CN118263750A

CN118263750A - Laser and laser radar

Info

Publication number: CN118263750A
Application number: CN202211681467.8A
Authority: CN
Inventors: 李大汕; 刘武; 易昌申; 向少卿
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2022-12-27
Filing date: 2022-12-27
Publication date: 2024-06-28

Abstract

The embodiment of the invention provides a laser and a laser radar, wherein the laser comprises: a gain array comprising: a plurality of gain units sequentially arranged along a first direction; a frequency selective array comprising: a plurality of frequency selection units sequentially arranged along the first direction, wherein each frequency selection unit is respectively corresponding to the corresponding gain unit; a first coupling array comprising: the first coupling units are sequentially arranged along the first direction, and each first coupling unit is respectively positioned between the corresponding gain unit and the corresponding frequency selection unit; the gain units are respectively and sequentially arranged with the corresponding first coupling units and the frequency selection units along the second direction to form a laser emission unit. By adopting the scheme, the size and the use cost can be reduced while the multi-path emergent light is output.

Description

Laser and laser radar

Technical Field

The invention relates to the technical field of laser radars, in particular to a laser and a laser radar.

Background

The frequency modulation continuous wave (Frequency Modulated Continuous Wave, abbreviated as FMCW) laser radar combines the frequency modulation continuous wave ranging and the laser detection technology, and has the advantages of large ranging range, high range resolution, capability of Doppler speed measurement, on-chip integration and the like.

The narrow linewidth laser is a light source suitable for the FMCW laser radar, and the semiconductor external cavity narrow linewidth laser is an important type in the narrow linewidth laser and can also be used as the light source of the FMCW laser radar.

However, most of the existing semiconductor external cavity narrow linewidth lasers are packaged separately, so that in order to improve the spatial resolution, the FMCW laser radar needs to use a plurality of semiconductor external cavity narrow linewidth lasers as its light sources, and an independent packaging structure is adopted, which results in higher use cost and increased size of the FMCW laser radar.

The matters in the background section are only those known to the public and do not, of course, represent prior art in the field.

Disclosure of Invention

In view of this, an aspect of the embodiments of the present invention provides a laser, which is integrated with a plurality of laser emitting units, and outputs multiple paths of emitted light, while reducing the size and the use cost.

In another aspect of the embodiment of the present invention, a laser radar is provided, which uses a laser integrated with a plurality of laser emitting units as a light source, so that the size and the use cost of the laser radar can be reduced.

First, an embodiment of the present invention provides a laser including:

a gain array comprising: a plurality of gain units sequentially arranged along a first direction;

a frequency selective array comprising: a plurality of frequency selection units sequentially arranged along the first direction, wherein each frequency selection unit is respectively corresponding to the corresponding gain unit; a first coupling array comprising: the first coupling units are sequentially arranged along the first direction, and each first coupling unit is respectively positioned between the corresponding gain unit and the corresponding frequency selection unit;

The gain units are respectively and sequentially arranged with the corresponding first coupling units and the frequency selection units along the second direction to form a laser emission unit.

Optionally, the frequency selecting unit includes: a grating;

The first coupling unit includes: and a coupling lens.

Optionally, the frequency selecting unit further includes: an optical fiber, the grating being formed on the optical fiber;

The coupling lens includes: and the optical fiber lens is arranged at the end part of the optical fiber, which is close to the direction of the gain unit.

Optionally, the frequency selecting unit includes: and the grating is formed on the planar waveguide.

Optionally, each gain unit in the gain array is independently driven.

Optionally, the laser further comprises:

A probe array comprising: the detection units are sequentially arranged along the first direction, and are respectively arranged at the end parts of the light paths of the corresponding laser emission units so as to acquire light signals emitted by the corresponding laser emission units and convert the light signals into electric signals;

The filtering module is suitable for filtering the electric signal to enable the frequency of the output signal to be detected to be higher than a preset frequency;

and the judging module is used for judging the working mode of the laser transmitting unit based on the signal to be detected.

Optionally, the detection unit comprises a photoelectric detector, and is suitable for acquiring the optical signal sent by the laser emission unit and converting the optical signal into a current signal;

the detection unit further includes: and the transimpedance amplifier is suitable for converting the current signal into a voltage signal and amplifying the voltage signal.

Optionally, the judging module includes: the comparator is suitable for comparing the intensity value of the signal to be detected with a preset intensity threshold value and judging the working mode of the laser emission unit according to an output result; wherein: if the intensity value of the signal to be detected is smaller than the preset intensity threshold value, determining that the laser emission unit is in a single-mode state; and if the intensity value of the signal to be detected is not smaller than the preset intensity threshold value, determining that the laser emission unit is in a non-single mode state.

Optionally, the comparator continuously compares the intensity value of the signal to be detected with the preset intensity threshold for multiple times according to preset conditions, and determines the working mode of the laser emission unit based on the judgment result of the comparator for multiple times, where the method includes at least one of the following steps:

If the judgment results of the comparators all determine that the laser emission unit is in a single-mode state, determining that the laser emission unit is in a stable single-mode state;

If the laser emission unit is determined to be in a non-single mode state and the duty ratio in the non-single mode state is determined to be larger than a first preset ratio in the judging results of the comparators, the laser emission unit is determined to be in a multi-mode state;

and if the laser emission unit is determined to be in a non-single mode state and the duty ratio in the non-single mode state is determined to be smaller than a second preset ratio in the judging results of the comparators, determining that the laser emission unit is in a mode-skipping state.

Optionally, the laser further comprises: and the control module is suitable for outputting control signals to the corresponding laser emission units based on the judging result of the judging module so as to adjust the control parameters of the corresponding laser emission units.

Optionally, the control module is adapted to adjust a control parameter of the laser emitting unit when it is determined that the laser emitting unit is in a non-single mode state, so that the laser emitting unit is in a single mode state.

Optionally, the control module is adapted to output a first control signal when it is determined that the laser emission unit is in a non-single mode state, so as to control a control parameter of the laser emission unit to be adjusted by taking a first amplitude value as an adjustment unit until it is monitored that the laser emission unit enters a single mode state; and taking the control parameter of the laser emission unit when the laser emission unit enters a single-mode state as a reference value, outputting a second control signal, adjusting the control parameter of the laser emission unit by taking a second amplitude value as an adjusting unit, obtaining a parameter range for enabling the laser emission unit to be in a stable single-mode state, and controlling the laser emission unit to work by adopting the parameter value in the parameter range, wherein the second amplitude value is smaller than the first amplitude value.

Optionally, the control module is adapted to adjust the driving current and/or the temperature of the respective laser emitting unit.

Optionally, a first antireflection film is arranged on the first end face and the second end face of each frequency selecting unit in the frequency selecting array;

The first end face of each gain unit in the gain array is close to the second end face of the corresponding frequency selection unit, a second antireflection film is arranged on the first end face, and a high reflection film is arranged on the second end face opposite to the first end face;

Each detection unit in the detection array is respectively arranged at one side of the second end face of the corresponding gain unit and is suitable for acquiring optical signals transmitted through the second end face of the corresponding gain unit.

The first end face of each gain unit in the gain array is close to the second end face of the corresponding frequency selection unit, a second antireflection film is arranged on the first end face, and a partial reflection film is arranged on the second end face opposite to the first end face;

Each detection unit in the detection array is arranged on one side of the first end face of the corresponding frequency selection unit and is suitable for acquiring optical signals transmitted through the first end face of the corresponding frequency selection unit.

Optionally, the laser further comprises:

A light guiding array comprising: the light guide units are sequentially arranged along the first direction, and each light guide unit is respectively and correspondingly arranged with the corresponding frequency selection unit;

A second coupling array, comprising: the second coupling units are sequentially arranged along the first direction, and each second coupling unit is respectively positioned between the corresponding frequency selection unit and the corresponding light guide unit;

The gain units, the corresponding first coupling units, the frequency selection units, the second coupling units and the light guide units are sequentially arranged along a second direction to form the laser emission unit.

Alternatively, a plurality of laser emitting units are provided on the same semiconductor refrigerator.

The embodiment of the invention also provides a laser radar, which comprises:

the laser of any of the above embodiments, adapted to output multiple outgoing light;

The modulation module is suitable for carrying out linear frequency modulation on the multipath emergent light;

The first coupling module is suitable for separating the multipath emergent light into local oscillation light and detection light;

the coaxial module is suitable for receiving the detection light separated by the first coupling module and transmitting the detection light to the scanning module, and transmitting the echo of the detection light reflected by an external space object to the second coupling module;

The scanning module is suitable for reflecting the detection light and then emitting the detection light to an external space, and reflecting an echo of the detection light reflected by an object in the external space to the coaxial module;

the second coupling module is suitable for performing beat frequency processing on the local oscillation light and the echo of the detection light reflected by the external space object;

the detection module is suitable for detecting the signal output by the second coupling module;

And the processing module is suitable for obtaining at least one of distance, reflectivity and speed based on the output information of the detection module.

