Spatial light frequency characteristic detection device and detection method

Abstract

The invention provides a spatial light frequency characteristic detection device and detection method, and relates to the technical field of self-heterodyne detection. In the device, a narrow linewidth laser module continuously emits spatial light to a spatial beam splitting module, the spatial light is split into signal light and local oscillation light through a first beam splitting prism, the signal light is reflected to a spatial time delay module through a first reflector for time delay, and the local oscillation light enters a spatial frequency shift module for frequency shift; the delayed signal light is reflected to a second beam splitter prism through a second reflector, and the second beam splitter prism transmits the reflected signal light to a spatial light balance detection module in a preset transmission direction; the frequency-shifted local oscillator light enters a third reflector through a second beam splitter prism for reflection, and the third reflector transmits the reflected local oscillator light parallel to the transmission direction to a spatial light balance detection module; the spatial light balance detection module interferes the received signal light and the received local oscillator light, converts the signal light and the local oscillator light into electric signals, and detects the frequency characteristics of the spatial light based on the electric signals.

Description

Technical Field

[0001] This application relates to the field of self-heterodyne detection technology, and more specifically, to a spatial optical frequency characteristic detection device and detection method. Background Technology

[0002] Self-heterodyne detection technology is indispensable in scenarios such as optical signal frequency measurement, phase detection, and weak signal extraction due to its advantages such as high sensitivity and wide dynamic range.

[0003] Currently, in self-heterodyne systems, the realization of non-zero delay mainly relies on fiber delay lines, which form optical path differences through fibers of different lengths. However, optical fibers have inherent defects such as dispersion, transmission loss, poor flexibility, and strong environmental sensitivity. Although some improvement schemes attempt to introduce spatial light delay, they still retain fiber components such as fiber couplers, resulting in a "spatial light-fiber-spatial light" conversion link in the optical path. This not only introduces coupling loss (usually 3dB~5dB) but may also affect the stability of the signal due to coupling alignment errors, thus failing to fully utilize the advantages of spatial light, such as no dispersion and low loss.

[0004] However, zero-delay self-heterodyne cannot meet the needs of scenarios that rely on non-zero-delay beat frequency signals, such as frequency calculation and phase difference measurement. The hybrid system of half-space optical and half-fiber is still constrained by fiber-related issues. Summary of the Invention

[0005] In view of the above problems, this application provides a spatial optical frequency characteristic detection device and detection method.

[0006] This application provides a spatial light frequency characteristic detection device, comprising: a narrow-linewidth laser module, a spatial beam splitting module, a spatial delay module, a spatial frequency shifting module, a spatial beam combining module, and a spatial light balanced detection module. The spatial beam splitting module includes a first beam splitting prism and a first reflecting mirror, and the spatial beam combining module includes a second reflecting mirror, a third reflecting mirror, and a second beam splitting prism. The narrow-linewidth laser module continuously emits spatial light into the spatial beam splitting module. The spatial light is split into signal light and local oscillator light by the first beam splitting prism. The signal light is reflected by the first reflecting mirror to the spatial delay module for delay. The local oscillator light is incident on the spatial frequency shifting module for frequency shifting; the delayed signal light is reflected by the second reflector to the second beam splitter prism, which transmits the reflected signal light to the spatial light balance detection module in a preset transmission direction; the frequency-shifted local oscillator light is incident on the third reflector through the second beam splitter prism for reflection, and the third reflector transmits the reflected local oscillator light parallel to the transmission direction to the spatial light balance detection module; the spatial light balance detection module converts the received signal light and the received local oscillator light into an electrical signal after interference, and detects the frequency characteristics of the spatial light based on the electrical signal.

[0007] According to embodiments of this application, the linewidth of the spatial light is ≤1kHz, the output wavelength of the spatial light includes 850nm, 1310nm or 1550nm, and the beam divergence angle of the spatial light is ≤1mrad.

[0008] According to an embodiment of this application, the spatial beam splitting module further includes a first waveplate and a second waveplate. The first waveplate is a quarter-waveplate, and the second waveplate is a half-waveplate. The angle between the optical axis of the first waveplate and the polarization direction of the spatial light is 45°. The first waveplate is used to adjust the polarization type of the spatial light from circularly polarized light to linearly polarized light, and the second waveplate is used to adjust the polarization direction of the spatial light.

