CN113036582B - Laser, laser radar comprising same and laser radar scanning method - Google Patents
Laser, laser radar comprising same and laser radar scanning method Download PDFInfo
- Publication number
- CN113036582B CN113036582B CN201911335202.0A CN201911335202A CN113036582B CN 113036582 B CN113036582 B CN 113036582B CN 201911335202 A CN201911335202 A CN 201911335202A CN 113036582 B CN113036582 B CN 113036582B
- Authority
- CN
- China
- Prior art keywords
- laser
- unit
- light
- wavelength
- gain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims description 14
- 230000003287 optical effect Effects 0.000 claims abstract description 37
- 238000001914 filtration Methods 0.000 claims abstract description 21
- 238000005086 pumping Methods 0.000 claims abstract description 20
- 238000002310 reflectometry Methods 0.000 claims description 30
- 230000010355 oscillation Effects 0.000 claims description 19
- 238000001514 detection method Methods 0.000 claims description 15
- 239000006096 absorbing agent Substances 0.000 claims description 14
- 238000012545 processing Methods 0.000 claims description 6
- 238000002592 echocardiography Methods 0.000 claims description 5
- 239000007787 solid Substances 0.000 description 14
- 238000002834 transmittance Methods 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 6
- 239000004065 semiconductor Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 230000010354 integration Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000004806 packaging method and process Methods 0.000 description 4
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 3
- 239000002041 carbon nanotube Substances 0.000 description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910021389 graphene Inorganic materials 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000000411 transmission spectrum Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000003321 amplification Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 229910009372 YVO4 Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000012994 industrial processing Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 230000008447 perception Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910019655 synthetic inorganic crystalline material Inorganic materials 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/93—Lidar systems specially adapted for specific applications for anti-collision purposes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/484—Transmitters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/0602—Crystal lasers or glass lasers
- H01S3/0604—Crystal lasers or glass lasers in the form of a plate or disc
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1106—Mode locking
- H01S3/1112—Passive mode locking
- H01S3/1115—Passive mode locking using intracavity saturable absorbers
- H01S3/1118—Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Nanotechnology (AREA)
- Crystallography & Structural Chemistry (AREA)
- Lasers (AREA)
Abstract
The invention relates to a laser, comprising: a first pump unit configured to generate a first pump light; the resonance unit is arranged at the downstream of the optical path of the first pumping unit and is used for receiving the first pumping light and outputting first laser; and a filtering unit configured to receive the first laser light output by the resonance unit, and emit the first laser light after filtering, wherein the resonance unit is configured to receive seed light, and a wavelength of the first laser light output from the resonance unit is the same as a wavelength of the seed light.
Description
Technical Field
The present invention relates generally to the field of optoelectronics, and more particularly to a laser, a lidar including the laser, and a method of scanning using the lidar.
Background
Diode Pumped Solid State Lasers (DPSSL) have evolved rapidly in recent years as a new type of laser. Compared with the traditional lamp pumped solid state laser, DPSSL replaces a flash lamp with a laser diode with a specific wavelength, and achieves higher light-to-light conversion efficiency, longer working time and small size. Currently, many types of diode pumped solid state lasers are commercialized and widely applied to laser ranging, industrial processing and the like.
Passive Q-switching is one way for a solid state laser to produce pulsed laser light. The Q of a resonant cavity is defined as the ratio of the total energy stored to the energy lost per unit time in the cavity. The Q value in the cavity is adjusted by changing the loss in the cavity, and a laser pulse is formed when the Q switch is turned on.
The laser radar is a commonly used ranging sensor, has the characteristics of long detection distance, high resolution, small environmental interference and the like, and is widely applied to the fields of intelligent robots, unmanned aerial vehicles and the like. In recent years, the development of automatic driving technology is rapid, and a laser radar is indispensable as a core sensor for distance perception. TOF (Time of flight) the laser radar needs to reduce the laser pulse energy for the short-distance and strong-reflection measured object, otherwise, the saturation of the detector signal can occur, and the detection effect is affected. The passive Q-switched solid state laser is difficult to realize continuous adjustment of single pulse energy because the Q-switched solid state laser generates laser light by pumping a laser gain medium through a semiconductor diode. Once the pump power reaches the pump threshold power, the energy at which the laser pulses are generated varies little as the pump power increases. The output power cannot be directly adjusted by changing the injection current as in the case of a semiconductor laser.
To the best of the inventor's knowledge, the main problem of using a polarizer to adjust the laser power at present is that the whole device is large in size, which is not beneficial to the packaging and integration of a solid laser and is not beneficial to the miniaturization of the laser.
The matters in the background section are only those known to the inventors and do not, of course, represent prior art in the field.
Disclosure of Invention
In view of at least one of the drawbacks of the prior art, the present invention provides a laser, comprising:
a first pump unit configured to generate a first pump light;
the resonance unit is arranged at the downstream of the optical path of the first pumping unit and is used for receiving the first pumping light and outputting first laser; and
a filtering unit configured to receive the first laser light output from the resonance unit, emit the filtered laser light,
wherein the resonance unit is configured to receive seed light, and a wavelength of the first laser light output from the resonance unit is the same as a wavelength of the seed light.
According to one aspect of the invention, the resonant unit comprises:
a first laser resonator including a first resonance portion and a second resonance portion, the first pump light being transmitted from the first resonance portion into the first laser resonator, the first laser light being emitted from the second resonance portion, wherein the first laser resonator is configured to receive a seed light, and in the first laser resonator, a mode having a wavelength closest to a wavelength of the seed light preferentially oscillates, so that a wavelength of the first laser light output from the resonance unit is the same as a wavelength of the seed light;
A first gain unit;
a quality factor adjusting unit;
wherein the first gain unit and the quality factor adjusting unit are located between the first resonance portion and the second resonance portion.