Optionally, the laser radar further comprises: and the switch module is suitable for time-sharing control of the emergent time of the multipath emergent light.

Optionally, the switch module includes a plurality of switch units, and the switch units are respectively matched with the corresponding laser emission units, and are suitable for independently controlling the light emitting time of the corresponding laser emission units in a time-sharing mode.

Optionally, the laser radar further comprises: and the wavelength separation module is suitable for separating light with different wavelengths in the detection light.

By adopting the scheme, the laser comprises: the gain array, the first coupling array and the frequency-selecting array respectively comprise a plurality of gain units, first coupling units and frequency-selecting units which are sequentially arranged along a first direction and mutually correspond to each other, the gain units, the corresponding first coupling units and the corresponding frequency-selecting units are sequentially arranged along a second direction to form laser emission units, namely, the laser emission units with a plurality of channels are packaged in the laser, and compared with a laser emission module with a multi-channel function formed by a plurality of single-channel lasers which are packaged independently, the integration level can be greatly improved, and the size of a laser radar light source is effectively reduced; in addition, as only one-time encapsulation is needed, the encapsulation times can be reduced, the encapsulation materials can be saved, and the encapsulation cost can be reduced.

Further, since the laser emitting unit includes: the optical coupling device comprises a gain unit, a coupling lens and a grating, wherein light oscillates in a resonant cavity formed by the gain unit and the grating, the coupling lens can improve the optical coupling rate between the gain unit and the grating, and the energy loss caused by the oscillation of the light between the gain unit and the grating is reduced; and the grating can perform frequency selection on light, so that the laser emission unit can output an optical signal meeting the frequency requirement.

Further, the grating is formed on the optical fiber to form an optical fiber grating, the grating is used as a wavelength selector to filter the light transmitted in the optical fiber, the light meeting the Bragg reflection condition is reflected, and the rest of the light is transmitted continuously in the optical fiber through the grating; the optical fiber lens arranged at the end part of the optical fiber close to the gain unit direction can enable the light transmitted from one side of the gain unit to directly enter the optical fiber after passing through the optical fiber lens, so that the optical coupling rate between the gain unit and the optical fiber can be reduced.

Further, the grating is formed on the planar waveguide to constitute a planar waveguide grating, so that an optical circuit is limited in the planar waveguide, and the grating serves as a wavelength selector to perform interference separation on light transmitted in the planar waveguide to output an optical signal satisfying frequency requirements. The planar waveguide is easy to integrate, and is beneficial to reducing the volume of the laser.

Further, since each gain unit is respectively and sequentially arranged with the corresponding first coupling unit and the corresponding frequency selecting unit along the second direction to form the multi-channel laser emission unit, the independent control of the multi-channel laser emission unit can be realized by independently driving and setting each gain unit in the gain array, so that the laser emission units of a plurality of channels can emit light for detection simultaneously or in a round-robin manner, and the detection flexibility can be improved.

Further, the detection array comprises a plurality of detection units which are sequentially arranged along a first direction and are respectively arranged at the end parts of the light paths of the corresponding laser emission units, the detection units can acquire light signals sent by the corresponding laser emission units and convert the acquired light signals into electric signals, the filtering module can filter the electric signals from the detection array, and the filtering module can remove part of the electric signals which are not higher than the preset frequency in the output electric signals to acquire required signals to be detected, and then the judging module can acquire the working mode of the laser emission units based on the signals to be detected.

Further, by comparing the intensity value of the signal to be detected with the preset intensity value through the comparator, whether the laser emission unit is in a single-mode state or not can be directly determined, the whole process does not need to be manually participated, and the mode self-detection of the laser can be realized without complex analysis operation.

Further, compared with the monitoring result obtained based on the single judgment result of the comparator, the monitoring result obtained based on the multiple judgment results of the comparator can determine the working mode of the laser emission unit in a continuous period of time, that is, whether the laser emission unit is stably in a single-mode state (that is, a stable single-mode state), so that the reliability of the monitoring result can be improved. And because the duty ratio of the non-single mode state in the multiple judging results of the comparator is compared with the first preset ratio and the second preset ratio respectively, the non-single mode state is further divided into a multi-mode state and a mode-jump state, and the monitoring and understanding degree of the working mode of the laser transmitting unit are enhanced by the fine division of the non-single mode state, so that the more accurate monitoring of the working mode can be realized.

Further, the detection unit is used for acquiring an optical signal sent by the laser emission unit and converting the acquired optical signal into an electric signal; the filtering module can carry out filtering processing on the electric signals from the detection array, removes partial electric signals which are not higher than the preset frequency in the output electric signals to obtain required signals to be detected, and carries out processing analysis on the signals to be monitored through the judging module so as to obtain a judging result of the working mode of the laser transmitting unit; and adjusting the control parameters of the laser emission unit according to the judging result, and further adjusting the working mode of the laser emission unit, so that the laser emission unit works in a proper mode. The whole process can realize the mode self-checking and automatic control of the laser emission unit without the participation of external equipment, thereby being convenient and quick and saving the cost.

Further, when the laser emission unit is determined to be in a non-single-mode state, the control parameters of the laser emission unit are adjusted through the control module, so that the laser emission unit can be in a single-mode state, and further, an optical signal meeting the line width requirement can be output.

Further, when the control parameters of the laser emission unit in the non-single mode state are adjusted, the difference value of the control parameters corresponding to the laser emission unit in the non-single mode state and the control parameters corresponding to the laser emission unit in the single mode state is unknown, and the possibility of extremely large difference value exists, so that the control parameters corresponding to the laser emission unit in the non-single mode state are coarsely adjusted by taking the first amplitude as an adjusting unit, and the adjusting mode can enable the control parameters of the laser emission unit to quickly enter the parameter range corresponding to the single mode state of the laser emission unit; when the laser emission unit enters a single-mode state, the difference value corresponding to the boundary value of the control parameter and the single-mode state parameter range at the moment is smaller than the first amplitude, so that the control parameter at the moment is taken as a reference value, and the second amplitude smaller than the first amplitude is adopted to fine-adjust the control parameter, so that the parameter range of the laser emission unit in the single-mode state can be better obtained, the laser emission unit can be stably in the single-mode state (namely, the single-mode state is stabilized) even if the control parameter fluctuates along with the change of the environment, and the stability of the laser emission unit in the single-mode state is further improved.

Further, the control module can control the working mode of the laser emitting unit through at least one of driving current and temperature, so that the self-adaptive control of the working mode of the laser is realized.

Furthermore, each detection unit in the detection array is respectively arranged on one side of the second end face of the corresponding gain unit, and the optical signals emitted from one side of the second end face of the gain unit are utilized to monitor and control the mode of the laser emission unit, so that the mode monitoring and controlling process cannot influence the normal working process of the laser emission module, the emission power of the laser emission module does not need to be additionally increased, and the system power consumption can be reduced. In addition, because the optical signal emitted from the second end face side of the gain unit is the optical signal directly emitted after being amplified by the gain unit, the energy is high, and therefore, the energy of the output optical signal is reduced by arranging the high-reflection film on the second end face side of the gain unit, and the optical signal can be better matched with the detection range of the detection unit. And through setting up first antireflection coating and second antireflection coating respectively at the second terminal surface of frequency selection unit and the first terminal surface of gain unit, increase the incidence to frequency selection unit with the optical coupling rate of gain unit reduces the energy loss in the light oscillation process, through setting up first antireflection coating at the first terminal surface of frequency selection unit, also can reduce the energy loss when light is outgoing, so can improve the energy efficiency of laser instrument.

Further, each detection unit in the detection array is respectively arranged at one side of a first end face of a corresponding frequency selection unit, namely, the optical signal emitted from one side of the first end face of the frequency selection unit is utilized to monitor and control the mode of the laser emission unit, wherein the second end face of the gain chip is the light emitting end face of the laser emission unit, and a detection signal for working is emitted to the outside; the first antireflection film and the second antireflection film are respectively arranged on the second end face of the frequency selection unit and the first end face of the gain unit, so that the optical coupling rate of the light incident to the frequency selection unit and the gain unit can be increased, the energy loss in the optical oscillation process is reduced, and the first antireflection film is arranged on the first end face of the frequency selection unit, so that the energy loss in the light emergent process can be reduced, and the energy efficiency of the laser can be improved.

Further, the laser includes: the gain array, the first coupling array, the gain array, the second coupling array and the light guide array are sequentially arranged along a first direction and correspond to each other, and the gain units, the first coupling unit, the frequency selecting unit, the second coupling unit and the light guide unit are sequentially arranged along a second direction respectively with the corresponding first coupling unit, the frequency selecting unit, the second coupling unit and the light guide unit to form laser emission units of a plurality of channels; and the optical signals output by the frequency selection unit after frequency selection in the laser emission unit of each channel are processed by the second coupling unit and then enter the light guide unit. The second coupling unit can improve the optical coupling rate between the frequency selection unit and the light guide unit, and reduce the energy loss of the optical signal when the optical signal propagates between the frequency selection unit and the light guide unit.