[0009] According to an embodiment of this application, the spatial delay module includes a reflector and a driving unit. The driving unit is used to drive the reflector to perform linear displacement. The driving unit includes an electric translation stage, a piezoelectric ceramic driver, or a voice coil motor. The positioning accuracy of the driving unit is ≥ ±0.01. The delay adjustment range of the spatial delay module is 1ns~1ms, and the delay accuracy of the spatial delay module is ≤±0.05ns.

[0010] According to an embodiment of this application, the transmission direction of the delayed signal light is parallel to the transmission direction of the frequency-shifted local oscillator light.

[0011] According to embodiments of this application, the spatial frequency shifting module includes an acousto-optic frequency shifter or an electro-optic frequency shifter, and the frequency shift value range of the spatial frequency shifting module is 10MHz~1GHz.

[0012] According to an embodiment of this application, the spatial beam combining module further includes a third waveplate, which is a half-waveplate, and is used to adjust the polarization direction of the frequency-shifted local oscillator light to be parallel to the transmission direction.

[0013] According to an embodiment of this application, the spatial light balance detection module includes a collimating lens group with a focal length of 20mm to 100mm.

[0014] According to an embodiment of this application, the photosensitive surface of the spatial light balance detection module is perpendicular to the transmission direction.

[0015] This application, in another aspect, provides a method for detecting the frequency characteristics of spatial light, comprising: transmitting spatial light continuously emitted by a narrow-linewidth laser module to a spatial beam-splitting module, the spatial beam-splitting module including a first beam-splitting prism and a first reflecting mirror; splitting the spatial light using the first beam-splitting prism to obtain a signal light and a local oscillator light; reflecting the signal light using the first reflecting mirror to a spatial delay module, and delaying the reflected signal light using the spatial delay module before transmitting it to a spatial beam-combining module, the spatial beam-combining module including a second reflecting mirror, a third reflecting mirror, and a second beam-splitting prism; and using a spatial frequency-shifting module to... After frequency shifting, the signal light is transmitted to the spatial beam combining module. The delayed signal light is reflected by the second reflector to the second beam splitter prism, and the reflected signal light is transmitted to the spatial light balance detection module in a preset transmission direction by the second beam splitter prism. The frequency-shifted local oscillator light is incident on the third reflector for reflection by the second beam splitter prism, and the third reflector transmits the frequency-shifted local oscillator light parallel to the transmission direction to the spatial light balance detection module. The spatial light balance detection module converts the received signal light and the received local oscillator light into an electrical signal after interference, and detects the frequency characteristics of the spatial light based on the electrical signal.

[0016] The spatial light frequency characteristic detection device and method provided in this application can achieve the following beneficial effects:

[0017] (1) There is no fiber optic transmission and coupling link throughout the process, which can avoid problems such as fiber dispersion, transmission loss and environmental sensitivity, and improve signal fidelity by ≥40%; there is no “spatial light to fiber optic” conversion loss (reducing 3dB~5dB inherent loss), and the system light utilization rate is improved by ≥30%, which significantly improves detection sensitivity, especially suitable for wide spectrum, high frequency signal and long delay detection scenarios.

[0018] (2) Delay adjustment for spatial light is achieved by changing the optical path of spatial light through mechanical structure. The adjustment range is wide (delay τ can be from 1ns to 1ms). The driving unit can achieve micron-level optical path control and delay accuracy ≤ ±0.05ns. It has strong anti-environment interference capability. The spatial light path is affected by temperature and vibration by more than 50% compared with the optical fiber system, which improves the delay stability.

[0019] (3) The delay can be dynamically adjusted by controlling the movable reflector through the program, the optical path alignment is convenient, and there is no need for fiber fusion or coupling calibration; the device has a high degree of integration, no need to wrap long optical fibers, the size is more compact, and the deployment cost is reduced by 20%-30%. Attached Figure Description

[0020] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1This schematic diagram illustrates the structure of a spatial light frequency characteristic detection device according to an embodiment of this application;

[0022] Figure 2 A schematic diagram of a spatial delay module according to an embodiment of this application is shown.