According to one aspect of the invention, the laser further comprises a seed light generating unit comprising:
a second pump unit configured to generate a second pump light;
the second gain unit is positioned at the downstream of the optical path of the second pumping unit and receives the second pumping light;
a light splitting unit configured to generate the seed light and a plurality of tuning lights of different wavelengths, the tuning lights of different wavelengths having different propagation directions;
a scanning unit configured to receive the plurality of tuning lights of different wavelengths and return at least one original optical path of the tuning lights of different wavelengths to the spectroscopic unit;
and a reflecting unit between the second pumping unit and the second gain unit, wherein the reflecting unit is configured to reflect the light beam from the second gain unit towards the second pumping unit back to the second gain unit, the reflecting unit, the light splitting unit and the scanning unit form a second laser resonant cavity, and the tuned light returned to the light splitting unit by the original path finally forms oscillation in the second laser resonant cavity.
According to one aspect of the invention, the scanning unit changes the incident angles of the tuning lights in a swinging or rotating mode, and enables the tuning lights vertically incident to the scanning unit to return according to an original light path, and the tuning lights are projected to the reflecting unit through the light splitting unit so as to form back and forth reflection of the tuning lights with corresponding wavelengths in the second laser resonant cavity.
According to an aspect of the present invention, the spectroscopic unit includes: a grating, the grating comprising: at least one of a reflective grating or a transmissive grating.
According to one aspect of the invention, the grating comprises: -a level 1 diffraction efficiency grating or a +1 diffraction efficiency grating;
the beam splitting unit generates the emergent laser in the 0-order light emergent direction of the-1-order diffraction efficiency grating, and generates the plurality of tuning lights in the-1-order diffraction light emergent direction of the-1-order diffraction efficiency grating;
or, the beam splitting unit generates the outgoing laser light in a 0-order light outgoing direction of the +1-order diffraction efficiency grating, and generates the plurality of tuning lights in a +1-order diffraction light outgoing direction of the +1-order diffraction efficiency grating.
According to one aspect of the present invention, the filtering unit includes a narrow band filter whose transmittance varies continuously with a wavelength in a certain wavelength range.
According to one aspect of the present invention, the laser further includes a beam splitter configured to receive the seed light and reflect at least a portion of the seed light, and to receive the first laser light and transmit at least a portion of the first laser light, wherein the reflected at least a portion of the seed light is transmitted from the second resonator into the first laser resonator, and the transmitted at least a portion of the first laser light is incident on the filter unit.
According to one aspect of the present invention, the laser further includes an optical isolator that receives the seed light and allows only the seed light to pass unidirectionally, the seed light passing through the optical isolator being incident on the beam splitter.
According to one aspect of the present invention, the first gain unit and/or the second gain unit comprise a gain medium, and the first gain unit and/or the second gain unit are microchip type gain units; the quality factor adjusting unit comprises a saturable absorber, the saturable absorber is a microchip type saturable absorber, and the first gain unit and the quality factor adjusting unit are mutually attached.
According to one aspect of the invention, the laser further comprises a control unit coupled to the scanning unit and controlling the angle of the scanning unit to control the wavelength of the tuning light oscillating within the second laser resonator.
The invention also relates to a lidar comprising:
a transmitting device comprising a laser as described above;
the receiving device is configured to receive echoes of laser emitted by the laser after being reflected on an obstacle; and
and the signal processing device is configured to obtain the distance and/or the reflectivity of the obstacle currently scanned by the laser radar according to the echo.
According to one aspect of the invention, the lidar is configured to adjust the angle of the scanning unit of the laser in dependence on the obtained distance and/or reflectivity of the obstacle currently scanned by the lidar.
The invention also relates to a method for scanning by using the laser radar, which comprises the following steps:
emitting a detection laser beam to the outside of the laser radar;
receiving radar echoes;
obtaining the distance and/or reflectivity of an obstacle currently scanned by the laser radar;
And adjusting the transmitting power of the laser radar according to the distance and/or the reflectivity of the obstacle.
According to one aspect of the invention, the adjusting the transmit power of the laser of the lidar includes: and adjusting the wavelength of the seed light to adjust the emission power of a laser of the laser radar.
According to one aspect of the invention, the step of adjusting the transmit power of the laser of the lidar comprises: and when the distance is smaller than a distance threshold value and/or the reflectivity is higher than a reflectivity threshold value, adjusting the angle of a scanning unit of the laser, and changing the wavelength of tuning light oscillated in the laser resonant cavity so as to reduce the power of laser emitted from the filtering unit.
The invention mainly provides a passive Q-switched solid laser of a laser diode pump, and the output power of the passive Q-switched solid laser is continuously adjustable. For a pulsed laser, monopulse energy/pulse width = peak power, power refers to monopulse peak power, and energy refers to monopulse energy, unless otherwise specified below.
Compared with a mode of adjusting power by using a polaroid, the embodiment of the invention does not need to use a rotary part, and realizes an all-solid-state structure. Meanwhile, the core part of the laser adopts a microchip structure, which is beneficial to reducing the cost and realizing stable and reliable integral packaging.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 shows a schematic diagram of a laser with tunable output power according to one embodiment of the invention;
FIG. 2 shows the transmission lines of a narrow band filter according to one embodiment of the invention;
FIG. 3 shows a schematic diagram of a scanning unit scanning in accordance with one embodiment of the invention;
fig. 4 illustrates a method of scanning using a lidar according to an embodiment of the invention.
Detailed Description
As described above, the main problem of adjusting the output laser power using a polarizer is that the whole device is bulky. The inventors have found that the laser power adjustment device using a polarizer requires a motor to rotate the half-wave plate, changing the polarization direction of the laser, so that the laser energy passing through the later analyzer (polarizer) is changed. Therefore, due to the adoption of an additional mechanical mechanism (motor), the whole device has large volume, is unfavorable for the encapsulation and integration of the solid laser, and is unfavorable for the miniaturization of the laser.
The inventor analyzes and researches the requirement of the laser radar to obtain a conclusion that the solid laser needs to have the following characteristics as a light source of the laser radar:
1) The power of a laser device which is expected to be applied to the laser radar is continuously adjustable so as to avoid the condition that a detector detects signal saturation when detecting a close-range and strong-reflection target;
2) It is desirable for lidar to have high peak power and narrow pulse width. The light source wavelength of the laser radar is outside the visible light wave band range of human eyes, and the high peak power and the narrow pulse width are beneficial to improving the measurement distance and the signal-to-noise ratio;
3) The working environment of the laser radar is changeable, the performance of the laser radar is easily influenced by natural conditions such as atmospheric environment, air temperature and the like, and the reliability of the laser is required. If it can be packaged as a whole, high reliability and stability can be achieved;
4) A high integration level of the laser is desired, and the laser is compact and low-cost.
