Space-time complex amplitude measuring device based on mode decomposition
By adopting a spatiotemporal complex amplitude measurement device based on mode decomposition in fiber lasers, combined with comprehensive analysis of spatiotemporal complex amplitude, the difficulty of measuring the output beam quality of large-mode field fiber lasers in the prior art is solved, and the narrow line width is achieved The mode component measurement of wide spectrum output improves the anti-interference ability and stability of the measurement.
Patent Information
- Application Number
- CN202420594702.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-26
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2034-03-26
AI Technical Summary
The prior art is difficult to effectively measure and analyze the beam quality of large-mode field fiber laser output, especially in the case of high-power output. Traditional mode measurement methods have difficulty in attenuating high-order modes and insufficient mode analysis capabilities for narrow linewidth spectrum output. The problem.
A space-time complex amplitude measurement device based on mode decomposition is adopted, which includes a light source system, a laser power measurement system, a time domain resolution system, a dual-optical interference system and a mode field resolution system. Through the comprehensive analysis of space-time complex amplitude, laser is realized. A more comprehensive analysis of pattern components in the transmission light field.
The device can measure the output beam mode components of fiber lasers from narrow line-wide spectrum to wide spectrum under conditions of strong anti-interference ability and high stability, avoiding dependence on high-precision two-dimensional scanning equipment and protecting the fiber Probes and spectrometers and other equipment.
Smart Images
Figure CN222481634U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of laser mode measurement, in particular to a time-space complex amplitude measurement device based on mode decomposition. Background Art
[0002] Large mode field fiber is becoming increasingly important in the application fields of optical communication and high-power fiber lasers. Mode division multiplexing of optical fiber is an effective way to increase the information capacity of optical communication. It uses multiple fiber modes to transmit information to achieve the purpose of increasing information capacity. Therefore, real-time monitoring and analysis of fiber modal power is an important topic of the system. The performance of most fiber lasers depends on its beam quality. Single-mode fiber is known for its superior beam quality. However, in large mode field fiber lasers, the core power density is usually reduced by enlarging the effective area of the fiber, while increasing the threshold of nonlinear effects to obtain high power output, but this will lead to multi-transverse mode operation, thereby reducing the beam quality of the output laser. The classic standard for evaluating beam quality is M 2 , usually low M 2 In fact, it is very difficult to attenuate the high-order mode by bending technology. Even if there are 30% high-order mode components in the optical fiber, the beam can still show excellent beam quality (M 2 <1.1). Therefore, the measurement and analysis of fiber modes is one of the important means to control and optimize the output beam of fiber laser.
[0003] At present, the mode measurement technology is mainly divided into time domain and frequency domain coherent measurement methods according to the different analysis domains in the measurement process. The mode measurement technology based on spatial and spectral resolution method is a kind of frequency domain measurement method, which is divided into S 2 Law and F 2 Method. Based on S 2 The mode decomposition method of the method has strong stability and can know the number, type and power proportion of the transmission modes in the optical fiber. This method requires focusing the light beam, which limits its application in the mode of high-power fiber lasers. 2 When analyzing the output beam mode components of kilowatt-level or even megawatt-level fiber lasers, F 2 This method has the advantages of high stability, no need for high-precision two-dimensional scanning equipment, and good protection for equipment such as optical fiber probes and spectrometers.
[0004] When analyzing the mode components, the light field distribution and mode components are reconstructed according to the time-resolved spectral data, which is suitable for the case where the spectral linewidth of the light source is wide (greater than 2nm); when the light source to be measured has a narrow linewidth spectral output (less than 1nm), mode analysis based on spectral information cannot effectively distinguish the group delays of different modes. Mode resolution can be performed based on a phase-correlated spatial light modulator to effectively realize the decomposition of the mode in the light field; the dual-beam interferometry method changes the optical path between the object light and the reference light so that the two light beams produce an interference pattern that varies with time on the detector. The phase and amplitude information of the multi-frame interference pattern containing the object to be measured are used to solve it, which can better reconstruct the light field distribution. Utility Model Content
[0005] Based on the combination of the above-mentioned multiple technologies, the utility model provides a spatiotemporal complex amplitude measurement device based on mode decomposition. The spatiotemporal complex amplitude measurement device mainly includes a light source system, a laser power measurement system, a time domain resolution system, a dual optical path interference system and a mode field resolution system. The main body of the light source system adopts a 1080nm laser. The laser power measurement system is composed of a first splitting plate, a laser power meter or a light collecting tube, the time domain resolution system is composed of a second splitting plate, a fiber coupler, a fiber jumper, a two-dimensional linear displacement platform, a stepper motor, and a spectrometer, the dual optical path interference system is composed of a third splitting plate, a first beam splitting prism, a first reflector, a second reflector, a second beam splitting prism, and a first CMOS or CCD camera, and the mode field resolution system is composed of a third reflector, a polarization beam splitter, a phase-correlated spatial light modulator, a Fourier lens, and a second CMOS or CCD camera. The spatiotemporal complex amplitude measurement device is as shown in the attached figure. Figure 1 shown.
