is no gas in the optical resonant cavity.

Based on relation four, when there is no gas in the optical resonant cavity and the optical loss caused by the optical resonant cavity to the detection beam is ignored, the relationship between the reflectivity of the inner wall of the optical resonant cavity and the ring-down time is as follows:

R=L/(Cτ ₁ ) (relational formula 5).

Based on relation 4, in the case of ignoring the optical loss caused by the optical resonator to the probe beam, when the optical path of the probe beam in the optical resonator is equal to the single cavity length, the absorption rate of the gas in the optical resonator to the probe beam The relationship between and the ring down time is as follows:

β=L/[C(1/τ ₂ -1/τ ₁ )] (relationship six)

Among them, τ2 is the ring-down time obtained according to the relational formula ₁ when there is gas in the optical resonant cavity.

The application method based on the cavity ring-down optoelectronic system provided in the embodiment of the present application can realize fast and accurate measurement of the reflectivity of the inner wall of the optical cavity according to the ring-down time obtained when there is no gas in the optical cavity; It is also possible to realize fast and accurate measurement of the absorption rate of the gas based on the ring-down time obtained when there is no gas in the optical resonant cavity and the ring-down time obtained when there is gas in the optical resonant cavity.

It should be noted that, since the execution process of the above steps is based on the same concept as the embodiment of the cavity ring-down optoelectronic system of the present application, its specific functions and technical effects can be referred to in the part of the embodiment of the cavity ring-down optoelectronic system. I won't repeat them here.

The embodiment of the present application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program is executed by the data processing module, the steps in the above application method embodiments can be realized.

An embodiment of the present application provides a computer program product. When the computer program product runs on the cavity ring-down optoelectronic system, the cavity ring-down optoelectronic system can implement the steps in the above application method embodiments.

In application, a computer readable medium may at least include: any entity or system capable of carrying computer program codes to a data processing module, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), Random Access Memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium. Such as U disk, mobile hard disk, magnetic disk or optical disk, etc.

In the above-mentioned embodiments, the descriptions of each embodiment have their own emphases, and for parts that are not detailed or recorded in a certain embodiment, refer to the relevant descriptions of other embodiments.

Those skilled in the art can appreciate that the devices, units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.

In the embodiments provided in this application, it should be understood that the disclosed system and method can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated. , or some features can be ignored, or not implemented.

The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still apply to the foregoing embodiments Modifications to the technical solutions recorded, or equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the application, and should be included in this application. within the scope of protection.

Claims

A cavity ring-down optoelectronic system is characterized in that it comprises:

a laser for outputting a detection beam;

An optical resonant cavity, the detection beam is attenuated into an outgoing beam after being reflected back and forth by the optical resonant cavity;

a first light detector, configured to receive the outgoing light beam and convert it into a first electrical signal;

a photoelectric control module connected to the laser and the first photodetector, configured to adjust the working parameters of the laser so that the wavelength of the probe beam matches the longitudinal mode of the optical resonant cavity, according to the The first electrical signal obtains the light intensity of the outgoing light beam, and when the light intensity of the outgoing light beam is greater than a preset threshold, adjust the working parameters of the laser so that the wavelength of the detection light beam is the same as the longitudinal direction of the optical resonant cavity. mode mismatch to turn off the probe beam;

A data processing module connected to the first photodetector, configured to obtain the ring-down time of the probe beam in the optical resonant cavity according to the first electrical signal;

Wherein, the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector;

Alternatively, the cavity ring-down optoelectronic system further includes an output optical fiber connected to the first photodetector, the output optical fiber is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing light beam, and the outgoing optical fiber The light beam is transmitted to the first photodetector after being filtered by the output optical fiber to filter high-order transverse modes.
The cavity ring-down optoelectronic system according to claim 1, wherein when the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector, the distance from the plane reflector to the concave reflector is 1/2 of the radius of curvature of the concave reflector, and the beam waist of the fundamental transverse mode of the flat concave cavity is located in the plane reflector.
The cavity ring-down optoelectronic system according to claim 1, wherein when the output optical fiber is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing light beam, the optical resonant cavity is composed of two A confocal cavity composed of two concave mirrors, the beam waist of the fundamental transverse mode of the confocal cavity is located between the two concave mirrors.
The cavity ring-down optoelectronic system according to any one of claims 1 to 3, further comprising:

