Abstract: A semiconductor laser diode and a method for manufacturing a semiconductor laser diode are disclosed. In an embodiment a semiconductor laser diode includes an epitaxially produced semiconductor layer sequence comprising at least one active layer and a gallium-containing passivation layer on at least one surface region of the semiconductor layer sequence.

Abstract: The object of the invention relates to a field of devices for performing treatments in ophthalmology, preferably to a field of devices for selective laser trabeculoplasty and capsulotomy. The essence of a laser therapeutic device for performing treatments in ophthalmology lies in that it is based on a laser source with a short resonator based on a end pumping technique, wherein the pumping is ascertained by a VCSEL light source (vertical-cavity surface-emitting laser). Optimization of constructional and physical properties of a laser source is herewith achieved. The laser source meets all requirements for use in both above-mentioned treatments, wherein the device for capsulotomy is also suited for iridotomy and other surgeries, in which the effects of photodisruption are exploited.

Abstract: A light emitting element according to the present disclosure includes: a GaN substrate; a first strain correction layer disposed above the GaN substrate and including InxGa1-xN of a first conductivity type where x is greater than 0 and less than or equal to 1; a first low refractive index layer disposed above the first strain correction layer, including In1-a-bGaaAlbN of the first conductivity type, and having relationships of (a/0.98)+(b/0.8)?1, (a/1.02)+(b/0.85)?1, and (a/1.03)+(b/0.68)?1; a first clad layer disposed above the first low refractive index layer, including AlzGa1-zN of the first conductivity type where z is greater than or equal to 0.03 and less than or equal to 0.06, and having a refractive index higher than a refractive index of the first low refractive index layer; and an active layer disposed above the first clad layer.

Abstract: Vertical cavity light emitting sources that utilize patterned membranes as reflectors are provided. The vertical cavity light emitting sources have a stacked structure that includes an active region disposed between an upper reflector and a lower reflector. The active region, upper reflector and lower reflector can be fabricated from single or multi-layered thin films of solid states materials (“membranes”) that can be separately processed and then stacked to form a vertical cavity light emitting source.

Abstract: A method of fabricating a semiconductor device comprises providing a substrate with a shallow trench isolation (STI) within the substrate and a gate stack. A cavity is formed between the gate stack and the STI. The cavity comprises one sidewall formed by the STI, one sidewall formed by the substrate, and a bottom surface formed by the substrate. A film is grown in the cavity and thereafter an opening formed by removing a first portion of the strained film until exposing the bottom surface of the substrate while a second portion of the strained film adjoins the STI sidewall. Another epitaxial layer is then grown in the opening.

Abstract: A micromechanical component includes: at least one micromirror; and an integrated photodiode. The micromechanical component is part of a microprojector which further includes a light source. The integrated photodiode of the micromechanical component receives light from the light source.

Abstract: An ultraviolet laser diode having multiple portions in the n-cladding layer is described herein. The laser diode comprises a p-cladding layer, an n-cladding layer, a waveguide, and a light-emitting region. The n-cladding layer includes at least a first portion and a second portion. The first portion maintains material quality of the laser diode, while the second portion pulls the optical mode from the p-cladding layer toward the active region. The first portion may have a higher aluminum composition than the second portion. The waveguide is coupled to the n-cladding layer and the light-emitting region is coupled to the waveguide. The light-emitting region is located between the n-cladding layer and the p-cladding layer. Other embodiments are also described.

Abstract: Disclosed is a light emitting device including a conductive substrate, a first electrode layer disposed on the conductive substrate, a light emitting structure disposed on the first electrode layer, the light emitting structure including a first semiconductor layer, a second semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer, a second electrode layer electrically connected to the second semiconductor layer, and an anti-crack layer disposed on a boundary on which the light emitting structure is segmented on a chip basis, wherein the anti-crack layer is disposed under the light emitting structure and includes a metal material contacting the light emitting structure.

Abstract: A bi-section type GaN-based semiconductor laser device that has a configuration and a structure in which damage is less likely to be caused in a region in a saturable absorption region that faces a first light emission region is provided. The semiconductor laser device includes a first light emission region, a second light emission region, a saturable absorption region sandwiched by the foregoing light emission regions, a first electrode, and a second electrode. Laser light is emitted from an end face on a second light emission region side thereof. The second electrode is configured of a first portion, a second portion, and a third portion. 1<W2-ave/W1-ave is satisfied where W1-ave is an average width of a portion having a ridge stripe structure of the first portion and W2-ave is an average width of a portion having a ridge stripe structure of the second portion.