Based on the above research, the inventor provides the laser in the embodiment of the invention, so that the output power of the laser is adjustable, and the laser has an all-solid compact structure, thereby better meeting the requirement of a laser radar on a light source.
The laser schemes of the present application will be described in detail below with reference to the accompanying drawings. Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be fixedly connected, detachably connected, or integrally connected, and may be mechanically connected, electrically connected, or may communicate with each other, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is less level than the second feature.
The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.
The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
Fig. 1 shows a laser with an output power that is adjustable according to one embodiment of the invention, and preferably the output power of the laser is continuously adjustable. Described in detail below with reference to fig. 1.
As shown in fig. 1, the laser 10 includes a laser generating unit 20 and a seed light generating unit 30, wherein the seed light generating unit 30 is configured to generate a seed light Ls, the seed light Ls is coupled into the laser generating unit 20, and the laser generating unit 20 can generate an outgoing laser light having the same wavelength as the seed light Ls by injection locking of the seed light Ls. As will be described in detail below.
The laser generating unit 20 includes a first pump unit 21, a first pump optical element 22, a resonance unit, and a filter unit 26, wherein the first pump unit 21 is, for example, a semiconductor laser diode, and is configured to generate a first pump light L1 and to be incident on the first pump optical element 22. The first pump optical element 22 comprises a lens or a lens group or a coupling mirror for appropriately shaping-modulating the first pump light L1 and coupling it into a resonator element located downstream of the optical path of said first pump unit 21. The resonance unit is used for receiving the first pump light L1, and a beam with a certain wavelength can oscillate in the resonance unit and output first laser LO. The filtering unit 26 is configured to receive the first laser LO output by the resonance unit, perform filtering, and emit the filtered laser LO. According to an embodiment of the present invention, the resonance unit is configured to receive the seed light Ls output from the seed light generating unit 30, so that in the resonance unit, a mode having a wavelength closest to that of the seed light Ls preferentially oscillates, and thus the wavelength of the first laser light LO output from the resonance unit is the same as that of the seed light Ls. The structure of the resonance unit is described in detail below.
As shown in fig. 1, the resonance unit includes: a first laser resonator (27, 28), a first gain unit 23 and a quality factor adjustment unit 24. Wherein the first laser resonator comprises a first resonant portion 27 and a second resonant portion 28, and the first laser resonator is defined by the first resonant portion 27 and the second resonant portion 28. According to a preferred embodiment of the invention, the first resonator 27 is, for example, a reflective film coated on the incident surface of the first gain unit 23, which has a high transmittance for light of the first pump wavelength and a high reflectance for light of the laser wavelength, so that in the optical path of fig. 1, the first resonator 27 will allow the first pump light L1 from the first pump unit 21 to pass through and reflect the light beam from the first gain unit 23 towards the first pump unit 21 back to the first gain unit 23. Alternatively, the first resonant portion 27 may be disposed between the first gain unit 23 and the first pump unit 21 (or the first pump optical element 22), so long as it allows the first pump light L1 from the first pump unit 11 to pass through, and at the same time, light in the laser resonant cavity toward the first pump unit 21 is reflected back into the resonant cavity, which is not described herein. According to one embodiment of the invention, the second resonator portion 28 comprises, for example, a film of high reflectivity to the laser wavelength, which forms a first laser resonator with the first resonator portion 27 on the entrance face of the first gain medium 23, plated on the output face of the quality factor adjustment unit 24. The second resonator portion 28 simultaneously allows the seed light Ls to pass through and enter the first laser resonator to form oscillations of the first laser resonator specific wavelength light.
The first gain unit 23 includes a laser gain medium therein. The laser gain medium is used for realizing the population inversion so as to form optical amplification. The quality factor adjusting unit 24 includes a saturable absorber as a Q-switch for passively modulating Q to generate laser pulses.
The laser gain medium may be at least one of Nd: YAG, nd: YVO4, and Er, yb co-doped glass and crystal. The specific properties (center wavelength or wavelength range, etc.) of the gain medium and the specific selection of the gain medium may be set according to the application field of the laser or the wavelength of the laser light generated by the laser, which is not limited by the present invention. In this embodiment, the laser gain medium is a microchip gain medium.
In an embodiment of the invention, the quality factor adjustment unit 24 comprises, for example, a saturable absorber. In the present invention, the first gain unit 23 and the quality factor adjusting unit 24 are processed into micro-chips, reducing the laser size. The whole structure can be used for airtight packaging, so that the laser is small in size, compact in structure and low in cost. The materials of the saturable absorber within the figure of merit adjustment unit 24 include: at least one of YAG, carbon nano tube or graphene. Preferably, the material of the saturable absorber is at least one of carbon nanotubes or graphene. The carbon nano tube or the graphene has good thermal conductivity, and can effectively improve the heat conduction and heat dissipation effects of components in the laser resonant cavity. According to a preferred embodiment of the present invention, as shown in fig. 1, the laser gain medium of the first gain unit 23 and the saturable absorber of the quality factor adjusting unit 24 are attached to each other, that is, the surface of the gain medium in the first gain unit 23 facing the quality factor adjusting unit 24 and the surface of the saturable absorber in the quality factor adjusting unit 24 facing the first gain unit 23 are attached to each other in contact. The laser gain medium and the saturable absorber are processed into microchip and are attached together, so that the laser has a compact structure, the size of a laser resonant cavity can be effectively controlled, and the realization of high repetition frequency, narrow pulse width and high peak power is facilitated.
