TWI806092B - multi-channel transmitter - Google Patents

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 multiple modes, the modes of the continuous source light wave differing in wavelength and waveform. The pulse generator generates an intermediate light pulse with multiple modes according to the continuous source light wave, and the modes of the intermediate light pulse are different in wavelength and waveform. The mode separator has a plurality of output ends, and generates a plurality of output light pulses at the output ends according to the intermediate light pulse, and the output light pulses respectively correspond to the modes of the intermediate light pulse.

Description

multi-channel transmitter

The present invention relates to a multiple-input multiple-output (Multi-input Multi-output, MIMO) technology, in particular to a multi-channel transmitter.

A LiDAR (Light Detection And Ranging, LiDAR) system is a system that measures the distance from the LiDAR system to the target by irradiating a target with a laser light and measuring the flight time required for the laser light to return to the LiDAR system. system. Time-of-flight is calculated by calculating the cross-correlation of a return signal (i.e., the laser light received by the lidar system) and a reference signal (i.e., the laser light emitted by the lidar system)

Referring to FIG. 1 , a conventional multi-channel transmitter used in a MIMO LiDAR system includes multiple 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 part of the continuous light wave, and reflects the part of the continuous light wave back to the single-mode laser 91, so as to disturb the light in the single-mode laser 91 The field makes the continuous light wave chaotic. The remainder of the continuous light wave serves as an output of the conventional multi-channel transmitter.

Each light source 9 has its own chaotic characteristics, so the similarity between any two outputs of the traditional multi-channel transmitter is low, so that the multiple-input multiple-output lidar system has excellent anti-interference and anti-ambiguity capabilities in ranging .

However, the traditional multi-channel transmitter is bulky and expensive, which is not conducive to the miniaturization and cost reduction of the MIMO LiDAR system. In addition, the conventional multi-channel transmitter causes the MIMO LiDAR system to have a relatively poor detection probability, a relatively poor detection accuracy, and a relatively long computation time.

It is therefore an object of the present invention to provide a multi-channel transmitter which overcomes at least one disadvantage of the prior art.

Thus, the multi-channel transmitter of the present invention includes a light source, a pulse generator and a mode separator. The light source produces a continuous source light wave with multiple modes. The modes of the continuous source light waves vary in wavelength and waveform. The pulse generator is coupled with the light source to receive the continuous source light wave, and generates an intermediate light pulse with multiple modes according to the continuous source light wave. The modes of the intermediate light pulses vary in wavelength and waveform. The mode separator has an input coupled to the pulse generator to receive the intermediate optical pulse and a plurality of outputs. The mode separator generates a plurality of output light pulses at its output terminals respectively according to the intermediate light pulse. The output light pulses respectively correspond to the modes of the intermediate light pulse.

1: light source

11: Fabi-Perot Laser

12: Optical feedback loop

2: Pulse generator

21: filter

22:Modulator

23: Amplifier

26: filter

27: Amplifier

3: Modal Separator

31: wavelength demultiplexer

32: Amplifier

36: Delay line

37: wavelength multiplexer

38: Amplifier

39:Wavelength demultiplexer

4: Light-to-electricity converter

5: Antenna

6: Light to sound converter

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: FIG. 1 is a block diagram illustrating a conventional multi-channel transmitter for a multiple-input multiple-output lidar system; Fig. 2 is a block diagram illustrating a first embodiment of a multi-channel transmitter of the present invention used in a multi-input multi-output lidar system; Fig. 3 is a block diagram illustrating an implementation of a light source of the first embodiment ; Fig. 4 is a block diagram illustrating a first implementation of a pulse generator of the first embodiment; Fig. 5 is a block diagram illustrating a second implementation of the pulse generator; Fig. 6 is a block diagram Fig. 7 illustrates a third embodiment of the pulse generator; Fig. 7 is a block diagram illustrating a first embodiment of a mode separator of the first embodiment; Fig. 8 is a block diagram illustrating the mode A second embodiment of a state separator; FIG. 9 is a block diagram illustrating a second embodiment of a multi-channel transmitter of the present invention used in a multiple-input multiple-output lidar system; and FIG. 10 is a block diagram illustrating the present invention A third embodiment of the inventive multi-channel transmitter for a MIMO LiDAR system.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numerals.

