Wavelength division and time division multiplexing single-photon laser radar

Abstract

The invention discloses a wavelength division and time division multiplexing single-photon laser radar, which relates to the technical field of single-photon laser radars and comprises a narrow-linewidth multi-wavelength laser, an optical fiber beam splitter, a laser beam expander, a dense wavelength division multiplexing device, a single-photon detector and a time correlation single-photon counter. The narrow-linewidth multi-wavelength laser outputs multi-wavelength light beams, stable and fixed time delay exists between laser pulses of different wavelengths, the laser pulses pass through the optical fiber beam splitter and then are emitted by the laser beam expander, and meanwhile the narrow-linewidth multi-wavelength laser outputs synchronous signals to the time-dependent single-photon counting instrument. Echo signal photons reflected by a target are received by the laser beam expander, input into the dense wavelength division multiplexing device through the optical fiber beam splitter for wavelength separation, combined through the optical fiber beam splitter and finally received by the single-photon detector, and the signals are input into the time-dependent single-photon counter. According to the invention, the detection capability of the laser radar is improved by combining wavelength division multiplexing and time division multiplexing technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of single-photon laser radar, and in particular to a wavelength division and time division multiplexing single-photon laser radar. Background Art

[0002] As an active detection technology with high detection sensitivity and high temporal resolution, single-photon laser radar is widely used in remote sensing, long-distance active three-dimensional imaging, autonomous driving and many other fields. Single-photon laser radar has a detection sensitivity as low as a single photon, but it is easily affected by background noise. At the same time, the system is relatively complex and expensive. In order to improve the detection capability of single-photon laser radar, optimize the system structure, reduce the system cost, and improve the overall detection level of single-photon laser radar, it has gradually become a research focus. The current mainstream single-photon laser radar mainly uses a single wavelength emission combined with spectral filtering for detection. The detection method is relatively simple, the filtering method is insufficient, and the system is complex, which is not conducive to miniaturization application and affects the working performance of the single-photon laser radar system. Summary of the invention

[0003] In order to solve the above technical problems and improve the detection capability of single-photon laser radar, the present invention provides a wavelength division and time division multiplexing single-photon laser radar, which optimizes the system structure of single-photon laser radar by combining wavelength division multiplexing and time division multiplexing technology without using any filtering means, reduces system cost, and improves detection performance. The present invention has the characteristics of clear principle, convenient operation, simple structure, etc., and can effectively improve the detection capability of single-photon laser radar, reduce the system cost of single-photon laser radar, and optimize the system structure.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A wavelength division and time division multiplexing single-photon laser radar comprises a narrow-linewidth multi-wavelength laser, an optical fiber beam splitter, a laser beam expander, a dense wavelength division multiplexing device, a single-photon detector, and a time-correlated single-photon counter; the narrow-linewidth multi-wavelength laser outputs a multi-wavelength light beam which is emitted via the laser beam expander, and the narrow-linewidth multi-wavelength laser outputs a synchronization signal to the time-correlated single-photon counter; the echo signal photons reflected by the target are received via the laser beam expander, passed through the optical fiber beam splitter, and then wavelength-separated by the dense wavelength division multiplexing device, and finally received by the single-photon detector, and the multi-wavelength signal with a fixed time delay is input into the time-correlated single-photon counter.

[0006] Furthermore, a narrow-linewidth multi-wavelength laser with multiple emission wavelengths is used as a light source, the total linewidth of the multiple wavelength lasers is less than 2.5nm, while the linewidth of a single wavelength is less than 50pm, and the center wavelength interval is less than 1.5nm.

[0007] Furthermore, each wavelength output by the narrow-linewidth multi-wavelength laser has a fixed and stable time interval.

[0008] Furthermore, the dense wavelength division multiplexing device has a wavelength separation characteristic and can separate echo lights with a wavelength interval less than 1.5 nm.

[0009] Furthermore, multiple different central wavelengths can be detected simultaneously.

[0010] Furthermore, the dense wavelength division multiplexing device simultaneously outputs to the single photon detector.

[0011] Furthermore, a single single-photon detector receives a multi-wavelength echo light beam output by a dense wavelength division multiplexing device.

[0012] Furthermore, the dense wavelength division multiplexing device can emit echo lights of different central wavelengths through different channels.

[0013] Furthermore, the single-photon laser radar system can simultaneously perform wavelength separation on echo lights of different central wavelengths to ensure the signal light intensity.