Typically, the initiation of the Q-switching process in a laser is random, with large variations in the time interval between pulses. In the invention, the Q-switched pulse is triggered by injecting the seed light Ls, and the period jitter of the seed light Ls is very small (the seed light Ls can be realized by the modulated pump light), so that the time jitter of the finally output laser pulse is improved by injection locking, and the consistency of the laser is better. In addition, the laser resonator in the embodiment of fig. 1 is shorter and includes only the lengths of the first gain unit 23 and the quality factor adjusting unit 24, so that higher single pulse energy is more easily obtained. The laser gain medium and the saturable absorber are processed into micro-plates and are bonded together to form a whole. The whole laser has small size, short cavity length and compact structure, and can realize high repetition frequency, narrow pulse width and high peak power. In addition, the whole solid laser is arranged on the radiating bottom plate, and is hermetically packaged into the metal shell, so that high reliability and high stability are achieved.
In fig. 1, the first pump light L1 is transmitted from the first resonator 27 into the first laser resonator. The first laser resonator may receive the seed light Ls, and thus in the first laser resonator, a mode having a wavelength closest to the wavelength of the seed light Ls preferentially oscillates such that the wavelength of the first laser light LO output from the resonator unit is the same as the wavelength of the seed light Ls. Wherein the first gain unit 23 and the quality factor adjusting unit 24 are located between the first resonance portion 27 and the second resonance portion 28, and the first laser LO is emitted from the second resonance portion 28. In the first laser resonant cavity, when the gain is equal to or greater than the loss, stable laser oscillation can be established in the resonant cavity.
In addition, it will be readily appreciated by those skilled in the art that the first pump optical element 22 is not necessary. For example, when the first pump light L1 generated by the first pump unit 21 satisfies the condition of being coupled into the first gain unit 23, the first pump optical element 22 may not be required to be provided. Alternatively, the first pump optical element 22 may be integrated with the first pump unit 21 such that the pump light exiting the first pump unit 21 may be directly coupled into said first gain unit 23.
According to one embodiment of the present invention, the filtering unit 26 includes a narrow-band filter, and the transmittance of the narrow-band filter is continuously changed along with the wavelength in a certain wavelength range, and outputs laser light with different powers according to different wavelength transmittances, so as to realize adjustment of the output laser power. The narrowband filter of the present invention is, for example, an FP etalon, a narrowband filter, or other optical element having a narrowband transmission spectrum. The performance of the filtering unit 26 (e.g., FP etalon) varies with temperature changes, such as line slope, width, etc. Thus, according to a preferred embodiment of the present invention, the laser generating unit 20 further comprises a semiconductor refrigerator 29, the semiconductor refrigerator 29 acting on the filter unit 26, and by controlling the temperature of the filter unit 26, a change of the transmission line, such as line slope, width, etc., can be achieved as desired.
In fig. 2, curve I is an example of the transmission line of the narrow band filter, and curve II is a line from which the laser light is emitted from the second resonator portion 28. The central wavelength of the laser spectrum line is determined by the seed light Ls, and the laser beams with different central wavelengths correspond to different transmittances on the transmission spectrum line (as the arrow in the figure indicates the transmittance corresponding to the current laser spectrum line). By controlling the wavelength of the seed light Ls, wavelength tuning (shift of the center wavelength of the laser line) can be achieved, and different transmittances can be obtained in the narrow band filter. When the wavelength of the seed light Ls is continuously changed, the laser power transmitted through the narrow-band filter is continuously changed, so that the laser power can be continuously adjustable.
The seed light generating unit 30 according to a preferred embodiment of the present invention is described in detail below.
As shown in fig. 1, the seed light generating unit 30 includes a second pump unit 31, a second pump optical element 32, a second gain unit 33, a spectroscopic unit 34, and a scanning unit 35. The second pump unit 31 is, for example, a semiconductor laser diode, and is configured to generate the second pump light L2 and to be incident on the second pump optical element 32. The second gain unit 33 is located downstream of the optical path of the second pump unit 31 and receives the second pump light L2. The light splitting unit 34 is configured to generate the seed light Ls and a plurality of tuning lights of different wavelengths, which differ in propagation direction. The scanning unit 35 is configured to receive the plurality of tuning lights of different wavelengths, and return at least one original light path of the tuning lights of different wavelengths to the spectroscopic unit 34. Similar to the first gain unit 23, the second gain unit 33 also comprises a gain medium, and the second gain unit 33 may be a microchip type gain unit.
The seed light generating unit 30 further includes a reflecting unit 38 located between the second pumping unit 31 and the second gain unit 33, in fig. 1, the reflecting unit 38 is a reflecting film plated on an incident surface of the second gain unit 33, which has a high transmittance for light of a pumping wavelength and a high reflectance for light of a lasing wavelength, so in the optical path of fig. 1, the reflecting unit 38 will allow the second pumping light from the second pumping unit 31 to pass, and reflect the light beam from the second gain unit 33 toward the second pumping unit 31 back to the second gain unit 33, so that the reflecting unit 38, the spectroscopic unit 34, and the scanning unit 35 constitute a second laser resonator, and the tuned light returned to the spectroscopic unit 34 by the original optical path of the scanned unit 35 finally forms oscillation in the second laser resonator, and finally emits and forms the seed light Ls. Alternatively, the reflecting unit 38 may be disposed between the second gain unit 33 and the second pump unit 31 (or the second pump optical element 32), so long as it allows the second pump light from the second pump unit 31 to pass through, and at the same time, the light in the laser resonator toward the second pump unit 31 is reflected back into the resonator, which is not described herein.
The spectroscopic unit 34 includes, for example, a diffraction grating, and outputs the seed light Ls as 0 th order of the diffraction grating. The light passing through the second gain unit 33 is incident on the diffraction grating, and it can be seen from the grating equation that the diffraction angles of the light of different wavelengths are different at the same order (other than 0 order). The diffraction grating in the present invention is, for example, a-1-order diffraction efficiency grating, and the-1-order broadband diffraction efficiency can be realized to be more than 95%. Therefore, the light splitting unit 34 can generate a plurality of tuning lights of different wavelengths at-1 level, and emit seed lights Ls of different wavelengths at 0 level based on the oscillation of a part of the tuning lights in the laser resonator. In this embodiment, the grating of the light splitting unit 34 can effectively ensure the light splitting effect of the generated seed light Ls and the plurality of tuning lights, and the propagation direction difference of the tuning lights between different wavelengths can be sufficiently large by selecting a suitable grating (for example, having a smaller grating constant) so as to reduce the selection difficulty of the subsequent scanning unit. However, in other embodiments of the present invention, the light splitting unit 34 may be configured as other optical devices capable of splitting a plurality of tuning lights, such as a prism, which are within the scope of the present invention.