Abstract: A laser diode device includes a laminated structure in which a first compound semiconductor layer, a third compound semiconductor layer that has a light emitting region and a saturable absorption region, and a second compound semiconductor layer are sequentially layered, a second electrode, and a first electrode. The laminated structure has ridge stripe structure. The second electrode is separated into a first section to obtain forward bias state by applying a direct current to the first electrode through the light emitting region and a second section to add electric field to the saturable absorption region by an isolation trench. When minimum width of the ridge stripe structure is WMIN, and width of the ridge stripe structure of the second section of the second electrode in an interface between the second section of the second electrode and the isolation trench is W2, 1<W2/WMIN is satisfied.

Abstract: An Environmentally stable optical fiber mode-locked laser generating device having an achromatic quarter wave plate is disclosed. An optical fiber unit is formed of a polarization maintaining (PM) optical fiber, and a Bragg grating is formed on a first region from one end in direction to the other end, a gain material is doped on a core of a remaining second region. An optical coupling unit provides a pump laser input to one end of the optical fiber unit, and outputs a laser input from the optical fiber unit. A lens unit converts a laser output from the other end of the optical fiber unit and focuses the laser on a certain regime.

Abstract: A light oscillation device has a self oscillation semiconductor laser that has a double quantum well separated confinement heterostructure made of GaInN/GaN/AlGaN materials and that includes a saturable absorber section which is applied with a negative bias voltage and a gain section into which a gain current is injected, a light separation unit that separates a portion of laser light beams from the self oscillation semiconductor laser, a light sensing element that senses the laser light beams separated by the light separation unit, and a current control circuit which controls a current injected into the gain section of the self oscillation semiconductor laser based on an amount of the laser light beams which are sensed by the light sensing element.

Abstract: When an end-face-emitting photonic crystal laser element 10 is seen in an X axis, one end of an upper electrode E2 overlaps a laser light exit surface SF, the upper electrode E2 and an opposite end face SB are separated from each other, the upper electrode E2 is separated from both lateral end faces SR, SL, and one end of an active layer 3B overlaps the laser light exit surface SF.

Abstract: A quantum cascade semiconductor laser includes a n-type semiconductor substrate, the substrate having a main surface; a mesa waveguide disposed on the substrate, the mesa waveguide including a core layer and an n-type upper cladding layer disposed on the core layer; a first semiconductor layer disposed on a side surface of the mesa waveguide and the main surface of the substrate, the first semiconductor layer being in contact with the side surface of the mesa waveguide; and a second semiconductor layer disposed on the first semiconductor layer. The first semiconductor layer and the second semiconductor layer constitute a burying region embedding the side surfaces of the mesa waveguide. The first semiconductor layer is formed of at least one of a semi-insulating semiconductor and a p-type semiconductor. In addition, the second semiconductor layer is formed of an n-type semiconductor.

Abstract: A laser diode capable of performing self-pulsation operation, and capable of sufficiently reducing the coherence of laser light and stably obtaining low-noise laser light is provided. The laser diode includes: a laser chip including at least one laser stripe which extends in a resonator length direction between a first end surface and a second end surface opposed to each other, in which the laser stripe includes a gain region and a saturable absorption region in the resonator length direction, and the width of the laser stripe in the saturable absorption region is larger than the width of the laser stripe in the gain region.

Abstract: A laser diode capable of performing self-pulsation operation, and capable of sufficiently reducing the coherence of laser light and stably obtaining low-noise laser light is provided. A laser diode includes: a laser chip including at least one laser stripe which extends in a resonator length direction between a first end surface and a second end surface opposed to each other, in which the laser stripe includes a gain region and a saturable absorption region in the resonator length direction, and the width of the laser stripe in the saturable absorption region is larger than the width of the laser stripe in the gain region.

Abstract: A bi-section type GaN-based semiconductor laser device that has a configuration and a structure in which damage is less likely to be caused in a region in a saturable absorption region that faces a first light emission region is provided. The semiconductor laser device includes a first light emission region, a second light emission region, a saturable absorption region sandwiched by the foregoing light emission regions, a first electrode, and a second electrode. Laser light is emitted from an end face on a second light emission region side thereof. The second electrode is configured of a first portion, a second portion, and a third portion. 1<W2-ave/W1-ave is satisfied where W1-ave is an average width of a portion having a ridge stripe structure of the first portion and W2-ave is an average width of a portion having a ridge stripe structure of the second portion.

