CN115548870A - Semiconductor laser with tunable frequency - Google Patents
Semiconductor laser with tunable frequency Download PDFInfo
- Publication number
- CN115548870A CN115548870A CN202110724813.5A CN202110724813A CN115548870A CN 115548870 A CN115548870 A CN 115548870A CN 202110724813 A CN202110724813 A CN 202110724813A CN 115548870 A CN115548870 A CN 115548870A
- Authority
- CN
- China
- Prior art keywords
- laser
- phase shifter
- waveguide
- optical amplifier
- optical
- 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.)
- Pending
Links
- 239000004065 semiconductor Substances 0.000 title claims abstract description 139
- 230000003287 optical effect Effects 0.000 claims abstract description 185
- 239000000463 material Substances 0.000 claims abstract description 58
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 49
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 49
- 239000010703 silicon Substances 0.000 claims abstract description 49
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 47
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 47
- 238000010168 coupling process Methods 0.000 claims abstract description 20
- 238000005859 coupling reaction Methods 0.000 claims abstract description 20
- 230000008878 coupling Effects 0.000 claims abstract description 19
- 238000001514 detection method Methods 0.000 claims description 32
- 230000001276 controlling effect Effects 0.000 claims description 10
- 230000008859 change Effects 0.000 claims description 8
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 238000013461 design Methods 0.000 description 31
- 238000010586 diagram Methods 0.000 description 30
- 230000005540 biological transmission Effects 0.000 description 20
- 238000000034 method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 8
- 230000008901 benefit Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 230000008054 signal transmission Effects 0.000 description 5
- 238000004891 communication Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 230000004044 response Effects 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000010408 sweeping Methods 0.000 description 3
- 239000006117 anti-reflective coating Substances 0.000 description 2
- 230000035559 beat frequency Effects 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 230000009022 nonlinear effect Effects 0.000 description 2
- 238000012014 optical coherence tomography Methods 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 239000002096 quantum dot Substances 0.000 description 1
Images
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
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/1003—Waveguide having a modified shape along the axis, e.g. branched, curved, tapered, voids
- H01S5/1014—Tapered waveguide, e.g. spotsize converter
-
- 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
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
-
- 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
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
- H01S5/0687—Stabilising the frequency of the laser
-
- 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
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
-
- 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
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
- H01S5/125—Distributed Bragg reflector [DBR] lasers
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
The application discloses a semiconductor laser with tunable frequency for providing a laser which is low in coupling difficulty and can meet requirements of rapid frequency modulation, narrow line width and high power. The laser includes a first reflective semiconductor optical amplifier and an optical resonator cavity coupled. The optical resonator includes: a spot-size converter made of a silicon nitride waveguide material, a first waveguide converter, and a first phase shifter made of a silicon waveguide material. The first reflective semiconductor optical amplifier is used for injecting light beams into the optical resonant cavity; the spot size converter is used for converting the spot size output by the first reflective semiconductor optical amplifier into the spot size input by the first waveguide converter; a first waveguide converter comprising a silicon nitride waveguide and a silicon waveguide for transmitting the light beam from the spot-size converter into the first phase shifter; and the first phase shifter is used for controlling and changing the phase of the light beam by changing the refractive index in the optical resonant cavity.
Description
Technical Field
The application relates to the technical field of lasers, in particular to a semiconductor laser with tunable frequency.
Background
The semiconductor laser with tunable frequency is used as an important photoelectric device and can be applied to the fields of laser radar, optical communication and the like. For example, in the field of laser radar, frequency Modulated Continuous Wave (FMCW) laser radar technology has received attention in recent years due to its advantages of higher sensitivity and higher ranging accuracy. The most central of the FMCW lidar technology is a frequency tunable semiconductor laser (which may be referred to simply as a "frequency-modulated laser").
At present, a frequency-modulated laser may be, for example, a Distributed Feedback (DFB) laser, and the frequency of the laser is tunable by using an electrical injection method, but the resonant cavity of the DFB semiconductor laser is generally short, so that the linewidth of emitted laser is large, and the thermal effect of the injection current also brings about an obvious frequency modulation nonlinear effect, thereby reducing the signal-to-noise ratio. The frequency modulation laser can also use the optical resonant cavity technology of the whispering gallery mode, can reduce the line width of the laser through optical feedback, but has the defects that the laser has a complex structure, a plurality of optical elements are needed to carry out space optical coupling, the coupling difficulty is larger, and the cost is higher.
Therefore, the semiconductor laser device which can simultaneously meet the requirements of rapid frequency modulation, narrow line width, high power and low coupling difficulty is provided, and the semiconductor laser device has important significance for the development of the fields of laser radars, optical communication and the like.
Disclosure of Invention
The application provides a tunable semiconductor laser of frequency for provide a coupling degree of difficulty lower, and can satisfy the semiconductor laser who exports quick frequency modulation, narrow linewidth, high power laser signal simultaneously.
In a first aspect, the present application provides a frequency tunable semiconductor laser, including a first reflective semiconductor optical amplifier and an optical resonant cavity; the first reflective semiconductor optical amplifier is coupled with the optical resonant cavity; the optical resonator includes: a spot size converter, a first waveguide converter and a first phase shifter; wherein the spot-size converter is made of a silicon nitride waveguide material and the first phase shifter is made of a silicon waveguide material; the first reflective semiconductor optical amplifier is used for injecting beams into the optical resonant cavity; the spot size converter is used for converting the spot size output by the first reflective semiconductor optical amplifier into the spot size input by the first waveguide converter; the first waveguide converter, including a silicon nitride waveguide and a silicon waveguide, for transmitting the optical beam from the spot-size converter into the first phase shifter; the first phase shifter is used for controlling and changing the phase of the light beam by changing the refractive index in the optical resonant cavity, so that the laser outputs a laser signal with tunable frequency.
Through the semiconductor laser that this application provided, in the optical resonator that realizes frequency tunable, because silicon nitride waveguide has the loss low and can ensure laser signal's output's characteristic when transmitting the light beam, silicon waveguide has the characteristic of higher modulation efficiency. Therefore, on one hand, the first phase shifter is made of silicon waveguide materials, the response time of the first phase shifter can reach the nanosecond (ns) order almost, so that the small-range fast frequency sweeping can be realized by changing the current applied to the first phase shifter, and the corresponding laser power and the line width do not change greatly. On the other hand, in the optical resonant cavity of the semiconductor laser provided by the present application, other functional optical elements except the first phase shifter may be made of a silicon nitride waveguide material, so that power and the like during transmission of a laser signal can be ensured. It can be understood that the laser designed by the application can simultaneously meet the laser signal characteristics of outputting rapid frequency modulation, narrow line width and high power, and also has the advantage of small coupling difficulty. Further, through adopting the laser instrument that this application designed, detection distance and detection accuracy when can also promote laser survey.
In one possible design, the first phase shifter is a PIN phase shifter. The PIN phase shifter includes: the semiconductor device comprises an I-type undoped region, a P-type doped region and an N-type doped region. The laser further comprises a drive circuit; the positive pole of the driving circuit is connected to the P-type doped region, and the negative pole of the driving circuit is connected to the N-type doped region. The driving circuit is used for injecting different driving currents into the first phase shifter so as to enable the first phase shifter to change the refractive index in the optical resonant cavity.
Based on the design of the first phase shifter, the response time of the electro-optical phase shifter made of the silicon waveguide material is fast, so that the small-range fast frequency sweeping can be realized by changing the current applied to the first phase shifter, and the corresponding laser power and line width do not change greatly. In addition, the length of the PIN phase shifter can be designed to be longer, so that the first phase shifter works under the condition of smaller carrier concentration, and the loss in the process of transmitting laser signals is reduced.
In another possible design, the first phase shifter is a cascade of multiple PIN phase shifters. Each of the PIN phase shifters comprising: the semiconductor device comprises an I-type undoped region, a P-type doped region and an N-type doped region. In the cascaded PIN phase shifters, the N-type doped region of the previous PIN phase shifter is connected with the P-type doped region of the next PIN phase shifter. The laser further comprises a drive circuit; the positive electrode of the driving circuit is connected to the P-type doped region of the first-stage PIN phase shifter of the first phase shifter, and the negative electrode of the driving circuit is connected to the N-type doped region of the last-stage PIN phase shifter of the first phase shifter. The driving circuit is used for injecting different driving currents into the first phase shifter so as to enable the first phase shifter to change the refractive index in the optical resonant cavity.
Based on the design of the first phase shifter, on one hand, the first phase shifter is enabled to work under the condition of smaller carrier concentration by increasing the length of the first phase shifter, and the loss in the process of transmitting the light beam is reduced. On the other hand, the driving voltage of the whole first phase shifter can be improved through the cascade structure, which is equivalent to improving the voltage resolution which can be obtained by each PIN phase shifter, and further improving the phase shifting precision.
In one possible design, the optical resonant cavity further includes a second waveguide converter and one or more filters in cascade. Each of the filters is made of a silicon nitride waveguide material. The second waveguide converter comprises a silicon waveguide and a silicon nitride waveguide for transmitting the optical beam from the first phase shifter made of the silicon waveguide material to the first stage filter made of the silicon nitride waveguide material. The cascaded one or more filters are used for controlling the laser to output the frequency-tunable laser signal with a specified wavelength.
In the design, the semiconductor laser provided by the application can further realize outputting laser signals with tunable wavelength on the basis of realizing tunable frequency. And the filter can also be made of silicon nitride waveguide materials, so that the loss in the process of generating the laser signal can be reduced when the laser signal is output, and the power of the output laser signal can be guaranteed.
In one possible design, the optical resonator further includes a mirror. The mirror is made of a silicon nitride waveguide material. The reflector is used for transmitting and outputting a first part of the light beams as laser signals, and reflecting a second part of the light beams back to the first reflective semiconductor optical amplifier.
In this design, generally, the output of the laser signal requires that the light beam be reflected multiple times by the semiconductor laser and output when the signal threshold at which the laser can output is reached. When the application is implemented, the reflecting mirror can also be made of silicon nitride waveguide materials. The reflector made of the silicon nitride waveguide material can reduce loss in the process of generating laser signals when the laser signals are output, so that the power of the output laser signals can be guaranteed.
In another possible design, the optical resonant cavity further includes a second waveguide converter and a distributed bragg reflector DBR. The DBR is made of a silicon nitride waveguide material. The second waveguide converter comprises a silicon waveguide and a silicon nitride waveguide for transmitting the optical beam from the first phase shifter made of the silicon waveguide material to the first stage filter made of the silicon nitride waveguide material. The DBR is used for controlling the laser to output the frequency tunable laser signal with the appointed wavelength; and transmitting and outputting a first part of the light beams as laser signals, and reflecting a second part of the light beams back to the first reflective semiconductor optical amplifier.
The laser structure provided in the design can achieve similar technical effects with the previous possible design. And the structure provided by the design can further reduce the number of optical elements contained in the laser, and compared with the former possible design, the design can simplify the structure of the frequency tunable semiconductor laser and is beneficial to reducing the size of the obtained laser.
In one possible design, the optical resonant cavity further includes a second phase shifter; the second phase shifter is made of a silicon waveguide material. The second phase shifter is located between the first waveguide converter and the first phase shifter and is used for controlling the initial phase of the light beam by changing the refractive index in the optical resonant cavity.
In the design, the initial phase of the laser signal can be adjusted through the second phase shifter, so that the longitudinal mode wavelength of the optical resonant cavity is aligned with the wavelength of the filter, the optimal power output can be realized, and the transmission loss is reduced. Therefore, the initial phase can be adjusted through the second phase shifter, and the fast frequency modulation can be carried out by combining the first phase shifter, so that the line width of the output laser signal can be reduced, and the power of the output laser signal can be improved. Therefore, the laser that this application provided can satisfy the output simultaneously can fast frequency modulation, narrow linewidth and the laser signal of high power to can promote the distance and the accuracy of surveying.
In one possible design, a second semiconductor optical amplifier and an optical phased array scanner are also included. And the second semiconductor optical amplifier is used for receiving the laser signal output by the optical resonant cavity, providing signal gain for the output laser signal and injecting the laser signal into the optical phased array scanner. And the optical phased array scanner is used for regulating and controlling the output direction of the laser signal after the signal gain is provided.
In the design, the output power of the output laser signal can be improved through the second semiconductor optical amplifier, and meanwhile, the transmission loss problem existing in the silicon-based functional optical element integrated in the optical resonant cavity can be compensated, so that the detection distance of the laser can be increased. And if the laser provided by the design is adopted, the functions of the emitting optical module and the scanner included in the laser radar can be realized by combining the optical phased array scanner, so that the laser under the design can also realize the scanning of the target object, thereby expanding the functions of the laser and simplifying the structure of optical equipment applying the laser, for example, the emitting optical module and the scanner do not need to be integrated in the laser radar.
In one possible design, a third semiconductor optical amplifier is also included. The first reflective semiconductor optical amplifier is further configured to transmit the second part of the light beam reflected by the mirror to the third semiconductor optical amplifier. And the third semiconductor optical amplifier is used for providing signal gain for the second part of beams and then outputting the beams.
In the design, the output power of the output laser signal can be improved through the third semiconductor optical amplifier, and meanwhile, the transmission loss problem existing in the silicon-based functional optical element integrated in the optical resonant cavity can be compensated, so that the detection distance of the frequency modulation laser can be increased.
In another possible design, the first side surface of the first reflective semiconductor optical amplifier is plated with an antireflection film, and the second side surface of the first reflective semiconductor optical amplifier is plated with a low reflection film. The first side surface of the first reflective semiconductor optical amplifier is a coupling surface of the first reflective semiconductor optical amplifier and the optical resonant cavity; the second side of the first reflective semiconductor optical amplifier is a face opposite to the first side of the first reflective semiconductor optical amplifier. And the first side surface and the second side surface of the third semiconductor optical amplifier are plated with antireflection films. The first side surface of the third semiconductor optical amplifier is a coupling surface of the third semiconductor optical amplifier and the first reflective semiconductor optical amplifier; the second side surface of the third semiconductor optical amplifier is a surface opposite to the first side surface of the third semiconductor optical amplifier.
In the design, the third semiconductor optical amplifier can also improve the output power of the laser signal output from the second side surface of the first reflection type semiconductor optical amplifier, and meanwhile, the transmission loss problem existing in the silicon-based functional optical element integrated in the optical resonant cavity can be compensated, so that the detection distance of the frequency modulation laser can be increased.
In one possible design, the optical resonant cavity further includes a frequency detection unit. And the frequency detection unit is used for carrying out linear detection on the laser signal output by the optical resonant cavity to obtain a linear detection result. The driving circuit is specifically configured to inject different driving currents into the first phase shifter according to the linear detection result when injecting different driving currents into the first phase shifter.
In the design, the laser signal with better linear characteristic can be output by carrying out linear detection on the output laser signal, timely adjusting the driving current injected by the driving circuit according to the obtained linear detection result and carrying out nonlinear compensation in time.
In a second aspect, embodiments of the present application further provide an optical device comprising a frequency-tunable semiconductor laser as in any one of the possible designs of the first aspect above. The frequency tunable semiconductor laser can be used for outputting a frequency tunable laser signal.
Drawings
FIG. 1 is a system block diagram of an FMCW lidar;
fig. 2 is a schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a first waveguide converter 2022 according to an embodiment of the present disclosure;
fig. 4 is a second schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 5a is a schematic structural diagram of a first phase shifter 2023 according to an embodiment of the present disclosure;
fig. 5b is a schematic diagram of optical signal transmission of a first phase shifter 2023 according to an embodiment of the present application;
fig. 5c is a schematic structural diagram of another first phase shifter 2023 according to this embodiment;
fig. 6a is a third schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 6b is a schematic structural diagram of a filter 2025 according to the embodiment of the present application;
fig. 7 is a fourth schematic diagram illustrating a structure of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 8 is a fifth schematic diagram illustrating a structure of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 9 is a sixth schematic diagram illustrating a structure of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 10 is a seventh schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 11 is an eighth schematic diagram of a structure of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure;
fig. 12 is a nine-fold schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present invention.
Detailed Description
The embodiments of the present application can be applied to various technologies including a frequency tunable semiconductor laser, such as laser radar, optical Coherence Tomography (OCT), and the like.
Taking the lidar technology as an example, the lidar can be widely applied to the fields of robots, automatic driving, unmanned aerial vehicles and the like, and can measure the distance between the lidar and a target object by using laser. Currently, the mainstream lidar ranging method is a pulse of flight (ToF) lidar. The principle of the pulse ToF laser radar is as follows: the distance detection is realized by emitting laser pulse signals with high peak power and measuring the round trip time of the light pulse emitted from a target object.
Compared with a pulse TOF laser radar, the FMCW laser radar has higher sensitivity and ranging precision, can realize ultra-long distance detection (generally more than 300 m), can resist interference of sunlight and other lasers and measure speed in real time, and is a very potential laser radar technology. The principle of the FMCW laser radar is as follows: and obtaining the distance information of the target object by comparing the difference value of the frequency of the reflected signal reflected by the target object and the frequency of the transmitted signal at the moment by adopting a coherent measurement technology.
For example, fig. 1 is a system block diagram of an FMCW lidar. The FMCW lidar 100 may include: a signal control 101, a frequency tunable semiconductor laser 102 (also referred to as "frequency-modulated laser" for short, and in the following embodiments, the "frequency tunable semiconductor laser" and the "frequency-modulated laser" may be used interchangeably), a transmitting optical module 103, a scanner 104, a receiving optical module 105, a balanced detector 106, and a signal processing system 107. The signal control 101 sends out a control signal, so that the frequency tunable semiconductor laser 102 emits frequency modulated continuous laser light. The laser beam is divided into two beams by the emitting module 103, one beam is an intrinsic beam, and the other beam is a signal beam. The signal light is irradiated onto the target object through the scanner 104. The signal light reflected from the object is received by the receiving optical module 105, and is mixed with the intrinsic light at the balanced detector 106 to obtain a beat frequency electrical signal. Finally, the beat frequency electric signal output by the balance detector 106 is sent to the signal processing system 107 for analysis, and the 3D point cloud image is output and the speed information of the target object is obtained, so that the distance information of the target object can be obtained through calculation.
Based on the above description of the principle of the laser radar, it can be obtained that in the technical field of applying frequency modulation lasers, the requirement for the frequency modulation lasers is very high in order to obtain more accurate detection results. For example, for laser radar, in order to achieve a long detection distance and a sufficiently high point cloud density, it is required that the frequency modulation laser can emit laser light with a sufficiently fast frequency modulation rate, a sufficiently narrow line width, a high optical power, and a frequency modulation linearity.
At present, in the prior art, a converted current is directly injected into a Distributed Feedback (DFB) semiconductor laser, and a refractive index in a cavity of the DFB semiconductor laser is changed based on the converted current, so that the DFB semiconductor laser can emit laser with a fast frequency modulation rate. However, the resonant cavity of the DFB semiconductor laser is generally short, so that the linewidth of the laser emitted by the technical scheme is large. Moreover, the current injection-based mode has a thermal effect, and the thermal effect brings a relatively obvious nonlinear effect, so that the signal-to-noise ratio of the detection signal can be reduced.
Another solution in the prior art is that the DFB semiconductor laser emits laser light, which is coupled into a Whispering Gallery Mode (WGM) resonator through a first optical coupler. Of the laser light emitted from the DFB semiconductor laser, only laser light satisfying the resonance mode of the WGM resonator can be coupled into the WGM resonator. In this way, the DFB semiconductor laser is frequency-locked at the resonant frequency of the WGM resonator by injection, so that the line width of the output laser is compressed, and thus laser having a narrow line width can be obtained. And the frequency of the WGM resonator can be rapidly changed through the electro-optic effect, so that laser frequency modulation can be realized. However, the technical solution has a complex structure, and requires a plurality of optical elements for spatial optical coupling, so that there are disadvantages of high coupling difficulty and high integration cost. Further, the efficiency of the WGM resonator feedback injection frequency locking is limited by the proportion of the laser light fed back to the DFB semiconductor laser, and therefore high power output of the laser light cannot be achieved.
In view of this, how to realize that the frequency-modulated laser can emit a laser signal with a sufficiently fast frequency modulation rate, a sufficiently narrow line width, a relatively high optical power, and a frequency modulation linearity is not yet provided in the prior art. Therefore, the semiconductor laser which can simultaneously output laser signals with rapid frequency modulation, narrow line width and high power and has low coupling difficulty is provided, and the semiconductor laser has great significance for the development of the fields of laser radars, optical communication and the like. The application provides a frequency modulation laser because the silicon nitride waveguide has advantages such as the loss is low, power upper limit height to and silicon waveguide can realize quick frequency modulation's characteristic, thereby can combine the optical element who adopts two kinds of waveguides to provide a frequency tunable semiconductor laser.
The present application will now be described in further detail with reference to the accompanying drawings, using several embodiments.
It should be noted that, in the various embodiments of the present application, unless otherwise specified or conflicting in logic, terms and/or descriptions between different embodiments have consistency and may be mutually cited, and technical features in different embodiments may be combined to form a new embodiment according to their inherent logical relationships. In the present application, "at least one" means one or more, "a plurality" means two or more. It is to be understood that the various numerical designations referred to in this application are merely for ease of description and are not intended to limit the scope of the embodiments of the present application. The sequence numbers of the above processes do not mean the execution sequence, and the execution sequence of the processes should be determined by the functions and the inherent logic. The terms "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
Furthermore, the terms "comprises" and "comprising," as well as any variations thereof, are intended to cover a non-exclusive inclusion, such as a list of steps or elements. A method, system, article, or apparatus is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, system, article, or apparatus.
Example one
Referring to fig. 2, a schematic structural diagram of a frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure is shown. The frequency tunable semiconductor laser 102 includes a first Reflective Semiconductor Optical Amplifier (RSOA) 201 and an optical resonator 202. The first RSOA201 is coupled to an optical resonator 202.
Wherein the first RSOA201 is used for injecting a light beam into the optical resonant cavity. And provides signal gain to the beam prior to injection, may also be understood as signal amplification to compensate for losses that occur when the beam oscillates in the optical cavity. In an alternative embodiment, the first RSOA201 may be coated with an anti-reflective coating on the first side and a high reflective coating on the second side. Wherein the first side is a coupling surface of the first RSOA201 and the optical resonator 202, such as a right side of the first RSOA201 in fig. 2; the second side is the side opposite the first side of the first RSOA201, such as the left side of the first RSOA201 in fig. 2. It will be appreciated that the light beam may be reflected at the second side and transmitted at the first side such that the first RSOA201 may inject the light beam into the optical cavity 202 for oscillation through an anti-reflective coating on the first side. Also, the active region of the first RSOA201 may be implemented using III-V quantum well or quantum dot materials.
Next, the optical resonant cavity 202 may specifically include: a spot-size converter 2021, a first waveguide converter 2022, and a first phase shifter 2023. The spot-size converter 2021 may be made of a silicon nitride waveguide material, and the first phase shifter 2023 may be made of a silicon waveguide material.
For example, the output terminal of the first RSOA201 and the input terminal of the spot-size converter 2021 may be connected in a butt-coupling manner, or may be coupled in other manners, which is not limited in this application.
The spot-size converter 2021 may be implemented by an inverted cone coupler, a suspended waveguide coupler, or a trident coupler. The implementation may determine the structure of the spot size converter 2021 according to the actual scene of the output spot size of the first RSOA201 and the input spot size of the first waveguide converter 2022.
In practice, the spot size converter 2021 is configured to convert the spot size output by the first RSOA201 to the spot size input by the first waveguide converter 2022. Alternatively, if the transmission direction of the light beam is from the first waveguide converter 2022 to the first RSOA201, the spot size converter 2021 may be further configured to convert the spot size output by the first waveguide converter 2022 into the spot size input by the first RSOA 201. This can improve the coupling efficiency of the first RSOA201 and the optical resonator 202, and reduce the loss of the light beam when the light beam resonates between the first RSOA201 and the optical resonator 202.
In practice, the first waveguide converter 2022, comprising a silicon nitride waveguide and a silicon waveguide, is used to transfer the optical beam from the spot-size converter 2021 made of the silicon nitride waveguide material to the first phase shifter 2023 made of the silicon waveguide material. Alternatively, if the transmission direction of the light beam is from the first phase shifter 2023 to the spot size converter 2021, the light beam from the first phase shifter 2023 may be transmitted to the spot size converter 2021. It is understood that since the spot-size converter 2021 is made of a silicon nitride waveguide material and the first phase shifter 2023 is made of a silicon waveguide material, the light beam has different transmission characteristics on different transmission waveguide materials, and in order to realize signal transmission of the light beam on two different materials, the first waveguide converter 2022 may be used for conversion.
Exemplarily, referring to fig. 3, a schematic structural diagram of a first waveguide converter 2022 according to an embodiment of the present application is provided. In this example, the first waveguide converter 2022 may be mainly implemented by an upper waveguide and a lower waveguide, where the upper waveguide may be a tapered silicon nitride waveguide and the lower waveguide may be an inverted tapered silicon waveguide. The two layers of waveguides may be optically transmissive by vertical coupling. In practice, the light beam enters the first waveguide converter 2022 from the input end (e.g., end a in fig. 3) of the tapered silicon nitride waveguide in the first waveguide converter 2022, and when the light beam is transmitted to the input end (e.g., end B in fig. 3) of the tapered silicon nitride waveguide, the light beam may continue to be transmitted to the input end (e.g., end C in fig. 3) of the inverted tapered silicon waveguide, and finally output to the first phase shifter 2023 from the output end (e.g., end D in fig. 3) of the inverted tapered silicon waveguide. In this way, by the transmission of the first waveguide converter 2022, the transmission of the light beam between the optical elements made of different waveguide materials can be realized, so that the laser provided by the present application can be designed by combining the transmission characteristics of different waveguide materials.
In specific implementation, the first phase shifter 2023 is configured to controllably change the phase of the light beam by changing the refractive index in the optical resonant cavity 202, so that the laser outputs a laser signal with a tunable frequency. The response time of the first phase shifter 2023 made of a silicon waveguide material can reach the order of nanoseconds (ns), so that a small-range fast frequency sweep can be realized by changing the current applied to the first phase shifter 2023, and the corresponding laser power and line width do not change much. It can be understood that based on the silicon nitride waveguide has the advantage of low loss and high upper limit of power, and the phase shifter made of the silicon waveguide material is combined, so that the rapid frequency modulation of the light beam can be realized, and therefore the frequency tunable semiconductor laser provided by the application can simultaneously meet the characteristics of rapid frequency modulation, narrow line width, high power and low coupling difficulty.
Based on the above design, the tunable frequency semiconductor laser 102 provided by the present application may further include a driving circuit. Referring to fig. 4, a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure is shown. The frequency tunable semiconductor laser 102 further comprises a driver circuit 203. The driving circuit 203 is configured to inject different driving currents into the first phase shifter 2023, so that the first phase shifter 2023 changes the refractive index in the optical cavity. The driving circuit 203 may be implemented by the signal controller 101 described in fig. 1, or may be implemented by a separate chip, or the like.
In one possible implementation, the first phase shifter 2023 may be a PIN phase shifter formed by etching and doping of silicon. Fig. 5a is a schematic structural diagram of a first phase shifter 2023 according to an embodiment of the present disclosure. The PIN phase shifter includes: the semiconductor device comprises an I-type undoped region, a P-type doped region and an N-type doped region. Wherein the I-type undoped region is a silicon waveguide. In addition, the first phase shifter 2023 and the driving circuit 203 may be connected in a specific manner such that the positive electrode of the driving circuit 203 is connected to the P-type doped region of the PIN phase shifter and the negative electrode of the driving circuit 203 is connected to the N-type doped region of the PIN phase shifter. Alternatively, the PIN phase shifter may be an electro-optical phase shifter with a response time that may be up to approximately ns orders of magnitude.
When the frequency sweeping device is implemented, the driving current applied to the first phase shifter 2023 through the driving circuit 203 can be changed, so that the frequency can be swept quickly in a small range, and the corresponding laser power and line width do not change greatly. For example, referring to fig. 5b, a schematic diagram of optical signal transmission of a first phase shifter 2023 according to an embodiment of the present application is provided. And the first phase shifter 2023 can receive the optical beam from two directions since the optical beam oscillates in the optical resonator. For example, the first direction may be the direction of the outgoing beam from the first RSOA201, and the second direction may be the direction of the beam reflected back from the mirror as described in the embodiments below. The light beam can be transmitted through the silicon waveguide in the I-type undoped region, and the P-type doped region and the N-type doped region receive the control of the driving current of the driving circuit 203, so as to tune the frequency of the output laser signal.
In addition, by increasing the length of the first phase shifter, the first phase shifter can also work under the condition of smaller carrier concentration, and the loss in the process of transmitting the light beam is reduced. Thus, in one implementation, the length of the PIN shifter shown in fig. 5a may be designed to be a longer length, such as may be greater than 1 millimeter (mm).
In another possible implementation, the first phase shifter 2023 may also be composed of a plurality of PIN phase shifters in cascade to obtain a longer length of the first phase shifter 2023, where each PIN phase shifter is as shown in fig. 5a and 5b for structure and optical signal transmission principle. Referring to fig. 5c, a schematic structural diagram of another first phase shifter 2023 according to an embodiment of the present application is shown. In the cascaded PIN phase shifters, an N-type doped region of a previous PIN phase shifter is connected with a P-type doped region of a next PIN phase shifter; for example, the N-type doped region of the previous stage PIN shifter and the P-type doped region of the next stage PIN shifter may be connected by a conductive metal electrode. In the first phase shifter 2023 shown in fig. 5c, the anode of the driving circuit 203 may be connected to the P-type doped region in the first stage PIN shifter of the first phase shifter 2023, and the cathode of the driving circuit 203 may be connected to the N-type doped region in the last stage PIN shifter of the first phase shifter 2023. The driving circuit 203 is configured to inject different driving currents into the first phase shifter 2023, so that the first phase shifter 2023 changes the refractive index within the optical resonant cavity 202.
Optionally, the length of one PIN phase shifter or a plurality of cascaded PIN phase shifters may be designed to be greater than 1 millimeter (mm), and the first phase shifter 2023 formed by one PIN phase shifter or a plurality of cascaded PIN phase shifters has the advantages of low loss and high phase shift precision.
Based on the design of the first phase shifter, the driving voltage of the whole first phase shifter can be improved through the cascade structure, which is equivalent to improving the voltage resolution ratio which can be obtained by each PIN phase shifter, and further, the phase shifting precision can be improved when the transmission loss is reduced.
Example two
On the basis that the frequency tuning of the frequency tunable semiconductor laser 102 can be realized through the contents described in the first embodiment, the wavelength of the output laser signal can be further tunable.
Illustratively, the tunability of the wavelength may be achieved by adding filters. Referring to fig. 6a, a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure is shown. The optical resonant cavity 202 may further include a second waveguide switch 2024 and one or more cascaded filters 2025 (fig. 6a illustrates two cascaded filters, i.e., a first filter 2025a and a second filter 2025 b) based on the structure described in the first embodiment.
Here, each of the filters 2025, i.e., the first filter 2025a and the second filter 2025b, may be made of a silicon nitride waveguide material, and the first phase shifter 2023 is made of a silicon waveguide material, so that the second waveguide converter 2024 may be used to realize signal transmission of the light beam on two different waveguide materials. The difference from the first waveguide converter 2022 is that in the direction of the injected beam of the first RSOA201, the first waveguide converter 2022 is a silicon nitride waveguide material to silicon waveguide material converter and the second waveguide converter 2024 is a silicon waveguide material to silicon nitride waveguide material converter.
Based on the structure of the frequency tunable semiconductor laser 102 shown in fig. 6a, the second waveguide converter 2024, which includes a silicon waveguide and a silicon nitride waveguide, is used to transmit the optical beam from the first phase shifter 2023 made of the silicon waveguide material to the first filter 2025a made of the silicon nitride waveguide material. The cascaded one or more filters 2025 are configured to control the laser to output the frequency-tunable laser signal with a specified wavelength, so that the frequency of the laser signal output by the laser can be tunable.
Illustratively, as shown in fig. 6a, the cascaded one or more filters 2025 are assumed to include a first filter 2025a and a second filter 2025b, and the first filter 2025a and the second filter 2025b may be micro-loop filters. Due to the difference of the two micro-ring filters, the wavelength of the output laser signal can be tunable based on the vernier effect in the optics. Alternatively, in another alternative embodiment, the laser may also be implemented by using other types of filters, and the number of the filters to be used may be determined according to actual needs, which is not limited in this application.
Wavelength tunability may also be achieved by integrating a thermo-optic phase shifter on filter 2025 when implemented. Fig. 6b is a schematic structural diagram of a filter 2025 according to an embodiment of the present disclosure. By adjusting the driving current of the thermo-optic phase shifter on each stage of filter 2025, the laser can output laser signals with different specified wavelengths.