[0006] In order to better realize the present utility model, the following configuration structure is particularly adopted: the main body of the light source system (1) adopts a 1080nm laser.
[0007] In order to further better realize the utility model, the following configuration structure is particularly adopted: the laser power measurement system is composed of a first light splitting plate (2a), a laser power meter or a light collecting tube (2b).
[0008] In order to better realize the utility model, the following setting structure is particularly adopted: the specific optical route of the time domain resolution system is composed of a second splitting plate (3f), an optical fiber coupler (3a), a stepping motor (3b), a two-dimensional linear displacement platform (3c), an optical fiber jumper (3d), and a spectrometer (3e).
[0009] In order to further better realize the utility model, the following setting structure is particularly adopted: the dual-light path interference system is composed of a third splitting plate (4g), a first beam splitting prism (4a), a first reflecting mirror (4b), a second reflecting mirror (4e), a second beam splitting prism (4f), and a first CMOS or CCD camera (4c).
[0010] In order to better realize the utility model, the following configuration structure is particularly adopted: the mode field resolution system is composed of a third reflector (5f), a polarization beam splitter (5a), a phase-dependent spatial light modulator (5b), a Fourier lens (5c), and a second CMOS or CCD camera (5e).
[0011] In order to further better realize the utility model, the following setting structure is particularly adopted: when the light path is debugged and the light beam is transmitted to the first splitting plate (2a), more energy of the laser beam continues to be transmitted forward to the laser power meter or the light collecting tube (2b).
[0012] In order to better realize the utility model, the following setting structure is particularly adopted: the light beam passes through the second splitting plate (3f), so that part of the laser light is split to the optical fiber coupler (3a), and then coupled to the spectrometer (3e) through the optical fiber jumper (3d), and the optical fiber coupler (3a) is moved by a two-dimensional linear displacement platform (3c) driven by a stepping motor (3b) to obtain n*n groups of spectral data, where n is a positive integer.
[0013] In order to further better realize the utility model, the following setting structure is particularly adopted: the light beam is split into part of the laser beam to the first beam splitting prism (4a) through the third light splitting plate (4g); the first beam splitting prism (4a) splits the transmission light beam into an m light wave and an n light wave; the two light waves are respectively vertically incident on the second beam splitting prism (4f) through the first reflecting mirror (4b) and the second reflecting mirror (4e); the m light wave is incident from the L surface of the second beam splitting prism (4f); the n light wave is incident from the R surface of the second beam splitting prism (4f); the second beam splitting prism (4f) is rotated with the center of the second beam splitting prism (4f) as a fulcrum, so that the m reflected light on the S surface and the n transmitted light are combined and output. By adjusting the distance between the first CMOS or CCD camera (4c) and the second beam splitting prism (4f), the light fields of the m and n light waves are completely overlapped at the position where the first CMOS or CCD camera (4c) is located, thereby obtaining an interference pattern (4d), and obtaining an interference pattern (4d) in which a series of fringes move with time on the receiving surface of the first CMOS or CCD camera (4c).
[0014] In order to further better realize the utility model, the following setting structure is particularly adopted: the third reflector (5f) vertically reflects the transmission laser to the polarization beam splitter (5a), the linear polarized light continues to be transmitted to the phase-dependent spatial light modulator (5b), the phase of the transmission light field is superimposed by the phase-dependent spatial light modulator (5b), and after passing through the Fourier lens (5c), at the Fourier plane of the Fourier lens (5c), a second CMOS or CCD camera (5e) is used to collect a diffraction image (5d) on its detection surface, and the diffraction image (5d) includes two first-order diffraction maxima and a zero-order light spot.