As shown in fig. 1, the light splitting unit 34 is a transmissive grating, such as a deep etched binary phase grating, and the seed light exits from the transmissive 0-stage, and the tuning light with a plurality of different wavelengths propagates in different directions after being split at the transmissive-1 stage. The light splitting is implemented in the light splitting unit 34 by using a transmission grating is only an example. In other embodiments of the present invention, the grating may also include a reflective grating, which is not described herein.
Furthermore, in addition to the-1 order diffraction efficiency grating, the grating may also include a +1 order diffraction efficiency grating. When the grating is a-1-order diffraction efficiency grating, the light splitting unit 34 generates the seed light Ls in a 0-order light emission direction of the-1-order diffraction efficiency grating, and generates the plurality of tuning lights in a-1-order diffraction light emission direction of the-1-order diffraction efficiency grating; when the grating is a +1-order diffraction efficiency grating, the light splitting unit 34 generates the seed light Ls in the 0-order light emission direction of the +1-order diffraction efficiency grating, and generates the plurality of tuning lights based on the +1-order diffraction light emission direction of the +1-order diffraction efficiency grating.
The beam splitting unit 34 adopts a-1-level diffraction efficiency grating or a +1-level diffraction efficiency grating to achieve beam splitting, so that the energy of the tuning lights generated by the beam splitting unit 34 can be effectively improved, and meanwhile, the output transmittance of the second laser resonant cavity (namely, the energy loss of the light to the outside when the light is reflected back and forth in the laser resonant cavity) is reduced, so that the loss of the laser resonant cavity can be effectively reduced, the energy waste of pump light is reduced, and the pulse energy of the seed light can be effectively controlled.
The scanning unit 35 performs angular scanning within a certain range, the surface of the scanning unit 35 is coated with a dielectric film with high reflectivity for the seed light wavelength range (or the second gain unit gain wavelength range), and the scanning unit 35, the reflecting unit 38 and the light splitting unit 34 together form a second laser resonant cavity. The scanning unit 35 changes the incident angles of the tuning lights by swinging or rotating, and makes the tuning lights vertically incident to the scanning unit 35 return along the original light path, and after passing through the light splitting unit 34, the second gain unit 33 is projected to the reflecting unit 38 so as to form back and forth reflection of the tuning lights with corresponding wavelengths in the second laser resonant cavity. Light that is not normally incident on the scanning unit 35 is reflected out of the laser resonator. As shown in fig. 3, at times t0, t1, and t2, the tuning lights with wavelengths λ0, λ1, and λ2 are respectively perpendicularly incident to the scanning unit 35, and reflected by the scanning unit 35 and return along the original optical path to finally form laser oscillation in the laser resonator. In the laser resonant cavity, when the gain is equal to or greater than the loss, stable laser oscillation is established in the resonant cavity. Therefore, at the times t0, t1 and t2, the laser resonant cavities start to form the oscillation of the tuning light with the wavelengths of λ0, λ1 and λ2 respectively, that is, the laser resonant cavities can realize the oscillation of the light with different wavelengths at different times, so that the wavelength tuning of the seed light Ls is realized. The seed light generating unit 30 is shown in fig. 1 to include one scanning unit 35, but the present invention is not limited thereto and may include a plurality of scanning units.
It follows that the speed of wavelength tuning of the seed light generating unit 30 is related to the speed of selection of different wavelength tuned light by the scanning unit 35. In this embodiment, the speed of selection of the scanning unit 35 for different wavelength tuning light is related to the speed of oscillation or rotation of the scanning unit 35. According to one embodiment of the invention, the scanning unit 35 comprises a galvanometer. The incidence angles of the tuning lights can be changed rapidly through the high vibration frequency of the vibrating mirror, and high-speed selection is realized among the tuning lights, so that the tuning lights forming laser oscillation in the second laser resonant cavity are changed at high speed, and high-speed wavelength tuning is realized. Moreover, the scanning unit 35 may include a MEMS galvanometer, so that the volume of the scanning unit 35 can be effectively reduced, which is beneficial to improving the integration level of the laser. In the present invention, the scanning unit 35 is, for example, a micro-scanning mirror based on a silicon process or a non-silicon process of a MEMS processing technology, and the oscillation of the micro-scanning mirror can be generated by applying an alternating current to electrodes connected to the coils of the MEMS scanning mirror. The micro-scanning mirror is resonant, millimeter-sized, for example, which is advantageous for laser miniaturization.
According to one embodiment of the present invention, no quality factor adjusting unit is provided in the seed light generating unit 30, and thus the generated seed light energy is low. The spectroscopic unit 34 and the scanning unit 35 can select light of a specific wavelength at different times, and generate the seed light Ls by outputting the 0 th order of the diffraction grating.
In order to couple the seed light Ls into the first laser resonator of the laser, the laser generating unit 20 of the laser 10 further comprises a beam splitter 25, such as a half mirror, the beam splitter 2 being configured to receive the seed light Ls and reflect at least a part of the seed light Ls onto the second resonator 28 and to transmit it into the first laser resonator through the second resonator 28, and the beam splitter 25 being configured to receive the first laser light LO and transmit at least a part of the first laser light LO, at least a part of the transmitted first laser light LO being incident on the filtering unit 26.
