CN114488192A

CN114488192A - Vehicle-mounted laser radar light source based on optical router and working method thereof

Info

Publication number: CN114488192A
Application number: CN202210048626.4A
Authority: CN
Inventors: 蒋友山; 吴玉霞
Original assignee: Fujian Tianrui Optoelectronics Co ltd
Current assignee: Fujian Tianrui Optoelectronics Co ltd
Priority date: 2022-01-17
Filing date: 2022-01-17
Publication date: 2022-05-13

Abstract

The invention relates to a vehicle-mounted laser radar light source based on an optical router and a working method thereof, wherein the light source comprises a seed light source, a pumping light source, the optical router, an amplifying optical fiber and a light splitting detector, the seed light source is connected with a first port of the optical router, the pumping light source is connected with a second port of the optical router through the amplifying optical fiber, and the light splitting detector is connected with a third port of the optical router; the seed light source is used for providing a light signal; the amplifying optical fiber is used for amplifying an optical signal; the pumping light source is used for providing energy for the amplifying optical fiber to amplify the optical signal of the seed light source; the optical router is used for providing two-stage isolation of an input end and an output end and preventing self-oscillation and echo damage in the amplification process; the light splitting detector splits a part of the optical signals to realize the real-time monitoring of the working state of the amplifier, and the rest of the optical signals are output. The vehicle-mounted laser radar light source has the advantages of compact light path, low manufacturing cost and small volume, and is favorable for realizing the miniaturization of the light source.

Description

Vehicle-mounted laser radar light source based on optical router and working method thereof

Technical Field

The invention belongs to the technical field of optical fiber communication and laser radars, and particularly relates to a vehicle-mounted laser radar light source based on an optical router and a working method thereof.

Background

The vehicle-mounted laser radar is one of the essential core sensors in a multi-sensor system of intelligent auxiliary driving and unmanned automobiles in the future, and with the rapid development of the unmanned market, more and more enterprises add new application development of the laser radar and pursuit of advanced technology. According to the statement of 'Chinese automatic driving development report 2020', laser radar application is accelerated after 2025 years, timely policies, technologies and infrastructures are relatively perfect, and an L3-grade vehicle model is also released in a large scale, so that along with the fact that the price of the laser radar is greatly reduced due to the mature technology, the vehicle model carrying the laser radar is not limited to a high-end vehicle model any more, but is explored to a medium-high-end vehicle model.

With the development of the current vehicle-mounted laser radar technology becoming mature, in order to improve the detection precision and the detection distance, the requirements on the narrow pulse and high peak value light power indexes of a laser light source are also improved. Laser light source is one of vehicle-mounted laser radar's core device, vehicle-mounted laser radar's light source is the same with the laser radar in the machine of sweeping the floor at present, mostly adopt 905nm laser instrument, there is eye safety problem, especially working distance reaches more than 150 m, when 905nm laser instrument's optical power has exceeded eye safety's threshold value, must adopt eye safety's laser instrument, 1550nm is just the typical representative of eye safety wave band, compare in 905nm laser, 1550nm laser eye safety of equal power improves 40 times. Under the same spot size and pulse width conditions, the maximum allowable exposure and the maximum allowable peak light power value of the 1550nm laser are higher than those of the 905nm laser by several orders of magnitude. The interference problem of background light is relatively small, and remote detection can be realized; meanwhile, a coherent technology is adopted, the detector only responds to the laser echo emitted by the detector, the signal-to-noise ratio is far higher than that of a 905nm-ToF laser radar, the maximum detection distance can reach more than 1000 meters, and the maximum detection distance can reach several kilometers in a special scene. Under the power of the same eye safety level, the 905nm laser radar hardly sees objects with the height of about 10 cm on expressways beyond 200 m, but the 1550nm laser radar can improve the detection distance to more than 300 m. In addition, 1550nm, in conjunction with Frequency Modulated Continuous Wave (FMCW) technology, can not only detect range, but also measure the velocity of an object using Doppler frequency shift. In conclusion, the ideal light source of the vehicle-mounted laser radar is high safety of human eyes, high power, short pulse, high beam quality, high reliability, low price, small volume and longer detection distance. The application of the vehicle-mounted laser radar light source in the vehicle-mounted radar system is shown in figure 1, the light source sends out a detection signal to a target through a transmitting light path, the signal reflected by the target is received by a receiving light path, and then the signal enters a signal processing analysis.

As shown in figure 2, a conventional vehicle-mounted laser radar light source is characterized in that a seed light source emits 1550nm waveband signal light which is input from an input end of a high-power isolator, an output end of the high-power isolator is double-fiber wavelength division multiplexing, a pump light source (980 nm) is combined with 1550nm waves at an output end of the high-power isolator through the wavelength division multiplexing, and the seed light source and the pump light source are coupled together and enter an erbium-doped optical fiber together. The optical signal amplified by the erbium-doped optical fiber is partially separated by a detector to realize the real-time monitoring of the working state of the amplifier, and the rest amplified optical signals are output by a high-power isolator. Two high-power isolators are needed in the light source structure, wherein one isolator has a wavelength division multiplexing function to realize the multiplexing of the seed light source and the pump light source, and the other isolator is used at the output end; erbium doped fibers are only single use, require longer lengths and are costly. Because optical devices are more, the erbium-doped optical fiber is longer, and the isolator can only output the optical fiber from the left port and the right port, the light source module needs to have enough space for the devices to be placed and the optical fiber to be coiled when the light source module is in a disc box, so that the volume of the whole light source module is larger.

Disclosure of Invention

The invention aims to provide a vehicle-mounted laser radar light source based on an optical router and a working method thereof.

In order to achieve the purpose, the invention adopts the technical scheme that: a vehicle-mounted laser radar light source based on an optical router comprises a seed light source, a pumping light source, the optical router, an amplifying optical fiber and a light splitting detector, wherein the seed light source is connected with a first port of the optical router;

the seed light source is used for providing a light signal; the amplifying optical fiber is used for amplifying an optical signal; the pumping light source is used for providing energy for the amplifying optical fiber to amplify the optical signal of the seed light source; the optical router is used for providing two-stage isolation of an input end and an output end and preventing self-oscillation and echo damage in the amplification process; the light splitting detector splits a part of the optical signals to realize the real-time monitoring of the working state of the amplifier, and the rest of the optical signals are output.

Further, the pump light source adopts single-fiber wavelength division multiplexing, couples the pump light source optical signal into the amplification optical fiber, and reflects the seed light source optical signal.

Further, the optical signal of the seed light source is input from the first port of the optical router, is output from the second port of the optical router to the amplifying optical fiber for amplification, and is reflected by the pump light source to be amplified by the amplifying optical fiber, and the amplifying optical fiber is multiplexed in positive and negative twice.

Further, the amplifying fiber is erbium-doped fiber or erbium-ytterbium co-doped fiber.

Further, in the case where the optical source is not provided with a seed optical source, the remaining structure is used as an optical amplifier for amplifying an optical signal input from the first port of the optical router.

Furthermore, all devices adopt a single-end fiber outlet structure, and the whole light source achieves the minimum volume and the miniaturization.

Further, at the optical router end, single-mode optical fiber of signal light is used for coupling transmission; and at the coupling end of the pump light source, single-mode and double-cladding multimode fibers of pump light are used for coupling transmission.

Further, the pump light source optical signal is coupled into a single-mode amplification optical fiber or a double-clad multi-mode amplification optical fiber.

The invention also provides a working method of the vehicle-mounted laser radar light source based on the optical router, wherein the seed light source generates an optical signal, the optical signal is input from the first port of the optical router, then is output from the second port of the optical router to the amplification optical fiber for amplification, and then is reflected by the pumping light source to the amplification optical fiber for amplification; the amplified optical signal is output to the optical splitting detector from the third port of the optical router, the optical splitting detector splits a part of the optical signal for real-time monitoring of the working state of the amplifier, and the rest of the optical signal is output.

Compared with the prior art, the invention has the following beneficial effects: the vehicle-mounted laser radar light source based on the optical router is provided, the light source multiplexes the amplifying optical fiber in the forward direction and the reverse direction based on the optical router structure, the amplification of optical signals of the seed light source is realized, the optical signals with the same power are amplified, the length of the amplifying optical fiber is halved, and the cost is reduced. Meanwhile, the optical router provides two-stage isolation of an input end and an output end to prevent self-oscillation and echo damage in the amplification process. In addition, signal light is subjected to single-mode transmission amplification, and pump light is efficiently coupled into the amplification optical fiber at an independent port in a single-mode or multi-mode. Because optical devices are reduced and all the devices can adopt a single-end fiber outlet structure, the optical path is compact, and the miniaturization of the light source is realized. The invention can be widely applied to a vehicle-mounted laser radar system, and realizes the development of the vehicle-mounted laser radar in the direction of miniaturization and low cost.

Drawings

Fig. 1 is an application of a vehicle-mounted laser radar light source in a vehicle-mounted radar system.

Fig. 2 is a schematic diagram of a light path structure of a conventional vehicle-mounted laser radar light source.

Fig. 3 is a schematic view of an optical path structure of a light source according to a first embodiment of the invention.

Fig. 4 is a schematic view of a light path structure of a light source according to a second embodiment of the invention.

Fig. 5 is a schematic diagram of an optical router implementing three-port optical path transmission structure in the embodiment of the present invention.

Fig. 6 is a schematic diagram of an optical path structure of an optical router according to an embodiment of the present invention, in which a secondary pump light source is added to a second port of the optical router.

Fig. 7 is a schematic structural diagram of adding fiber gratings on the first port optical path of the seed light source and the optical router in the embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a pump light source according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of another pump light source structure according to an embodiment of the present invention.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As shown in fig. 3, the present embodiment provides an optical router-based vehicle-mounted laser radar light source, which is composed of a seed light source 11, a pump light source 12, an optical router 31, an amplifying optical fiber 41, a small-sized spectral detector 21, and the like. The seed light source 11 is connected with port 1 of the optical router 31; the pump light source 12 is connected to the 2-port of the optical router 31 through the amplification fiber 41; the compact optical splitter 21 is connected to the 3-port of the optical router 31.

Wherein, the seed light source 11 is used to provide the light signal λ 1; the amplifying optical fiber 41 is used for amplifying the optical signal λ 1; the pumping light source 12 is used for providing energy to the amplifying optical fiber 41 to realize the amplification of the optical signal lambda 1 of the seed light source 11; the optical router 31 is used for providing two-stage isolation of the input end 2-1 and the output end 3-2, and preventing self-oscillation and echo damage in the amplification process; the small-sized light splitting detector 21 splits a part of the optical signals to realize real-time monitoring of the working state of the amplifier, and the rest of the amplified optical signals are output. The optical router 31 is composed of a first collimator 311, a second collimator 312, a third collimator 313, an optical router optical core 314, and the like. The second collimator 312 integrates a filter 3121, the filter 3121 is transparent to the amplified signal light λ 1 and reflects the pump light λ 2, the third collimator 313 integrates a filter 3131, the filter 3131 is transparent to the amplified signal light λ 1 and reflects other stray light (background light including spontaneous emission and remaining pump light) to block them out of the output end; in addition, the film system of the filter can be directly plated on the lens of the collimator.

The seed light source 11 can be packaged for coaxial refrigeration, so that stable work is realized. The

ports

2 and 3 of the optical router 31 adopt a high-power optical fiber structure, for example, the optical fiber heads of the

ports

2 and 3 can be made of common high-power optical fibers or erbium-doped optical fibers. The amplifying fiber 41 may be erbium-doped fiber, erbium-ytterbium co-doped fiber, or other amplifying fiber. The typical wavelength of the seed light source 11 is 1530nm, and the working wavelength range is 1525 and 1565 nm. The pumping light source 12 has various packaging modes, typically a butterfly band cooling 940nm pumping laser, or 980nm, 976nm, 1480nm and other wavelengths, or a coaxial band cooling package under the condition of low power. Aiming at light sources and amplifiers with high power levels of 1W, 5W, 10W and the like, erbium-ytterbium co-doped double-clad fibers are adopted, and 940nm high-power pump lasers are adopted in coupling. For low power light source and amplifier within 1W, 980nm, 976nm, 1480nm low power pump light source can be used.

The amplification of the optical signal can adopt a single-stage pump light source and can also adopt a double-pole pump light source.

When all devices adopt a single-end fiber outlet structure, the whole light source achieves the minimum volume and the miniaturization.

The working method of the vehicle-mounted laser radar light source based on the optical router comprises the following steps: the seed light source generates an optical signal, the optical signal is input from a first port of the optical router, then the optical signal is output from a second port of the optical router to the amplification optical fiber for amplification, and then the optical signal is reflected by the pumping light source to the amplification optical fiber for amplification, and the erbium-doped optical fiber is multiplexed for the positive time and the negative time; the amplified optical signal is output to the optical splitting detector from the third port of the optical router, the optical splitting detector splits a part of the optical signal for real-time monitoring of the working state of the amplifier, and the rest of the optical signal is output.

Fig. 3 is a schematic view of a light path structure of a vehicle-mounted laser radar light source according to a first embodiment of the present invention. As shown in fig. 3, in the first embodiment of the present invention, the optical router 31 is a reflective optical router structure, and has a single-end fiber outlet, the

collimators

312 and 313 of the

ports

2 and 3 of the optical router adopt optical fibers capable of bearing high power, so as to provide two-stage isolation at the input end 2-1 and the output end 3-2 to prevent the amplifier from generating self-oscillation; the seed light source 11 is output by single fiber tail fiber; the pumping light source 12 is output by a single-fiber wavelength division multiplexing pigtail, and the end surface of the single-fiber optical fiber head 121 of the pumping light source 12 is coated with a wavelength division multiplexing film or is attached with a wavelength division multiplexing film, so that the pumping light source optical signal λ 2 is coupled into the amplifying optical fiber 41 and simultaneously reflects the seed light source optical signal λ 1. The compact spectral detector 21 is a dual fiber pigtail output, using a TAP collimator 211 coupling approach. The pump light source 12 emits a pump light source optical signal λ 2, which is coupled to the amplification optical fiber 41 through the single optical fiber head 121, so as to realize the amplification of the optical signal λ 1 of the seed light source 11; the seed light source 11 emits a laser light signal λ 1, the signal light λ 1 is input from the port 1 of the optical router 31 through the collimator 311, and then the signal light λ 1 is output from the port 2 of the optical router 31 through the collimator 312 to the amplification optical fiber 41, so that the amplification of the optical signal λ 1 is realized; the optical signal λ 1 primarily amplified by the amplifying fiber 41 is reflected by the single fiber head 121 of the pump light source 12 and enters the amplifying fiber 41 for secondary amplification; the optical signal λ 1 after the secondary amplification is input through the collimator 312 via the port 2 of the optical router 31, and then the amplified signal light λ 1 is output through the collimator 313 via the port 3 of the optical router 31. The amplified signal light λ 1 output by the port 3 reaches the small-sized spectral detector 21, the TAP collimator 211 divides the transmission of the amplified light signal λ 1 into a part to realize real-time monitoring of the working state of the amplifier, and reflects the rest of the amplified light signal λ 1 for output.

Fig. 4 is a schematic view of a light path structure of a vehicle-mounted laser radar light source according to a second embodiment of the present invention. As shown in fig. 4, the second embodiment of the present invention is different from the first embodiment in that the compact spectroscopic detector 22 is a single fiber pigtail output; the collimator 312 of the port 2 of the optical router 31 is a dual-fiber TAP collimator, a part of the amplified optical signal λ 1 is reflected by the dual-fiber TAP collimator 312 of the port 2 and is divided out to be directly connected with the small-sized optical splitting detector 22, so that the working state of the amplifier is monitored in real time, and the rest of the amplified optical signal λ 1 is transmitted by the dual-fiber TAP collimator 312 of the port 2 and is directly output by the collimator 313 of the port 3 of the optical router.

Fig. 5 is a schematic structural diagram of an optical router implementing optical path transmission of three ports according to an embodiment of the present invention. As shown in fig. 5, the optical core 314 of the optical router 31 includes a first prism 3141, a wave plate 3142, a magneto-optical crystal 3143, and a second prism 3144. The signal light input by the first port is output from the second port 2 after passing through the first prism 3141, the wave plate 3142, the magneto-optical crystal 3143 and the second prism 3144, and the signal light input by the second port 2 is output from the third port 3 after passing through the second prism 3144, the magneto-optical crystal 3143, the wave plate 3142 and the first prism 3141. The optical router of the present invention is not limited to the above optical path core structure, and all optical structures capable of realizing optical path transmission between the three ports belong to the patent scope of the optical router of the present invention.

Fig. 6 is a schematic diagram of an optical path structure of an optical router port 2 added with a secondary pump light source in the embodiment of the present invention. According to the specific amplification requirement of the optical signal of the seed light source, a bipolar pump light source can be adopted. As shown in fig. 6, a primary pump light source 12 and a secondary pump light source 13 are added to port 2 of the optical router 31. The collimator 312 of the port 2 is a dual-fiber collimator, the dual-fiber head 3123 adopts an optical fiber capable of bearing high power, and the end surface of the lens 3122 is plated with a wavelength division multiplexing film 3121 or is pasted with a wavelength division multiplexing film 3121, so as to realize the wave combination of the pump light source signal light λ 2 and the seed light source signal light λ 1, and couple into the amplifying optical fiber 41.

Fig. 7 is a schematic structural diagram of adding fiber gratings on the optical paths of the seed light source and the port 1 of the optical router in the embodiment of the present invention. The amplified optical signal of the seed light source 11 has a narrower line width and a longer detection distance under the same optical power condition. The fiber bragg grating is added, so that the line width of the wavelength card can be locked. Therefore, according to the actual application requirement of the vehicle-mounted laser radar, a fiber grating can be added in the light path, and shown in fig. 7, the fiber grating is added on the light path of the seed light source 11 and the optical router port 1. Similarly, fiber grating may be added to the optical path at port 2 of the optical router 31. The transmission wavelength of the fiber grating is just the amplified optical signal of the seed light source 11 wavelength, and other stray light (background light containing spontaneous radiation and residual pump light) is blocked. When the fiber grating is on the optical path of port 2 of the optical router 31, the pump light is reflected back to the amplifying fiber, so as to reduce the waste of the pump light and further improve the pumping efficiency.

Similarly, a narrow-band filter may be integrated at port 2 or port 3 of the optical router 31, so that only the amplified optical signal of the wavelength of the seed light source 11 is transmitted, and other stray light (background light including spontaneous emission and residual pump light) is blocked out of the output end. When the narrow-band filter is on the optical path of port 2 of the optical router 31, the pump light can be further designed to be reflected back to the amplifying optical fiber, so as to reduce the waste of the pump light and further improve the pumping efficiency.

Fig. 8 is a schematic structural diagram of a pump light source according to an embodiment of the present invention. As shown in fig. 8, the built-in high-performance pump laser 122 of the pump light source 12 emits a converged beam optical signal λ 2, which is coupled into the optical fiber by a single fiber stub 121 of the pump light source 12. The end surface of the single fiber head 121 is coated with a wavelength division multiplexing film 123 or attached with a wavelength division multiplexing film 123, so as to couple the pump light source optical signal λ 2 into the amplifying fiber 41 and reflect the seed light source optical signal λ 1. The optical fiber of the optical fiber head 121 may be a multimode optical fiber, and may be a single multimode coupled, double clad, or multi-clad optical fiber.

FIG. 9 is a schematic diagram of another pump light source structure according to an embodiment of the present invention. As shown in fig. 9, the built-in high performance pump laser 141 of the pump light source 14 emits a converged light beam λ 2, the converged light beam is changed into a parallel light beam by the negative lens 145, the single fiber head 142 and the lens 143 form a collimator, and the parallel light beam is received and output by the collimator. The end surface of the lens 143 is coated with a wavelength division multiplexing film 144 or attached with a wavelength division multiplexing film 144, so as to couple the pump light source optical signal λ 2 into the amplification optical fiber 41 and reflect the seed light source optical signal λ 1. The optical fiber of the optical fiber head 142 may be a multimode optical fiber, and may be a single multimode coupled, double clad, or multi-clad optical fiber.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims

1. A vehicle-mounted laser radar light source based on an optical router is characterized by comprising a seed light source, a pumping light source, the optical router, an amplifying optical fiber and a light splitting detector, wherein the seed light source is connected with a first port of the optical router, the pumping light source is connected with a second port of the optical router through the amplifying optical fiber, and the light splitting detector is connected with a third port of the optical router;

2. The optical router-based vehicle lidar light source of claim 1, wherein the pump light source employs single-fiber wavelength division multiplexing to couple the pump light source optical signal into the amplification fiber and reflect the seed light source optical signal.

3. The optical router-based vehicle-mounted lidar light source of claim 1, wherein the seed light source optical signal is input from a first port of the optical router, is output from a second port of the optical router to the amplification optical fiber for amplification, is reflected by the pump light source and is amplified by the amplification optical fiber, and the amplification optical fiber is multiplexed twice.

4. The optical router-based vehicle lidar light source of claim 1, wherein the amplifying fiber is erbium-doped fiber or erbium-ytterbium co-doped fiber.

5. The optical router-based vehicle lidar light source of claim 1, wherein the remaining structure is used as an optical amplifier to amplify the optical signal input from the first port of the optical router without providing a seed light source.

6. The vehicle-mounted laser radar light source based on the optical router as claimed in claim 1, wherein all the devices adopt a single-end fiber outlet structure, and the whole light source achieves the minimum volume and the miniaturization.

7. The optical router-based vehicle-mounted lidar light source is characterized in that the optical router end is used for coupling transmission by a single-mode optical fiber of signal light; and at the coupling end of the pump light source, single-mode and double-cladding multimode fibers of pump light are used for coupling transmission.

8. The optical router-based vehicle lidar optical source of claim 2, wherein the pump source optical signal is coupled into a single-mode amplification fiber or a double-clad multimode amplification fiber.

9. An operating method of a vehicle-mounted laser radar light source based on an optical router as claimed in any one of claims 1 to 8, wherein the seed light source generates an optical signal, the optical signal is input from the first port of the optical router, then is output from the second port of the optical router to the amplifying optical fiber for amplification, and then is reflected by the pumping light source to the amplifying optical fiber for amplification; the amplified optical signal is output to the optical splitting detector from a third port of the optical router, the optical splitting detector splits off a part of the optical signal for real-time monitoring of the working state of the amplifier, and the rest of the optical signal is output.