Further, by arranging a plurality of laser emission units on the same semiconductor refrigerator, the synchronous adjustment of temperature can be realized, the integration level is high, the use is convenient, and the cost is saved.

By adopting the laser radar in the embodiment of the invention, a laser with a laser emission unit with a plurality of channels can output multiple paths of emergent light to the modulation module, the emergent light enters the first coupling module after being subjected to linear frequency modulation by the modulation module, the first coupling module separates the emergent light with different frequencies into local oscillation light and detection light, wherein the local oscillation light is directly transmitted to the second coupling module, the detection light is transmitted to the scanning module through the coaxial module and is emitted to an external space after being reflected by the scanning module, then the detection light is reflected to the coaxial module after being re-entered into the laser radar through an echo formed by an external space object, the coaxial module transmits the echo to the second coupling module, the second coupling module transmits corresponding optical signals to the detection module after performing beat frequency processing on the incident local oscillation light and echo, the detection module detects signals output by the second coupling module, and the processing module processes the detection information based on the output information of the detection module, and the laser radar can further realize at least one integrated circuit, thereby achieving the volume improvement of the laser radar.

Furthermore, the outgoing time of the multiple paths of outgoing lights is controlled in a time-sharing manner through the switch module, and simultaneous or round inspection of the multiple paths of outgoing lights can be realized as required during use, so that the detection flexibility of the laser radar can be improved.

Further, since the switch module comprises a plurality of switch units, each of the laser emission units is provided with a corresponding switch unit in a matching manner, and the switch units independently control the emission time of the corresponding laser emission units in a time-sharing manner, the switch units are simultaneously or sequentially started to realize simultaneous or round inspection of multiple paths of emitted light, and the detection flexibility of the laser radar is improved.

Further, the wavelength separation module separates light with different wavelengths in the detection light, and the separated light with different wavelengths is distributed along one dimension (for example, the vertical direction), which is beneficial to reducing the scanning dimension of the scanning module.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present description, the drawings that are required to be used in the embodiments of the present description or the description of the prior art will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present description, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIGS. 1 to 4 are schematic views showing structures of various lasers in the embodiment of the present invention, respectively;

FIGS. 5A and 5B show a spectral diagram and a linewidth diagram, respectively, of an optical signal emitted by a laser emitting unit of a laser;

FIG. 6 shows a spectral diagram of an optical signal emitted by a laser emitting unit of a laser;

fig. 7 and 8 are schematic views respectively showing the structures of two other lasers in the embodiment of the present invention;

fig. 9A to 9C respectively show time domain voltage signal distribution diagrams of an optical signal emitted from a laser emitting unit;

fig. 10 shows a schematic structural diagram of a lidar according to an embodiment of the present invention.

Detailed Description

The light source of the FMCW lidar needs to have a narrow linewidth output, i.e., to stably operate in a single mode state. In the prior art, a semiconductor external cavity narrow linewidth laser is an important type of narrow linewidth laser, and can stably work in a single mode state through control.

However, most of the existing semiconductor external cavity narrow linewidth lasers are packaged separately, and when a light source formed by a plurality of semiconductor external cavity narrow linewidth lasers is used as a light source of the FMCW laser radar, the light source volume is large and the use cost is too high, so that the size and the cost of the FMCW laser radar are increased.

In order to solve the technical problems, the technical scheme of the embodiment of the invention provides a laser, wherein the laser comprises a plurality of laser emitting units, and the plurality of laser emitting units are sequentially arranged and mutually independent and output multiple paths of optical signals. Compared with a laser emission module formed by lasers formed by packaging a plurality of laser emission units, the size of the laser emission module is obviously reduced, so that the size of a laser radar light source can be effectively reduced; in addition, the laser with the multichannel laser emitting unit only needs to be packaged once, so that the packaging times can be reduced, packaging materials can be saved, and the packaging cost can be reduced.

For a better understanding and to be obtained by anyone skilled in the art to practice the present embodiments, the following concepts, solutions, principles, advantages, etc. of the embodiments of the present invention are described in detail by way of specific examples of application with reference to the accompanying drawings.

First, an embodiment of the present invention provides a laser, where the laser may include: a gain array, a frequency selective array, and a first coupling array. Wherein:

The gain array comprises a plurality of gain units which are sequentially arranged along a first direction;

the frequency selection array comprises a plurality of frequency selection units which are sequentially arranged along a first direction;

The first coupling array comprises a plurality of first coupling units which are sequentially arranged along a first direction, and each first coupling unit is respectively positioned between the corresponding gain unit and the corresponding frequency selection unit;

And each gain unit is respectively and sequentially arranged with the corresponding first coupling unit and the corresponding frequency selecting unit along the second direction to form a laser emitting unit.

In the above scheme, each laser emission unit is formed by sequentially arranging a corresponding gain unit, a corresponding first coupling unit and a corresponding frequency selection unit along a second direction, and a plurality of gain units, first coupling units and frequency selection units are sequentially arranged along the first direction, so that the lasers form a plurality of laser emission units through the gain array, the frequency selection array and the first coupling array. Compared with a laser emission module of a plurality of channels formed by lasers independently packaged by a laser emission unit of a single channel, the integration level can be greatly improved, and the sizes of the lasers and the laser radar applying the lasers can be effectively reduced; in addition, compared with a light source formed by a plurality of single-channel lasers which are packaged independently, the multi-channel lasers only need to be packaged once, so that the packaging times are reduced, packaging materials are saved, and the corresponding use cost is reduced.

In some embodiments of the present invention, the frequency selecting unit may include: a grating; the first coupling unit may include: and a coupling lens.

For better understanding and implementation by those skilled in the art, some practical examples of the frequency selection unit and the first coupling unit in the laser described in the present specification are shown below.

In other embodiments of the present invention, the frequency selecting unit may further include: an optical fiber, the grating may be formed on the optical fiber.

By adopting the scheme, the grating is formed on the optical fiber to form the optical fiber grating, the grating can be used as a wavelength selector to filter the light transmitted in the optical fiber, the light meeting the Bragg reflection condition is reflected, and the rest of light is transmitted in the optical fiber continuously through the grating.

In a specific example, referring to a schematic structural diagram of a laser shown in fig. 1, the laser 100 includes: gain array 110, frequency selective array 130, and first coupling array 120. Wherein:

The gain array 110 includes a plurality of gain units 111 sequentially arranged along a first direction F1;

The frequency selection array 130 includes a plurality of fiber gratings 131 sequentially arranged along a first direction F1;

The first coupling array 120 includes a plurality of coupling lenses 121 sequentially arranged along a first direction F1, and each coupling lens 121 is located between a corresponding gain unit 111 and the fiber grating 131;

each gain unit 111 is sequentially arranged with the corresponding coupling lens 121 and the fiber bragg grating 131 along the second direction F2 to form a laser emission unit 140;

The fiber grating 131 is a grating structure formed on the optical fiber 132.

In a specific implementation, a gap may be formed between the coupling lens 121 and the end portion of the optical fiber 132 near the direction of the gain unit 111, or may be in direct contact with the coupling lens.

By adopting the above scheme, the light oscillates in the resonant cavity formed by the gain unit 111 and the fiber bragg grating 131, and the coupling lens 121 can improve the optical coupling rate between the gain unit 111 and the fiber bragg grating 131, and can reduce the energy loss caused by the oscillation of the light between the gain unit 111 and the fiber bragg grating 131; the fiber grating 131 may perform frequency selection on the light, so that the laser emitting unit 140 may obtain an optical signal meeting the frequency requirement.

In another specific example, referring to the schematic diagram of another laser structure shown in fig. 2, the laser 200 also includes a gain array 210, a first coupling array 220, and a frequency selective array 230. The difference from the laser 100 is that the coupling lens is specifically: the optical fiber lens 221 may be disposed at an end of the optical fiber in a direction close to the gain unit 211.

With the above laser, each gain unit 211 is sequentially arranged with the corresponding fiber lens 221 and fiber grating 231 along the second direction F2 to form a laser emission unit 240; the fiber grating 231 is a grating structure formed on the optical fiber 232.

The optical fiber lens 221 disposed at the end of the optical fiber 232 near the direction of the gain unit 211 can make the light transmitted from one side of the gain unit 211 directly enter the optical fiber 232 after passing through the optical fiber lens 221, and the optical fiber 232 has good light transmission characteristics, so that the optical coupling rate between the gain unit 211 and the optical fiber 232 can be increased.

In other embodiments of the present specification, the frequency selecting unit may further include: and the grating is formed on the planar waveguide.