Further in accordance with a preferred embodiment of the present invention, as shown in fig. 1, the laser 10 further includes a mirror 36 and an optical isolator 37, the mirror 36 receiving the seed light Ls and changing its direction by reflection so as to be incident on the optical isolator 37, the optical isolator 37 receiving the seed light Ls and allowing only the seed light Ls to pass unidirectionally, the seed light Ls passing through the optical isolator being incident on the beam splitter 25 and at least partially entering the first laser resonator, whereby a weak signal is injected during the Q-switched start-up so that in the first laser resonator, a mode having a frequency closest to the frequency of the injected signal preferentially oscillates, and the other modes are suppressed so that the wavelength of the first laser LO output by the laser is the same as the wavelength of the seed light Ls. Therefore, the wavelength of the laser pulse emitted from the first laser resonant cavity is locked to the wavelength of the seed laser. It will be appreciated that the mirror 36 is not required, and the seed light Ls may be directly incident into the optical isolator 37, and the use of the mirror 36 may further turn the light beam, making the structure more compact. The first laser LO enters a filtering unit 26 (e.g., a narrow-band filter) after passing through the beam splitter 25, and exits after being subjected to power adjustment by filtering. The narrow band filter in this patent application may be an FP etalon, a narrow band filter, or other optical element having a narrow band transmission spectrum.
Therefore, in the embodiment of the invention, the output power of the passive Q-switched solid laser is adjustable by adopting a mode of combining seed light injection locking and laser tuning with a narrow-band filter.
The laser 10 is shown in fig. 1 as comprising a seed light generating unit 30. It will be readily appreciated by those skilled in the art that the invention is not limited thereto, and that the laser 10 may not include a seed light generating unit, but may be directly coupled into the seed light, which is within the scope of the invention.
According to a preferred embodiment of the present invention, the laser 10 further comprises a control unit coupled to the scanning unit 35 and controlling the angle of the scanning unit 35 to control the wavelength of the tuning light oscillating within the second laser resonator and thereby the wavelength of the seed light and the wavelength of the first laser LO.
According to one embodiment of the present invention, the laser 10 further includes a detection unit, where the detection unit may detect a moment when the laser oscillation in the first laser resonator forms to generate the output laser light. The detection unit may comprise a photodiode. The detection unit detects the output beam of the beam splitter 25 to obtain the timing at which the laser oscillation forms the generation output laser light.
Compared with a mode of adjusting power by using a polaroid, the embodiment of the invention does not need to use a rotary part, and realizes an all-solid-state structure. Meanwhile, the core part of the laser adopts a microchip structure, which is beneficial to reducing the cost and realizing stable and reliable integral packaging.
The invention also relates to a lidar comprising: transmitting means, receiving means, and signal processing means. Wherein the emitting means comprise one or more lasers 10 as described above for emitting a detection laser beam. The detection laser beam is diffusely reflected on the obstacle, and a part of the reflected beam returns to the laser radar and is received as a radar echo by the receiving device. The signal processing device is configured to obtain the distance and/or reflectivity of an obstacle currently scanned by the laser radar according to the radar echo, and generate point cloud data.
According to one embodiment of the present invention, the lidar may adjust the wavelength of the seed light Ls (e.g., adjust the wavelength of the seed light Ls by adjusting the angle of the scanning unit 35) according to the obtained distance and/or reflectivity of the obstacle currently scanned by the lidar, thereby adjusting the light-emitting power of the laser. For example, the lidar may determine whether the distance is less than a preset distance threshold and whether the reflectivity is greater than a preset reflectivity threshold based on the distance and/or reflectivity of the currently detected obstacle. When it is determined that the distance between the obstacles is smaller than the preset distance threshold and/or the reflectivity is higher than the preset reflectivity threshold, the transmitting device of the laser radar preferably needs to reduce the energy of the laser pulse of the laser when transmitting the next detection beam, otherwise, the condition that the detector signal of the receiving device is saturated will occur, and the detection performance is affected. For this purpose, the lidar is configured to control the laser to adjust the angle of the scanning unit of the laser such that the wavelength of the seed light (and thus the wavelength of the first laser light) that forms oscillation and exits in the second laser resonator is further deviated from the center wavelength of the passband of the narrow-band filter in the filtering unit, thereby reducing the energy of the laser pulse. Additionally or alternatively, when it is determined that the distance of the obstacle is greater than the preset distance threshold and/or the reflectivity is less than the preset reflectivity threshold, the transmitting device of the laser radar preferably needs to increase the energy of the laser pulse of the laser device when transmitting the probe beam next time, so as to improve the detection performance. For this purpose, the lidar is configured to control the laser to adjust the angle of the scanning unit of the laser such that the wavelength of the seed light (and thus the wavelength of the first laser light) that forms oscillation and exits in the laser resonator is further closer to the center wavelength of the passband of the narrow-band filter in the filter unit, thereby increasing the energy of the exiting laser pulse.
The invention also relates to a method 200 of scanning using a lidar as described above, comprising:
in step S201, a detection laser beam is emitted to the outside of the lidar.
In step S202, a radar echo is received. Radar echoes may be received, for example, by photodetectors in a lidar receiving device and the echo signals converted into electrical signals.
In step S203, the distance and/or reflectivity of the obstacle currently scanned by the lidar is obtained. Parameters such as distance and/or reflectivity of the currently scanned obstacle may be obtained by processing the electrical signal, including but not limited to amplification, filtering, analog-to-digital conversion, and the like.
