Multi-channel transmitter

Abstract

A multi-channel transmitter includes a light source, a pulse generator, and a mode separator. The light source generates a continuous source light wave having a plurality of modes, the modes of the continuous source light wave being different in wavelength and wave shape. The pulse generator generates an intermediate light pulse having a plurality of modes from the continuous source light wave, the modes of the intermediate light pulse being different in wavelength and wave shape. The mode separator has a plurality of outputs and generates a plurality of output light pulses at the outputs thereof respectively from the intermediate light pulse, the output light pulses respectively corresponding to the modes of the intermediate light pulse.

Description

TECHNICAL FIELD

[0001] The present application relates to a Multi-input Multi-output (MIMO) technology, and in particular, to a multi-channel transmitter. BACKGROUND

[0002] A Light Detection And Ranging (LiDAR) system is a system that measures the distance from the LiDAR system to a target by illuminating the target with a laser and measuring the time of flight of the return of the laser to the LiDAR system. The time of flight is calculated by cross-correlating a return signal (i.e., the LiDAR system receives the laser) and a reference signal (i.e., the LiDAR system emits the laser).

[0003] Reference Figure 1 The existing multi-channel transmitter used in a Multi-input Multi-output LiDAR system includes a plurality of light sources 9. Each light source 9 is a single-mode chaotic light source and includes a single-mode laser 91 and an optical feedback loop 92. The single-mode laser 91 generates a continuous light wave with a single mode. The optical feedback loop 92 couples the single-mode laser 91 to receive a portion of the continuous light wave and reflects the portion of the continuous light wave back to the single-mode laser 91 so as to disturb the optical field in the single-mode laser 91 to make the continuous light wave chaotic. The remaining portion of the continuous light wave is an output of the existing multi-channel transmitter.

[0004] Each light source 9 has its own chaotic characteristics, so the similarity of any two outputs of the existing multi-channel transmitter is low, making the Multi-input Multi-output LiDAR system have excellent anti-interference and anti-ambiguity capabilities in ranging.

[0005] However, the existing multi-channel transmitter is bulky and expensive, which is not conducive to the miniaturization and cost reduction of the Multi-input Multi-output LiDAR system. In addition, the existing multi-channel transmitter causes the Multi-input Multi-output LiDAR system to have a relatively poor detection probability, a relatively poor detection accuracy, and a relatively long calculation time. SUMMARY

[0006] The present application aims to provide a multi-channel transmitter that can at least overcome the shortcomings of the prior art.

[0007] The multi-channel transmitter of the present application comprises a light source, a pulse generator and a mode separator. The light source generates a continuous source light wave having a plurality of modes. The modes of the continuous source light wave are different in wavelength and wave shape. The pulse generator is coupled to the light source to receive the continuous source light wave and generates an intermediate light pulse having a plurality of modes according to the continuous source light wave. The modes of the intermediate light pulse are different in wavelength and wave shape. The mode separator has an input end coupled to the pulse generator to receive the intermediate light pulse and a plurality of output ends. The mode separator generates a plurality of output light pulses at its output ends respectively according to the intermediate light pulse. The output light pulses respectively correspond to the modes of the intermediate light pulse.

[0008] The present application has the beneficial effect that, by virtue of the light source generating the continuous source light wave having a plurality of modes, the multi-channel transmitter can be made compact and inexpensive, which is conducive to the miniaturization and cost reduction of the multi-input multi-output laser radar system. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 FIG. 1 is a block diagram illustrating a prior art multi-channel transmitter for a multi-input multi-output laser radar system;

[0010] Figure 2 FIG. 2 is a block diagram illustrating a first embodiment of a multi-channel transmitter of the present application for a multi-input multi-output laser radar system;

[0011] Figure 3 FIG. 3 is a block diagram illustrating an implementation of a light source of the first embodiment;

[0012] Figure 4 FIG. 4 is a block diagram illustrating a first implementation of a pulse generator of the first embodiment;

[0013] Figure 5 FIG. 5 is a block diagram illustrating a second implementation of the pulse generator;