[0014] Furthermore, the dense wavelength division multiplexing device outputs echo light beams with extremely narrow center wavelength intervals according to channels, thereby isolating background light while ensuring the signal strength of each channel.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] (1) The multi-wavelength narrow linewidth pulse laser of the present invention has a spectral filtering bandwidth of the picometer level and can simultaneously output multiple narrow linewidth pulse lights with wavelengths as low as the picometer level.

[0017] (2) The multi-wavelength narrow linewidth laser output by the multi-wavelength narrow linewidth pulse laser of the present invention has a stable and fixed time interval in time distribution.

[0018] (3) The dense wavelength division multiplexing device of the present invention can perform wavelength separation within a narrow spectral range, effectively separate echo signal lights of different wavelengths, and isolate background noise light.

[0019] (4) The single single-photon detector receiving method of the present invention can detect echo signals of multiple wavelengths with only one single-photon detector, which can effectively reduce the system cost.

[0020] (5) The present invention has a clear principle, simple structure, and convenient operation. It greatly optimizes the structure of the single-photon laser radar system and reduces the system cost. By simultaneously utilizing wavelength division and time division multiplexing technology, the system detection capability is comprehensively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1A schematic diagram of a wavelength division and time division multiplexing single photon laser radar according to an embodiment of the present invention;

[0022] Figure 2 This is a measured diagram of the laser output spectrum of a wavelength division and time division multiplexing single-photon laser radar according to an embodiment of the present invention;

[0023] Figure 3 This is a measured diagram of the laser output pulse timing of a wavelength division and time division multiplexing single-photon laser radar according to an embodiment of the present invention.

[0024] Among them, the figure markings are: 1 is a narrow-linewidth multi-wavelength pulse laser, 2 is a fiber optic beam splitter, 3 is a laser beam expander, 4 is a dense wavelength division multiplexing device, 5 is a single photon detector, and 6 is a time-correlated single photon counter. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application. All other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of this application.

[0026] like Figure 1 As shown, a wavelength division and time division multiplexing single-photon laser radar according to an embodiment of the present invention includes.

[0027] The narrow linewidth multi-wavelength pulse laser 1 emits a multi-wavelength, fixed-delay pulse laser, and simultaneously outputs a synchronization signal to the time-correlated single photon counter 6 as a local synchronization signal, which is output by the laser beam expander 3, reflected by the target to be measured, and then received by the same laser beam expander 3. After passing through the optical fiber beam splitter 2, it is wavelength-separated by the dense wavelength division multiplexing device 4. The remaining background noise photons will not pass through the dense wavelength division multiplexing device 4. Subsequently, the separated wavelengths are combined by another optical fiber beam splitter 2 and then received simultaneously by a single single photon detector 5, and a multi-wavelength signal detection signal with a fixed time delay is output to the time-correlated single photon counter 6. The time-correlated single photon counter 6 accumulates the echo signals to obtain photon counts, preferably represented by a histogram, and the target distance depth information is obtained through the histogram.

[0028] After wavelength separation by the dense wavelength division multiplexing device 4, the noise level is low, and there is a fixed time interval between different wavelengths. Multi-wavelength multiplexing and time multiplexing are combined with time-correlated single photon counting technology to perform cross-correlation operations on multi-wavelength signals to enhance signal strength, thereby achieving the effect of improving the detection capability of the laser radar.

[0029] Without relying on external filtering methods, signal strength is guaranteed through multi-wavelength multiplexing and time multiplexing with fixed time delay. At the same time, the background noise intensity and the probability of false alarm detection can be effectively reduced, the system structure can be effectively simplified, the system cost can be reduced, and the overall detection level of single-photon lidar can be improved.

[0030] Furthermore, the narrow-linewidth multi-wavelength pulse laser 1 can emit a plurality of pulse light beams with fixed and narrow center wavelength intervals at one time.

[0031] Furthermore, the light beams with different central wavelengths output by the narrow-linewidth multi-wavelength pulse laser 1 have stable and fixed time delays.

[0032] Furthermore, the dense wavelength division multiplexing device 4 can emit echo lights of different central wavelengths through different channels.

[0033] Furthermore, the single-photon laser radar system can simultaneously perform wavelength separation on echo lights of different central wavelengths to ensure the signal light intensity.