The incident light shaping unit is arranged on the optical path between the laser and the optical resonant cavity, and the probe beam is spatially modulated by the incident light shaping unit and then transmitted to the optical resonant cavity;

Alternatively, the outgoing light shaping unit is arranged on the optical path between the optical resonant cavity and the first photodetector, and the outgoing light beam is spatially light modulated by the outgoing light shaping unit and then transmitted to the first light beam detector.
The cavity ring-down optoelectronic system according to claim 4, wherein the incident light shaping unit comprises:

an optical isolator connected to the laser, for isolating a reverse beam whose propagation direction is opposite to that of the detection beam;

an input optical fiber connected to the optical isolator;

a collimating lens, the detection beam is sequentially transmitted to the optical resonant cavity through the optical isolator, the input optical fiber and the collimating lens;

The outgoing light shaping unit includes a first focusing lens, and the outgoing light beam is focused by the first focusing lens and transmitted to the first light detector.
The cavity ring-down optoelectronic system according to any one of claims 1 to 3, wherein the data processing module is also used for:

obtaining the reflectivity of the inner sidewall of the optical resonant cavity according to the ring-down time obtained when there is no gas in the optical resonant cavity;

Alternatively, the absorption rate of the gas is obtained according to the ring-down time obtained when there is no gas in the optical resonant cavity and the ring-down time obtained when there is gas in the optical resonant cavity.
The cavity ring-down optoelectronic system according to claim 6, wherein the relational expression between the reflectivity and the ring-down time is as follows:

R=L/(Cτ 1 )

Wherein, R is the reflectivity of the inner wall of the optical resonant cavity, L is the cavity length of the optical resonant cavity, C is the speed of light, and τ1 is the ring - down time obtained when there is no gas in the optical resonant cavity.
The cavity ring-down optoelectronic system according to claim 6, wherein the relationship between the absorptivity of the gas and the ring-down time is as follows:

β=L/[C(1/τ 2 -1/τ 1 )]

Wherein, β is the absorptivity of the gas when the optical path of the probe beam in the optical resonant cavity is equal to a single cavity length, L is the cavity length of the optical resonant cavity, C is the speed of light, and τ1 is The ring-down time obtained when there is no gas in the optical resonant cavity, τ2 is the ring - down time obtained when there is gas in the optical resonant cavity.
A cavity ring-down optoelectronic system is characterized in that it comprises:

a laser for outputting a detection beam;

light switch;

An optical resonant cavity, the detection beam is attenuated into an outgoing beam after being reflected back and forth by the optical resonant cavity;

a first light detector, configured to receive the outgoing light beam and convert it into a first electrical signal;

The piezoelectric ceramic actuator is arranged on the outer cavity wall of the optical resonant cavity;

A photoelectric control module connected with the optical switch, the piezoelectric ceramic actuator and the first photodetector, used to control the piezoelectric ceramic actuator to adjust the cavity length of the optical resonant cavity, so that The wavelength of the detection beam matches the longitudinal mode of the optical resonant cavity, the light intensity of the outgoing light beam is obtained according to the first electrical signal, and when the light intensity of the outgoing light beam is greater than a preset threshold, the control The optical switch changes the transmission direction of the detection beam or reduces the light intensity of the detection beam to turn off the detection beam;

A data processing module connected to the first photodetector, configured to obtain the ring-down time of the probe beam in the optical resonant cavity according to the first electrical signal;

Wherein, the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector;