Abstract: The invention relates to a saturable absorber mirror comprised of a) a rear-side reflector layer (2), b) an intermediate layer (6), the boundary areas of which form an interference filter, c) at least one absorber layer arranged within the interference filter and comprised of a material absorbing a light at operating wavelength of the saturable absorber mirror depending on intensity, and d) a front-side cover layer. It is the object of the invention to provide a saturable absorber mirror having improved properties. To this effect the invention proposes that the interference filter is neither resonant nor anti-resonant at operating wavelength, with the intensity (I) of the electromagnetic stationary wave field of the light in the interior of the cover layer (5) having a local extremum (8).

Abstract: A laser diode element assembly includes: a laser diode element; and a light reflector, in which the laser diode element includes (a) a laminate structure body configured by laminating, in order, a first compound semiconductor layer of a first conductivity type made of a GaN-based compound semiconductor, a third compound semiconductor layer made of a GaN-based compound semiconductor and including a light emission region, and a second compound semiconductor layer of a second conductivity type made of a GaN-based compound semiconductor, the second conductivity type being different from the first conductivity type, (b) a second electrode formed on the second compound semiconductor layer, and (c) a first electrode electrically connected to the first compound semiconductor layer, the laminate structure body includes a ridge stripe structure, and a minimum width Wmin and a maximum width Wmax of the ridge stripe structure satisfy 1<Wmax/Wmin<3.3 or 6?Wmax/Wmin?13.3.

Abstract: An photonic device, comprising one section of a material which is different from the material of another section such that the two sections present different optical birefringent index values. This causes a first set of polarization modes to move in a spectral space with a different velocity than a second set of polarization modes. A bias current, or voltage, is used for controlling the overall birefringence effect in the device. The biasing for controlling the birefringence effect is performed such the TE modes and the TM modes of the device are made to coincide in their respective spectral position. Thus the device is made insensitive, or presents substantially reduced sensitivity, to the polarization of any incoming optical signal.

Abstract: Provided is a driving method of a mode-locked semiconductor laser device comprising a laminated structure in which a first compound semiconductor layer, a third compound semiconductor layer having an emission region and a second compound semiconductor layer are successively laminated, a second electrode, and a first electrode. The laminated structure is formed on a compound semiconductor substrate having polarity, the third compound semiconductor layer includes a quantum well structure having a well layer and a barrier layer. The well layer has a depth of 1 nm or more and 10 nm or less. The barrier layer has an impurity doping density of 2×1018 cm?3 or more and 1×1020 cm?3 or less. An optical pulse is generated in the emission region by passing a current from the second electrode to the first electrode via the laminated structure.

Abstract: A three-terminal VCSEL is provided that has a reduced fall time that allows the VCSEL to be operated at higher speeds. Methods of operating the three-terminal VCSEL are also provided. The VCSEL can be operated at higher speeds without decreasing the optical output of the VCSEL when it is in the logical HIGH state.

Abstract: The invention relates to an optically pumped ultrashort pulse microchip laser for generating a laser emission having femto- or picosecond pulses, comprising a substrate, an amplifying laser medium, a first resonator mirror that is at least partially transparent to optical pump radiation, and in particular a saturable absorber structure. The laser medium is applied to the resonator mirror and the substrate and subsequently reduced from the original material thickness to a thickness of less than 200 ?m. In order to achieve satisfactory power absorption despite said low thickness, the optical pump radiation is coupled into the laser medium such that resonance occurs for the laser emission and excess intensity increases occur for the pump radiation.

Abstract: An optical semiconductor device includes a lower electrode layer formed over a semiconductor substrate, an infrared absorption layer formed over the lower electrode layer 26, and an upper electrode layer 38 formed over the infrared absorption layer 36. The infrared absorption layer includes a quantum dot having dimensions different among directions stacked, and is sensitive to infrared radiation of wavelengths different corresponding to polarization directions.

Abstract: A three-terminal VCSEL is provided that has a reduced fall time that allows the VCSEL to be operated at higher speeds. Methods of operating the three-terminal VCSEL are also provided. The VCSEL can be operated at higher speeds without decreasing the optical output of the VCSEL when it is in the logical HIGH state.