[0023] Figure 3 A flowchart illustrating a spatial light frequency characteristic detection method according to an embodiment of this application is shown.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1- Narrow linewidth laser module; 2- Spatial beam splitting module, 21- First waveplate, 22- Second waveplate, 23- First beam splitting prism, 24- First reflector; 3- Spatial delay module; 31- Fourth reflector; 32- Fifth reflector; 33- Driving unit; 34- Sixth reflector; 35- Seventh reflector; 4- Spatial frequency shifting module; 5- Spatial beam combining module, 51- Third waveplate, 52- Second reflector, 53- Third reflector, 54- Second beam splitting prism; 6- Spatial optical balance detection module. Detailed Implementation

[0026] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] Figure 1 The diagram illustrates the structure of a spatial light frequency characteristic detection device according to an embodiment of this application.

[0030] like Figure 1As shown, the spatial light frequency characteristic detection device of this embodiment includes: a narrow linewidth laser module 1, a spatial beam splitting module 2, a spatial delay module 3, a spatial frequency shifting module 4, a spatial beam combining module 5, and a spatial light balance detection module 6. The spatial beam splitting module 2 includes a first beam splitting prism 23 and a first reflecting mirror 24. The spatial beam combining module 5 includes a second reflecting mirror 52, a third reflecting mirror 53, and a second beam splitting prism 54.

[0031] In this process, the narrow linewidth laser module 1 continuously emits spatial light into the spatial beam splitting module 2. The spatial light is split into signal light and local oscillator light by the first beam splitting prism 23. The signal light is reflected by the first reflector 24 to the spatial delay module 3 for delay, and the local oscillator light is injected into the spatial frequency shifting module 4 for frequency shifting.

[0032] The delayed signal light is reflected by the second reflector 52 to the second beam splitter 54, and the second beam splitter 54 transmits the reflected signal light to the spatial light balance detection module 6 in a preset transmission direction.

[0033] The frequency-shifted local oscillator light is incident on the third reflector 53 through the second beam splitter prism 54 and reflected. The third reflector 53 transmits the reflected local oscillator light parallel to the transmission direction to the spatial light balance detection module 6.

[0034] The spatial light balance detection module 6 converts the received signal light and the received local oscillator light into an electrical signal after interference, and detects the frequency characteristics of the spatial light based on the electrical signal.

[0035] For example, the beam splitting ratio of the spatial beam splitting module can be adjusted from 0 to 100%, and the beam splitting efficiency of the spatial beam splitting module can be adjusted from 0 to 100%.

[0036] For example, the frequency characteristics of spatial light can include the frequency offset, phase difference, or amplitude information of spatial light.

[0037] The spatial light frequency characteristic detection device based on the embodiments of this application can effectively avoid problems such as fiber dispersion, transmission loss and environmental sensitivity by transmitting and coupling without optical fibers throughout the entire process, greatly reducing signal distortion, ensuring good interference between signal light and local oscillator light, and improving the accuracy of obtaining the frequency characteristics of spatial light.

[0038] In the embodiments of this application, the linewidth of the spatial light is ≤1kHz, the output wavelength of the spatial light includes 850nm, 1310nm or 1550nm, and the beam divergence angle of the spatial light is ≤1mrad.

[0039] For example, the beam divergence angle can be the angular range of the cross-section of a spatial light beam expanding during its propagation. The beam divergence angle of spatial light can be calculated using the following formula.

[0040]

[0041] In the formula, The wavelength of light in space. Let be the waist radius of the spatial light at the source. The divergence angle of the spatial light beam.

[0042] The spatial light frequency characteristic detection device based on the embodiments of this application can be adapted to a variety of optical application scenarios by outputting spatial light of different wavelengths. The beam divergence angle ≤1mrad can ensure beam quality, reduce energy loss, and improve signal fidelity and detection accuracy.

[0043] In the embodiments of this application, the spatial beam splitting module 2 further includes a first waveplate 21 and a second waveplate 22. The first waveplate 21 is a quarter-wave plate, and the second waveplate 22 is a half-wave plate. The angle between the optical axis of the first waveplate 21 and the polarization direction of the spatial light is 45°. The first waveplate 21 is used to adjust the polarization type of the spatial light from linearly polarized light to circularly polarized light, and the second waveplate 22 is used to adjust the polarization direction of the spatial light to be parallel to the transmission direction.