Referring to FIG. 2 , a first embodiment of the multi-channel transmitter of the present invention used in a MIMO LiDAR system includes a light source 1 , a pulse generator 2 and a mode separator 3 . The light source 1 generates a continuous source light wave with multiple modes. The modes of the continuous source light waves vary in wavelength and waveform. The pulse generator 2 is coupled to the light source 1 for receiving the continuous source light wave, and generates an intermediate light pulse with multiple modes according to the continuous source light wave. The modes of the intermediate light pulses vary in wavelength and waveform. The mode separator 3 has an input terminal coupled to the pulse generator 2 to receive the intermediate optical pulse and a plurality of output terminals. The mode separator 3 respectively generates a plurality of output light pulses at its output terminals according to the intermediate light pulse, and the output light pulses respectively correspond to the modes of the intermediate light pulse.

In this embodiment, the light source 1 is a multi-mode chaotic light source, which can generate chaos by using at least one of light feedback, light injection or photoelectric feedback. In the embodiment shown in FIG. 3 , the light source 1 includes a Fabry-Perot laser 11 and an optical feedback loop 12 . The Fabi-Perot laser 11 is a multimode laser. The optical feedback loop 12 can be a fiber optic loop, a free space loop or a planar waveguide loop.

In this embodiment, the pulse generator 2 may be configured to modulate at least one continuous output light wave derived from the continuous source light wave to generate a source light pulse, and the intermediate light pulse is derived from the source light pulse. Optionally, the pulse generator 2 can be configured to An input light pulse derived from the source light pulse is amplified in one step to generate the intermediate light pulse. Alternatively, the pulse generator 2 may be configured to amplify the continuous input light waves at least for a predetermined period of time to generate the intermediate light pulses.

4 to 6 respectively illustrate the first to third implementations of the pulse generator 2, which are suitable for the case where the total number of modes of the intermediate light pulse is smaller than the total number of modes of the continuous source light wave.

As shown in the first embodiment shown in FIG. 4 , the pulse generator 2 includes a filter 21 , a modulator 22 and an amplifier 23 . The filter 21 couples the light source 1 (see FIG. 2 ) 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 for receiving the continuous input light wave and modulating the continuous input light wave to generate the source light pulse. The modulator 22 can be an electro-optic modulator (electro-optic modulator, EOM) that modulates the continuous input light wave according to an electric field, or can be an acousto-optic modulator that modulates the continuous input light wave according to an acoustic wave (acousto-optic modulator, AOM). The amplifier 23 is coupled to the modulator 22 for receiving the source optical pulse as the input optical pulse, and further coupled to the input terminal of the mode separator 3 (see FIG. 2 ). The amplifier 23 amplifies the input optical pulse to generate the intermediate optical pulse for the input terminal of the mode separator 3 (see FIG. 2 ).

The second embodiment as shown in FIG. 5 is similar to the first embodiment as shown in FIG. 2) for receiving the continuous source light wave as the continuous output light wave; (b) the filter 21 coupled to the modulator 22 for receiving the source light pulse, and filtering the source light pulse to remove the source light at least one mode of pulses for generating the output optical pulse; and (c) the amplifier 23 coupled to the filter 21 for receiving the output optical pulse.

As shown in the third embodiment shown in FIG. 6 , the pulse generator 2 includes a filter 26 and an amplifier 27 . The filter 26 is coupled to the light source 1 (see FIG. 2 ) for receiving the continuous source light wave. 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 is coupled to the filter for receiving the continuous output light wave, and further coupled to the input terminal of the mode separator 3 (see FIG. 2 ), and is operable in an on state and an off state. The amplifier 27 is controlled to be in the on-state during the predetermined time period and to be in the off-state outside the predetermined time period, so as to amplify the continuous output light wave in the predetermined time period to generate the intermediate light pulse for the This input of the mode separator 3 (see FIG. 2 ) receives. The amplifier 27 may be a Semiconductor Optical Amplifier (SOA).