Alternatively, the cavity ring-down optoelectronic system further includes an output optical fiber connected to the first photodetector, the output optical fiber is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing light beam, and the outgoing optical fiber The light beam is transmitted to the first photodetector after being filtered by the output optical fiber to filter high-order transverse modes.
The cavity ring-down optoelectronic system according to claim 9, wherein when the optical resonant cavity is a flat concave cavity composed of a plane reflector and a concave reflector, the distance from the plane reflector to the concave reflector is 1/2 of the radius of curvature of the concave reflector, and the beam waist of the fundamental transverse mode of the flat concave cavity is located in the plane reflector.
The cavity ring-down optoelectronic system according to claim 9, wherein when the output optical fiber is a single-mode optical fiber whose fundamental mode matches the fundamental transverse mode of the outgoing light beam, the optical resonant cavity is composed of two A confocal cavity composed of two concave mirrors, the beam waist of the fundamental transverse mode of the confocal cavity is located between the two concave mirrors.
The cavity ring-down optoelectronic system according to any one of claims 9 to 11, further comprising:

The incident light shaping unit is arranged on the optical path between the optical switch and the optical resonant cavity, and the probe beam is transmitted to the optical resonant cavity after being spatially modulated by the optical switch to the incident light shaping unit;

The outgoing light shaping unit is arranged on the optical path between the optical resonant cavity and the first photodetector, and the outgoing light beam is spatially modulated by the outgoing light shaping unit and then transmitted to the first photodetector .
The cavity ring-down optoelectronic system according to claim 12, wherein the incident light shaping unit comprises:

an optical isolator connected to the laser, for isolating a reverse beam whose propagation direction is opposite to that of the detection beam;

an input optical fiber connected to the optical switch;

a collimating lens, the detection beam is sequentially transmitted to the optical resonant cavity through the optical isolator, the optical switch, the input optical fiber and the collimating lens;

The outgoing light shaping unit includes a first focusing lens, and the outgoing light beam is focused by the first focusing lens and transmitted to the first light detector.
The cavity ring-down optoelectronic system according to any one of claims 9 to 11, wherein the data processing module is also used for:

obtaining the reflectivity of the inner sidewall of the optical resonant cavity according to the ring-down time obtained when there is no gas in the optical resonant cavity;

Alternatively, the absorption rate of the gas is obtained according to the ring-down time obtained when there is no gas in the optical resonant cavity and the ring-down time obtained when there is gas in the optical resonant cavity.
The cavity ring-down optoelectronic system according to claim 14, wherein the relational expression between the reflectivity and the ring-down time is as follows:

R=L/(Cτ 1 )

Wherein, R is the reflectivity of the inner wall of the optical resonant cavity, L is the cavity length of the optical resonant cavity, C is the speed of light, and τ1 is the ring - down time obtained when there is no gas in the optical resonant cavity.
The cavity ring-down optoelectronic system according to claim 14, wherein the relationship between the absorptivity of the gas and the ring-down time is as follows:

β=L/[C(1/τ 2 -1/τ 1 )]

Wherein, β is the absorptivity of the gas when the optical path of the probe beam in the optical resonant cavity is equal to a single cavity length, L is the cavity length of the optical resonant cavity, C is the speed of light, and τ1 is The ring-down time obtained when there is no gas in the optical resonant cavity, τ2 is the ring - down time obtained when there is gas in the optical resonant cavity.
A method for adjusting an incident optical path, characterized in that it is implemented based on the cavity ring-down optoelectronic system according to claim 2 or 10, the method comprising:

During the process of adjusting the beam waist position and incident angle of the probe beam, the probe beam is transmitted to the optical resonant cavity through a circulator, and the circulator is connected to the laser;

converting the reflected light beam reflected by the plane reflector into a second electrical signal through a second photodetector, the second photodetector is connected to the circulator and the photoelectric control module;

Obtain the light intensity of the reflected light beam through the photoelectric control module according to the second electrical signal, so as to monitor the coupling degree of the detection beam and the fundamental transverse mode of the optical resonator until the coupling degree is greater than the coupling degree Up to a threshold value, the light intensity of the reflected light beam is positively correlated with the coupling degree.