[0044] Based on the birefringence phenomenon, when spatial light is incident on a waveplate, it will be decomposed into ordinary light and extraordinary light. The ordinary light and extraordinary light have different propagation speeds in the waveplate, which will produce a phase difference. This phase difference depends on factors such as the thickness of the waveplate, the birefringence, and the wavelength of the spatial light.

[0045] A quarter-wave plate can create a 90° phase difference between ordinary and extraordinary light. By adjusting the angle between the wave plate and the polarization of the incident light, circular / elliptical polarized light can be converted into linearly polarized light.

[0046] A half-wave plate can create a 180° phase difference between ordinary and extraordinary light. When linearly polarized light is incident perpendicularly on the half-wave plate, and its polarization direction makes an angle of θ with the optical axis of the half-wave plate, the phase difference is... When this happens, the polarization direction of the emitted spatial light will rotate relative to the polarization direction of the incident spatial light. .

[0047] After the first waveplate 21 adjusts the spatial light into linearly polarized light, the linearly polarized light then passes through the second waveplate 22. Since linearly polarized light can be considered as the synthesis of two linearly polarized light components with equal amplitude and a 90° phase difference, after passing through the half-waveplate, both linearly polarized light components will experience a 90° phase change, but the relative phase difference between the two linearly polarized light components will remain at 180°. By setting the optical axis direction of the half-waveplate, the circularly polarized light is converted back into linearly polarized light, and its polarization direction is adjusted. In this embodiment, the second waveplate 22 adjusts the polarization direction of the spatial light to a 45° angle for transmission.

[0048] The spatial light frequency characteristic detection device based on the embodiments of this application can ensure that the light beam can interact more effectively with various optical components such as the spatial beam splitting module, spatial delay module, and spatial beam combining module when passing through them, by adjusting the polarization direction to be parallel to the transmission direction. This reduces energy loss and signal interference caused by polarization direction mismatch, and improves optical efficiency and detection accuracy.

[0049] In the embodiments of this application, the spatial delay module 3 includes a reflector and a driving unit 33. The driving unit 33 is used to drive the reflector to perform linear displacement. The driving unit 33 includes an electric translation stage, a piezoelectric ceramic driver, or a voice coil motor. The positioning accuracy of the driving unit 33 is ≥ ±0.01. The delay adjustment range of the spatial delay module 3 is 1ns~1ms, and the delay accuracy of the spatial delay module 3 is ≤±0.05ns.

[0050] The following is combined with Figure 2 The structure of the spatial delay module in this embodiment will be described in detail.

[0051] Figure 2 A schematic diagram of a spatial delay module according to an embodiment of this application is shown.

[0052] like Figure 2 As shown, the drive unit 33 is mounted on the fifth reflector 32, the fourth reflector 31 is perpendicular to the incident direction of the signal light, and the sixth reflector 34 and the seventh reflector 35 are parallel to each other. When the drive unit 33 is activated, the fifth reflector 32 is reset to its mechanical zero position or optical reference position. The signal light travels to the fifth reflector 32 in a preset transmission direction, is reflected by the fifth reflector 32 to the fourth reflector 31, undergoes multiple reciprocating reflections between the fifth reflector 32 and the fourth reflector 31, and finally reflects from the fourth reflector 31 to the sixth reflector 34, and then from the sixth reflector 34 to the seventh reflector 35 before exiting parallel to the transmission direction.

[0053] According to the control command, the drive unit 33 can drive the fifth reflector 32 to make linear displacement (such as moving in a direction perpendicular or parallel to the optical path). The displacement of the fifth reflector 32 will directly change the path length of the light from the fifth reflector 32 to the reflection to the subsequent optical path. Finally, by precisely controlling the displacement of the fifth reflector 32, the delay of the signal light can be adjusted.

[0054] The spatial light frequency characteristic detection device based on the embodiments of this application compresses physical space through a multi-reflection optical path design, while utilizing a drive unit for displacement control, thus balancing adjustment flexibility and accuracy. Furthermore, the reset reference design ensures consistency across multiple adjustments, adapting to the signal timing control requirements of high-precision optical systems.

[0055] In the embodiments of this application, the transmission direction of the delayed signal light is parallel to the transmission direction of the frequency-shifted local oscillator light.