Referring to the schematic structure of another laser shown in fig. 3, in a specific example, the laser 300 includes: gain array 310, first coupling array 320, and frequency selective array 330. Wherein:

The gain array 310 includes a plurality of gain units 311 sequentially arranged along a first direction F1;

the frequency-selective array 330 includes a plurality of planar waveguide gratings 331 sequentially arranged along a first direction F1;

The first coupling array 320 includes a plurality of coupling lenses 321 sequentially arranged along the first direction F1, and each coupling lens 321 is located between the corresponding gain unit 311 and the planar waveguide grating 331;

Each gain unit 311 is sequentially arranged with the corresponding coupling lens 321 and the corresponding planar waveguide grating 331 along the second direction F2 to form a laser emitting unit 340;

The planar waveguide grating 331 is a grating structure formed on the planar waveguide 332.

In a specific implementation, a gap may be formed between the coupling lens 321 and the end of the planar waveguide 332 near the gain unit 311, or may be in direct contact with the coupling lens.

By adopting the above scheme, the light exits to the planar waveguide grating 331 through the gain unit 311 and the coupling lens 321, the planar waveguide grating 331 limits a propagation path of the light in the planar waveguide grating 331, and the planar waveguide grating 331 may be used as a wavelength selector to perform frequency selection on the light transmitted in the planar waveguide 332 so as to output an optical signal meeting the frequency requirement.

In specific implementation, the structure of the laser can be further expanded and optimized. As an alternative example, the laser may further comprise a second coupling array and a light guiding array, wherein:

the light guide array may include a plurality of light guide units sequentially arranged along a first direction, each of the light guide units being respectively disposed corresponding to a corresponding frequency selection unit;

The second coupling array may include a plurality of second coupling units sequentially arranged along the first direction, each of the second coupling units being respectively located between a corresponding frequency selection unit and light guide unit;

In a specific implementation, the second coupling unit may include a coupling lens; the light guide unit may include an optical fiber.

For better understanding and implementation by those skilled in the art, a specific example of the second coupling unit and the light guiding unit in the laser described in the present specification is shown below.

Referring to another schematic structure of a laser shown in fig. 4, in some embodiments of the present invention, as shown in fig. 4, a laser 400 may include: gain array 410, first coupling array 420, frequency selective array 430, second coupling array 440, and light guide array 450. Wherein:

the gain array 410 includes a plurality of gain units 411 sequentially arranged along a first direction F1;

The first coupling array 420 includes a plurality of first coupling lenses 421 sequentially arranged along a first direction F1, and the frequency-selective array 430 includes a plurality of planar waveguide gratings 431 sequentially arranged along the first direction F1; each first coupling lens 421 is located between the corresponding gain unit 411 and the planar waveguide grating 431;

The second coupling array 440 includes a plurality of second coupling lenses 441 sequentially arranged along the first direction F1, and the light guiding array 450 includes a plurality of optical fibers 451 sequentially arranged along the first direction F1; each of the second coupling lenses 441 is located between the corresponding planar waveguide grating 431 and the optical fiber 451, respectively.

Each of the gain units 411 is sequentially arranged with the corresponding first coupling lens 421, planar waveguide grating 431, second coupling lens 441, and optical fiber 451 along the second direction F2, so as to form a laser emitting unit 460.

In the above-mentioned scheme, each laser emitting unit 460 is formed by arranging each gain unit 411 and the corresponding first coupling lens 421, planar waveguide grating 431, second coupling lens 441 and optical fiber 451 in sequence along the second direction F2, and each of the above units is arranged in sequence along the first direction F1, so that a plurality of laser emitting units 460 arranged in sequence along the first direction F1 are formed, that is, the laser 400 forms a multi-channel output laser through the gain array 410, the first coupling array 420, the frequency-selecting array 430, the second coupling array 440 and the light guiding array 450.

By adopting the above scheme, the light oscillates in the resonant cavity formed by the gain unit 411 and the planar waveguide grating 431, and after exiting from the planar waveguide grating 431, the light passes through the second coupling lens 441 and enters the optical fiber 451 to be conducted; the second coupling lens 441 may enhance the optical coupling ratio between the planar waveguide grating 431 and the optical fiber 451, and the optical fiber has good optical conduction characteristics, so that the optical signal entering the optical fiber 451 may be effectively conducted according to specific requirements.

In some embodiments of the present invention, each gain cell 411 in the gain array 410 is independently driven.

By independently driving and setting each gain unit in the gain array, independent control of a plurality of laser emitting units in the multichannel laser can be realized, and independent adjustment is facilitated.

In a specific implementation, there is at least one of the frequency selective units having a frequency passband parameter that is different from the frequency passband parameters of the other frequency selective units. Specifically, the frequency passband parameters of the plurality of frequency selection units may be set to be different from each other, or may be set to be the same for some of the frequency selection units.

By adopting the scheme, the laser can output optical signals with at least two frequencies based on the setting of the frequency passband parameters of the frequency selection unit by the frequency selection array, and when the laser is applied to a laser radar, the laser can be combined with a dispersion element to form scanning of one dimension.

As described in the background art, a narrow linewidth laser is required to be used as a light source in the FMCW lidar, and the narrow linewidth laser should always operate in a single longitudinal mode state (for short, a stable single mode state) in an ideal state. However, with the variation of the driving current or the temperature, the laser is often in a state where a plurality of modes are simultaneously operated (for short, multimode state), or in a state where a plurality of single mode states jump from each other (for short, mode jump state).

In order to better understand the different operating states of the optical signals emitted by the respective laser emitting units of the laser, a detailed description is given by means of fig. 5A, 5B and 6.

FIG. 5A is a spectral diagram of an optical signal emitted by a laser emitting unit in a laser, showing the spectral distribution of the optical signal at different driving currents; fig. 5B is a line width diagram corresponding to fig. 5A, showing a variation curve of line width of the optical signal at different driving currents.

As can be seen from fig. 5A and fig. 5B, when the driving current of one laser emitting unit in the laser is 180mA, the spectral distribution of the optical signal emitted by the laser emitting unit in the spectrogram shows a unimodal structure, and at this time, the laser emitting unit is in a single-mode state, and the linewidth of the optical signal is 2kHz; in the process that the driving current of the laser emission unit is increased to 217mA, the two sides of the original unimodal structure in the spectrum distribution of the optical signal gradually appear side peaks, the height of the side peaks of the optical signal is gradually increased, the number of the side peaks is also gradually increased, but the line width of the optical signal basically keeps unchanged at 2kHz and is close to the line width of the optical signal in a single mode state; when the driving current of the laser emission unit reaches 217.7mA and continues to increase, the height of the side peaks of the optical signal continues to increase, the number of the side peaks continues to increase, and the line width of the optical signal is greatly increased, so that the laser emission unit is in a multimode state.

Fig. 6 is a spectral diagram of an optical signal emitted by a laser emitting unit of a laser, showing the spectral distribution of the optical signal at different moments in time.

Referring to fig. 6, at a certain moment, the spectral distribution of the optical signal emitted by the laser emission unit presents a unimodal structure, and the corresponding center wavelength is located at 1551.75 nm; at another moment, the spectral distribution of the optical signal emitted by the laser emission unit also presents a unimodal structure, and the corresponding center wavelength is located at 1551.92 nm.

From the above, the spectral distribution of the optical signal emitted by the laser emission unit at two moments shows a single-peak structure, but the central wavelengths corresponding to the two are different, that is, the laser emission unit operates in a single-mode state at any moment, but operates in different single-mode states at different moments, that is, when the laser emission unit operates, the optical signal emitted by the laser emission unit jumps from one single-mode state to another single-mode state, which is called a mode jump state.

Aiming at the problems, the embodiment of the specification provides a corresponding mode monitoring scheme and a corresponding mode control scheme, and can realize self-detection and self-adaptive control of the working modes of all laser emitting units of the laser. Specifically, the working mode of the laser can be determined based on the characteristics of the optical signal sent by the laser emission unit, so as to realize the mode monitoring of the laser emission unit; and after the working mode of the laser module is determined, the working mode of the laser emitting unit can be further controlled.

In order to better understand and implement the embodiments of the present invention, the following describes the conception, scheme, principle, advantages, etc. of the mode monitoring scheme and the mode control scheme in the embodiments of the present invention in detail by means of specific application examples with reference to the accompanying drawings.

First, to enable modal monitoring, the laser may further comprise: the device comprises a detection array, a filtering module and a judging module. Wherein:

The detection array comprises: the detection units are sequentially arranged along the first direction, and are respectively arranged at the end parts of the light paths of the corresponding laser emission units so as to acquire light signals emitted by the corresponding laser emission units and convert the light signals into electric signals;

By adopting the mode monitoring scheme, each laser emission unit corresponds to one detection unit, and the detection unit is used for acquiring an optical signal sent by the corresponding laser emission unit and converting the acquired optical signal into an electric signal; the filtering module can carry out filtering processing on the electric signals from the detection array to obtain signals to be detected with the frequency higher than the preset frequency, and the judging module is used for carrying out processing analysis on the signals to be monitored to obtain a judging result of the working mode of the laser emission unit, so that the monitoring of the working mode of the emission unit is completed. The whole process can realize the automatic monitoring of the working mode of the laser emission unit without the participation of external monitoring equipment, thereby being convenient and quick and saving the cost.