[0015] In summary, the utility model has the following beneficial effects and advantages:
[0016] The utility model conducts a more comprehensive analysis of the mode components contained in the laser transmission light field from the time domain, spatial domain, frequency domain, and spectral domain, has the advantages of strong anti-interference ability, high stability, and no need for high-precision two-dimensional scanning equipment, and can realize the measurement of the mode components of the output light beam of the optical fiber laser from a narrow linewidth spectrum to a wide spectrum. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a schematic diagram of the overall structure of the utility model;
[0018] The numbers in the figure are:
[0019] 1—light source system; 1a—laser light source;
[0020] 2—laser power measurement system; 2a—first splitting plate; 2b—power meter;
[0021] 3—time domain resolution system; 3f—second splitting plate; 3a—fiber coupler; 3b—stepping motor; 3c—two-dimensional linear displacement platform; 3d—fiber jumper; 3e—spectrometer;
[0022] 4—dual-path interference system; 4g—third splitting plate; 4a—first beam splitter prism; 4b—first reflector; 4c—first CMOS or CCD camera; 4d—schematic diagram of dual-path interference pattern; 4e—second reflector; 4f—second beam splitter prism;
[0023] 5—mode field resolution system; 5f—third reflector; 5a—polarization beam splitter; 5b—phase-dependent spatial light modulator; 5c—Fourier lens; 5e—second CMOS or CCD camera; 5d—schematic diagram of diffraction image; DETAILED DESCRIPTION
[0024] In order to more clearly demonstrate the technical solutions and device advantages involved in the utility model, the technical details and specific implementation methods of the utility model are described in detail below:
[0025] The utility model provides a time-space complex amplitude measurement device based on mode decomposition. The time-space complex amplitude measurement device mainly includes a light source system, a laser power measurement system, a time domain resolution system, a dual-light path interference system and a mode field resolution system. The main body of the light source system adopts a 1080nm laser. The laser power measurement system is composed of a first splitting plate, a laser power meter or a light collecting tube, the time domain resolution system is composed of a second splitting plate fiber coupler, a fiber jumper, a two-dimensional linear displacement platform, a stepper motor, and a spectrometer, the dual-light path interference system is composed of a third splitting plate, a first beam splitter prism, a first reflector, a second reflector, a second beam splitter prism, and a first CMOS or CCD camera, and the mode field resolution system is composed of a third reflector, a polarization beam splitter, a phase-dependent spatial light modulator, a Fourier lens, and a second CMOS or CCD camera.
[0026] Embodiment 1:
[0027] Turn on the light source system (1); Step 1: Debug the optical path. When the light beam is transmitted to the first splitting plate (2a), more energy of the laser beam continues to be transmitted forward to the laser power meter or the light collecting tube (2b). Step 2: The light beam passes through the second splitting plate (3f) so that part of the laser is reflected to the optical fiber coupler (3a), and then coupled to the optical fiber jumper (3d) to the spectrometer (3e). The optical fiber coupler (3a) is moved by a two-dimensional linear displacement platform (3c) driven by a stepping motor (3b) to obtain n*n groups of spectral data. n is a positive integer. Step 3: The light beam passes through the third splitting plate (4g) so that part of the laser is reflected to the first beam splitting prism (4a). The first beam splitting prism (4a) splits the transmission light beam into m light waves and n light waves. The two light waves are respectively incident vertically on the second beam splitting prism (4f) through the first reflector (4b) and the second reflector (4e). The m light wave is incident from the L surface of the second beam splitting prism (4f), and the n light wave is incident from the R surface of the second beam splitting prism (4f). The second beam splitting prism (4f) is rotated with the center of the second beam splitting prism (4f) as a fulcrum, so that the m reflected light on the S surface and the n transmitted light are combined and output. By adjusting the distance between the first CMOS or CCD camera (4c) and the second beam splitter prism (4f), the light fields of the m and n light waves completely overlap at the position of the first CMOS or CCD camera (4c), and an interference pattern (4d) is obtained. A series of interference patterns with fringes moving over time are obtained on the receiving surface of the first CMOS or CCD camera (4c). Step 4: The third reflector (5f) vertically reflects the transmission laser to the polarization beam splitter (5a), and the linearly polarized light continues to be transmitted to the phase-dependent spatial light modulator (5b). The phase of the transmission light field is superimposed by the phase-dependent spatial light modulator (5b), and after passing through the Fourier lens (5c), the diffraction image (5d) is collected on the Fourier plane using the second CMOS or CCD camera (5e). The diffraction image (5d) includes two first-order diffraction maxima and a zero-order light spot.