Note that the total number of modes in the middle light pulse is equal to the continuous source In the case of the total number of modes of light waves, the filter 21 of the first embodiment and the second embodiment shown in FIG. 4 and FIG. 5 and the filter of the third embodiment shown in FIG. 6 26 can be omitted.

In this embodiment, the output light pulses may be parallel or interleaved in time. The mode separator 3 is configured to separate at least the modes of the intermediate light pulses to generate a plurality of separated light pulses respectively originating from the output light pulses.

Fig. 7 illustrates a first embodiment of the mode separator 3, which generates the output light pulses in parallel. As shown in the first embodiment shown in FIG. 7 , the mode separator 3 includes a wavelength demultiplexer 31 and a plurality of amplifiers 32 . The wavelength demultiplexer 31 has an input coupled to the input of 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 pulses to generate the separated optical pulses at the outputs thereof respectively. 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 respectively receive the separated optical pulses, and further coupled to the output terminals of the mode separator 3 . Each amplifier 32 amplifies a respective split optical pulse to generate a respective output optical pulse at a respective output terminal of the mode separator 3 . Each amplifier 32 can be an Erbium-Doped Fiber Amplifier (EDFA).

Fig. 8 illustrates a second embodiment of the mode separator 3, which generates the output light pulses which are interleaved in time. The second embodiment shown in FIG. 8, The mode separator 3 includes a wavelength demultiplexer 31 as shown in FIG. 7 , 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 ends of the wavelength demultiplexer 31 to respectively receive the split optical pulses, and delay the split optical pulses by different delay times to generate a plurality of split optical pulses respectively at time Interleaved delayed light pulses on top. The wavelength multiplexer 37 has a plurality of input terminals respectively coupled to the delay lines 36 to respectively receive the delayed optical pulses, and an output terminal. The wavelength multiplexer 37 combines the delayed optical pulses to produce a combined optical signal at its output. The amplifier 38 is coupled to the output end of the wavelength multiplexer 37 to receive the combined optical signal, and amplifies the combined optical signal to generate an amplified optical signal. The amplifier 38 may be an erbium-doped fiber amplifier. The wavelength demultiplexer 39 has an input terminal coupled to the amplifier 38 to receive the amplified optical signal, and a plurality of output terminals respectively coupled to the output terminals of the mode separator 3 . The wavelength demultiplexer 39 separates the delayed optical pulses contained in the combined optical signal to generate the output optical pulses respectively at the output terminals thereof. The wavelength multiplexer 37 and the wavelength demultiplexer 39 can be implemented using fiber Bragg gratings.

To sum up, the multi-channel transmitter of this embodiment has the following advantages.

First, by virtue of the light source 1 generating the continuous source light wave with multiple modes, the multi-channel transmitter can be small and inexpensive, which is beneficial to the miniaturization and cost reduction of the MIMO LiDAR system.

Second, by virtue of the pulse generator 2 according to the continuous source light wave to generate the The multimode intermediate optical pulse, the multichannel transmitter can have a relatively large signal-to-noise ratio (SNR), because it can have a relatively high peak value even if its power budget is limited Output Power. Therefore, the MIMO LiDAR system has a relatively better detection probability and a relatively better detection accuracy. Furthermore, the computing time of the MIMO LiDAR system can be reduced by shortening the width of the intermediate light pulse.

Referring to FIG. 9 , the multi-channel transmitter of the present invention is used in a second embodiment of a multiple-input multiple-output lidar system. The second embodiment is similar to the first embodiment, but different from the first embodiment, The multi-channel transmitter of the second embodiment further includes an optical-to-electrical converter 4 and a plurality of antennas 5 .