For better understanding and implementation by those skilled in the art, some examples of the detection array, the filtering module, and the determining module that can be implemented in this specification are shown below.

In a specific implementation, the detection unit may include a photodetector adapted to acquire the optical signal emitted by the laser emitting unit and convert the optical signal into a current signal.

In some alternative examples, the detection unit may further comprise a transimpedance amplifier adapted to convert the current signal into a voltage signal and amplify the signal.

In another alternative example, for a current signal with a smaller intensity, the detection unit may further comprise a current amplifier, which amplifies the current signal before being amplified by the transimpedance amplifier and converted into a voltage signal.

Wherein the photodetector is a generic term having a type of device that acquires an optical signal and converts the optical signal into a current signal. In some embodiments of the present description, the photodetector may be a photodiode, photomultiplier tube, or the like. When the photoelectric detector acquires the optical signal sent by the laser emission unit and converts the optical signal into a current signal to be output, the intensity of the current signal converted by the photoelectric detector is different according to the type of the photoelectric detector and the intensity of the optical signal sent by the laser emission unit acquired by the photoelectric detector, so that the current signal output by the photoelectric detector is amplified by the current amplifier first and then is converted into a voltage signal by the transimpedance amplifier or is directly amplified by the transimpedance amplifier, and the current signal can be selected according to the actual situation.

Based on the fact that the signal to be detected is an electric signal with frequency higher than the preset frequency, the filtering module selects to use a high-pass filter, passband parameters of the high-pass filter are set according to the preset frequency, electric signals which are not higher than the preset frequency and are contained in the electric signal output by the detection unit are removed in the filtering process, and the signal to be detected with frequency higher than the preset frequency is output. Specifically, the types that the high-pass filter can use include, but are not limited to, a bat Wo Sigao-pass filter, an LC high-pass filter, an RC high-pass filter, a Pi type high-pass filter, and the like, and other types of high-pass filters are also possible; the high-pass filter can be a single filter or a high-order high-pass filter formed by combining a plurality of filters, and the embodiment of the invention does not limit related schemes which are expanded due to different filter types and numbers.

In a specific implementation, the determining module may include: and the comparator is used for comparing the intensity value of the signal to be detected with a preset intensity threshold value and outputting a monitoring result about the working mode of the laser emission unit according to the judging result. Specifically: if the intensity value of the signal to be detected is smaller than the preset intensity threshold value, the judging result can determine that the laser transmitting unit is in a single-mode state, and a corresponding monitoring result is output; if the intensity value of the signal to be detected is not smaller than the preset intensity threshold value, determining that the laser emission unit is in a non-single mode state, and outputting a corresponding monitoring result.

If the signal to be detected is a voltage signal, the comparator may specifically be a voltage comparator, and the voltage comparator compares a voltage intensity value of the signal to be detected with a preset threshold intensity and outputs a judgment result. Specifically, the types of the voltage comparator may include, but are not limited to, a single-limit comparator, a hysteresis comparator, a window comparator, and the like, and other types of voltage comparators are also possible, and the embodiments of the present disclosure are not limited to the related schemes that extend from the types of the voltage comparators.

In a specific implementation, the comparator continuously compares the intensity value of the signal to be detected with the preset intensity threshold for a plurality of times according to preset conditions, and determines the working mode of the laser emitting unit based on the judgment result of the comparator for a plurality of times, wherein the method comprises at least one of the following steps:

Wherein the preset conditions, three optional examples are given below.

As an optional example, a mode that the preset condition is a first preset duration may be adopted, that is, multiple determinations are performed within the first preset duration, and a monitoring result is obtained according to multiple determination results, where the mode may directly reflect an operation mode of the laser emission unit within the first preset duration.

As another alternative example, a manner of continuously performing the judging action for the first preset number of times under the preset condition may be adopted, and since there is a time interval between the multiple judgments, that is, the first preset number of times is performed corresponding to the first preset number of times being performed in a continuous period of time, the monitoring result is obtained according to multiple judging results generated by performing the preset number of times, and the manner may reflect the working mode of the laser emitting unit in a continuous period of time corresponding to the first preset number of times being performed.

As another alternative example, a manner of setting the first preset number of times and the first preset duration at the same time as the preset condition may be adopted, that is, the judging action is continuously performed for the preset number of times within the first preset duration.

The above manner is merely an example, and in the embodiment of the present invention, a specific setting manner of the preset condition is not limited as long as it is capable of satisfying that the comparison is performed a plurality of times in a continuous period of time.

Compared with the monitoring result obtained based on the single judgment result of the comparator, the monitoring result obtained based on the multiple judgment results of the comparator can determine the working mode of the laser emission unit in a continuous period of time, namely whether the laser emission unit is stably in a single-mode state (namely, a stable single-mode state), so that the reliability of the monitoring result can be improved.

In addition, the non-single mode state is further divided into the multimode state and the mode-jump state by comparing the duty ratio of the non-single mode state in the multiple judging results of the comparator with the first preset ratio and the second preset ratio, so that the monitoring and the understanding degree of the working mode of the laser emitting unit are enhanced by the fine division of the non-single mode state, and more accurate monitoring of the working mode can be realized.

In some embodiments of the present invention, when the monitoring result for determining that the laser emission unit is in the stable single mode state is given after the performing of the multiple comparisons, in order to reduce the monitoring power consumption while guaranteeing the monitoring quality, the monitoring of the laser emission unit may be stopped for a second preset period of time.

In order to realize the adaptive control of the working mode, in a specific implementation, the laser may further include: and the control module is suitable for outputting control signals to the corresponding laser emission units based on the judging result of the judging module so as to adjust the control parameters of the corresponding laser emission units.

By adopting the mode control scheme, the detection unit is used for acquiring the optical signal sent by the laser emission unit and converting the acquired optical signal into an electric signal; the filtering module can carry out filtering processing on the electric signals from the detection array, removes partial electric signals which are not higher than the preset frequency in the output electric signals to obtain required signals to be detected, and carries out processing analysis on the signals to be monitored through the judging module so as to obtain a judging result of the working mode of the laser transmitting unit; and adjusting the control parameters of the laser emission unit according to the judging result, and further adjusting the working mode of the laser emission unit, so that the laser emission unit works in a proper mode. The whole process can realize the mode monitoring and the mode control of the laser emission unit without the participation of external equipment, thereby being convenient and quick and saving the cost.

In a specific implementation, the control module is adapted to adjust a control parameter of the laser emission unit when determining that the laser emission unit is in a non-single mode state, so that the laser emission unit is in a single mode state, and further outputs an optical signal meeting the line width requirement. Among them, three optional examples are given below.

As an alternative example, a driving current may be employed as the control parameter.

As another alternative example, temperature may be employed as a control parameter.

As another alternative example, the driving current and the temperature may be employed simultaneously as the control parameters.

The above manner is merely an example, and in the embodiment of the present invention, a specific manner of the control parameter is not limited, as long as the working mode of the laser emitting unit can be adjusted.

When the laser emission unit is in a non-single mode state, the linewidth of the optical signal is greatly increased or the wavelength is changed compared with the linewidth of the optical signal in the single mode state, the linewidth does not meet the standard of a narrow linewidth laser light source and cannot be used as the narrow linewidth laser light source, so that the control parameters of the laser emission unit need to be adjusted, the laser emission unit is in the single mode state, and the linewidth of an output light beam is narrow linewidth so as to meet corresponding requirements.

In the practical application process, the inventor finds that the control parameters of the laser emitting unit are not fixed, but fluctuate within a certain parameter range along with the environmental change.

In particular embodiments, the control module is adapted to output a first control signal when the judging module determines that the laser emission unit is in a non-single mode state, so as to control a control parameter of the laser emission unit to be adjusted by taking a first amplitude value as an adjustment unit until the laser emission unit is monitored to enter a single mode state; and the control parameter when the laser emission unit enters a single mode state is taken as a reference value, a second control signal is output, the control parameter of the laser emission unit is regulated by taking a second amplitude value as a regulating unit, a parameter range which enables the laser emission unit to be in a stable single mode state is obtained, and the laser emission unit is controlled to work by adopting the parameter value in the parameter range; when the judging module compares for the first time, the laser transmitting unit is determined to be in a single-mode state, the control parameter at the moment is taken as a reference value, the control parameter of the laser transmitting unit is adjusted by taking a third amplitude value as an adjusting unit, a parameter range which enables the laser transmitting unit to be in a stable single-mode state is obtained, the laser transmitting unit is controlled to work by adopting a parameter value in the parameter range, and the second amplitude value is smaller than the first amplitude value.

By adopting the scheme, when the laser emission unit is determined to be in a non-single mode state, setting control parameters from low to high and/or from high to high in sequence by taking a preset first amplitude as an adjusting unit, and determining the working mode of the laser emission unit again under the reset control parameters until the laser emission unit is determined to enter the single mode state; and then, setting the control parameters in turn by taking the control parameters when the laser emission unit enters a single-mode state as reference values, namely taking the current control parameter values from low to high and/or from high to low, taking a preset second amplitude value as an adjusting unit, acquiring the control parameter range in the stable single-mode state, and further controlling the laser emission unit to work by adopting the parameter values in the parameter range.

Taking the adjusted control parameters as examples to illustrate the driving current, when the driving current of the laser emission unit in the non-single mode state is adjusted, the difference value of the two corresponding control parameters is unknown when the laser emission unit is in the non-single mode state and in the single mode state, and the difference value is extremely large. When the laser emission unit enters a single-mode state, the driving current at the moment is taken as a reference value, the difference value corresponding to the boundary value of the driving current and the single-mode state parameter range at the moment is smaller than a first amplitude value, the driving current is finely regulated by adopting a second amplitude value smaller than the first amplitude value, and when the laser emission unit is in the single-mode state after continuously executing the judgment result of the preset times comparison, the regulation of the control parameters of the laser emission unit can be stopped, so that the parameter range of the control parameters in the stable single-mode state, which float up and down relative to the reference value, can be obtained, and therefore, the requirement that the laser emission unit can be stably in the single-mode state (namely in the stable single-mode state) even if the driving current fluctuates in a certain parameter range in the actual working process of the laser emission unit can be met.

And adjusting the control parameters of the laser emission unit by using the third amplitude as an adjusting unit, obtaining a parameter range for enabling the laser emission unit to be in a stable single-mode state, and controlling the laser emission unit to work by using the parameter values in the parameter range.

In the implementation, when the laser emission unit is in a single-mode state, the first comparison is performed, the control parameter is determined to be in the single-mode state, the control parameter is taken as a reference value at the moment, a preset third amplitude is taken as an adjusting unit, namely, the current control parameter value is reset from low to high and/or from high to low, the control parameter range in the stable single-mode state is acquired, and then the laser emission unit is controlled to work by adopting the parameter value in the parameter range.

It will be appreciated that, since there is no reference value in comparison with the third amplitude, the range of the control parameter (e.g. the driving current) obtained in the stable single mode state may be shifted up and down with respect to the reference value, or the reference value may be used as a boundary value, and the control parameter value may be gradually increased or decreased in units of adjustment based on the third amplitude.

In a specific implementation, as mentioned above, the control parameter may be a driving current, a temperature, or other control parameters. The first amplitude, the second amplitude and the third amplitude are specific adjusting units or are called adjusting step sizes, the corresponding amplitude values can be the same control parameter, or can correspond to different control parameters, for example, the first amplitude, the second amplitude and the third amplitude are all driving currents, or the first amplitude and the second amplitude correspond to driving currents, the third amplitude corresponds to temperature, or the first amplitude corresponds to driving currents, the second amplitude and the third amplitude correspond to temperature, or the first amplitude, the second amplitude and the third amplitude correspond to temperature. As an alternative example, when the second amplitude value and the third amplitude value correspond to the same control parameter, they may be the same or different.

In a specific implementation, the second amplitude may be applied to control parameter adjustment after the laser emission unit is converted from a non-single mode state to a single mode state; the third amplitude can be applied to subsequent control parameter adjustment when the laser emission unit is in a single mode state for the first time; the two may be the same or different, and the second amplitude may be equal to the third amplitude for simplicity of the mode monitoring method and the mode control method.

As known from the background art, the line width corresponding to the optical signal emitted by the laser emission unit is related to the driving current, that is, the driving current is increased in a certain driving current range, the line width corresponding to the optical signal is increased, the working mode is changed to a non-single mode state, the driving current is reduced, the line width corresponding to the optical signal is reduced, and the working mode is changed to a single mode state; similarly, the line width and the temperature corresponding to the optical signal emitted by the laser emitting unit have similar relations.

The end face, close to the frequency selection unit, of the gain unit is taken as a first end face of the gain unit, and the end face, far away from the frequency selection unit, is taken as a second end face of the gain unit; the end face, close to the gain unit, of the frequency selection unit is a second end face of the frequency selection unit, and the end face, far away from the gain unit, is a first end face of the frequency selection unit; when the laser emission unit works, light oscillates in the resonant cavity formed by the gain unit and the frequency selection unit, and an optical signal emitted outwards can be emitted from the first end face of the frequency selection unit or from the second end face of the gain unit, so that the detection positions of the two detection units are given below.

In an alternative example, each detection unit in the detection array is respectively disposed on one side of the second end surface of the corresponding gain unit, and is adapted to obtain the optical signal transmitted through the second end surface of the corresponding gain unit.

In another alternative example, each detection unit in the detection array is disposed on one side of the first end surface of the corresponding frequency selection unit, and is adapted to obtain an optical signal transmitted through the first end surface of the corresponding frequency selection unit.

For better understanding and implementation by those skilled in the art, the following describes in detail the positional relationship of the detection array and the laser emitting unit by way of specific examples and with specific application scenarios.

Referring to a schematic diagram of a laser structure shown in fig. 7, in some embodiments of the present disclosure, the detection array 550 is disposed on the second end side of the gain array 510. Specifically, the detection unit 551 is located on an outgoing optical path of a side optical signal of the second end surface of the gain unit 511 by the laser emission unit 540, and uses an optical signal emitted from the second end surface of the gain unit 511 to monitor and/or control the mode of the laser emission unit 540, where the first end surface of the frequency selection unit 531 is used as an outgoing optical end surface of the laser emission unit 540 by the laser emission unit 540, and a detection signal for working is emitted to the outside.

However, based on the gain of the gain unit 511 for light, the output light intensity of the second end surface of the gain unit 511 may be far greater than that of the first end surface of the frequency selection unit 531, which is detrimental to the normal operation of the detection unit 551.

In view of the above, a reflective film is provided on the second end surface of the gain unit 511 in the laser emission unit 540 to reduce the intensity of the outgoing light from the second end surface of the gain unit 511, while providing oscillation of light between the second end surface of the gain unit 511 and the frequency selection unit 531. Preferably, the light output intensity of the second end surface of the gain unit 511 may be controlled within a range lower than that of the first end surface of the frequency selecting unit 531. In implementations, the reflective film may include a highly reflective film, for example, that reflects greater than 99% of the optical signal.

In a specific implementation, at least one of the first end face, the second end face and the first end face of the gain unit is provided with an antireflection film.

In a specific example, the first end surface and the second end surface of the frequency selection unit are respectively provided with a first antireflection film, and the first end surface of the gain unit is provided with a second antireflection film.

By arranging the first antireflection film and the second antireflection film on the second end face of the frequency selection unit and the first end face of the gain unit respectively, the optical coupling rate of incidence to the frequency selection unit and the gain unit can be increased, and the energy loss in the optical oscillation process can be reduced; and the energy loss during light emergence is reduced by arranging the first antireflection film on the first end face of the frequency selection unit. By reducing energy loss during light transmission, the energy efficiency of the laser may be improved.

In other embodiments of the present disclosure, referring to the schematic structural diagram of another laser shown in fig. 8, the laser 600 differs from the laser 500 shown in fig. 7 in that: the detection array 650 is disposed on the first end face side of the frequency selecting unit 631.

Since the detection unit 651 is located on the outgoing optical path of the optical signal on the first end face side of the frequency selection unit 631 corresponding to the laser emission unit 640, the optical signal on the first end face side of the frequency selection unit 631 is used to monitor and control the mode of the laser emission unit 640, and the second end face of the gain unit 611 is used as the outgoing optical end face of the laser emission unit by the laser emission unit 640, so as to send out the detection signal for working to the outside.

In a specific implementation, a partially reflective film may be provided on the second end surface of the gain unit 611 for providing oscillation of light between the second end surface of the gain unit 611 and the frequency selective unit 631.

In some embodiments of the present disclosure, a plurality of the laser emission units are disposed on the same semiconductor refrigerator, so that temperatures of the plurality of laser emission units are synchronously adjusted to perform whole temperature control, thereby ensuring stable working temperature of the system, and simultaneously achieving high integration level and saving cost. In other embodiments of the present disclosure, a plurality of the laser emitting units are not disposed on the same semiconductor refrigerator, and flexibility is improved.

The structure of the laser will be described in detail below by way of specific examples for better understanding and implementation by those skilled in the art.

Referring to fig. 7, the laser includes a gain array 510, a frequency selective array 530, and a first coupling array 520, wherein:

the gain array 510 includes a plurality of gain units 511 sequentially arranged in a vertical direction, and the plurality of gain units 511 are independently driven;

The frequency selection array 530 includes a plurality of frequency selection units 531 sequentially arranged along the F1 direction, and passband center wavelengths of the plurality of frequency selection units 531 are all different;

the first coupling array 520 includes a plurality of coupling lenses 521 sequentially arranged along the F1 direction, and each coupling lens 521 is respectively located between the corresponding gain unit 511 and the frequency selection unit 531;

The gain units 511 are respectively arranged in the coupling lenses 521 and the frequency selecting units 531 along the horizontal direction in sequence to form a plurality of laser emitting units 540;

In addition, the laser 500 may further include a detection array 550, a filtering module 560, a judging module 570, and a control module 580, wherein:

The detection array 550 may include a plurality of detection units 551 sequentially arranged in a vertical direction, and the plurality of detection units 551 are electrically connected to the filtering module 560, the judging module 570, and the control module 580, respectively;

The detection units 551 are disposed on one side of the second end face of the corresponding gain unit 511.

The gain array 510 and the frequency-selective array 530 form a plurality of the laser emission units 540, when the laser 500 works, the laser 500 including the plurality of the laser emission units 540 can emit multiple paths of narrow linewidth optical signals with different wavelengths, and when the laser emission units 540 work in a non-single mode state, the individual regulation and control of the working mode of one of the laser emission units 540 can be realized by independently regulating the driving current of the gain unit 511.

The transmission direction of the light in the laser emission unit 540 is along the F2 direction, the second end surface of the gain unit 511 and the first end surface of the frequency selection unit 531 are both output ports of optical signals, the detection unit 551 is disposed on one side of the second end surface of the corresponding gain unit 511, that is, the optical signals output by the side are used for performing modal monitoring and control on the laser emission unit 540, and the optical signals output by the first end surface of the frequency selection unit 531 are used for performing radar detection; each detection unit 551 converts the obtained optical signal into a voltage signal, the voltage signal is sent to a filtering module 560 to be filtered so as to obtain a signal to be detected with a frequency higher than a preset frequency, and the judging module 570 obtains the voltage intensity value of the signal to be detected, compares and judges the voltage intensity value with a preset intensity threshold value and outputs a monitoring result according to a judging result; the control module 580 controls the laser emitting unit 540 to adjust the driving current and/or the temperature based on the determination result, so that the laser emitting unit operates in a single mode state.

As an alternative example, the gain array may be implemented by an array gain chip; the frequency selection array can be implemented by a planar waveguide grating array chip and a fiber grating array chip.

The above example integrates a narrow linewidth laser emitting unit with multiple light paths, and can reduce assembly difficulty due to the adoption of an array device; and the driving current of the gain unit in each laser emission unit can be independently adjusted; by means of monitoring and feedback control of the detection units, each laser emission unit can be guaranteed to work in a single-mode state.

Referring to fig. 8, the laser includes a gain array 610, a frequency selection array 630, a first coupling array 620 (including a plurality of coupling lenses 621 sequentially arranged along the F1 direction), a filtering module 660, a judging module 670, and a control module 680, whose functions are similar to the filtering module 560, the judging module 570, and the control module 580, respectively, and will not be described herein.

It will be appreciated that the above examples are illustrative only, and that in practical applications, a person skilled in the art may set the specific number of ways according to the actual requirements and application scenarios; meanwhile, the F1 direction and the F2 direction are not limited to the vertical direction and the horizontal direction shown in the drawings, and may be other directions as long as a plurality of laser emitting units having independent light paths can be formed; the embodiments of the present specification are not limited to the above-described extension schemes.

When the control module is not arranged, the laser does not have the function of controlling the laser emission unit to adjust the control parameters, but the working mode of the laser emission unit can still be monitored.

In the following, with reference to fig. 9A to 9C, respectively, it is described in detail how three operation modes of the laser emitting unit are monitored by specific examples.

Referring to the time domain voltage signal distribution diagram of the optical signal emitted by one laser emitting unit of the laser shown in fig. 9A, voltage signal distribution curves when the driving current of the laser emitting unit is 180mA and when the driving current of the laser emitting unit is 220mA are respectively shown in the diagram, and comparing and analyzing the two voltage signal distribution curves, it is known that the amplitude levels of the voltage signal distribution curves in the single mode state and the multi-mode state are similar in the whole observation period, the convergence characteristic is poor, and the distinction degree is low.

As an optional example, the preset frequency is set to be 1MHz, and the voltage signal converted by the optical signal after the conversion process is subjected to high-pass filtering with a filtering parameter of 1MHz, so as to obtain a signal to be detected with a frequency higher than 1 MHz.

Referring to the time domain voltage signal distribution diagram of the optical signal sent by one laser emitting unit of the laser shown in fig. 9B, the voltage signal distribution curves of the laser emitting unit after the filtering treatment are respectively shown in the time domain voltage signal distribution diagram in the stable single-mode state and the multi-mode state, and comparing and analyzing the two voltage signal distribution curves, compared with fig. 9A, the voltage signal distribution curves in the stable single-mode state and the multi-mode state have better convergence characteristics, the voltage signal distribution curves in the stable single-mode state are mostly in the amplitude low level, the voltage signal distribution curves in the multi-mode state are mostly in the amplitude high level, the distinction degree of the two voltage signal distribution curves is higher, and at this time, whether the laser emitting unit is in the single-mode state (in single comparison) can be judged by setting a proper preset intensity threshold. The preset intensity threshold value is larger than the maximum amplitude of the voltage signal distribution curve in the single-mode state, meanwhile, the preset intensity threshold value is smaller than the maximum amplitude of the voltage signal distribution curve in the multi-mode state, and based on a specific use scene, the preset intensity threshold value is smaller than the intensity value of the voltage signal distribution curve in the multi-mode state, which corresponds to the intensity value of the voltage signal distribution curve and occupies most time, so that the occupation ratio of the laser emission unit in the non-single-mode state is larger than the first preset ratio.

With continued reference to fig. 9B, if the preset intensity threshold V _T1 =12 mV, the second preset duration is 2s, the preset number of times is 9, the first preset ratio is 70%, and when the preset intensity threshold V _T1 =12 mV is-1.00 s, -0.75s, -0.5s, -0.25s, 0.00s, 0.25s, 0.5s, 0.75s and 1.00s, the voltage intensity value of the signal to be detected by the laser emission unit and the preset intensity threshold are respectively compared, and when the driving current is I1, the comparison and judgment are performed at all the above moments, the voltage intensity value is smaller than the preset intensity threshold, and the above 9 judgment results determine that the laser emission unit is in the single-mode state, so that the monitoring result that the laser emission unit is in the stable single-mode state when the driving current is I1 can be obtained. And when the driving current is I2, in the comparison of-1.00 s, -0.75s, -0.5s, -0.25s, 0.00s, 0.25s and 1.00s, the voltage intensity values are all greater than the preset intensity threshold, the above 7 determination results all determine that the laser emission unit is in a non-single mode state, in the comparison of 0.5s and 0.75s, the voltage intensity values are all less than the preset intensity threshold, the above 2 determination results all determine that the laser emission unit is in a single mode state, that is, the laser emission unit has a non-single mode state within the second preset duration, and the duty ratio of the non-single mode state is 77.8% and is greater than the first preset ratio of 60%, so that the monitoring result that the laser emission unit is in a multi-mode state when the driving current is I2 can be obtained.

Referring to the time domain voltage signal distribution diagram of the optical signal sent by one laser emitting unit of the laser shown in fig. 9C, the voltage signal distribution curve when the laser emitting unit is in the mode-skipping state is shown, and it is known that, compared with fig. 9A, by analyzing the voltage signal distribution curve, the voltage signal distribution curve in the mode-skipping state has better convergence characteristics, and the voltage signal distribution curve in a certain single mode state is at a low amplitude level most of the time, and the voltage signal distribution curve in another single mode state is at a low amplitude level most of the time, and the voltage signal amplitude in the two mode-skipping processes has a short abrupt change time period, so that the distinction degree of the voltage signal distribution curve in different time periods is higher, and therefore, by setting a suitable preset intensity threshold, whether the laser emitting unit is in the mode-skipping state can be judged. The preset intensity threshold value is larger than the maximum amplitude of the voltage signal distribution curve when the amplitude is at a low level, and meanwhile the preset intensity threshold value is smaller than the maximum amplitude of the voltage signal distribution curve when the amplitude is at a high level, so that the duty ratio of the laser module in a non-single mode state is smaller than a second preset ratio.

It should be noted that, the mode-skip state is an aggregate of different mode states at different times, and in the above description, only for convenience of understanding, the mode state in the mode-skip state in which the amplitude of the voltage signal distribution curve is higher than the preset intensity threshold is referred to as a non-single mode state.

With continued reference to fig. 9C, assuming that the preset intensity threshold V _T2 =16 mV, the second preset duration is 20s, the second preset ratio is 10%, and the voltage intensity values of the signals to be detected by the laser emission unit and the preset intensity threshold are respectively compared and judged at intervals of 0.5s when the driving current is I3, it can be seen that, in the comparison and judgment performed at-3.5 s, -3.0s and-2.5 s, the voltage intensity values are all greater than the preset intensity threshold, the above 3 judgment results determine that the laser emission unit is in a non-single mode state, and in the other multiple comparison and judgment except three comparisons at-3.5 s, -3.0s and-2.5 s in the time range of-10.0 s to 10.0s, the voltage intensity values are all less than the preset intensity threshold, and the above multiple judgment results determine that the laser emission unit is in a single mode state; that is, the laser emission unit has a non-single mode state within a second preset time period, and the duty ratio of the non-single mode state is 7.3% and is smaller than the second preset ratio by 10%, so that the monitoring result that the laser emission unit is in the mode-skipping state when the driving current is I3 can be obtained.

Through the preset intensity threshold value, the single-mode state and the non-single-mode state can be directly distinguished through single comparison, and the stable single-mode state, the multi-mode state and the mode-jump state can be distinguished and compared for a plurality of times under preset conditions, so that the preset intensity threshold value corresponding to the multi-mode state and the mode-jump state can be the same preset intensity threshold value during actual monitoring, and can be set under the specific condition comprehensive consideration of time domain voltage signal distribution diagrams of the optical signals emitted by the laser emission units under different modes after filtering treatment only when the preset intensity threshold value parameters are set before monitoring; similarly, the preset conditions (for example, the first preset times and the first preset duration) corresponding to the comparison and judgment are also set based on comprehensive consideration of the actual situations of the stable single-mode state, the multi-mode state and the mode-skip state.

In specific implementation, the laser can be applied to various occasions of applying the laser and corresponding equipment, and an application example in the laser radar is given below.

Referring to a schematic structural diagram of a lidar shown in fig. 10, an embodiment of the present disclosure provides a lidar, wherein the lidar 700 includes: any of the lasers 710, the modulation module 720, the first coupling module 740, the coaxial module 750, the scanning module 770, the second coupling module 780, the detection module 790, and the processing module (not shown) previously described. Wherein:

The laser 710 is adapted to output multiple paths of emergent light with narrow linewidth;

The modulation module 720 is adapted to perform linear frequency modulation on the multiple paths of emergent light;

the first coupling module 740 is adapted to separate the multiple paths of outgoing light into local oscillation light and detection light;

The coaxial module 750 is adapted to receive the probe light separated by the first coupling module 740 and transmit it to the scanning module 770, and transmit an echo of the probe light reflected by an external spatial object to the second coupling module 780;

The scanning module 770 is adapted to reflect the probe light to exit to an external space and reflect an echo of the probe light reflected by an object in the external space to the coaxial module 750;

the second coupling module 780 is adapted to perform beat frequency processing on the local oscillation light and the echo reflected by the external space object by the probe light;

the detection module 790 is adapted to detect the signal output by the second coupling module 780;

the processing module is adapted to obtain at least one of distance, reflectivity and speed based on the output information of the detection module 790.

With the above laser radar, the laser 710 with multiple channels of laser emission units may output multiple paths of outgoing light (for example, with wavelength λ ₁、λ₂、λ₃…λ_m) to the modulation module 720, where the outgoing light enters the first coupling module 740 after being chirped by the modulation module 720, the outgoing light with different frequencies is separated into local oscillation light and detection light by the first coupling module 740, where the local oscillation light is directly transmitted to the second coupling module 780, the detection light is transmitted to the scanning module 770 through the coaxial module 750, and is reflected by the scanning module 770 and then emitted to an external space. Then, the echo formed by the reflection of the detected light by the external space object re-enters the laser radar 700 and is reflected to the coaxial module 750 by the scanning module 770, the coaxial module 750 transmits the echo to the second coupling module 780, the second coupling module 780 processes the beat frequency of the incident local oscillation light and the echo and transmits the corresponding optical signal to the detection module 790, the detection module 790 detects the signal output by the second coupling module 780, and the processing module processes and analyzes the signal based on the output information of the detection module 790 to obtain at least one information of distance, reflectivity, speed and the like.

In a specific implementation, the lidar 700 further includes a switch module 730 adapted to time-share control of the emission times of the multiple emission light. Specifically, the switch module 730 includes a plurality of switch units, which are respectively matched with the corresponding laser emitting units, and are adapted to independently and time-divisionally control the light emitting time of the corresponding laser emitting units.

Because each laser emission unit is provided with a corresponding switch unit in a matching way, the switch units independently and time-sharing control the emergent time of emergent light of the corresponding laser emission units, and therefore, the simultaneous or round inspection of the emergent light can be realized by simultaneously or sequentially starting a plurality of switch units, and the detection flexibility of the laser radar is improved.

Further, the laser radar 700 may further include a wavelength separation module 760, where the wavelength separation module 760 separates light with different wavelengths in the detected light, and the separated different wavelengths are distributed along one dimension (e.g. a vertical direction), which is beneficial to reducing the scanning dimension of the scanning module, so that the scanning module only needs to have one scanning dimension to realize three-dimensional detection in space, thereby reducing the design difficulty of the scanning module and the laser radar.

Although the embodiments of the present specification are disclosed above, the present specification is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is therefore intended to be limited only by the appended claims.

Claims

1. A laser, comprising:

A frequency selective array comprising: a plurality of frequency selection units sequentially arranged along the first direction, wherein each frequency selection unit is respectively corresponding to the corresponding gain unit;

A first coupling array comprising: the first coupling units are sequentially arranged along the first direction, and each first coupling unit is respectively positioned between the corresponding gain unit and the corresponding frequency selection unit;

2. A laser as claimed in claim 1, wherein,

The frequency selecting unit includes: a grating;

The first coupling unit includes: and a coupling lens.

3. The laser of claim 2, wherein the frequency selection unit further comprises:

an optical fiber, the grating being formed on the optical fiber;

4. The laser of claim 2, wherein the frequency selection unit comprises: and the grating is formed on the planar waveguide.

5. The laser of claim 1, wherein each gain cell in the gain array is independently driven.

6. The laser of claim 5, further comprising:

7. The laser of claim 6, wherein the detection unit comprises a photodetector adapted to acquire an optical signal emitted by the laser emitting unit and convert the optical signal into a current signal;

the detection unit further includes:

and the transimpedance amplifier is suitable for converting the current signal into a voltage signal and amplifying the voltage signal.

8. The laser of claim 6, wherein the determining module comprises:

The comparator is suitable for comparing the intensity value of the signal to be detected with a preset intensity threshold value and judging the working mode of the laser emission unit according to an output result; wherein: if the intensity value of the signal to be detected is smaller than the preset intensity threshold value, determining that the laser emission unit is in a single-mode state; and if the intensity value of the signal to be detected is not smaller than the preset intensity threshold value, determining that the laser emission unit is in a non-single mode state.

9. The laser of claim 8, wherein the comparator continuously compares the magnitude between the intensity value of the signal to be detected and the preset intensity threshold a plurality of times according to a preset condition, and determines the operation mode of the laser emission unit based on the judgment result of the comparator a plurality of times, comprising at least one of:

10. The laser of claim 6, further comprising:

and the control module is suitable for outputting control signals to the corresponding laser emission units based on the judging result of the judging module so as to adjust the control parameters of the corresponding laser emission units.

11. The laser of claim 10, wherein the control module is adapted to adjust the control parameters of the laser emitting unit such that the laser emitting unit is in a single mode state when it is determined that the laser emitting unit is in a non-single mode state.

12. The laser of claim 11, wherein the control module is adapted to output a first control signal to control the control parameter of the laser emitting unit to be adjusted in a first amplitude as an adjustment unit when it is determined that the laser emitting unit is in a non-single mode state until it is monitored that the laser emitting unit is in a single mode state; and taking the control parameter of the laser emission unit when the laser emission unit enters a single-mode state as a reference value, outputting a second control signal, adjusting the control parameter of the laser emission unit by taking a second amplitude value as an adjusting unit, obtaining a parameter range for enabling the laser emission unit to be in a stable single-mode state, and controlling the laser emission unit to work by adopting the parameter value in the parameter range, wherein the second amplitude value is smaller than the first amplitude value.

13. The laser according to claim 10, characterized in that the control module is adapted to adjust the driving current and/or the temperature of the respective laser emitting unit.

14. The laser of claim 6, wherein the first end face and the second end face of each frequency selection unit in the frequency selection array are provided with a first antireflection film;

15. The laser of claim 6, wherein the first end face and the second end face of each frequency selection unit in the frequency selection array are provided with a first antireflection film;

16. The laser of claim 2, further comprising:

17. The laser of claim 1, wherein the plurality of laser emitting units are disposed on the same semiconductor refrigerator.

18. A lidar, comprising:

the laser of any one of claims 1-17 adapted to output multiple outgoing light;

19. The lidar of claim 18, further comprising: and the switch module is suitable for time-sharing control of the emergent time of the multipath emergent light.

20. The lidar of claim 19, wherein the switching module comprises a plurality of switching units respectively arranged to be matched with the respective laser emitting units, and adapted to independently time-share control the light emission times of the respective laser emitting units.

21. The lidar of claim 18, further comprising:

And the wavelength separation module is suitable for separating light with different wavelengths in the detection light.