[0028] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention.
Claims
1. A spatiotemporal complex amplitude measurement device based on mode decomposition, comprising a light source system, a laser power measurement system, a time domain resolution system, a dual optical path interference system, and a mode field resolution system, characterized in that: The light source system (1) is composed of a laser (1a); the laser power measurement system is composed of a first splitting plate (2a), a laser power meter or a light collecting tube (2b); the specific optical path of the time domain resolution system is composed of a second splitting plate (3f), an optical fiber coupler (3a), a stepping motor (3b), a two-dimensional linear displacement platform (3c), an optical fiber jumper (3d), and a spectrometer (3e); the dual-light path interference system is composed of a third splitting plate (4g), a first beam splitting prism (4a), a first reflector (4b), a second reflector (4e), a second beam splitting prism (4f), and a first CMOS or CCD camera (4c); and the mode field resolution system is composed of a third reflector (5f), a polarization beam splitter (5a), a phase-dependent spatial light modulator (5b), a Fourier lens (5c), and a second CMOS or CCD camera (5e).
2. The spatiotemporal complex amplitude measurement device according to claim 1, characterized in that: The light source system (1) adopts a 1080nm laser.
3. The spatiotemporal complex amplitude measurement device according to claim 1, characterized in that: The laser beam emitted by the light source system (1) first enters the laser power test system (2), and when it is vertically incident on the first splitting plate (2a), the laser beam with more energy continues to be transmitted forward to the laser power meter or the light receiving tube (2b).
4. The spatiotemporal complex amplitude measurement device according to claim 1, characterized in that: The time domain resolution system (3) is vertically incident on the second splitting plate (3f) so that part of the laser is reflected to the optical fiber coupler (3a), coupled to the optical fiber jumper (3d) and then to the spectrometer (3e). The optical fiber coupler (3a) is moved using a two-dimensional linear displacement platform (3c) driven by a stepping motor (3b) to obtain n*n groups of spectral data, where n is a positive integer.
5. The spatiotemporal complex amplitude measurement device according to claim 1, characterized in that: The dual-light path interference system (4) has a light beam passing through a third splitting plate (4g) so that part of the laser is reflected to a first beam splitting prism (4a). The first beam splitting prism (4a) splits the transmission light beam into an m light wave and an n light wave. The two light waves are respectively incident vertically on a second beam splitting prism (4f) through a first reflector (4b) and a second reflector (4e). The m light wave is incident from the L surface of the second beam splitting prism (4f), and the n light wave is incident from the R surface of the second beam splitting prism (4f). The second beam splitting prism (4f) is rotated with the center of the second beam splitting prism (4f) as a fulcrum, so that the m reflected light and the n transmitted light on the S surface are combined and output; by adjusting the distance between the first CMOS or CCD camera (4c) and the second beam splitting prism (4f), the light fields of the m and n light waves are completely overlapped at the position of the first CMOS or CCD camera (4c), thereby obtaining an interference pattern (4d), and a series of interference patterns (4d) with fringes moving over time are obtained on the receiving surface of the first CMOS or CCD camera (4c).
6. The spatiotemporal complex amplitude measurement device according to claim 1, characterized in that: The mode field resolution system (5) vertically reflects the transmission laser to the polarization beam splitter (5a) via a third reflector (5f), and the linearly polarized light is further transmitted to the phase-dependent spatial light modulator (5b). The phase of the transmission light field is superimposed by the phase-dependent spatial light modulator (5b), and after passing through a Fourier lens (5c), a second CMOS or CCD camera (5e) is used at the Fourier plane of the Fourier lens (5c) to collect a diffraction image (5d) on its detection surface, wherein the diffraction image (5d) includes two first-order diffraction maxima and one zero-order light spot.