In step S204, the emission power of the laser of the lidar is adjusted according to the distance and/or the reflectivity of the obstacle. Wherein according to a preferred embodiment, when the distance is smaller than a distance threshold and/or the reflectivity is higher than a reflectivity threshold, the angle of the scanning unit of the laser is adjusted, and the wavelength of tuning light oscillating in the second laser resonator is changed, so that the wavelength of seed light (and thus the wavelength of the first laser light) forming oscillation and outgoing in the second laser resonator is further away from the center wavelength of the passband of the narrow-band filter in the filtering unit, thereby reducing the energy of the outgoing laser pulse. Additionally or alternatively, when it is determined that the distance of the obstacle is greater than the preset distance threshold and/or the reflectivity is less than the preset reflectivity threshold, the transmitting device of the laser radar preferably needs to increase the energy of the laser pulse of the laser device when transmitting the probe beam next time, so as to improve the detection performance. For this purpose, the lidar is configured to control the laser to adjust the angle of the scanning unit of the laser such that the wavelength of the seed light (and thus the wavelength of the first laser light) that forms oscillation and exits in the second laser resonator is further closer to the center wavelength of the passband of the narrow-band filter in the filter unit, thereby increasing the energy of the exiting laser pulse.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (16)
1. A laser, comprising:
a first pump unit configured to generate a first pump light;
the resonance unit is arranged at the downstream of the optical path of the first pumping unit and is used for receiving the first pumping light and outputting first laser; and
a filtering unit configured to receive the first laser light output from the resonance unit, emit the filtered laser light,
Wherein the resonance unit is configured to receive a seed light, and a wavelength of the first laser light output from the resonance unit is the same as a wavelength of the seed light; the laser power transmitted through the filtering unit is adjusted by adjusting the wavelength of the seed light, the filtering unit comprises a narrow-band filter, and when the wavelength of the seed light is continuously changed, the laser power transmitted through the narrow-band filter is continuously changed, so that the laser power can be continuously adjustable; the resonant unit comprises a first laser resonant cavity, the first laser resonant cavity comprises a first resonant part and a second resonant part, and the seed light enters the first laser resonant cavity through the second resonant part.
2. The laser of claim 1, the first pump light being transmitted from the first resonant portion into the first laser resonator, the first laser light exiting from the second resonant portion, wherein the first laser resonator is configured to receive seed light, in which a mode having a wavelength closest to a wavelength of the seed light preferentially oscillates such that a wavelength of the first laser light output from the resonant unit is the same as a wavelength of the seed light;
A first gain unit;
a quality factor adjusting unit;
wherein the first gain unit and the quality factor adjusting unit are located between the first resonance portion and the second resonance portion.
3. The laser according to claim 1 or 2, further comprising a seed light generating unit comprising:
a second pump unit configured to generate a second pump light;
the second gain unit is positioned at the downstream of the optical path of the second pumping unit and receives the second pumping light;
a light splitting unit configured to generate the seed light and a plurality of tuning lights of different wavelengths, the tuning lights of different wavelengths having different propagation directions;
a scanning unit configured to receive the plurality of tuning lights of different wavelengths and return at least one original optical path of the tuning lights of different wavelengths to the spectroscopic unit;
and a reflecting unit between the second pumping unit and the second gain unit, wherein the reflecting unit is configured to reflect the light beam from the second gain unit towards the second pumping unit back to the second gain unit, the reflecting unit, the light splitting unit and the scanning unit form a second laser resonant cavity, and the tuned light returned to the light splitting unit by the original path finally forms oscillation in the second laser resonant cavity.
4. A laser as claimed in claim 3 wherein the scanning unit changes the angle of incidence of the plurality of tuning lights by swinging or rotating and returns the tuning light normally incident to the scanning unit as an original optical path, and projects the tuning light to the reflecting unit via the beam splitting unit to form back and forth reflection of the tuning light of a corresponding wavelength in the second laser resonator.
5. A laser as claimed in claim 3 wherein the light splitting unit comprises: a grating, the grating comprising: at least one of a reflective grating or a transmissive grating.
6. The laser of claim 5, wherein the grating comprises: -a level 1 diffraction efficiency grating or a +1 diffraction efficiency grating;
the light splitting unit generates outgoing laser in the 0-order light outgoing direction of the-1-order diffraction efficiency grating, and generates the plurality of tuning lights in the-1-order diffraction light outgoing direction of the-1-order diffraction efficiency grating;
or, the beam splitting unit generates the outgoing laser light in the 0-order light outgoing direction of the +1-order diffraction efficiency grating, and generates the plurality of tuning lights in the +1-order diffraction light outgoing direction of the +1-order diffraction efficiency grating.
7. A laser as claimed in claim 1 or 2 wherein the filtering unit comprises a narrow band filter having a transmissivity that varies continuously over a range of wavelengths.
8. The laser of claim 1 or 2, further comprising a beam splitter configured to receive the seed light and reflect at least a portion of the seed light and to receive the first laser light and transmit at least a portion of the first laser light, wherein the reflected at least a portion of the seed light is transmitted from the second resonant portion into the first laser resonator and the transmitted at least a portion of the first laser light is incident on the filtering unit.
9. The laser of claim 8, further comprising an optical isolator that receives the seed light and allows only one-way passage of the seed light, the seed light passing through the optical isolator being incident on the beam splitter.
10. The laser of claim 3, wherein the first gain element and/or the second gain element comprises a gain medium, the first gain element and/or the second gain element being microchip gain elements; the quality factor adjusting unit comprises a saturable absorber, the saturable absorber is a microchip type saturable absorber, and the first gain unit and the quality factor adjusting unit are mutually attached.
11. A laser as claimed in claim 3 wherein the laser further comprises a control unit coupled to the scanning unit and controlling the angle of the scanning unit to control the wavelength of tuned light oscillating within the second laser resonator.
12. A lidar, comprising:
transmitting means comprising a laser as claimed in any one of claims 1 to 11;
the receiving device is configured to receive echoes of laser emitted by the laser after being reflected on an obstacle; and
and the signal processing device is configured to obtain the distance and/or the reflectivity of the obstacle currently scanned by the laser radar according to the echo.
13. The lidar of claim 12, wherein the lidar is configured to adjust an angle of a scanning unit of the laser based on an obtained distance and/or reflectivity of an obstacle currently scanned by the lidar.
14. A method of scanning using the lidar of any of claims 12-13, comprising:
emitting a detection laser beam to the outside of the laser radar;
receiving radar echoes;
Obtaining the distance and/or reflectivity of an obstacle currently scanned by the laser radar;
and adjusting the transmitting power of the laser radar according to the distance and/or the reflectivity of the obstacle.
15. The method of claim 14, wherein said adjusting the transmit power of the laser of the lidar comprises: and adjusting the wavelength of the seed light to adjust the emission power of a laser of the laser radar.