[0034] The principle of the present invention is as follows:

[0035] Single-photon laser radar has extremely high detection sensitivity, but single wavelength detection is easily affected by background noise, resulting in the system not being able to work effectively. At the same time, the single-photon laser radar system is complicated and costly. The present invention uses a multi-wavelength narrow-linewidth pulse laser 1 as a light source, and there is a stable and fixed time delay between each center wavelength, and uses a dense wavelength division multiplexing device 4 to perform spectral wavelength separation on the laser radar echo signal. The echo beams of different center wavelengths are split and output in different channels. The dense wavelength division multiplexing device 4 with excellent performance can output the echo beams with extremely narrow center wavelength intervals by channel, ensuring the signal strength of each channel while isolating the background light. The receiving end receives multiple wavelengths simultaneously with a single single-photon detection device 5, and outputs the multi-wavelength signal with a fixed time delay to a time-correlated single photon counter 6. The present invention can effectively reduce background noise interference, and at the same time, the use of dense wavelength division multiplexing combined with wavelength time delay can effectively extract the signal light from the background noise, which can effectively simplify the system structure and reduce the system cost.

[0036] According to the above embodiments, compared with the traditional laser radar, the present invention solves the problem of complex and high cost of single-photon laser radar system, simplifies the system structure of single-photon laser radar, and improves the convenience of single-photon laser radar. At the same time, the combination of wavelength division multiplexing and time division multiplexing technology can effectively improve the detection capability of the system and expand the application scope of laser radar.

[0037] Figure 2The detailed wavelength distribution of the laser is given. A single laser outputs optical pulses with multiple different central wavelengths. The bandwidth of each band is less than 50pm, the total bandwidth is less than 2.5nm, and the wavelength interval is less than 1.5nm, providing wavelength correlation for the system. Figure 3 The time delay between each wavelength is given, and the output optical pulses of different central wavelengths have a fixed and stable time delay, which is equivalent to using one laser to achieve the dual multiplexing effect of wavelength and time.

Claims

1. A wavelength division and time division multiplexing single photon laser radar, characterized in that: The invention comprises a narrow-linewidth multi-wavelength laser (1), an optical fiber beam splitter (2), a laser beam expander (3), a dense wavelength division multiplexing device (4), a single-photon detector (5), and a time-correlated single-photon counter (6); the narrow-linewidth multi-wavelength laser (1) outputs a multi-wavelength light beam which is emitted via the laser beam expander (3), and the narrow-linewidth multi-wavelength laser (1) outputs a synchronization signal to the time-correlated single-photon counter (6); the echo signal photons reflected by the target are received via the same laser beam expander (3), passed through the optical fiber beam splitter (2), and then wavelength-separated by the dense wavelength division multiplexing device (4), and finally received by the single-photon detector (5); the multi-wavelength signal with a fixed time delay is input into the time-correlated single-photon counter (6), and the time-correlated single-photon counter (6) accumulates the echo signal to obtain photon counts, and the target distance depth information is obtained by photon counting.

2. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: A narrow linewidth multi-wavelength laser (1) with multiple emission wavelengths is used as a light source. The total linewidth of the multiple wavelength lasers is less than 2.5 nm, while the linewidth of a single wavelength is less than 50 pm, and the center wavelength interval is less than 1.5 nm.

3. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: Each wavelength output by the narrow linewidth multi-wavelength laser (1) has a fixed and stable time interval.

4. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: The dense wavelength division multiplexing device (4) has a wavelength separation characteristic and is capable of separating echo light with a wavelength interval of less than 1.5 nm.

5. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: Capable of detecting multiple different central wavelengths simultaneously.

6. The wavelength division and time division multiplexing single photon laser radar according to claim 5, characterized in that: The dense wavelength division multiplexing device (4) simultaneously outputs the single photon detector (5).

7. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: The single photon detector (5) receives the multi-wavelength echo light beam output by the dense wavelength division multiplexing device (4).

8. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: The dense wavelength division multiplexing device (4) can emit echo lights with different central wavelengths through different channels.

9. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: The single-photon laser radar system can simultaneously perform wavelength separation on echo lights of different central wavelengths to ensure the intensity of signal light.

10. The wavelength division and time division multiplexing single photon laser radar according to claim 1, characterized in that: The dense wavelength division multiplexing device (4) outputs echo light beams with extremely narrow central wavelength intervals according to channels, thereby ensuring the signal strength of each channel while isolating background light.

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