Abstract: Light emitting systems are disclosed. The light emitting system includes an electroluminescent device that emits light at a first wavelength. The light emitting system further includes an optical cavity that enhances emission of light from a top surface of the light emitting system and suppresses emission of light from one or more sides of the light emitting system. The optical cavity includes a semiconductor multilayer stack that receives the emitted first wavelength light and converts at least a portion of the received light to light of a second wavelength. The semiconductor multilayer stack includes a II-VI potential well. The integrated emission intensity of all light at the second wavelength that exit the light emitting system is at least 10 times the integrated emission intensity of all light at the first wavelength that exit the light emitting system.

Abstract: An embodiment of the invention provides a light emitting device in which a semiconductor laser diode is used as a light source to emit visible light in a wide range. The light emitting device includes a semiconductor laser diode that emits a laser beam; and a luminescent component that is provided while separated from the semiconductor laser diode and absorbs the laser beam to emit the visible light. In the light emitting device, the luminescent component includes an optical path through which the laser beam is incident to a center portion of the luminescent component.

Abstract: An optical device, a method of making a laser gain medium, and a method of suppressing parasitics in a laser device include a core region comprising a plurality of a first type of ions that absorb energy at a first wavelength and transfer the absorbed energy to a plurality of a second type of ions that lase at a second wavelength after receiving the transferred energy. A cladding region coupled to the core region comprising another plurality of the second type of ions that suppress parasitics in the optical device by absorbing energy of at least a transverse portion of the second wavelength that enters the cladding region.

Abstract: A laser diode device includes a laminated structure in which a first compound semiconductor layer, a third compound semiconductor layer that has a light emitting region and a saturable absorption region, and a second compound semiconductor layer are sequentially layered, a second electrode, and a first electrode. The laminated structure has ridge stripe structure. The second electrode is separated into a first section to obtain forward bias state by applying a direct current to the first electrode through the light emitting region and a second section to add electric field to the saturable absorption region by an isolation trench. When minimum width of the ridge stripe structure is WMIN, and width of the ridge stripe structure of the second section of the second electrode in an interface between the second section of the second electrode and the isolation trench is W2, 1<W2/WMIN is satisfied.

Abstract: A design of a semiconductor saturable absorber that offers a convenient and reliable way to control/decrease the recovery time of the absorption. The absorption recovery time is controlled during the epitaxial growth by using lattice-mismatched layer(s) to induce dislocations, and implicitly non-radiative recombination centers within the nonlinear absorbing region. These lattice reformation layer(s) are interposed between the distributed Bragg reflector and the nonlinear absorption region, containing quantum-wells, quantum-dots or bulk semiconductor material. The thickness and composition of the lattice reformation layer(s) is an instrumental to control the amount of non-radiative recombination centers used to trap the optically excited carriers generated in the absorption region.

Abstract: An photonic device, comprising one section of a material which is different from the material of another section such that the two sections present different optical birefringent index values. This causes a first set of polarization modes to move in a spectral space with a different velocity than a second set of polarization modes. A bias current, or voltage, is used for controlling the overall birefringence effect in the device. The biasing for controlling the birefringence effect is performed such the TE modes and the TM modes of the device are made to coincide in their respective spectral position. Thus the device is made insensitive, or presents substantially reduced sensitivity, to the polarization of any incoming optical signal.

Abstract: A vertical cavity surface emitting laser including a substrate, a first semiconductor multilayer film reflector formed on the substrate, an active region formed on the first semiconductor multilayer film reflector, a second semiconductor multilayer film reflector formed on the active region, an electrode formed on the second semiconductor multilayer film reflector, a light absorption layer, and a light transmission layer. In the electrode, a light emitting aperture is formed. The light absorption layer is formed in a peripheral region of the light emitting aperture, and absorbs emitted light. The light transmission layer is composed of a material which the emitted light can pass through, and formed in a central region of the light emitting aperture. Thicknesses of the light absorption layer and the light transmission layer are selected so that phases of light from the light absorption layer and from the light transmission layer are adjusted.

Abstract: A semiconductor laser is provided capable of generating very narrow laser beams and having stable characteristics, a method for generating the laser beams and a method for reducing a spectral line-width of the laser beams. The semiconductor laser includes a semiconductor active layer, a photonic crystal optical waveguide forming a periodic structure of two-dimensional refractive index within a plane perpendicular to a semiconductor laminate direction directly or indirectly connected to the semiconductor active layer; and an optical cavity that contains the semiconductor active layer and the photonic crystal optical waveguide and oscillates light that is generated from the semiconductor active layer and is guided through the photonic crystal optical waveguide as laser.