16. The method of claim 14 or 15, wherein the step of adjusting the transmit power of the laser of the lidar comprises: and when the distance is smaller than a distance threshold value and/or the reflectivity is higher than a reflectivity threshold value, adjusting the angle of a scanning unit of the laser, and changing the wavelength of tuning light oscillated in the laser resonant cavity so as to reduce the power of laser emitted from the filtering unit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911335202.0A CN113036582B (en) | 2019-12-23 | 2019-12-23 | Laser, laser radar comprising same and laser radar scanning method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911335202.0A CN113036582B (en) | 2019-12-23 | 2019-12-23 | Laser, laser radar comprising same and laser radar scanning method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113036582A CN113036582A (en) | 2021-06-25 |
| CN113036582B true CN113036582B (en) | 2024-01-26 |
Family
ID=76451237
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911335202.0A Active CN113036582B (en) | 2019-12-23 | 2019-12-23 | Laser, laser radar comprising same and laser radar scanning method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113036582B (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120140782A1 (en) * | 2010-12-07 | 2012-06-07 | Raytheon Company | Low timing jitter, single frequency, polarized laser |
| CN103022860A (en) * | 2011-09-21 | 2013-04-03 | 中国科学院福建物质结构研究所 | Tunable ytterbium-doping double-clad fiber mode-locked laser |
| CN103474872A (en) * | 2013-10-14 | 2013-12-25 | 哈尔滨工业大学 | Single longitudinal mould Ho:YAP solid laser generator for pulse operation |
| CN106911060A (en) * | 2017-03-30 | 2017-06-30 | 电子科技大学 | The high-efficiency high power middle infrared laser of Wavelength tunable |
| CN107248695A (en) * | 2017-06-16 | 2017-10-13 | 深圳博睿丰科技发展有限公司 | A kind of narrow linewidth inner chamber Ramar laser of fundamental frequency light injection seeded |
| CN109557547A (en) * | 2018-12-27 | 2019-04-02 | 武汉万集信息技术有限公司 | Laser radar, range measurement and/or method for determining speed and storage medium |
| CN109950784A (en) * | 2019-04-10 | 2019-06-28 | 上海禾赛光电科技有限公司 | Laser and laser radar |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106329297A (en) * | 2016-10-21 | 2017-01-11 | 华南理工大学 | Multi-wavelength and narrow line width single-frequency fiber laser light source for laser radar system |
-
2019
- 2019-12-23 CN CN201911335202.0A patent/CN113036582B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120140782A1 (en) * | 2010-12-07 | 2012-06-07 | Raytheon Company | Low timing jitter, single frequency, polarized laser |
| CN103022860A (en) * | 2011-09-21 | 2013-04-03 | 中国科学院福建物质结构研究所 | Tunable ytterbium-doping double-clad fiber mode-locked laser |
| CN103474872A (en) * | 2013-10-14 | 2013-12-25 | 哈尔滨工业大学 | Single longitudinal mould Ho:YAP solid laser generator for pulse operation |
| CN106911060A (en) * | 2017-03-30 | 2017-06-30 | 电子科技大学 | The high-efficiency high power middle infrared laser of Wavelength tunable |
| CN107248695A (en) * | 2017-06-16 | 2017-10-13 | 深圳博睿丰科技发展有限公司 | A kind of narrow linewidth inner chamber Ramar laser of fundamental frequency light injection seeded |
| CN109557547A (en) * | 2018-12-27 | 2019-04-02 | 武汉万集信息技术有限公司 | Laser radar, range measurement and/or method for determining speed and storage medium |
| CN109950784A (en) * | 2019-04-10 | 2019-06-28 | 上海禾赛光电科技有限公司 | Laser and laser radar |
Non-Patent Citations (1)
| Title |
|---|
| 杨晓芳.新型掺铥陶瓷激光器及其应用.中国矿业大学出版社,2018,(第978-7-5646-4291-4版),第72-73页. * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113036582A (en) | 2021-06-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN211655309U (en) | Laser and laser radar including the same | |
| CN109950784B (en) | Laser and laser radar | |
| US5255274A (en) | Broadband laser source | |
| US7813390B2 (en) | Injection-seeded monolithic laser | |
| US5189676A (en) | Broadband laser source | |
| US7599413B2 (en) | Self-contained module for injecting signal into slave laser without any modifications or adaptations to it | |
| US5394238A (en) | Look-ahead windshear detector by filtered Rayleigh and/or aerosol scattered light | |
| US9124064B2 (en) | Ultrashort pulse microchip laser, semiconductor laser, and pump method for thin laser media | |
| US11462881B2 (en) | Method and device for altering repetition rate in a mode-locked laser | |
| US5077747A (en) | Alignment-insensitive method for wideband tuning of an unmodified semiconductor laser | |
| EP2901531B1 (en) | Microchip laser with single solid etalon | |
| US5272708A (en) | Two-micron modelocked laser system | |
| JP4793675B2 (en) | Distance measuring device | |
| WO2022166102A1 (en) | Servo matching control mid-infrared differential dual-wavelength laser based on multi-period nd:mgo:ppln | |
| JPH11514162A (en) | Eye-safe laser transmitter with Brewster angle Q-switch in single cavity of both pump laser and optical parametric oscillator | |
| WO1986001347A1 (en) | A co2 tea laser utilizing an intra-cavity prism q-switch | |
| CN113036582B (en) | Laser, laser radar comprising same and laser radar scanning method | |
| CN109904720B (en) | Injection frequency-locking 1342nm annular solid laser and control method | |
| JPH0797675B2 (en) | Semiconductor laser pumped solid-state laser device | |
| JPH0482069B2 (en) | ||
| CN113036590B (en) | Laser, laser radar including the same, and scanning method of the laser radar | |
| US11054523B1 (en) | LiDAR with signal-resonance range enhancement | |
| CN113097852A (en) | Laser, lidar comprising same and method of scanning using lidar | |
| US20220368099A1 (en) | Tunable microchip laser and laser system for ranging applications | |
| CN102801098A (en) | Pulsed laser and method for controlling same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: No.2 building, no.468 xinlai Road, Jiading District, Shanghai, 201821 Applicant after: Shanghai Hesai Technology Co.,Ltd. Address before: No.2 building, no.468 xinlai Road, Jiading District, Shanghai, 201821 Applicant before: Shanghai Hesai Technology Co.,Ltd. |
|
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |