Laser source, lidar system and method for adjusting a laser source

Abstract

The invention relates to a laser source (10) comprising a laser diode (103), a modulation device (140) and a feedback device (109). The modulation device (140) comprises a current source (149) and is adapted to vary the intensity of the current injected into the laser diode (103), wherein the emission frequency of the laser diode (103) can be varied. The feedback device (109) is adapted to vary the intensity of the current injected into the laser diode (103) by the current source (149) depending on the electromagnetic radiation (15) emitted by the laser diode (103).

Description

Technical Field

[0001] LIDAR (Light Detection and Ranging) systems, especially FMCW-LIDAR (Frequency Modulated Continuous Wave) systems, are increasingly used in transportation, such as for autonomous driving. For example, they are used to measure distances or identify objects. To reliably identify objects at greater distances, a laser source with correspondingly high power is required. Background Technology

[0002] A general approach is to improve existing LIDAR systems.

[0003] In particular, the following laser sources are studied, whose frequency can be modulated in a simple manner and have improved temperature stability of the emission wavelength. Summary of the Invention

[0004] The purpose of this invention is to provide an improved laser source, an improved LIDAR system, and an improved method for operating a laser source.

[0005] According to embodiments, the objective is achieved through the subject matter of the invention. Advantageous improvements are defined in the following description.

[0006] The laser source includes a laser diode, a modulation device, and a feedback device. The modulation device includes a current source and is adapted to change the current intensity injected into the laser diode, thereby changing the emission frequency of the laser diode. The feedback device is adapted to change the current intensity injected into the laser diode through the current source according to the electromagnetic radiation emitted by the laser diode.

[0007] For example, the feedback device includes an interferometer adapted to generate a signal from a measurement beam branched by emitted electromagnetic radiation, the intensity of which varies periodically depending on the emitted wavelength.

[0008] According to the implementation, the feedback device is adapted to transmit a feedback signal to the modulation device that is related to the intensity within a preset wavelength range.

[0009] According to one embodiment, the feedback device includes multiple interferometers. The measurement beam is divided into multiple partial beams, each of which is fed to a different interferometer. Furthermore, the feedback device includes a selection device adapted to select the signal from the interferometer whose intensity has a linear correlation with the wavelength.

[0010] For example, the interferometer can be a Mach-Zehnder interferometer. According to another embodiment, the interferometer can be a Fabry-Perot interferometer.

[0011] For example, components of the feedback device can be integrated into the optoelectronic chip. For example, the feedback device can include one or more interferometers. Components of the interferometer, such as beam splitters or beam combiners, can be implemented as fiber optic components, such as optical splitters or optical couplers.

[0012] For example, a laser diode can be a surface-emitting laser diode.

[0013] According to an implementation, the LIDAR system includes the laser source described above. For example, the LIDAR system can be implemented at least partially as an integrated optical circuit.

[0014] Methods for adjusting a laser source include: injecting a current intensity into a laser diode; changing the current intensity injected into the laser diode, thereby changing the emission frequency of the laser diode; and adjusting the current intensity injected into the laser diode in relation to the electromagnetic radiation emitted by the laser diode.

[0015] For example, adjusting the current intensity can include: generating a signal related to the emission wavelength; generating a feedback signal from the signal; and adjusting the current intensity using the feedback signal.

[0016] For example, a laser diode can be a surface-emitting laser diode. Attached Figure Description

[0017] The accompanying drawings are provided for understanding embodiments of the invention. The drawings illustrate and explain embodiments, and are used in conjunction with the description to elucidate these embodiments. Other embodiments and numerous intentional advantages will become apparent directly from the following detailed description. Elements and structures shown in the drawings are not necessarily shown to scale. The same reference numerals indicate the same or corresponding elements and structures.

[0018] Figure 1A A schematic diagram of a laser source according to an embodiment is shown.

[0019] Figure 1B Elements of a laser source according to another embodiment are shown.

[0020] Figure 2 The time-varying curves of the signals in the two photodetectors are shown.

[0021] Figure 3A A schematic vertical cross-sectional view of a laser source according to an embodiment is shown.

[0022] Figure 3B A schematic top view of a laser source according to an embodiment is shown.

[0023] Figure 4 The diagram illustrates a LIDAR system according to an implementation method.

[0024] Figure 5 The method according to the implementation method is summarized. Detailed Implementation

[0025] Referring in the following detailed description are the accompanying drawings, which form part of the disclosure and illustrate specific embodiments for illustrative purposes. In this context, directional terms such as “upper,” “bottom,” “front,” “rear,” “above,” “up,” “front,” “rear,” “forward,” “rear,” etc., refer to the orientation of the drawings just described. Because components of the embodiments can be positioned in different orientations, the directional terms are for illustrative purposes only and are by no means limiting.

[0026] The description of the embodiments is not limiting, as other embodiments exist and structural or logical changes can be made without departing from the scope defined by the invention. In particular, elements of the embodiments described below can be combined with elements of other described embodiments, provided that no other meaning is derived from the context.

[0027] The terms "wafer" or "semiconductor substrate" as used in the following description can include all semiconductor-based structures having a semiconductor surface. Wafers and structures should be understood to include doped and undoped semiconductors, epitaxial semiconductor layers, supported by a substrate if necessary, and other semiconductor structures. For example, a layer made of a first semiconductor material may be grown on a growth substrate made of a second semiconductor material, such as a GaAs, GaN, or Si substrate, or on a growth substrate made of an insulating material, such as a sapphire substrate.

[0028] Depending on the application, semiconductors can be based on direct or indirect semiconductor materials. Examples of semiconductor materials particularly suitable for generating electromagnetic radiation include: nitride semiconductor compounds, which can generate ultraviolet, blue, or longer wavelength light, such as GaN, InGaN, AlN, AlGaN, AlGaInN, and AlGaInBN; phosphide semiconductor compounds, which can generate green or longer wavelength light, such as GaAsP, AlGaInP, GaP, and AlGaP; and other semiconductor materials such as GaAs, AlGaAs, InGaAs, AlInGaAs, SiC, ZnSe, ZnO, Ga2O3, diamond, hexagonal BN, and combinations thereof. The stoichiometry of compound semiconductor materials can be varied. Other examples of semiconductor materials may include silicon, silicon-germanium, and germanium. In the context of this specification, the term "semiconductor" also includes organic semiconductor materials.

[0029] The term "substrate" generally includes insulating, conductive, or semiconductor substrates.

[0030] As used herein, the terms "lateral" and "horizontal" should describe an orientation or direction that extends substantially parallel to the first surface of the substrate or semiconductor body. This could be, for example, the surface of a wafer or chip (die).

[0031] The horizontal direction can be located, for example, in a plane perpendicular to the growth direction during layer growth.

[0032] As used herein, the term "vertical" should describe an orientation that extends substantially perpendicular to the first surface of the substrate or semiconductor body. A vertical direction may, for example, correspond to the growth direction during layer growth.

[0033] In the context of this specification, the term "electrical connection" refers to a low-ohm electrical connection between connected components. Components in an electrical connection do not necessarily have to be directly connected to each other. Other components may be positioned between the electrically connected components.

[0034] The term "electrical connection" also includes tunneling contact between connected components.

[0035] Figure 1AA view of a laser source 10 according to an embodiment is shown. The laser source 10 includes a laser diode 103 and a modulation device 140. The modulation device 140 has a current source 149. Current is injected into the laser diode 103 via the current source 149. The modulation device 140 is adapted to change the current intensity injected into the laser diode 103. Therefore, the emission frequency of the laser diode 103 is changeable. The laser source 10 also includes a feedback device 109. The feedback device 109 is adapted to change the current intensity injected into the laser diode in relation to the electromagnetic radiation emitted by the laser diode.

[0036] For example, laser diode 103 can be a surface-emitting laser diode (VCSEL, "Vertical Cavity Surface Emitting Laser"). According to an embodiment, laser diode 103 can also be a laser diode with an optical resonator extending in a direction perpendicular to the growth direction of the semiconductor layer of laser diode 103. For example, a laser diode with such a horizontal resonator can have additional deflection devices, such as a mirror reflector, through which the emitted electromagnetic radiation 15 can be deflected in any manner.

[0037] Current source 149 injects current into laser diode 103. By slightly varying the injected current, for example, within a few μA, the wavelength can be altered, resulting in a frequency difference in the emitted radiation within the range of MHz to GHz. Modulation of the injected current intensity leads to modulation of the carrier density, which causes a change in the refractive index in the optical resonator. As a result, the wavelength shifts. Furthermore, the increased carrier density causes a temperature rise, which also alters the emission wavelength. Accordingly, the emission wavelength can be modulated within the range of MHz to GHz.

[0038] A portion of the emitted electromagnetic radiation 15 can be separated as a measuring beam 16. The remaining portion of the emitted electromagnetic radiation remains as an object beam 19. The intensity of the measuring beam 16 can be less than 10% of the intensity of the emitted electromagnetic radiation 15. For example, the intensity of the measuring beam 16 can exceed 1% of the emitted electromagnetic radiation 15. The measuring beam 16 is fed to a measuring device 104. A signal is generated from the measuring beam by the measuring device 104, the intensity of which changes periodically depending on the emitted wavelength. For example, a feedback device 109 can be adapted to supply a feedback signal to the modulation device 140 corresponding to an intensity within a preset wavelength range.

[0039] As in Figure 1AAs shown, the measurement beam 16 is divided into partial beams 21, 24 and, if necessary, a reference measurement beam 112. Each partial beam is delivered to a different interferometer 118.

[0040] Interferometer 118 can be configured, for example, as a Mach-Zehnder interferometer, such as in Figure 1A As shown in the diagram, for example, the first beam splitter 107 splits the partial beams 21 and 24 into two sub-beams 22 and 23. The first and second sub-beams 22 and 23 are then converged again via the second beam splitter 108 after passing through different optical path lengths and associated steering mirrors 106.

[0041] For example, the first beam splitter 107 can be a partially transmissive mirror. The second beam splitter 108 can be implemented, for example, as a Bragg mirror, which shifts the phase of the reflected beam by 180° on one side but not on the other. This causes constructive interference at one output and destructive interference at the other. As a result, beam I is generated on one side. c,1 and beam I s,1 Beam I c,1 Detected by the first photodetector 1051. Second beam I s,1 Detected by the second photodetector 1052. First beam I c,1 It is a beam with the following intensity, the difference between which is obtained from the difference of different path lengths. Proportional. Second beam I s,1 Having the following strength, the strength differs from the phase. Proportional. The difference is shown below:

[0042]

[0043] Where Γ represents the system's confinement factor, i.e., the ratio of the mode's radiation fraction in the core and cladding regions of the waveguide (typically < or approximately equal to 1), and λ represents the emission wavelength. In other words, the phase difference, and thus the arguments of the sine and cosine functions, are wavelength-dependent. Furthermore, phase differences exceeding ΔL are related to the difference in path length between the two paths. As temperature increases, the emission wavelength, and thus the phase difference, changes.

[0044] According to the embodiment, the measurement beam 16 is divided into multiple partial beams 21 and 24, each of which is analyzed by a different interferometer 118. For example, the interferometer 118 divides the partial beams 21 and 24 into a first sub-beam and a second sub-beam, each with a different optical path length. The different interferometers 118 are arranged such that a different phase difference is obtained for each interferometer. Therefore, for each separate partial beam 21 and 24, a different intensity variation curve with respect to the emission wavelength λ is obtained using the corresponding interferometer. Because the variation curve with respect to the emission wavelength changes with temperature in the same way for all interferometers, precise wavelength stabilization of the laser itself is no longer necessary.

[0045] Figure 2 Examples of signals detected by detectors 1051 and 1052 are shown. Feedback device 109 includes a selection device 110 or a controller adapted to select signals from photodetectors 1051, ..., 1054 that extend within a linear range. The spacing between two maximum values ​​can, for example, correspond to a frequency of 5 GHz, while the range corresponding to the modulated wavelength is approximately 1 GHz.

[0046] By dividing the measuring beam 16 into different partial beams, each partial beam being transmitted to a different interferometer 118 with a different path length difference, at any given time, there exist interferometer or photodetector pairs 1051, ..., 1054, in which the intensity changes linearly with wavelength. A current signal corresponding to the measured intensity within the linear range is transmitted to the modulation device 140. As a result, the current intensity injected through the current source 149 is adjusted accordingly. Consequently, it is possible to achieve a stable emission wavelength even under elevated temperatures. In particular, the emission wavelength lies within a preset range.

[0047] For example, the path length of the optical path can be within the range of 8mm.

[0048] The optional reference measurement beam 112 can be used, for example, to measure the power of a signal. Because no periodic changes occur within the reference measurement beam 112, and the reference measurement beam is wavelength-independent, the signal can be used, for example, for calibration or as a power monitor, or it can also be used as… Figure 2 The reference for the signal in the signal.

[0049] By generating two periodic signals via interferometer 118 as described, it is possible to determine the linear range from the signal shape. This is elaborated further below. As a result, frequency-amplitude demodulation is possible.

[0050] Figure 1B An alternative design scheme for interferometer 118 is shown. (Compared to...)Figure 1A Similarly, as illustrated in the diagram, the measuring beam 16 is divided into multiple partial beams 21 and 24. These partial beams are then respectively fed to a Fabry-Perot interferometer. Each Fabry-Perot interferometer includes an optical resonator 131 and a first resonant mirror 132 and a second resonant mirror 133, respectively, located on opposite sides of the optical resonator 131. The Fabry-Perot interferometers for the corresponding partial beams have different resonator lengths. Here, photodetectors 1051, ..., 1053 are also respectively disposed at the output end of the Fabry-Perot interferometer. Because standing waves are formed in the resonators when the resonator length is an integer multiple of half the wavelength of the incident laser power in the corresponding propagation medium, periodically changing signals are also formed in the corresponding photodetectors 1051, ..., 1053. For example, the length of the Fabry-Perot resonator can be approximately 2 cm. For example, according to... Figure 1B It is possible to select a portion of the beam whose measured intensity corresponds to a predetermined percentage of the reference measurement beam 112. Within this range, a linear correlation between intensity and wavelength can be assumed.

[0051] Figure 2 The diagram shows the intensities detected at the Mach-Zehnder interferometer by two detectors, respectively. As described above, the intensity detected by photodetector 1051 is related to cos... 2 The intensity detected by photodetector 1052 is proportional to the intensity of the light. Proportional. Here. The phase difference, corresponding to different path lengths, is proportional to the wavelength of the emitted radiation. According to the embodiment, wavelength ranges in which the intensity is linear are determined as follows: intensity I1 is detected at the first photodetector 1051, and intensity I2 is detected at the second photodetector 1052. If the two intensities I1 and I2 are the same, then it is considered to be within a wavelength range where the intensity increases or decreases linearly, such as, for example, in... Figure 2 As shown at locations "I1" and "I2". The selection device 110 is adapted to read the signals from all photodetectors and compare them in pairs. If the intensity of a pair of detectors is consistent, then it is assumed that there is a linear increase or decrease in intensity. The corresponding photodetector signal is then used to adjust the modulation device 140. Active feedback adjustment of the modulation device 140 is performed in this way.

[0052] Correspondingly, the possible wavelength drift or manufacturing tolerance of the laser Bragg reflector with respect to temperature, compared to the resonator length of the Mach-Zehnder interferometer, is compensated for by measuring signals from multiple Mach-Zehnder interferometers. The signals from the Mach-Zehnder interferometers, which have linear variation curves, are used to adjust the current applied to the laser diode 103.

[0053] Figure 3A A vertical cross-sectional view of the laser source 10 according to an embodiment is shown. A waveguide system is disposed above an arbitrary substrate 115, such as an insulating substrate. Furthermore, a laser diode 103 is disposed above the substrate 115. Radiation emitted by the laser diode 103 is coupled into the waveguide 111, for example, via a steering mirror 106. The waveguide material can include, for example, SiO or SiN. When the emission wavelength of the laser diode 103 is >1000 nm, Si can also be used as the material for the waveguide 111.

[0054] For example, the laser diode 103 can be adapted to emit electromagnetic radiation with a wavelength greater than 850 nm, such as 905 nm. For example, a highly reflective coating can be provided on one side of the laser diode, while a reflective-reducing coating can be provided on the other side. In this way, the generated electromagnetic radiation is coupled out at this location. The coupled-out electromagnetic radiation can be coupled into the waveguide 111, for example, via a steering mirror 106. For example, the steering mirror 106 can also be a prism or a suitable grating. As described above, a portion of the emitted electromagnetic radiation 15 is split off as a measurement beam 16. For example, the measurement beam can include approximately 1% to 10% of the emitted electromagnetic radiation 15. Furthermore, the measurement beam 16 can be divided into different partial beams and a reference measurement beam 112.

[0055] Figure 3B A top view of a laser source 10 according to an embodiment is shown. As can be seen, the laser source 10 has a system including a laser diode 103 and a waveguide 111. The waveguide 111 is configured to split a portion of the emitted electromagnetic radiation into a measurement beam 16 and an object beam 19. Furthermore, components of the interferometer are implemented via the waveguide 111. The measurement beam 16 is split in a manner corresponding to that described above. For example, corresponding integrated optical elements can be used to split the beam and then refocus it. For example, this functionality can be achieved by a splitter, coupler, or coupled waveguide.

[0056] For example, the different path lengths of the waveguides in a Mach-Zehnder interferometer or a Fabry-Perot interferometer can be constructed in a space-saving manner by meandering or rolling up the waveguides.

[0057] For example, in Figure 3B The waveguide structure shown can be fabricated by photolithography structuring, which involves structuring waveguide materials such as Si, SiO, or SiN.

[0058] As described, laser diodes can be combined with various optical components, such as interferometers. These optical components can be implemented, for example, as optical or optoelectronic chips. Correspondingly, the optical components can be integrated optical circuits. For example, a laser diode can integrate an integrated optical circuit. As a result, a laser source with temperature-stable emission wavelength characteristics can be provided.

[0059] As described, at least one interferometer exists within an approximately linear range of wavelength-dependent intensity, independent of the emission wavelength of the laser diode, enabling it to be used as an FM-AM demodulator. This allows for automatic compensation for temperature fluctuations and manufacturing tolerances. The signal from the photodetector is here converted into an adjustment signal for the modulation device 140.

[0060] The described laser source can be used, for example, in a LIDAR system. Figure 4 A schematic diagram of a LiDAR system 20 is shown. Figure 4 The LIDAR system 20 shown is an FMCW (Frequency Modulated Continuous Wave) LIDAR system. Laser radiation emitted by laser source 10 has varying wavelengths. The emitted radiation is split into a reference beam 18 and an object beam 19 by beam splitter 121. The object beam 19 is incident on and reflected by object 25, resulting in a reflected beam 17. The reflected beam 17 is shaped appropriately by receiving optics 128 and collimator 127 and delivered to detector 150 via mirror 123 and another optics 125. The reference beam 18 is delivered directly to detector 126 via mirror 123 and optics 125. When the coherent reflected beams 17 and 18 are superimposed, a mixed signal is generated at detector 126, from which, for example, spacing and other information about the detected object can be evaluated.

[0061] A mixed signal of the following formula was detected at detector 126:

[0062] Here, f LO The frequency corresponding to the object beam 19 or the reference beam 18, and f a This corresponds to the frequency of the reflected beam 17. The frequency of the reflected beam 17 is delayed due to the transit time difference resulting from reflection at object 25. At f a and f LOThe difference between them is a measure of the motion and distance of object 25. The frequency difference between the reference beam 18 and the reflected beam 17 is determined by photodetector 126. According to the implementation, the LIDAR system or a part thereof can be implemented as an integrated optical circuit. For example, components of the LIDAR system can be implemented as corresponding fiber optic components.

[0063] Figure 5 The method according to the embodiment is summarized. The method for adjusting a laser source includes injecting (S100) a current intensity into a laser diode and changing (S110) the current intensity injected into the laser diode, thereby changing the emission frequency of the laser diode. The method further includes adjusting (S120) the current injected into the laser diode in relation to the electromagnetic radiation emitted by the laser diode.

[0064] For example, adjusting the current intensity (S120) can include generating a signal related to the emission wavelength (S130) and generating a feedback signal from the signal (S140). The feedback signal is then used to adjust the current intensity. The adjustment is performed continuously.

[0065] Although specific embodiments are illustrated and described herein, those skilled in the art will recognize that the specific embodiments shown and described can be replaced by numerous alternative and / or equivalent design solutions without departing from the scope of protection of the invention. This application is intended to cover all modifications or variations of the specific embodiments discussed herein. Therefore, the invention is limited only by the examples and their equivalents.

[0066] List of reference numerals in the attached diagram:

[0067] 10 laser sources

[0068] 15. Emitted electromagnetic radiation

[0069] 16. Measuring the beam

[0070] 17. Reflected beam

[0071] 18 Reference Beam

[0072] 19. Object Beam

[0073] 20LIDAR system

[0074] 21 First part of the beam

[0075] 22 First Sub-beam

[0076] 23 Second Sub-beam

[0077] 24 Second part of the beam

[0078] 25 objects

[0079] 103 Laser Diode

[0080] 104 Measuring device

[0081] 1051, 1052, ..., 1054 photodetectors

[0082] 106 Turning Mirror

[0083] 107 First beam splitter

[0084] 108 Second beam splitter

[0085] 109 Feedback Device

[0086] 110 Selection Device

[0087] 111 Waveguide

[0088] 112 Reference Measurement Beam

[0089] 115 substrate

[0090] 118 interferometer

[0091] 121 beam splitter

[0092] 123 Reflector

[0093] 125 Optical Components

[0094] 126 detectors

[0095] 127 Collimator

[0096] 128 Receiving Optical Components

[0097] 131 Optical Resonator

[0098] 132 First Resonant Mirror

[0099] 133 Second Resonant Mirror

[0100] 140 Modulation device

[0101] 149 Current Source

[0102] S100 Injection Current Intensity

[0103] S110 Change current intensity

[0104] S120 Adjustable Current Intensity

[0105] S130 generates a signal

[0106] S140 generates a feedback signal

Claims

1. A laser source (10), the laser source comprising: Laser diode (103); A modulation device (140) comprising a current source (149) and adapted to change the current intensity injected into the laser diode (103), wherein the emission frequency of the laser diode (103) can be changed; and Feedback device (109), the feedback device being adapted to supply a feedback signal to the modulation device (140) that is related to the intensity within a preset wavelength range, wherein The feedback device (109) includes a plurality of interferometers (118), each adapted to generate a signal based on a measurement beam (16) branched from electromagnetic radiation (15) emitted by the laser diode (103), the intensity of which changes periodically in relation to the emission wavelength, and the measurement beam (16) is divided into a plurality of partial beams (21, 24), each of which is fed to a different interferometer (118). The feedback device (109) also includes a selection device (110) adapted to select the signal of the interferometer (118) whose intensity is linearly correlated with the wavelength and feed it to the modulation device (140) such that the current intensity injected into the laser diode (103) through the current source (149) changes in relation to the electromagnetic radiation (15) emitted by the laser diode (103).

2. The laser source (10) according to claim 1, The interferometer (118) mentioned therein is a Mach-Zehnder interferometer.

3. The laser source (10) according to claim 1, The interferometer (118) mentioned therein is a Fabry-Perot interferometer.

4. The laser source (10) according to any one of claims 1 to 3, The components of the feedback device (109) are integrated into the optoelectronic chip.

5. The laser source (10) according to any one of claims 1 to 3, The laser diode (103) therein is a surface-emitting laser diode (103).

6. The laser source (10) according to claim 4, The laser diode (103) therein is a surface-emitting laser diode (103).

7. A LIDAR system (20), the LIDAR system comprising: The laser source (10) according to any one of claims 1 to 6.

8. The LIDAR system of claim 7, wherein the LIDAR system is at least partially implemented as an integrated optical circuit.

9. A method for modulating a laser source (10), the laser source having a laser diode (103) and a modulation device (140), the modulation device including a current source (149), the method comprising: Inject current intensity into laser diode (103); The emission frequency of the laser diode (103) is changed by changing the current intensity injected into the laser diode (103); and The current intensity injected into the laser diode (103) is adjusted in relation to the electromagnetic radiation (15) emitted by the laser diode (103), wherein adjusting the current intensity includes the following: A signal is generated from a measurement beam derived from the emitted electromagnetic radiation, wherein the signal is related to the emitted wavelength and its intensity changes periodically in relation to the emitted wavelength; A feedback signal is generated from the signal, and the current intensity is adjusted using the feedback signal, wherein the feedback signal is related to the intensity in a preset wavelength range, wherein the measurement beam (16) is divided into multiple partial beams, the partial beams are respectively delivered to different interferometers, and the signal of the interferometer having a linear correlation with the intensity of the wavelength is selected and delivered to the modulation device (140), such that the current intensity injected into the laser diode (103) through the current source (149) is changed in relation to the electromagnetic radiation (15) emitted by the laser diode (103).

10. The method according to claim 9, The laser diode (103) therein is a surface-emitting laser diode (103).

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