Abstract: There is provided a driving method of a self-oscillating semiconductor laser device including a first compound semiconductor layer having a first conductive type and composed of a GaN base compound semiconductor, a third compound semiconductor layer and a second compound semiconductor layer configuring an emission region and a saturable absorption region, are successively laminated, a second electrode formed on the second compound semiconductor layer, and a first electrode electrically connected to the first compound semiconductor layer. The second electrode is separated into a first portion to create a forward bias state by passing current to the first electrode via the emission region and a second portion to apply an electric field to the saturable absorption region by a separation groove. The current greater than a current value where kink is occurred in optical output-current characteristics is to be passed to the first portion of the second electrode.

Abstract: A semipolar {20-21} III-nitride based laser diode employing a cavity with one or more etched facet mirrors. The etched facet mirrors provide an ability to arbitrarily control the orientation and dimensions of the cavity or stripe of the laser diode, thereby enabling control of electrical and optical properties of the laser diode.

Abstract: Light sources are disclosed. A disclosed light source includes a III-V based pump light source (170) that includes nitrogen and emits light at a first wavelength. The light source further includes a vertical cavity surface emitting laser (VCSEL) that converts at least a portion of the first wavelength light (174) emitted by the pump light source (170) to at least a partially coherent light at a second wavelength (176). The VCSEL includes first and second mirrors (120, 160) that form an optical cavity for light at the second wavelength. The first mirror (120) is substantially reflective at the second wavelength and includes a first multilayer stack. The second mirror (160) is substantially transmissive at the first wavelength and partially reflective and partially transmissive and the second wavelength. The second mirror includes a second multilayer stack.

Abstract: An edge-emitting semiconductor optical device comprises a first cladding layer, an active layer, and a second cladding layer. The first cladding layer is provided on a semiconductor substrate. The active layer is provided on the first cladding layer. The semiconductor substrate has a higher band gap than that of the active layer. The first cladding layer includes a first light-absorbing layer and a first light-transmitting layer. The first light-absorbing layer has a lower band gap than that of the active layer, and the first light-transmitting layer has a higher band gap than that of the active layer. The second cladding layer is provided on the active layer.

Abstract: Provided is a semiconductor laser which has a low operating current and stably oscillates even for high-temperature output. The semiconductor laser is provided with a substrate (10); an n-type clad layer (12) arranged on the substrate (10); an active layer (13) arranged on the n-type clad layer (12); a p-type clad layer (14), which is arranged on the active layer (13) and composed of a compound containing Al and has a stripe-shaped ridge structure to be a current channel; a current block layer (16), which is arranged on the surface of the p-clad layer (14) excluding an upper surface of the ridge structure and composed of a compound containing Al and has an Al composition ratio not more than that of the p-type clad layer (14); and a light absorption layer (17), which is arranged on the current block layer (16) and absorbs light at the laser oscillation wavelength.

Abstract: A light emitting device including a waveguide having an electrically pumped gain region, a saturable absorber, a nonlinear crystal, an inclined mirror, and a light-concentrating structure. Light pulses emitted from the gain region are reflected by the inclined mirror and focused by the light-concentrating structure into the nonlinear crystal in order to generate frequency-converted light pulses. The gain region, the saturable absorber, the light-concentrating structure and the inclined mirror are implemented on or in a common substrate. The resulting structure is stable and compact, and allows on-wafer testing of produced emitters. The folded structure allows easy alignment of the nonlinear crystal.

Abstract: This invention relates to a self-induced transparency mode-locked quantum cascade laser having an active section comprising a plurality of quantum well layers deposited in alternating layers on a plurality of quantum barrier layers and form a sequence of alternating gain and absorbing periods, said alternating gain and absorbing periods interleaved along the growth axis of the active section.

Abstract: In a vertical cavity surface-emitting semiconductor laser device, first and second resonance wavelengths which are different are provided while a first resonator and a second resonator are coupled optically, and a gain of an active layer at the first resonance wavelength on the side of short wavelength is higher than that at the second resonance wavelength on the side of long wavelength. An absorption coefficient of an optical absorption layer when no electric field is applied is small for the first and second resonance wavelengths, and when an electric field is applied, an absorption coefficient of the optical absorption layer for the first resonance wavelength on the side of short wavelength is larger than that for the second resonance wavelength on the side of long wavelength.

Abstract: An active layer has a quantum well structure formed of InGaAsP, and includes a saturable absorption region and optical amplification regions. To the saturable absorption region, a voltage is applied through a p-electrode, independent from the optical amplification region. To the optical amplification regions, currents are injected through p-electrodes, respectively. An input light Pin entering through a plane of incidence is generated by adding optical noise of white noise, to a light signal assuming binary optical intensity of “1” or “0”. The saturable absorption region and optical amplification regions are formed satisfying conditions that a waveform converting element provides a semiconductor laser of bistable state.

Abstract: Semiconductor devices such as VCSELs, SELs, LEDs, and HBTs are manufactured to have a wide bandgap material near a narrow bandgap material. Electron injection is improved by an intermediate structure positioned between the wide bandgap material and the narrow bandgap material. The intermediate structure is an inflection, such as a plateau, in the ramping of the composition between the wide bandgap material and the narrow bandgap material. The intermediate structure is highly doped and has a composition with a desired low electron affinity. The injection structure can be used on the p-side of a device with a p-doped intermediate structure at high hole affinity.

Abstract: A planar waveguide laser device forms a waveguide by a plate-like laser medium having birefringence and clad attached to at least one of the surfaces of the laser medium perpendicular to its thickness direction, amplifies laser light by a gain produced by excitation light incident on the laser medium, and performs laser oscillation. The laser medium is formed of a material having an optic axis on a cross section perpendicular to the light axis, which is the laser travelling direction. The clad is formed of a material having a refractive index in a range between refractive indexes of two polarized lights that travel along the light axis in the laser medium and have oscillation surfaces that are orthogonal to each other. The planar waveguide laser device readily oscillates linearly polarized laser light.

Abstract: A light emitting device includes: a semiconductor laser element having a first emission face for emitting laser light; a light guiding body buried in the concave portion of the supporting base, guiding the laser light emitted from the semiconductor laser element, and having an incident face to which the laser light enters, and a second emission face from which the laser light traveling through the light guiding body is emitted, the incident face of the light guiding body being such a curved face that an incident angle of the laser light is within a predetermined range including the Brewster angle in a plane formed by a traveling direction of the laser light and a short axis of a light emitting spot of the laser light; and a fluorescent substance scattered in the light guiding body, absorbing the laser light, and emitting the light having a different wavelength from a wavelength of the laser light.

Abstract: A semiconductor laser diode device with small driving current and no distortion in the projected image.

Abstract: The invention relates to a saturable absorber mirror comprised of a) a rear-side reflector layer (2), b) an intermediate layer (6), the boundary areas of which form an interference filter, c) at least one absorber layer arranged within the interference filter and comprised of a material absorbing a light at operating wavelength of the saturable absorber mirror depending on intensity, and d) a front-side cover layer, it is the object of the invention to provide a saturable absorber mirror having improved properties. To this effect the invention proposes that the interference filter is neither resonant nor anti-resonant at operating wavelength, with the intensity (I) of the electromagnetic stationary wave field of the light in the interior of the cover layer (5) having a local extremum (8).

Abstract: A surface emitting laser (SEL) with an integrated absorber. A lower mirror and an output coupler define a laser cavity of the SEL. A monolithic gain structure positioned in the laser cavity includes a gain region and an absorber, wherein a saturation fluence of the absorber is less than a saturation fluence of the gain region.

Abstract: A semiconductor light emission device is provided that has a current confinement region that comprises a diffusion accommodation layer located adjacent the active region. The diffusion accommodation layer comprises a material that has a higher bandgap than the bandgap of the material in the active region. Diffusion of dopants into portions of the diffusion accommodation layer forms p+/n junctions on each side of the p/n junction that exists in the active region. The material of the diffusion accommodation layer has a bandgap that is higher than the bandgap of the material of the active region, which ensures that the p+/n junctions turn on at a threshold voltage level that is higher than the threshold voltage level at which the p/n junction turns on.

Abstract: A laser diode capable of performing self-pulsation operation, and capable of sufficiently reducing the coherence of laser light and stably obtaining low-noise laser light is provided. A laser diode includes: a laser chip including at least one laser stripe which extends in a resonator length direction between a first end surface and a second end surface opposed to each other, in which the laser stripe includes a gain region and a saturable absorption region in the resonator length direction, and the width of the laser stripe in the saturable absorption region is larger than the width of the laser stripe in the gain region.