[0056] The spatial light frequency characteristic detection device based on the embodiments of this application uses parallel transmission to ensure that the delayed signal light and the frequency-shifted local oscillator light are collinearly overlapped in the subsequent spatial beam combining module, maximizing the effective area of ​​light field superposition and avoiding signal loss caused by angular offset. This ensures the spatial synchronization of the two light paths and improves the accuracy of coherent processing.

[0057] In the embodiments of this application, the spatial frequency shifting module 4 includes an acousto-optic frequency shifter or an electro-optic frequency shifter, and the frequency shift value of the spatial frequency shifting module 4 is in the range of 10MHz to 1GHz.

[0058] In the embodiments of this application, the spatial beam combining module 5 further includes a third waveplate 51, which is a half-waveplate. The third waveplate 51 is used to adjust the polarization direction of the frequency-shifted local oscillator light to be parallel to the transmission direction.

[0059] The spatial light frequency characteristic detection device based on the embodiments of this application can precisely control the polarization direction of the frequency-shifted local oscillator light by integrating a half-wave plate, ensuring that the polarization state of the frequency-shifted local oscillator light and the delayed signal light are matched when they are combined, thereby reducing signal noise caused by polarization crosstalk.

[0060] In the embodiments of this application, the spatial light balance detection module 6 includes a collimating lens group with a focal length of 20mm to 100mm.

[0061] In the embodiments of this application, the photosensitive surface of the spatial light balance detection module 6 is perpendicular to the transmission direction.

[0062] The spatial light frequency characteristic detection device based on the embodiments of this application, by aligning the photosensitive surface perpendicular to the transmission direction, allows the received signal light and the received local oscillator light to be incident perpendicularly onto the photosensitive surface. This ensures the light spot coverage area matches the effective detection area of ​​the photosensitive surface, avoiding energy reflection loss caused by oblique incident light and improving the utilization rate of the optical signal. It also enhances the signal contrast and phase matching degree of balanced detection, guaranteeing the accuracy of the detection results.

[0063] Based on the aforementioned spatial light frequency characteristic detection device, this application also provides a spatial light frequency characteristic detection method, which is described below in conjunction with... Figure 3 This method will be described in detail.

[0064] Figure 3 A flowchart illustrating a spatial light frequency characteristic detection method according to an embodiment of this application is shown.

[0065] like Figure 3As shown, the spatial light frequency characteristic detection method of this embodiment includes steps S310 to S370.

[0066] In step S310, the spatial light continuously emitted by the narrow linewidth laser module 1 is transmitted to the spatial beam splitting module 2, which includes a first beam splitting prism 23 and a first reflector 24.

[0067] In step S320, the spatial light is split using the first beam splitter prism 23 to obtain signal light and local oscillator light.

[0068] In step S330, the signal light is reflected to the spatial delay module 3 using the first reflector 24, and the reflected signal light is delayed by the spatial delay module 3 before being transmitted to the spatial beam combining module 5. The spatial beam combining module 5 includes a second reflector 52, a third reflector 53, and a second beam splitter prism 54.

[0069] In step S340, the local oscillator light is frequency-shifted by the spatial frequency shifting module 4 and then transmitted to the spatial beam combining module 5.

[0070] In step S350, the delayed signal light is reflected by the second reflector 52 to the second beam splitter 54, and the reflected signal light is transmitted to the spatial light balance detection module 6 in a preset transmission direction by the second beam splitter 54.

[0071] In step S360, the frequency-shifted local oscillator light is incident on the third reflector 53 by the second beam splitter prism 54 for reflection, and the third reflector 53 transmits the frequency-shifted local oscillator light parallel to the transmission direction to the spatial light balance detection module 6.

[0072] In step S370, the received signal light and the received local oscillator light are interfered by the spatial light balance detection module 6 and converted into an electrical signal. Based on the electrical signal, the frequency characteristics of the spatial light are detected.

[0073] The spatial optical frequency characteristic detection method of this application will be described in detail below based on specific embodiments.

[0074] Example 1

[0075] The narrow-linewidth laser module uses a semiconductor laser with a linewidth of 500Hz, outputting spatial light with a wavelength of 1550nm, a power of 10mW, and a beam divergence angle of 0.8mrad. The spatial beam splitting module uses a half-wave plate, a quarter-wave plate, a reflecting mirror 'a', and a polarizing beam splitting prism. The spatial delay module uses three fixed high-reflectivity mirrors with a reflectivity of 99.9%, one movable high-reflectivity mirror with a reflectivity of 99.9%, and a travel distance of 500mm and a positioning accuracy of [missing information]. The electric translation stage; the spatial beam combining module uses a 1 / 2 wave plate, a reflector b, and a beam splitter prism; the spatial light balanced detection module uses a spatial light input balanced photodetector with a bandwidth of 1GHz, a low-noise amplifier (gain 0dB~60dB), and a spectrum analyzer.

[0076] The semiconductor laser outputs spatial light with a wavelength of 1550nm. The spatial light is incident on the spatial beam splitting module and split into two spatial beams (i.e., signal light and local oscillator light). The intensity ratio of the two spatial beams is adjusted, and the power of each beam is 5mW.

[0077] After the signal light is reflected by mirror a, the reflected signal light continues to propagate horizontally after being delayed by the spatial delay module.

[0078] For example, an electric translation stage can be used to change the spatial propagation path length of the delayed signal light. When the electric translation stage moves a distance of d, the optical path of the delayed signal light increases by 2d (round trip spatial path). The delay can be calculated using the following formula.

[0079]

[0080] In the formula, At the speed of light, d is the signal light delay time, and d is the moving distance of the electric translation stage.

[0081] The local oscillator light continues to propagate horizontally after being frequency-shifted by the spatial frequency-shifting module. At the same time, the electric translation stage drives the movable high-reflectivity mirror to move vertically along the optical path.

[0082] Adjust the electric translation stage to move a distance d = 75mm, so that the optical path difference ΔL between the frequency-shifted local oscillator light and the delayed signal light is 150mm, and the delay... .

[0083] Two parallel spatial beams (i.e., the frequency-shifted local oscillator beam and the delayed signal beam) are incident on the spatial beam combining module and directly superimposed to form a beat frequency light signal, which is then incident perpendicularly on the photosensitive surface of the spatial light input type balanced photodetector.

[0084] The spatial light input type balanced photodetector converts spatial light signals into electrical signals. After the electrical signals are amplified and filtered by a low-noise amplifier, the beat frequency is obtained by a spectrum analyzer. The target parameters (i.e., frequency characteristics) of the spatial light are calculated based on the beat frequency.

[0085] Example 2

[0086] In scenarios requiring sub-ns precision delay adjustment, the motorized translation stage in the spatial delay module can be replaced with a piezoelectric ceramic actuator (stroke). Positioning accuracy It can achieve precise control of the minimum delay step size of 0.067ns, and is suitable for scenarios with extremely high delay accuracy requirements, such as phase noise detection and ultra-high frequency signal phase difference measurement; the selection of other components is the same as in Example 1, and pure spatial light propagation is maintained throughout the process.

[0087] In summary, the embodiments of this application provide a spatial light frequency characteristic detection method. Through the coordinated operation of a narrow-linewidth laser module, a spatial beam splitting module, a spatial delay module, a spatial frequency shifting module, a spatial beam combining module, and a spatial light balanced detection module, there are no optical fiber transmission and coupling links throughout the process. This avoids problems such as optical fiber dispersion, transmission loss, and environmental sensitivity, and improves signal fidelity by ≥40%. There is no "spatial light to optical fiber" conversion loss (reducing 3dB~5dB of inherent loss), and the system light utilization rate is improved by ≥30%, significantly improving detection sensitivity. It is especially suitable for wide-spectrum, high-frequency signal, and long-delay detection scenarios.

[0088] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined or combined in various ways without departing from the spirit and teachings of this application. All such combinations or combinations fall within the scope of this application.

[0089] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A spatial optical frequency characteristic detection device, characterized in that, include: The system includes a narrow linewidth laser module (1), a spatial beam splitter module (2), a spatial delay module (3), a spatial frequency shifter module (4), a spatial beam combiner module (5), and a spatial light balance detector module (6). The spatial beam splitter module (2) includes a first beam splitter prism (23) and a first reflector (24). The spatial beam combiner module (5) includes a second reflector (52), a third reflector (53), and a second beam splitter prism (54). The narrow linewidth laser module (1) continuously emits spatial light into the spatial beam splitting module (2). The spatial light is split into signal light and local oscillator light by the first beam splitting prism (23). The signal light is reflected by the first reflector (24) to the spatial delay module (3) for delay. The local oscillator light is injected into the spatial frequency shifting module (4) for frequency shifting. The delayed signal light is reflected by the second reflector (52) to the second beam splitter (54), and the second beam splitter (54) transmits the reflected signal light to the spatial light balance detection module (6) in a preset transmission direction. The frequency-shifted local oscillator light is incident on the third reflector (53) through the second beam splitter prism (54) and reflected. The third reflector (53) transmits the reflected local oscillator light parallel to the transmission direction to the spatial light balance detection module (6). The spatial light balance detection module (6) converts the received signal light and the received local oscillator light into an electrical signal after interference, and detects the frequency characteristics of the spatial light based on the electrical signal.

2. The apparatus according to claim 1, characterized in that, The linewidth of the spatial light is ≤1kHz, the output wavelength of the spatial light includes 850nm, 1310nm or 1550nm, and the beam divergence angle of the spatial light is ≤1mrad.

3. The apparatus according to claim 1, characterized in that, The spatial beam splitting module (2) further includes a first waveplate (21) and a second waveplate (22). The first waveplate (21) is a quarter-wave plate, and the second waveplate (22) is a half-wave plate. The angle between the optical axis of the first waveplate (21) and the polarization direction of the spatial light is 45°. The first waveplate (21) is used to adjust the polarization type of the spatial light from circularly polarized light to linearly polarized light, and the second waveplate (22) is used to adjust the polarization direction of the spatial light.

4. The apparatus according to claim 1, characterized in that, The spatial delay module (3) includes a reflector and a drive unit (33). The drive unit (33) is used to drive the reflector to perform linear displacement. The drive unit (33) includes an electric translation stage, a piezoelectric ceramic driver, or a voice coil motor. The positioning accuracy of the drive unit (33) is ≥ ±0.

01. The delay adjustment range of the spatial delay module (3) is 1ns~1ms, and the delay accuracy of the spatial delay module (3) is ≤±0.05ns.

5. The apparatus according to claim 1, characterized in that, The transmission direction of the delayed signal light is parallel to the transmission direction of the frequency-shifted local oscillator light.

6. The apparatus according to claim 1, characterized in that, The spatial frequency shift module (4) includes an acoustic-optical frequency shifter or an electro-optical frequency shifter, and the frequency shift value range of the spatial frequency shift module (4) is 10MHz~1GHz.

7. The apparatus according to claim 1, characterized in that, The spatial beam combining module (5) also includes a third waveplate (51), which is a half-waveplate and is used to adjust the polarization direction of the local oscillator light after frequency shifting.

8. The apparatus according to claim 1, characterized in that, The spatial light balance detection module (6) includes a collimating lens group with a focal length of 20mm to 100mm.

9. The apparatus according to claim 1, characterized in that, The photosensitive surface of the spatial light balance detection module (6) is perpendicular to the transmission direction.

10. A method for detecting spatial optical frequency characteristics, characterized in that, include: The spatial light continuously emitted by the narrow linewidth laser module (1) is transmitted to the spatial beam splitting module (2), which includes a first beam splitting prism (23) and a first reflecting mirror (24). The spatial light is split using the first beam splitter prism (23) to obtain signal light and local oscillator light; The signal light is reflected to the spatial delay module (3) using the first reflector (24), and the reflected signal light is delayed by the spatial delay module (3) and then transmitted to the spatial beam combining module (5). The spatial beam combining module (5) includes a second reflector (52), a third reflector (53) and a second beam splitter (54). The local oscillator light is frequency shifted by the spatial frequency shifting module (4) and then transmitted to the spatial beam combining module (5). The delayed signal light is reflected by the second reflector (52) to the second beam splitter (54), and the reflected signal light is transmitted to the spatial light balance detection module (6) in a preset transmission direction by the second beam splitter (54). The frequency-shifted local oscillator light is incident on the third reflector (53) by the second beam splitter (54) for reflection, and the third reflector (53) transmits the frequency-shifted local oscillator light parallel to the transmission direction to the spatial light balance detection module (6). The spatial light balance detection module (6) is used to convert the received signal light and the received local oscillator light into an electrical signal after interference, and the frequency characteristics of the spatial light are detected based on the electrical signal.

Images