In the second embodiment, the optical-to-electrical converter 4 is coupled to the output ends of the mode separator 3 to receive the output optical pulses and convert the output optical pulses into a plurality of output electrical pulses respectively. pulse. The antennas 5 are coupled to the optical-to-electrical converter 4 for respectively receiving the output electrical pulses and radiating the output electrical pulses respectively.

Referring to FIG. 10 , the multi-channel transmitter of the present invention is used in a third embodiment of a multiple-input multiple-output lidar system. The third embodiment is similar to the first embodiment, but different from the first embodiment, The multi-channel transmitter of the third embodiment further includes a light-to-acoustic converter 6 .

In the third embodiment, the optical-to-acoustic converter 6 is coupled to the output terminals of the mode separator 3 to receive the output optical pulses and divide the output optical pulses into Do not convert to multiple output sound pulses.

In the foregoing description, for purposes of explanation, numerous specific details have been 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 may be practiced without some of these specific details. It should also be understood that in this specification, reference to "an embodiment" and an embodiment indicated by an ordinal number means that specific features, structures or characteristics may be included in the practice of the present invention. It should be further understood that in this specification, for the purpose of streamlining the invention and helping to understand the various aspects of the invention, sometimes in a single embodiment, various features are combined together in the illustrations or descriptions, and Where appropriate, one or more features or specific details from one embodiment may be practiced with one or more features or specific details from another embodiment in practicing the invention.

Although the invention has been described in connection with the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various arrangements including the broadest spirit and scope of the interpretation to encompass all such Modifications and Equivalent Arrangements.

But the above-mentioned ones are only embodiments of the present invention, and should not limit the scope of the present invention. All simple equivalent changes and modifications made according to the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of the present invention.

1: light source

2: Pulse generator

3: Modal Separator

Claims (13)

A multi-channel transmitter, comprising: a light source, generating a continuous source light wave with multiple modes, the modes of the continuous source light wave are different in wavelength and waveform; a pulse generator, coupled to the light source to receive the a continuous source light wave from which an intermediate light pulse having a plurality of modes is generated, the modes of the intermediate light pulse being different in wavelength and waveform; and a mode separator having a coupling coupled to the pulse generating The device is used to receive the input end and a plurality of output ends of the intermediate optical pulse; wherein, the mode separator generates a plurality of output optical pulses at the output ends of the intermediate optical pulse respectively, and the output optical pulses correspond to The mode of the intermediate optical pulse; the pulse generator includes: a modulator for receiving a continuous input optical wave from the continuous source optical wave, and modulating the continuous input optical wave to generate a source optical pulse, the intermediate The optical pulse is derived from the source optical pulse; the pulse generator also includes: an amplifier coupled to the input end of the mode separator for receiving an input optical pulse derived from the source optical pulse and amplifying the input optical pulse to generate the intermediate optical pulse for receiving by the input end of the mode separator. The multi-channel transmitter as claimed in claim 1, wherein the light source is a multi-mode chaotic light source. The multi-channel transmitter as claimed in claim 1, wherein the modulator is an electro-optic modulator. The multi-channel transmitter as claimed in item 1, wherein the modulator is a light modulator. The multi-channel transmitter as claimed in item 1, wherein the pulse generator further includes: a filter coupled to the light source to receive the continuous source light wave, and further coupled to the modulator, the filter to the continuous The source lightwave is filtered to remove at least one mode of the continuous source lightwave for generating the continuous input lightwave for receipt by the modulator. The multi-channel transmitter as claimed in claim 1, wherein the pulse generator further includes: a filter coupled to the modulator to receive the source light pulse, and further coupled to the amplifier, the filter is coupled to the source light pulse The pulses are filtered to remove at least one mode of the source light pulses for generating the input light pulses for receipt by the amplifier. A multi-channel transmitter, comprising: a light source, generating a continuous source light wave with multiple modes, the modes of the continuous source light wave are different in wavelength and waveform; a pulse generator, coupled to the light source to receive the a continuous source light wave from which an intermediate light pulse having a plurality of modes is generated, the modes of the intermediate light pulse being different in wavelength and waveform; and a mode separator having a coupling coupled to the pulse generating The device is used to receive the input end and a plurality of output ends of the intermediate optical pulse; wherein, the mode separator generates a plurality of output optical pulses at the output ends of the intermediate optical pulse respectively, and the output optical pulses correspond to mode of the intermediate optical pulse; the pulse generator includes: an amplifier coupled to the input of the mode separator for receiving a continuous input light originating from the continuous source light wave wave, and amplifying the successive input light waves for a predetermined period of time to generate the intermediate light pulses for receipt by the input of the mode separator. The multi-channel transmitter as claimed in item 7, wherein, the pulse generator further includes: a filter coupled to the light source to receive the continuous source light wave, and further coupled to the amplifier, the filter to the continuous source light wave Filtering is performed to remove at least one mode of the continuous source light wave for generating the continuous output light wave for receipt by the amplifier. A multi-channel transmitter, comprising: a light source, generating a continuous source light wave with multiple modes, the modes of the continuous source light wave are different in wavelength and waveform; a pulse generator, coupled to the light source to receive the a continuous source light wave from which an intermediate light pulse having a plurality of modes is generated, the modes of the intermediate light pulse being different in wavelength and waveform; and a mode separator having a coupling coupled to the pulse generating The device is used to receive the input end and a plurality of output ends of the intermediate optical pulse; wherein, the mode separator generates a plurality of output optical pulses at the output ends of the intermediate optical pulse respectively, and the output optical pulses correspond to the mode of the intermediate optical pulse; the mode splitter includes: a first wavelength demultiplexer having a coupling to the input of the mode splitter to receive the intermediate optical pulse an input terminal, and a plurality of output terminals, the first wavelength demultiplexer separates the modes of the intermediate optical pulse to generate a plurality of separate optical pulses at the output terminals thereof respectively, the output optical pulses are respectively separated from the Light pulses are generated. The multi-channel transmitter as claimed in item 9, wherein the mode separator further includes: a plurality of amplifiers respectively coupled to the output terminals of the first wavelength demultiplexer to receive the separated optical pulses respectively, And further respectively coupled to the output ends of the mode separator, each amplifier amplifies a respective split light pulse to generate a respective output light pulse at a respective output port of the mode splitter. The multi-channel transmitter as claimed in item 9, wherein the mode splitter further includes: a plurality of delay lines, respectively coupled to the output ends of the first wavelength demultiplexer to receive the separated light respectively pulse, and delaying the split optical pulses by different delay times to generate a plurality of delayed optical pulses respectively; a wavelength multiplexer, the wavelength multiplexer has a plurality of delay lines respectively coupled to receive the an input terminal for delayed optical pulses, and an output terminal, the wavelength multiplexer combines the delayed optical pulses to produce a combined optical signal at the output terminal thereof; an amplifier, coupled to the output terminal of the wavelength multiplexer The terminal is used to receive the combined optical signal, and amplifies the combined optical signal to generate an amplified optical signal; and a second wavelength demultiplexer, the second wavelength demultiplexer has a coupling to the amplifier to receive the amplified optical signal and a plurality of output ports respectively coupled to the output ports of the mode splitter, the second wavelength demultiplexer separates the delayed optical pulses contained in the combined optical signal to separate them in the The output terminals generate the output light pulses. The multi-channel transmitter as described in claim 1, further comprising: an optical-to-electrical converter coupled to the output terminals of the mode separator for receiving the output optical pulses and converting the output optical pulses into a plurality of output electrical pulses; and a plurality of antennas coupled to the The light-to-electricity converter is used for respectively receiving the output electrical pulses and radiating the output electrical pulses respectively. The multi-channel transmitter as claimed in claim 1, further comprising: an optical-to-acoustic converter coupled to the output terminals of the mode separator to receive the output optical pulses, and separate the output optical pulses Convert to multiple output sound pulses.

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