Referring to fig. 7, a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure is shown. The optical cavity 202 may further include a mirror 2026 on the structure shown in fig. 6 a. The mirror 2026 may be made of a silicon nitride waveguide material. The mirror 2026 is configured to transmit a first part of the light beams to be output as a laser signal, and reflect a second part of the light beams back to the first RSOA 201. In this way, the reflected light beam can repeatedly oscillate in the frequency tunable semiconductor laser 102 shown in fig. 7, and is transmitted and output through the output end of the reflecting mirror 2026 when the light beam reaches the oscillation start condition of the frequency tunable semiconductor laser 102. Wherein the oscillation starting condition of the frequency tunable semiconductor laser 102 indicates that the laser signal can be output when the gain of the laser signal in the frequency tunable semiconductor laser 102 is larger than the loss in the frequency tunable semiconductor laser 102.
EXAMPLE III
On the basis that the frequency of the frequency tunable semiconductor laser 102 can be tuned through the content described in the first embodiment, in addition to the second embodiment, another embodiment of the tunable laser wavelength can be implemented by using a Distributed Bragg Reflector (DBR).
Referring to fig. 8, a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure is shown. The optical resonant cavity 202 further comprises a second waveguide converter 2024 and a distributed bragg reflector DBR 2027; the DBR 2027 is made of a grating etched from silicon nitride waveguide material.
In practice, the second waveguide converter 2024, comprising a silicon waveguide and a silicon nitride waveguide, is used to transfer the optical beam from the first phase shifter 2023 made of the silicon waveguide material to the first filter 2025a made of the silicon nitride waveguide material. The DBR 2027 is configured to control the laser to output the frequency-tunable laser signal with a specified wavelength; and transmitting a first portion of the light beams out as a laser signal and reflecting a second portion of the light beams back to the first RSOA 201.
The structure of the tunable-frequency semiconductor laser provided in the third embodiment and the structure of the tunable-frequency semiconductor laser provided in the second embodiment can achieve similar technical effects. Moreover, the structure provided by the third embodiment can further reduce the number of optical elements included in the frequency-modulated laser, so that the structure of the frequency-modulated laser is more simplified compared with the second embodiment, and the size of the obtained frequency-modulated laser is reduced.
Example four
On the basis of the foregoing several embodiments, the present application further provides an embodiment, before the frequency modulation processing is performed on the light beam by the first phase shifter, the initial phase of the laser signal may be aligned by the second phase shifter, so that the loss caused by the first phase shifter to the generated laser signal may be reduced.
Fig. 9 is a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure. The optical resonant cavity 202 may also include a second phase shifter 2028; the second phase shifter 2028 may be made of a silicon waveguide material. The second phase shifter 2028 is located between the first waveguide converter 2022 and the first phase shifter 2023, and is configured to control and adjust an initial phase of the optical beam by changing a refractive index in the optical resonator, and output the adjusted optical beam to the first phase shifter 2023.
Optionally, the second phase shifter 2028 may adjust the initial phase of the light beam by adjusting the driving current applied to the second phase shifter 2028 through a thermo-optical phase shifter, so as to achieve the best power output and reduce the loss. In this way, the adjustment of the initial phase of the light beam by the second phase shifter 2028, in combination with the fast frequency modulation of the light beam by the first phase shifter 2023, can reduce the line width of the output laser signal and increase the power of the output laser signal. Compared with an electro-optical phase shifter, the thermo-optical phase shifter does not need a doping region, can realize light beam transmission by heating a silicon waveguide, and has the advantage of low loss. Moreover, after the thermo-optical phase shifter is used for adjusting the initial phase, the light beam transmitted to the first phase shifter can be in a better phase position, so that the transmission loss of the light beam in the first phase shifter can be reduced, and the signal power of a laser signal output by the laser can be further ensured.
It should be noted that fig. 9 illustrates the structure of the frequency-modulated laser described in the first embodiment, and the second phase shifter 2028 described in the fourth embodiment may also be applied to the second embodiment or the third embodiment, which is not described herein again.
EXAMPLE five
Based on any one of the first to fourth embodiments, the present application further provides an embodiment, which can realize regulation and control of an output direction of an output laser signal.
Referring to fig. 10, a schematic structural diagram of another tunable-frequency semiconductor laser 102 according to an embodiment of the present disclosure is shown. The frequency tunable semiconductor laser 102 further comprises a second SOA204 and an Optical Phase Array (OPA) scanner 206. Wherein the OPA scanner 206 may be made of a silicon nitride waveguide material.
In operation, the second SOA204 is configured to receive the laser signal output by the optical resonant cavity 202, provide a signal gain for the output laser signal, and inject the signal gain onto the OPA scanner 206. Alternatively, the second SOA204 may employ a U-shaped semiconductor optical amplifier, such as the structure shown in fig. 10. The second SOA204 can improve the output power of the output laser signal, and compensate the transmission loss problem of the silicon-based functional optical element integrated in the optical resonant cavity 202, so as to improve the detection distance of the frequency modulation laser.
The OPA scanner 206 is configured to adjust an output direction of the laser signal after providing the signal gain. It should be noted that, in the design of this embodiment, the OPA scanner 206 can regulate the output direction of the laser signal, and can scan the target. Therefore, compared to the FMCW lidar 100 shown in fig. 1, the tunable frequency semiconductor laser 102 provided in this embodiment can use the OPA scanner 206 to perform the functions of the transmitting optical module 103 and the scanner 104, and scan the target object with the tunable frequency semiconductor laser 102.
Note that the OPA scanner 206 may be an optical element independent of the frequency tunable semiconductor laser 102. It is understood that after the frequency tunable semiconductor laser 102 outputs the laser signal, the OPA scanner 206 can be used to adjust the direction of the laser signal. Alternatively, the present invention may also be implemented in an integrated manner as described in the above embodiments, which is not limited in the present application.
EXAMPLE six
In order to compensate the transmission loss problem of integrating the silicon-based functional optical element in the optical resonant cavity, the detection distance of the frequency modulation laser can be increased. In addition to the embodiment shown in example five, in another embodiment, the present application further provides a structure of a frequency tunable semiconductor laser, and a third semiconductor optical amplifier is adopted to provide a signal gain for a laser signal output from an optical resonator.
Fig. 11 is a schematic structural diagram of another frequency tunable semiconductor laser 102 according to an embodiment of the present disclosure. The frequency tunable semiconductor laser 102 further comprises a third semiconductor optical amplifier SOA 205.
In this embodiment, the first side of the first RSOA201 may be coated with an anti-reflection film and the second side may be coated with a low reflection film, wherein the anti-reflection film represents a film capable of increasing the amount of light transmission, and the low reflection film represents a film having a certain reflection capability, for example, a low reflection film having a reflection capability of 30%. As shown in fig. 11, the first side of the first RSOA201 may be a coupling surface of the first RSOA201 and the optical resonant cavity 202; the second side of the first RSOA201 is the side opposite to the first side of the first RSOA 201. The first side face and the second side face of third SOA 205 may both be plated with an antireflection film. The first side of the third SOA 205 is a coupling surface of the third SOA 205 and the first RSOA 201; the second side of third SOA 205 is the opposite side to the first side of third SOA 205. It should be noted that the first side and the second side are mainly used for distinguishing different sides, and may be used alternatively.
