Full-skewed high-power laser source of laser radar and debugging method of full-skewed high-power laser source

Abstract

A laser radar full-polarization high-power laser source comprises a full-polarization synthesis system, the full-polarization synthesis system comprises a first laser and a second laser, a first lens and a second lens are arranged in the light emitting direction of the first laser and the light emitting direction of the second laser respectively, a polarization rotator is arranged in the light emitting direction of the first lens, and a second lens is arranged in the light emitting direction of the second lens. A first reflector plate is arranged in the light-emitting direction of the polarization rotator, the full-skew high-power laser source further comprises a polarization wave-combining prism, and the light-emitting directions of the first reflector plate and the second lens are respectively aligned with the vertical input end and the horizontal input end of the polarization wave-combining prism. The invention further discloses an installation and debugging method of the laser radar full-skewed high-power laser source. Compared with the existing design that two groups of radar amplification light paths need to be arranged independently, the design of one amplification light path is reduced, only one light amplifier needs to be used, the integration level is improved, and the cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of laser technology, specifically relating to a fully polarized high-power laser source for lidar and its debugging method. Background Technology

[0002] Currently, near-infrared lasers with wavelengths of 850nm or 905nm are commonly used in short-range lidar applications such as short-range detection. Silicon materials have a high absorption rate around 905nm, and lasers of this wavelength are relatively inexpensive. Furthermore, silicon-based detectors are mature and suitable for short to medium-range measurements. For example, 850nm lidar is often used in short-range scenarios, but it is prone to red glow due to interference from visible light components. 905nm lidar has the advantage of a mature and low-cost supply chain for silicon-based detectors and lasers, but its power must be strictly controlled due to eye safety standards, limiting its long-range detection capability. The maximum range is typically around 150 meters, making it suitable for short to medium-range scenarios.

[0003] Currently, long-range applications of lidar, such as high-speed autonomous driving, tend to use 1550nm wavelength lasers. This wavelength is far from the visible light range that the human eye is sensitive to, making it 40 times safer for the human eye than 905nm. It allows for the emission of higher-power lasers, thus achieving detection distances of over 300 meters or even kilometers and higher resolutions. However, this requires the use of indium gallium arsenide (InGaAs) detectors, which are costly, and the light source relies on fiber lasers, indicating insufficient supply chain maturity. Currently, it is mainly used in high-end autonomous driving systems.

[0004] Some manufacturers adopt a multi-wavelength fusion strategy, such as a short-range + long-range combination: 905nm is used for short-to-medium range sensing, and 1550nm covers long-range detection. The 1550nm wavelength scheme requires the use of EDFA to amplify the optical power. The general optical path design is: 1550 nm fiber laser → collimating lens → splitter → EDFA amplification → MEMS galvanometer scanning → receiving optical system.

[0005] As mentioned earlier, current short-range LiDAR applications typically use near-infrared lasers with wavelengths of 850nm or 905nm. However, due to safety standards for the human eye, power must be strictly controlled, limiting long-range detection capabilities. Long-range applications use 1550nm lasers, but require indium gallium arsenide (InGaAs) detectors, resulting in higher costs. Some manufacturers employ multi-wavelength fusion strategies, such as a short-range + long-range combination: 905nm for short-to-medium range sensing and 1550nm for long-range detection. However, this still requires two separate radar arrays to ensure the detection range includes both short-range blind spot coverage and long-range detection, leading to high overall costs. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention discloses a fully polarized high-power laser source for lidar and its debugging method.

[0007] The fully polarized high-power laser source for lidar of the present invention includes a fully polarized light combining system, which includes a first laser and a second laser. The first laser and the second laser are respectively provided with a first lens and a second lens in their light output directions. A polarization rotator is provided in the light output direction of the first lens, and a first reflector is provided in the light output direction of the polarization rotator. The fully polarized high-power laser source also includes a polarization wave combining prism, and the light output directions of the first reflector and the second lens are respectively aligned with the vertical input end and the horizontal input end of the polarization wave combining prism. The polarizing beam combiner is provided with a fully polarized amplification and collimation system in the light output direction, and a probe light separation system is provided in the light output direction of the fully polarized amplification and collimation system. The probe light separation system includes a filter, a fourth lens is provided in the transmission light direction of the filter, and an optical path reflection system is provided in the reflection light direction of the filter. The first laser and the second laser generate lasers with wavelengths of CW1 and CW2, respectively. The filter allows light with wavelength CW1 to pass through the filter and reflects light with wavelength CW2. CW1 is greater than CW2 and the difference is less than 30 nanometers.

[0008] Preferably, the first laser and the second laser are formed by using the same light source and passing it through two laser generators with different excitation wavelengths, and generating two laser sources using coarse wavelength division multiplexing (CWDM) technology.

[0009] Preferably, a first polarization-dependent isolator is provided in the optical path between the first lens and the polarization rotator, and a second polarization-dependent isolator is provided between the second lens and the polarization combining prism.

[0010] Preferably, the fully polarized amplification and collimation system includes a semiconductor optical amplifier, a third lens, and a bipolar isolator located sequentially along the optical path.

[0011] Preferably, the optical path reflection system includes a second reflector disposed in the direction of light reflection of the filter, a third reflector disposed in the direction of light reflection of the second reflector, and a fifth lens disposed in the direction of light reflection of the third reflector.

[0012] This invention also discloses a method for installing and debugging a full-polarization high-power laser source for lidar, comprising the following steps: Step 1: Fix the first laser on the optical path mounting plate and power it on to emit laser light. Fix the straight-line distance L0 between the power meter and the first laser. Adjust the angle position of the power meter relative to the first laser to maximize the received optical power value. Then reset it to zero. At this time, the position of the power meter G is S1. Step 2: Fix the position of the power meter. Place the first lens on the straight line L1 connecting the first laser and the power meter position S1. Adjust the position of the first lens to maximize the optical power received by the power meter. Fix the first lens. Step 3: Place the second laser and the power meter on a straight line L2 that is parallel to the straight line L1 in step 2. Receive the optical power through the power meter, fix the second laser, adjust the position of the power meter on the straight line L2 so that the straight distance between the power meter and the second laser is L0, and then fix the position of the power meter S2. Next, place the second lens on line L2 between the second laser and the power meter. Adjust the position of the second lens so that the optical power received by the power meter is at its maximum, which is when the insertion loss is at its minimum. Then fix the second lens. Step 4: Place the first reflector on line L1 to the right of the polarization rotator, place the polarization combining prism on line L2 to the right of the second lens, fix the power meter at position S2, and receive the optical power. Adjust the positions of the first reflector and the polarizing beam combiner to maximize the optical power received by the power meter, then fix the first reflector and the polarizing beam combiner. Step 5: Adjust the various optical components of the fully polarized amplification and collimation system; Step 6: Fix the power meter at the first output port of the fully polarized high-power laser source, i.e., the near-end detection output port. Place the filter at position S2, where the straight line L2 is located on the right side of the fully polarized amplification and collimation system. Place the fourth lens at the position where the straight line L2 is located on the right side of the filter in the direction of transmitted light. Adjust the position of the fourth lens so that the power meter at the first output port receives the maximum optical power. Step 7: Adjust the various optical components of the optical path reflection system.

[0013] Preferably, the fully polarized amplification and collimation system includes a semiconductor optical amplifier, a third lens, and a bipolar isolator arranged sequentially on the optical path; step five specifically involves: placing the semiconductor optical amplifier, the third lens, and the bipolar isolator sequentially in the position where the straight line L2 is located to the right of the polarization combining prism; receiving the optical power with a power meter; adjusting the positions of the semiconductor optical amplifier, the third lens, and the bipolar isolator until the optical power of the power meter is at its maximum; and then fixing the semiconductor optical amplifier, the third lens, and the bipolar isolator.

[0014] Preferably, the optical path reflection system includes a second reflector disposed in the direction of light reflection of the filter, a third reflector disposed in the direction of light reflection of the second reflector, and a fifth lens disposed in the direction of light reflection of the third reflector; step seven specifically comprises: Place the second reflector in the direction of reflected light at the lower left of the filter. Position the power meter at position S3 in the direction of reflected light of the second reflector to receive the optical power. Adjust the position and orientation of the second reflector to maximize the optical power value received by the power meter, and then fix the second reflector. Next, place the third reflector at position S3, and place the fifth lens on the right side of the third reflector in the direction of reflected light. Fix the power meter at the second output port of the fully polarized high-power laser source, i.e., the far-end detection output port. Receive the optical power in the direction of transmitted light from the fifth lens. Adjust the positions of the third reflector and the fifth lens to maximize the optical power value received by the power meter, and then fix the third reflector and the fifth lens.

[0015] Compared with the prior art, the present invention has the following technical advantages: This invention employs two laser light sources with similar wavelengths, which are polarized and combined to form fully polarized light. After being amplified by the same SOA, the two wavelengths of light are separated by a filter coated with a reflective film. One beam is output directly, and the other is output through reflection. One beam is responsible for near-end detection, and the other is responsible for far-end detection. Compared with the existing design that requires two separate radar amplification optical paths, this invention reduces the design to a single amplification optical path, requiring only one optical amplifier, thus improving integration and reducing costs.

[0016] This invention uses a light source with similar wavelengths, allowing for wavelength detection or modulation separation detection using the same detector, resulting in greater integration than the previous method of using two separate radar receiving systems. This invention also uses a polarization-dependent isolator, which offers better reliability, lower cost, and smaller size compared to polarization-independent isolators.

[0017] This invention uses two C-band lasers with a wavelength interval of less than 10 nm. Each laser can output a single stable polarized light. Since the center wavelengths of the two lasers are similar, after polarization combining at the back end, a fully polarized light transmission can be formed, which has better signal stability and higher transmission efficiency than partially polarized light transmission. The anti-interference capability and system performance are also optimized. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a specific embodiment of the fully polarized high-power laser source for lidar described in this invention; Figure 2 This is a schematic diagram illustrating a specific implementation of steps one and two of the installation and debugging method described in this invention; Figure 3 This is a schematic diagram illustrating a specific implementation of step three in the installation and debugging method described in this invention; Figure 4 This is a schematic diagram illustrating a specific implementation of step four in the installation and debugging method described in this invention; Figure 5 This is a schematic diagram illustrating a specific implementation of step five in the installation and debugging method described in this invention; Figure 6 This is a schematic diagram illustrating a specific implementation of step six in the installation and debugging method described in this invention; Figure 7 This is a schematic diagram illustrating a specific implementation of step seven in the installation and debugging method described in this invention; The figures are labeled as follows: 10-substrate, 11-first lens, 12-first polarization-correlated isolator, 13-polarization rotator, 14-first reflector, 20-second laser, 21-second lens, 22-second polarization-correlated isolator, 23-polarization combining prism, 30-semiconductor optical amplifier, 31-third lens, 32-bipolar isolator, 40-filter, 41-fourth lens, 50-second reflector, 51-third reflector, 52-fifth lens, 61-first light outlet, 62-second light outlet. Detailed Implementation

[0019] To more intuitively and clearly describe the specific details of the technical solution of the present invention, a detailed description will be provided below in conjunction with specific embodiments and example drawings.

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] A specific embodiment of the fully polarized high-power laser source for lidar described in this invention is as follows: Figure 1 As shown: In the fully polarized light combining system, the first laser 10 emits vertically polarized light with a wavelength of CW1. After being collimated by the first lens 11, the light passes through the first polarization-correlated isolator 12, and then through the polarization rotator 13 to convert the vertically polarized light into horizontally polarized light. Finally, the light is reflected by the first reflector 14 to the vertical input end of the polarization combining prism 23. The function of the first polarization-correlated isolator 12 is to isolate the reflected light and protect the laser 10.

[0022] The second laser 20 emits vertically polarized light with a wavelength of CW2. After being collimated by the second lens 21, it passes through the second polarization-correlated isolator 22 and reaches the horizontal input end of the polarization combining prism 23. The function of the second polarization-correlated isolator 22 is to isolate the reflected light and protect the second laser 20.

[0023] The polarizing beam combiner 23 combines two wavelengths, CW1 and CW2, from the two vertical and horizontal input ends into fully polarized light with mutually perpendicular polarization directions. The light is then amplified and collimated by the fully polarized light amplification and collimation system. The semiconductor optical amplifier (SOA) 30 in the fully polarized light amplification and collimation system amplifies the power, and then the light is collimated by the third lens 31. Finally, the light passes through the bipolar isolator 32, which isolates reflected light and protects the front-end optical path equipment.

[0024] After being processed by the fully polarized amplification and collimation system, the fully polarized light reaches the filter 40 in the probe light separation system. The filter 40 uses a reflective coating technology to allow a portion of the fully polarized light with a wavelength of CW1 to pass through it. After being collimated by the fourth lens 41, it serves as a long-distance light detection source.

[0025] The filter 40 allows light with wavelength CW1 to pass through the filter and reflects light with wavelength CW2. In this application, the first laser and the second laser can be implemented using the same light source, which passes through two laser generators with different excitation wavelengths, and two laser sources with similar wavelengths are generated using coarse wavelength division dense multiplexing (CW) technology.

[0026] In the fully polarized light, a portion of the light with a wavelength of CW2 is reflected by the filter 40 onto the second reflector 50 of the optical path reflection system. The second reflector 50 and the third reflector 51 reflect the light with a wavelength of CW2 twice in succession, and the light reaches the fifth lens 52. The fifth lens 52 collimates the light and uses it as a medium-to-near distance optical detection source.

[0027] To achieve collimation, the light source of the incident light needs to be placed at the focal point of each lens, and the reflector is placed in a manner that can form the light path described above in this invention.

[0028] The difference between the laser wavelengths CW1 and CW2 generated by the two lasers is generally less than 30 nanometers, so as to form a fully polarized light transmission in the polarization combining prism.

[0029] The installation and debugging method of the fully polarized high-power laser source described in this invention is as follows: Step 1: Fix the first laser 10 on the optical path mounting plate and power it on to emit laser light. Fix the power meter G at a straight-line distance L0 from the first laser. Adjust the angle of the power meter G relative to the first laser to maximize the received optical power value, and then reset it to zero. At this time, the position of the power meter G is S1.

[0030] The straight-line distance L0 is generally set based on the size of the laser source to be designed and experience.

[0031] Step Two: As Figure 2As shown, with the power meter G fixed in position, the first lens 11 is placed on the straight line L1 connecting the first laser 10 and the power meter G at position S1. The position of the first lens 11 is then adjusted to maximize the optical power received by the power meter G, which is also the time when the insertion loss is minimized. The first lens 11 is then fixed. Next, the first polarization-dependent isolator 12 is placed in and adjusted to maximize the optical power received by the power meter G again. Finally, the polarization rotator 13 is placed in and its position is adjusted to maximize the optical power received by the power meter G.

[0032] Step 3: As Figure 3 As shown, the second laser 20 and the power meter G are placed on a straight line L2 that is parallel to the straight line L1 in step 2. The power meter G receives the optical power, the second laser 20 is fixed, and the position of the power meter G on the straight line L2 is adjusted so that the straight distance between it and the second laser is L0. Then the position S2 of the power meter G is fixed.

[0033] Next, place the second lens 21 and the second polarization-dependent isolator 22 on the straight line L2 between the second laser and the power meter G2. Adjust the position of the second lens 21 so that the optical power received by the power meter G2 is at its maximum, which is when the insertion loss is at its minimum. Fix the second lens 21, and then adjust the position of the second polarization-dependent isolator 22 again so that the optical power received by the power meter G2 is at its maximum. Finally, fix the second polarization-dependent isolator 22.

[0034] Step Four: As Figure 4 As shown, the first reflector 14 is placed to the right of the polarization rotator 13 on straight line L1, and the polarization combining prism 23 is placed to the right of the second polarization correlation isolator 22 on straight line L2. The power meter G is fixed at position S2 to receive the optical power. Adjust the positions of the first reflector 14 and the polarizing beam combiner 23 so that the optical power received by the power meter G is at its maximum, and then fix the first reflector 14 and the polarizing beam combiner 23.

[0035] The specific adjustment method can be to first place the first reflector 14 and adjust its position so that the optical power value received by the power meter G is maximized, then place the polarizing beam prism 23 and adjust its position so that the optical power value received by the power meter G is maximized.

[0036] Step 5: As Figure 5 The semiconductor optical amplifier 30, the third lens 31, and the bipolar isolator 32 are placed sequentially in the position where the straight line L2 is located to the right of the polarization combining prism 23. The power meter G is used to receive the optical power. The positions of the semiconductor optical amplifier 30, the third lens 31, and the bipolar isolator 32 are adjusted so that the optical power of the power meter G is at its maximum. Then the semiconductor optical amplifier 30, the third lens 31, and the bipolar isolator are fixed.

[0037] The specific adjustment method can be as follows: first, insert the semiconductor optical amplifier 30 and adjust its position so that the optical power value received by the power meter G is maximized; then insert the third lens 31 and adjust its position so that the optical power value received by the power meter G is maximized; then insert the bipolar isolator 32 and adjust its position so that the optical power value received by the power meter G is maximized.

[0038] Step Six: The power meter G is fixed at the first output port 61 of the fully polarized high-power laser source, i.e., the near-end detection output port. Figure 6 Place the filter 40 at position S2, where the straight line L2 is located on the right coaxial position of the bipolar isolator. Place the fourth lens 41 at position L2, where the straight line L2 is located on the right side of the filter 40 in the direction of transmitted light. Adjust the position of the fourth lens 41 so that the power meter G at the first light outlet 61 receives the maximum optical power.

[0039] Step 7: Place the second reflector 50 in the direction of reflected light at the lower left of the filter 40, place the power meter G at position S3 in the direction of reflected light of the second reflector 50, receive the optical power, adjust the position and orientation of the second reflector 50 to maximize the optical power value received by the power meter G, and fix the second reflector 50.

[0040] For example Figure 7 As shown, the third reflector 51 is placed at position S3, and the fifth lens 52 is placed on the right side of the third reflector 51 in the direction of reflected light. The power meter G is fixed at the second light output port 62 of the fully polarized high-power laser source, i.e., the far-end detection light output port. The power meter G receives the light power in the direction of transmitted light from the fifth lens. The positions of the third reflector 51 and the fifth lens 52 are adjusted to maximize the light power value received by the power meter G. The third reflector 51 and the fifth lens 52 are then fixed.

[0041] The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction between the preferred embodiments or a prerequisite for a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are only for clearly illustrating the inventor's invention verification process and are not intended to limit the patent protection scope of the present invention. The patent protection scope of the present invention is still determined by its claims. Similarly, any equivalent structural changes made based on the content of the specification of the present invention should also be included within the protection scope of the present invention.

Claims

1. A fully polarized high-power laser source for lidar, characterized in that, The system includes a fully polarized light combining system, which comprises a first laser and a second laser. The first laser and the second laser are respectively provided with a first lens and a second lens in their light output directions. A polarization rotator is provided in the light output direction of the first lens, and a first reflector is provided in the light output direction of the polarization rotator. The fully polarized high-power laser source also includes a polarization wavecombining prism, and the light output directions of the first reflector and the second lens are respectively aligned with the vertical input end and the horizontal input end of the polarization wavecombining prism. The polarizing beam combiner is provided with a fully polarized amplification and collimation system in the light output direction, and a probe light separation system is provided in the light output direction of the fully polarized amplification and collimation system. The probe light separation system includes a filter, a fourth lens is provided in the transmission light direction of the filter, and an optical path reflection system is provided in the reflection light direction of the filter. The first laser and the second laser generate lasers with wavelengths of CW1 and CW2, respectively. The filter allows light with wavelength CW1 to pass through the filter and reflects light with wavelength CW2. CW1 is greater than CW2 and the difference is less than 30 nanometers.

2. The fully polarized high-power laser source for lidar as described in claim 1, characterized in that, The first laser and the second laser are formed by using the same light source and passing it through two laser generators with different excitation wavelengths, and using coarse wavelength division multiplexing technology to generate two laser sources.

3. The fully polarized high-power laser source for lidar as described in claim 1, characterized in that, A first polarization-dependent isolator is provided in the optical path between the first lens and the polarization rotator, and a second polarization-dependent isolator is provided between the second lens and the polarization combining prism.

4. The fully polarized high-power laser source for lidar as described in claim 1, characterized in that, The fully polarized amplification and collimation system includes a semiconductor optical amplifier, a third lens, and a bipolar isolator, which are located sequentially on the optical path.

5. The fully polarized high-power laser source for lidar as described in claim 1, characterized in that, The optical path reflection system includes a second reflector disposed in the direction of light reflection of the filter, a third reflector disposed in the direction of light reflection of the second reflector, and a fifth lens disposed in the direction of light reflection of the third reflector.

6. A method for installing and debugging a fully polarized high-power laser source for lidar, characterized in that, Includes the following steps: Step 1: Fix the first laser on the optical path mounting plate and power it on to emit laser light. Fix the straight-line distance L0 between the power meter and the first laser. Adjust the angle position of the power meter relative to the first laser to maximize the received optical power value. Then reset it to zero. At this time, the position of the power meter G is S1. Step 2: Fix the position of the power meter. Place the first lens on the straight line L1 connecting the first laser and the power meter position S1. Adjust the position of the first lens to maximize the optical power received by the power meter. Fix the first lens. Step 3: Place the second laser and the power meter on a straight line L2 that is parallel to the straight line L1 in step 2. Receive the optical power through the power meter, fix the second laser, adjust the position of the power meter on the straight line L2 so that the straight distance between the power meter and the second laser is L0, and then fix the position of the power meter S2. Next, place the second lens on line L2 between the second laser and the power meter. Adjust the position of the second lens so that the optical power received by the power meter is at its maximum, which is when the insertion loss is at its minimum. Then fix the second lens. Step 4: Place the first reflector on line L1 to the right of the polarization rotator, place the polarization combining prism on line L2 to the right of the second lens, fix the power meter at position S2, and receive the optical power. Adjust the positions of the first reflector and the polarizing beam combiner to maximize the optical power received by the power meter, then fix the first reflector and the polarizing beam combiner. Step 5: Adjust the various optical components of the fully polarized amplification and collimation system; Step 6: Fix the power meter at the first output port of the fully polarized high-power laser source, i.e., the near-end detection output port. Place the filter at position S2, where the straight line L2 is located on the right side of the fully polarized amplification and collimation system. Place the fourth lens at the position where the straight line L2 is located on the right side of the filter in the direction of transmitted light. Adjust the position of the fourth lens so that the power meter at the first output port receives the maximum optical power. Step 7: Adjust the various optical components of the optical path reflection system.

7. The installation and debugging method as described in claim 6, characterized in that, The fully polarized amplification and collimation system includes a semiconductor optical amplifier, a third lens, and a bipolar isolator located sequentially on the optical path. Step five specifically involves: placing the semiconductor optical amplifier, the third lens, and the bipolar isolator sequentially in a position where the straight line L2 is located to the right of the polarization combining prism; receiving the optical power with a power meter; adjusting the positions of the semiconductor optical amplifier, the third lens, and the bipolar isolator until the optical power of the power meter is at its maximum; and then fixing the semiconductor optical amplifier, the third lens, and the bipolar isolator.

8. The installation and debugging method as described in claim 6, characterized in that, The optical path reflection system includes a second reflector disposed in the direction of light reflection of the filter, a third reflector disposed in the direction of light reflection of the second reflector, and a fifth lens disposed in the direction of light reflection of the third reflector; step seven specifically includes: Place the second reflector in the direction of reflected light at the lower left of the filter. Position the power meter at position S3 in the direction of reflected light of the second reflector to receive the optical power. Adjust the position and orientation of the second reflector to maximize the optical power value received by the power meter, and then fix the second reflector. Next, place the third reflector at position S3, and place the fifth lens on the right side of the third reflector in the direction of reflected light. Fix the power meter at the second output port of the fully polarized high-power laser source, i.e., the far-end detection output port. Receive the optical power in the direction of transmitted light from the fifth lens. Adjust the positions of the third reflector and the fifth lens to maximize the optical power value received by the power meter, and then fix the third reflector and the fifth lens.

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