[0014] Figure 6 FIG. 6 is a block diagram illustrating a third implementation of the pulse generator;

[0015] Figure 7 FIG. 7 is a block diagram illustrating a first implementation of a mode separator of the first embodiment;

[0016] Figure 8 FIG. 8 is a block diagram illustrating a second implementation of the mode separator;

[0017] Figure 9 FIG. 9 is a block diagram illustrating a second embodiment of a multi-channel transmitter of the present application for a multi-input multi-output laser radar system; and

[0018] Figure 10 is a block diagram illustrating a third embodiment of a multi-channel transmitter for a multi-input multi-output lidar system of the present application. DETAILED DESCRIPTION

[0019] The present application will be described in detail below with reference to the accompanying drawings and embodiments.

[0020] Referring to Figure 2 , a first embodiment of a multi-channel transmitter for a multi-input multi-output lidar system of the present application comprises a light source 1, a pulse generator 2, and a mode separator 3. The light source 1 generates a continuous source light wave having a plurality of modes. The modes of the continuous source light wave are different from each other in wavelength and waveform. The pulse generator 2 is coupled to the light source 1 to receive the continuous source light wave and generates an intermediate light pulse having a plurality of modes from the continuous source light wave. The modes of the intermediate light pulse are different from each other in wavelength and waveform. The mode separator 3 has an input end coupled to the pulse generator 2 to receive the intermediate light pulse and a plurality of output ends. The mode separator 3 generates a plurality of output light pulses at its output ends from the intermediate light pulse, respectively, the output light pulses corresponding to the modes of the intermediate light pulse, respectively.

[0021] In this embodiment, the light source 1 is a multimode chaotic light source, which can be generated using at least one of optical feedback, optical injection, or optoelectronic feedback. As shown in the embodiment, Figure 3 the light source 1 comprises a Fabry-Perot laser 11 and an optical feedback loop 12. The Fabry-Perot laser 11 is a multimode laser. The optical feedback loop 12 can be a fiber-type loop, a free-space loop, or a planar waveguide loop.

[0022] In this embodiment, the pulse generator 2 can be configured to at least modulate a continuous output light wave derived from the continuous source light wave to generate a light pulse source, the intermediate light pulse being derived from the light pulse source. Alternatively, the pulse generator 2 can be configured to further amplify an input light pulse derived from the light pulse source to generate the intermediate light pulse. Or, the pulse generator 2 can be configured to at least amplify the continuous input light wave for a predetermined time period to generate the intermediate light pulse.

[0023] Figures 4 to 6 The first to third embodiments of the pulse generator 2 are described, respectively, which are applicable to a case where the total number of modes of the intermediate light pulse is less than the total number of modes of the continuous source light wave.

[0024] As shown in the embodiment, Figure 4In the first embodiment shown, the pulse generator 2 includes a filter 21, a modulator 22, and an amplifier 23. The filter 21 couples to the light source 1 (see...). Figure 2 The amplifier 23 is coupled to the modulator 24 to receive the continuous source light wave. The filter 21 filters the continuous source light wave to remove at least one mode of the continuous source light wave to generate the continuous input light wave. The filter 21 may be a bandpass filter or may be implemented using fiber Bragg gratings (FBGs). The modulator 22 is coupled to the filter 21 to receive the continuous input light wave and modulate the continuous input light wave to generate the light pulse source. The modulator 22 may be an electro-optic modulator (EOM) that modulates the continuous input light wave according to an electric field, or an acousto-optic modulator (AOM) that modulates the continuous input light wave according to an acoustic wave. The amplifier 23 is coupled to the modulator 22 to receive the light pulse source as the input light pulse, and further coupled to the mode separator 3 (see...). Figure 2 The input terminal of the amplifier 23 is used to amplify the input optical pulse to generate the intermediate optical pulse, which is then supplied to the mode separator 3 (see...). Figure 2 The input terminal receives the signal.

[0025] like Figure 5 The second embodiment shown is similar to that described above. Figure 4 The difference between the first embodiment shown and the first embodiment is that: (a) the modulator 22 couples the light source 1 (see...) Figure 2 (a) the filter 21 receives the continuous source light wave as the continuous output light wave; (b) the filter 21 couples the modulator 22 to receive the light pulse source and filters the light pulse source to remove at least one mode of the light pulse source to generate the output light pulse; and (c) the amplifier 23 couples the filter 21 to receive the output light pulse.

[0026] like Figure 6 In the third embodiment shown, the pulse generator 2 includes a filter 26 and an amplifier 27. The filter 26 is coupled to the light source 1 (see...). Figure 2 The filter 26 filters the continuous source light wave to remove at least one mode of the continuous source light wave to generate the continuous output light wave. The filter 26 may be a bandpass filter or may be implemented using a fiber Bragg grating. The amplifier 27 couples the filter to receive the continuous output light wave and further couples the mode separator 3 (see...) Figure 2The amplifier 27 is controlled to be in the on state during the predetermined time period and in the off state outside the predetermined time period, thereby amplifying the continuous output light wave during the predetermined time period to generate the intermediate light pulse for the mode separator 3 (see...). Figure 2 The input terminal of the amplifier 27 is received. The amplifier 27 may be a semiconductor optical amplifier (SOA).

[0027] It should be noted that when the total number of modes of the intermediate optical pulse is equal to the total number of modes of the continuous source light wave, such as Figure 4 and Figure 5 The filter 21 of the first embodiment and the second embodiment shown, and as shown Figure 6 The filter 26 in the third embodiment shown can be omitted.

[0028] In this embodiment, the output optical pulses can be parallel or interleaved in time. The mode separator 3 is configured to separate at least the modes of the intermediate optical pulses to generate a plurality of separated optical pulses, each originating from the output optical pulses.

[0029] Figure 7 This describes a first embodiment of the mode separator 3, in which the generated output optical pulses are parallel. For example... Figure 7 In the first embodiment shown, the mode separator 3 includes a wavelength demultiplexer 31 and a plurality of amplifiers 32. The wavelength demultiplexer 31 has an input terminal coupled to the mode separator 3 to receive the intermediate optical pulse, and a plurality of output terminals. The wavelength demultiplexer 31 separates the modes of the intermediate optical pulse to generate the separated optical pulses at their respective output terminals. The wavelength demultiplexer 31 can be implemented using a fiber Bragg grating. The amplifiers 32 are respectively coupled to the output terminals of the wavelength demultiplexer 31 to receive the separated optical pulses, and further coupled to the output terminals of the mode separator 3. Each amplifier 32 amplifies its respective separated optical pulse to generate a respective output optical pulse at its respective output terminal of the mode separator 3. Each amplifier 32 can be an erbium-doped fiber amplifier (EDFA).

[0030] Figure 8 A second embodiment of the mode separator 3 is described, wherein the output optical pulses generated are staggered in time. For example... Figure 8 In the second embodiment shown, the mode separator 3 includes a... Figure 7The same wavelength demultiplexer 31, a plurality of delay lines 36, a wavelength multiplexer 37, an amplifier 38, and another wavelength demultiplexer 39. The delay lines 36 are respectively coupled to the output of the wavelength demultiplexer 31 to respectively receive the separated light pulses, and respectively delay the separated light pulses by different delay times to respectively generate a plurality of time-interleaved delayed light pulses. The wavelength multiplexer 37 has a plurality of inputs respectively coupled to the delay lines 36 to respectively receive the delayed light pulses, and an output. The wavelength multiplexer 37 combines the delayed light pulses together to generate a combined light signal at the output thereof. The amplifier 38 is coupled to the output of the wavelength multiplexer 37 to receive the combined light signal, and amplifies the combined light signal to generate an amplified light signal. The amplifier 38 can be an erbium-doped fiber amplifier. The wavelength demultiplexer 39 has an input coupled to the amplifier 38 to receive the amplified light signal, and a plurality of outputs respectively coupled to the outputs of the mode separator 3. The wavelength demultiplexer 39 separates the delayed light pulses contained in the combined light signal to respectively generate the output light pulses at the outputs thereof. The wavelength multiplexer 37 and the wavelength demultiplexer 39 can be implemented using fiber Bragg gratings.

[0031] In summary, the multi-channel transmitter of the present embodiment has the following advantages.

[0032] First, by virtue of the light source 1 generating the continuous source light wave having multiple modes, the multi-channel transmitter can be compact and inexpensive, which is conducive to the miniaturization and cost reduction of the multi-input multi-output laser radar system.

[0033] Second, by virtue of the pulse generator 2 generating the intermediate light pulse having multiple modes from the continuous source light wave, the multi-channel transmitter can have a relatively large signal-to-noise ratio (SNR), because even if its power budget is limited, it can have a relatively high peak output power. Therefore, the multi-input multi-output laser radar system has a relatively good detection probability and a relatively good detection accuracy. In addition, the calculation time of the multi-input multi-output laser radar system can be reduced by shortening the width of the intermediate light pulse.

[0034] Referring to Figure 9 , a second embodiment of a multi-channel transmitter for a multi-input multi-output laser radar system of the present application is shown, which is similar to the first embodiment, but different from the first embodiment in that the multi-channel transmitter of the second embodiment further comprises an optical-to-electrical converter 4 and a plurality of antennas 5.

[0035] In the second embodiment, the light-to-electricity converter 4 is coupled to the output of the mode separator 3 to receive the output light pulses and to convert the output light pulses into a plurality of output electrical pulses, respectively. The antenna 5 is coupled to the light-to-electricity converter 4 to receive the output electrical pulses, respectively, and to radiate the output electrical pulses, respectively.

[0036] Referring now to the drawings and in particular to FIG. 1, there is shown a first embodiment of a multi-channel transmitter for a multi-input multi-output lidar system in accordance with the present application. The multi-channel transmitter comprises a mode separator 3, a light-to-electricity converter 4, and an antenna 5. Figure 10 , showing a third embodiment of a multi-channel transmitter for a multi-input multi-output lidar system in accordance with the present application, which is similar to the first embodiment, but differs from the first embodiment in that the third embodiment's multi-channel transmitter further comprises a light-to-sound converter 6.

[0037] In the third embodiment, the light-to-sound converter 6 is coupled to the output of the mode separator 3 to receive the output light pulses and to convert the output light pulses into a plurality of output sound pulses, respectively.

[0038] In the above description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that one or more other embodiments can be practiced without some of these specific details. It should be understood that in this description, references to "embodiments" having ordinal indicators, e.g., first, second, etc., refer to structures or features called out by the ordinal indicator. It should further be understood that in this description, for purposes of brevity, circuit elements are shown in block diagram form, and that everyone having the benefit of this description can implement one or more of the embodiments using circuit elements drawn from a typically available element set.

[0039] While the application has been described in connection with exemplary embodiments, it will be understood that the application is not limited to the disclosed embodiments, but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation of the appended claims to encompass all such modifications and equivalent arrangements.

Claims

1. A multi-channel transmitter, characterized by Comprising: a multimode chaotic light source generating a continuous source light wave having a plurality of modes, the modes of the continuous source light wave being different in wavelength and shape; a pulse generator coupled to the multimode chaotic light source to receive the continuous source light wave and generate an intermediate light pulse having a plurality of modes from the continuous source light wave, the modes of the intermediate light pulse being different in wavelength and shape; a mode separator having an input coupled to the pulse generator to receive the intermediate light pulse and a plurality of outputs; wherein the mode separator generates a plurality of output light pulses from the intermediate light pulse at the outputs thereof, respectively, the output light pulses corresponding to the modes of the intermediate light pulse, respectively.

2. The multi-channel transmitter of claim 1, wherein, the pulse generator includes a modulator to receive a continuous input light wave from the continuous source light wave and modulate the continuous input light wave to generate a light pulse source, the intermediate light pulse being generated from the light pulse source.

3. The multi-channel transmitter of claim 2, wherein, the modulator is an electro-optical modulator.

4. The multi-channel transmitter of claim 2, wherein, the modulator is an acousto-optical modulator.

5. The multi-channel transmitter of claim 2, wherein, the pulse generator further includes an amplifier coupled to the modulator to receive an input light pulse from the light pulse source and amplify the input light pulse to generate the intermediate light pulse for the input of the mode separator.

6. The multi-channel transmitter of claim 5, wherein, the pulse generator further includes a filter coupled to the multimode chaotic light source to receive the continuous source light wave and further coupled to the modulator, the filter filtering the continuous source light wave to remove at least one mode of the continuous source light wave to generate the continuous input light wave for the modulator.

7. The multi-channel transmitter of claim 5, wherein, the pulse generator further includes a filter coupled to the modulator to receive the light pulse source and further coupled to the amplifier, the filter filtering the light pulse source to remove at least one mode of the light pulse source to generate the input light pulse for the amplifier.

8. The multi-channel transmitter of claim 1, wherein, the pulse generator includes an amplifier coupled to the multimode chaotic light source to receive a continuous input light wave from the continuous source light wave and amplify the continuous input light wave over a predetermined time period to generate the intermediate light pulse for the input of the mode separator.

9. The multi-channel transmitter of claim 8, wherein, the pulse generator further includes a filter coupled to the multimode chaotic light source to receive the continuous source light wave and further coupled to the amplifier, the filter filtering the continuous source light wave to remove at least one mode of the continuous source light wave to generate a continuous output light wave for the amplifier.

10. The multi-channel transmitter of claim 1, wherein, the mode separator includes a first wavelength demultiplexer having an input coupled to the input of the mode separator to receive the intermediate light pulse and a plurality of outputs, the first wavelength demultiplexer separating the modes of the intermediate light pulse to generate a plurality of separated light pulses at the outputs thereof, respectively, the output light pulses being generated from the separated light pulses, respectively.

11. The multi-channel transmitter of claim 10, wherein, The mode separator further comprises a plurality of amplifiers respectively coupled to the output ends of the first wavelength demultiplexer to respectively receive the separated optical pulses and further respectively coupled to the output ends of the mode separator, each amplifier amplifying the respective separated optical pulse to generate a respective output optical pulse at the respective output end of the mode separator.

12. The multi-channel transmitter of claim 10, wherein, The mode separator further comprises: a plurality of delay lines respectively coupled to the output ends of the first wavelength demultiplexer to respectively receive the separated optical pulses and respectively delay the separated optical pulses by different delay times to respectively generate a plurality of delayed optical pulses; a wavelength multiplexer having a plurality of input ends respectively coupled to the delay lines to respectively receive the delayed optical pulses and an output end, the wavelength multiplexer combining the delayed optical pulses together to generate a combined optical signal at the output end thereof; an amplifier coupled to the output end of the wavelength multiplexer to receive the combined optical signal and amplify the combined optical signal to generate an amplified optical signal; and a second wavelength demultiplexer having an input end coupled to the amplifier to receive the amplified optical signal and a plurality of output ends respectively coupled to the output ends of the mode separator, the second wavelength demultiplexer separating the delayed optical pulses contained in the combined optical signal to respectively generate the output optical pulses at the output ends thereof.

13. The multi-channel transmitter of claim 1, wherein, Further comprising: an optical-to-electrical converter coupled to the output ends of the mode separator to receive the output optical pulses and respectively convert the output optical pulses into a plurality of output electrical pulses; and a plurality of antennas coupled to the optical-to-electrical converter to respectively receive the output electrical pulses and respectively radiate the output electrical pulses. Further comprising an optical-to-acoustic converter coupled to the output ends of the mode separator to receive the output optical pulses and respectively convert the output optical pulses into a plurality of output acoustic pulses.

14. The multi-channel transmitter of claim 1, wherein, Further comprising: an optical-to-electrical converter coupled to the output ends of the mode separator to receive the output optical pulses and respectively convert the output optical pulses into a plurality of output electrical pulses; and a plurality of antennas coupled to the optical-to-electrical converter to respectively receive the output electrical pulses and respectively radiate the output electrical pulses. Further comprising an optical-to-acoustic converter coupled to the output ends of the mode separator to receive the output optical pulses and respectively convert the output optical pulses into a plurality of output acoustic pulses.

Images