Alternatively, the reflectivity of the mirror 2026 may be set to be greater than 95% to achieve that the mirror 2026 may reflect the light beam back into the first RSOA201 along the emitted path through the mirror 2026, assuming that a second portion of the light beam is reflected. It should be noted that, since the reflection mirror 2026 with a reflectivity of 100% is not usually present, there may be a first partial light beam in the light beam to be transmitted and output.
Based on the above design of the low reflection film on the second side of the first RSOA201, the first RSOA201 may also be used to transmit a portion of the second partial light beam reflected back by the mirror 2026 to the third SOA, and another portion may be reflected to be injected into the optical resonator 202 to continue oscillation. Then, the third SOA is used to provide a signal gain to the light beam transmitted through the low reflection film on the second side of the first RSOA201 and then output. In this way, the third SOA 205 can improve the output power of the output laser signal, and compensate the transmission loss problem of the silicon-based functional optical element integrated in the optical resonant cavity, thereby improving the detection distance of the frequency-modulated laser.
EXAMPLE seven
Based on the descriptions of the first to sixth embodiments, the present application further provides an implementation manner that can improve the linear characteristic of the frequency tunable semiconductor laser 102.
Referring to fig. 12, a schematic structural diagram of another tunable-frequency semiconductor laser 102 according to an embodiment of the present disclosure is shown. The optical resonant cavity 202 may also include a frequency detection unit 2029. Alternatively, the frequency detection unit 2029 may include an auxiliary mach-zehnder interferometer (AMZI) and a Balanced Photodetector (BPD), which may be made of a doped silicon waveguide material.
In implementation, the frequency detection unit 2029 is configured to perform linear detection on the laser signal output by the optical resonant cavity 202 to obtain a linear detection result. Accordingly, the driving circuit 203 may inject different driving currents for the first phase shifter according to the linearity detection result.
In addition, the AMZI can be made of a silicon nitride waveguide material, and the transmission loss based on the silicon nitride waveguide is small, so that the power loss caused by adopting the AMZI is reduced, and the power of the laser signal output by the frequency detection unit 2029 is ensured.
Through above several possible embodiments can obtain, the laser instrument that this application provided has the loss low and the characteristic of guarantee output power through combining the silicon nitride waveguide in optical resonator to and the silicon waveguide has the characteristic that can realize fast modulation, can provide one kind and can satisfy fast frequency modulation, narrow linewidth and high power's semiconductor laser simultaneously, have important meaning to the development in fields such as laser radar, optical communication. Moreover, the laser provided by the application is simple to integrate, and has the advantages of small size and low integration cost. And, use the equipment of the laser instrument that this application provided, can promote the distance and the precision of surveying, for example suppose that the laser instrument is applied to laser radar technique, can improve the point cloud density that laser radar surveyed and obtained.
Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely illustrative of the concepts defined by the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to encompass such modifications and variations.
Claims (11)
1. A frequency tunable semiconductor laser comprises a first reflective semiconductor optical amplifier and an optical resonant cavity; the first reflective semiconductor optical amplifier is coupled with the optical resonant cavity;
the optical resonator includes: a spot size converter, a first waveguide converter and a first phase shifter; wherein the spot-size converter is made of a silicon nitride waveguide material and the first phase shifter is made of a silicon waveguide material;
the first reflective semiconductor optical amplifier is used for injecting light beams into the optical resonant cavity;
the spot size converter is used for converting the spot size output by the first reflective semiconductor optical amplifier into the spot size input by the first waveguide converter;
the first waveguide converter, including a silicon nitride waveguide and a silicon waveguide, for transmitting the optical beam from the spot-size converter into the first phase shifter;
and the first phase shifter is used for controlling and changing the phase of the light beam by changing the refractive index in the optical resonant cavity so as to enable the laser to output a laser signal with tunable frequency.
2. The laser of claim 1, wherein the first phase shifter is a PIN phase shifter; the PIN phase shifter includes: the semiconductor device comprises an I-type undoped region, a P-type doped region and an N-type doped region;
the laser further comprises a drive circuit; the positive electrode of the driving circuit is connected to the P-type doped region, and the negative electrode of the driving circuit is connected to the N-type doped region;
the driving circuit is used for injecting different driving currents into the first phase shifter so as to enable the first phase shifter to change the refractive index in the optical resonant cavity.
3. The laser of claim 1, wherein the first phase shifter is a cascaded plurality of PIN phase shifters; each of the PIN phase shifters comprising: the semiconductor device comprises an I-type undoped region, a P-type doped region and an N-type doped region;
in the cascaded PIN phase shifters, an N-type doped region of a previous PIN phase shifter is connected with a P-type doped region of a next PIN phase shifter;
the laser further comprises a drive circuit; the positive electrode of the driving circuit is connected to the P-type doped region of the first-stage PIN phase shifter of the first phase shifter, and the negative electrode of the driving circuit is connected to the N-type doped region of the last-stage PIN phase shifter of the first phase shifter;
the driving circuit is configured to inject different driving currents into the first phase shifter, so that the first phase shifter changes a refractive index in the optical resonant cavity.
4. A laser according to any one of claims 1 to 3, wherein the optical resonant cavity further comprises a second waveguide converter and one or more filters in cascade; each filter is made of a silicon nitride waveguide material;
the second waveguide converter comprises a silicon waveguide and a silicon nitride waveguide for transmitting the optical beam from the first phase shifter made of the silicon waveguide material to the first stage filter made of the silicon nitride waveguide material;
the cascaded one or more filters are used for controlling the laser to output the frequency tunable laser signal with the specified wavelength.
5. The laser of claim 4, wherein the optical resonator further comprises a mirror; the reflector is made of a silicon nitride waveguide material;
and the reflector is used for transmitting and outputting a first part of the light beams as laser signals and reflecting a second part of the light beams back to the first reflective semiconductor optical amplifier.
6. A laser according to any one of claims 1 to 3, wherein the optical resonant cavity further comprises a second waveguide converter and a distributed bragg reflector DBR; the DBR is made of a silicon nitride waveguide material;
the second waveguide converter comprises a silicon waveguide and a silicon nitride waveguide for transmitting the optical beam from the first phase shifter made of the silicon waveguide material to the first stage filter made of the silicon nitride waveguide material;
the DBR is used for controlling the laser to output the frequency tunable laser signal with the appointed wavelength; and transmitting and outputting a first part of the light beams as laser signals, and reflecting a second part of the light beams back to the first reflective semiconductor optical amplifier.
7. The laser of any of claims 4 to 6, wherein the optical resonant cavity further comprises a second phase shifter; the second phase shifter is made of a silicon waveguide material;
the second phase shifter is positioned between the first waveguide converter and the first phase shifter and is used for controlling the initial phase of the light beam by changing the refractive index in the optical resonant cavity.
8. The laser of any one of claims 1 to 7, further comprising a second semiconductor optical amplifier and an optical phased array scanner;
the second semiconductor optical amplifier is used for receiving the laser signal output by the optical resonant cavity, providing signal gain for the output laser signal and injecting the laser signal into the optical phased array scanner;
and the optical phased array scanner is used for regulating and controlling the output direction of the laser signal after the signal gain is provided.
9. The laser of claim 5, further comprising a third semiconductor optical amplifier;
the first reflective semiconductor optical amplifier is further used for transmitting the second part of the light beams reflected back by the reflector to the third semiconductor optical amplifier;
and the third semiconductor optical amplifier is used for providing signal gain for the second part of beams and then outputting the beams.
10. The laser of claim 9, wherein the first side of the first reflective semiconductor optical amplifier is coated with an antireflection film and the second side is coated with a low reflection film; the first side surface of the first reflective semiconductor optical amplifier is a coupling surface of the first reflective semiconductor optical amplifier and the optical resonant cavity; the second side surface of the first reflective semiconductor optical amplifier is a surface opposite to the first side surface of the first reflective semiconductor optical amplifier;
the first side face and the second side face of the third semiconductor optical amplifier are plated with antireflection films; the first side surface of the third semiconductor optical amplifier is a coupling surface of the third semiconductor optical amplifier and the first reflective semiconductor optical amplifier; the second side surface of the third semiconductor optical amplifier is a surface opposite to the first side surface of the third semiconductor optical amplifier.
11. A laser as claimed in claim 2 or 3 wherein the optical resonator further comprises a frequency detection unit;
the frequency detection unit is used for carrying out linear detection on the laser signal output by the optical resonant cavity to obtain a linear detection result;
when injecting different driving currents into the first phase shifter, the driving circuit is specifically configured to: injecting different driving currents into the first phase shifter according to the linear detection result.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110724813.5A CN115548870A (en) | 2021-06-29 | 2021-06-29 | Semiconductor laser with tunable frequency |
| PCT/CN2022/089079 WO2023273565A1 (en) | 2021-06-29 | 2022-04-25 | Frequency-tunable semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110724813.5A CN115548870A (en) | 2021-06-29 | 2021-06-29 | Semiconductor laser with tunable frequency |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115548870A true CN115548870A (en) | 2022-12-30 |
Family
ID=84690215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110724813.5A Pending CN115548870A (en) | 2021-06-29 | 2021-06-29 | Semiconductor laser with tunable frequency |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN115548870A (en) |
| WO (1) | WO2023273565A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110837188A (en) * | 2018-08-17 | 2020-02-25 | 台湾积体电路制造股份有限公司 | Phase shifter, modulator, and light beam modulation method |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117092619B (en) * | 2023-10-18 | 2024-01-12 | 吉林大学 | Coherent laser radar transceiver chip and preparation method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2834131B1 (en) * | 2001-12-21 | 2005-06-17 | Thales Sa | MONOLITHIC POLYCRYSTALLINE PIN DIODE FASTENER PANEL AND ANTENNA USING THE SAME |
| CN107872005B (en) * | 2017-10-20 | 2019-07-05 | 中国科学院半导体研究所 | Silicon substrate hybrid integrated tunable laser and photon chip |
| EP3912236A1 (en) * | 2019-01-14 | 2021-11-24 | Lionix International BV | Integrated-optics-based external-cavity laser configured for mode-hop-free wavelength tuning |
| CN110911950A (en) * | 2019-11-27 | 2020-03-24 | 上海交通大学 | High-speed high-linearity silicon-lithium niobate external cavity frequency modulation laser |
| CN111613959B (en) * | 2020-04-10 | 2021-12-03 | 清华大学 | Narrow linewidth continuous wave frequency modulation laser based on silicon-based external cavity self-injection |
-
2021
- 2021-06-29 CN CN202110724813.5A patent/CN115548870A/en active Pending
-
2022
- 2022-04-25 WO PCT/CN2022/089079 patent/WO2023273565A1/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110837188A (en) * | 2018-08-17 | 2020-02-25 | 台湾积体电路制造股份有限公司 | Phase shifter, modulator, and light beam modulation method |
| CN110837188B (en) * | 2018-08-17 | 2024-04-12 | 台湾积体电路制造股份有限公司 | Phase shifter, modulator and light beam modulation method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2023273565A1 (en) | 2023-01-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Isaac et al. | Indium phosphide photonic integrated circuit transceiver for FMCW LiDAR | |
| JP7140784B2 (en) | Modular 3D optical detection system | |
| Seeds et al. | Microwave photonics | |
| US20190072672A1 (en) | Applications of optoelectronic oscillator (oeo) including light detection and ranging (lidar) and optical frequency domain reflectometer (ofdr) systems | |
| AU2007302314B2 (en) | Method and device for generating a synthetic wavelength | |
| Xu et al. | Fully integrated solid-state LiDAR transmitter on a multi-layer silicon-nitride-on-silicon photonic platform | |
| Klamkin et al. | Indium phosphide photonic integrated circuits: Technology and applications | |
| WO2023273565A1 (en) | Frequency-tunable semiconductor laser | |
| US4843609A (en) | Optical integrated circuit for heterodyne detection | |
| KR102425721B1 (en) | Lidar for measuring distance using self-heterodyne detection | |
| CN116806317A (en) | Radar sensor device and method for a motor vehicle | |
| US20230280633A1 (en) | Free-space Beam Steering Systems, Devices, and Methods | |
| Wu et al. | Multi-beam optical phase array for long-range LiDAR and free-space data communication | |
| Zhang et al. | Demonstration of high output power DBR laser integrated with SOA for the FMCW LiDAR system | |
| CN113534106B (en) | Microcavity optical comb laser, distance measuring device and distance measuring method | |
| Hashemi | A review of silicon photonics LiDAR | |
| Bowers | Integrated microwave photonics | |
| US20230400559A1 (en) | Detection apparatus, lidar, chip, and terminal device | |
| Misugi et al. | Compact and low power-consumption solid-state two-dimensional beam scanner integrating a passive optical phased array and hybrid wavelength-tunable laser diode | |
| KR20230170078A (en) | Light source for FMCW lidar devices | |
| CN114966717A (en) | Detection system and method based on collimated light beam and laser radar system | |
| JP2001211022A (en) | Array antenna and method of scanning its frequencies | |
| US20230113820A1 (en) | Wavelength bandwidth expansion for tuning or chirping with a silicon photonic external cavity tunable laser | |
| CN116577804B (en) | FMCW laser radar based on chip integration | |
| Misugi et al. | Silicon-based high-resolution and low-power-consumption two-dimensional beam scanner integrated with hybrid wavelength-tunable laser diode |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |