Abstract: A surface-emitting semiconductor laser including: an active layer including a nitride semiconductor; a first semiconductor layer of a first electrical conduction type and a second semiconductor layer of a second electrical conduction type that are opposed to each other with the active layer therebetween; and a current confinement layer that is opposed to the active layer with the second semiconductor layer therebetween and has an opening, in which a side surface of the current confinement layer is inclined at at least a portion of a peripheral edge of the opening.

Abstract: A depth camera assembly (DCA) determines depth information for a local area. The DCA includes a camera assembly and at least one illuminator. The DCA may select a subset of the VCSELs to provide illumination at any given time. The illuminator may comprise near-field VCSELs configured to generate a structured light (SL) pattern for depth sensing in the near-field and far-field VCSELs configured to generate a SL pattern for depth sensing in the far-field. The near-field VCSELs may comprise a linear emission region which is shorter than a linear emission region of the far-field VCSELs. The DCA may generate and phase shift a quasi-sinusoidal SL pattern. The DCA may phase shift the quasi-sinusoidal SL pattern by alternating which traces on the illuminator are active.

Abstract: A narrow linewidth laser includes a passive ring resonant cavity, an FP resonant cavity, and a first gain region. The passive ring resonant cavity and the FP resonant cavity are combined to form an M-Z (Mach-Zehnder interference structure) compound external cavity structure, and the M-Z compound external cavity structure is at least used for providing wavelength selection and narrowing laser linewidth. The first gain region is provided on the outer side of the M-Z compound external cavity structure and is used for providing a gain for the whole laser. The narrow linewidth laser is simple in structure, high in side-mode suppression ratio, narrow in linewidth, and high in output power. By further integrating a PN junction region or MOS junction region, broadband and rapid tuning with low power consumption can also be achieved, and tuning management is simple.

Abstract: Apparatuses, methods, and systems for generating signatures based on sensing one or more gas concentration conditions are disclosed. One method includes sensing, by one or more sensors, levels of a gas over time for a plurality of gas concentration conditions, receiving, by a controller, the sensed levels of gas over time for the plurality of gas concentration conditions, and generating, by the controller, a plurality of signatures, wherein one or more signatures is generated for one or more gas concentration conditions based on the sensed levels of gas over time, and determining whether to take action or not to take action.

Abstract: A microprobe is provided that includes a microsphere optical resonator operatively coupled to a nanoscatterer. The microsphere optical resonator includes a back surface and a front surface opposite the front surface. The front surface is configured to receive a focused laser beam, and the nanoscatterer is positioned adjacent to the back surface.

Abstract: In various embodiments, the concentration and deposition of siloxane materials within components of laser systems, such as laser resonators, is reduced or minimized utilizing mitigation systems that may also supply gas having low siloxane levels into multiple different components in series or in parallel.

Abstract: A post-synthetic method for stabilizing colloidal crystals programmed from nucleic acid is disclosed herein. In some embodiments, the method relies on Ag+ ions to stabilize the particle-connecting nucleic acid duplexes within the crystal lattice, essentially transforming them from loosely bound structures to ones with very strong interparticle links. In some embodiments, the nucleic acid is DNA. Such crystals do not dissociate as a function of temperature like normal DNA or DNA-interconnected colloidal crystals, and they can be moved from water to organic media or the solid state, and stay intact. The Ag+-stabilization of the nucleic acid (e.g., DNA) bonds is accompanied by a nondestructive contraction of the lattice, and both the stabilization and contraction are reversible with the chemical extraction of the Ag+ ions, e.g., by AgCl precipitation with NaCl.

Abstract: A display apparatus includes an image light generating unit that includes a laser light source unit and a MEMS mirror configured to reflect laser light emitted from the laser light source unit, and that is configured to generate image light, an exit pupil expander configured to expand a luminous flux diameter of the image light from the image light generating unit, a light-guiding plate, a first surface relief-type diffraction grating provided at a light incidence portion of the light-guiding plate and on which the image light passing through the exit pupil expander is incident and enters the light-guiding plate, and a second surface relief-type diffraction grating provided at a light emission portion of the light-guiding plate and through which the image light propagating inside the light-guiding plate exits, in which the image light generating unit includes a speckle noise reduction section configured to reduce speckle noise in the image light.

Abstract: The Nondestructive Fluid Sensing System is a device that rapidly scans fluids to determine physical and chemical properties of the sample fluid. The Nondestructive Fluid Sensing System can detect the presence of a sample fluid with various optical and electrical sensors, and determines physical and chemical properties. The system features several innovations that increase sample throughput, reduces sample cross contamination, and eliminates waste products typically used in chemical tests. The system may be applied to various industries including manufacturing quality control, and healthcare.

Abstract: Kerr and electro-optic frequency comb generation in integrated lithium niobate devices is provided. In various embodiments, a microring resonator comprising lithium niobate is disposed on a thermal oxide substrate. The microring resonator has inner and outer edges. Electrodes are positioned along the inner and outer edges of the microring resonator. The electrodes are adapted to modulate the refractive index of the microring. A pump laser is optically coupled to the microring resonator. The microring resonator is adapted to emit an electro-optical frequency comb when receiving a pump mode from the pump laser and when the electrodes are driven at a frequency equal to a free-spectral-range of the microring resonator.

Abstract: A Vertical Cavity Surface Emitting Laser (VCSEL) including a light emitting III-nitride active region including quantum wells (QWs), wherein each of the quantum wells have a thickness of more than 8 nm, a cavity length of at least 7 ?, or at least 20 ?, where lambda is a peak wavelength of the light emitted from the active region, layers with reduced surface roughness, a tunnel junction intracavity contact. The VCSEL is flip chip bonded using In—Au bonding. This is the first report of a VCSEL capable of continuous wave operation.

Abstract: A semiconductor optical device includes an SOI substrate having a waveguide of silicon, and at least one gain region of a group III-V compound semiconductor having an optical gain bonded to the SOI substrate. The waveguide has a bent portion and multiple linear portions extending linearly and connected to each other through the bent portion. The gain region is disposed on each of the multiple linear portions.

Abstract: An optical filter includes a first ring resonator a second ring resonator having different perimeters, and a waveguide optically coupled to the first ring resonator and transmit light to the first ring resonator. Light incident on the waveguide is transmitted to the second ring resonator through the first ring resonator. A free spectral range of a transmission spectrum of the first ring resonator and a free spectral range of a transmission spectrum of the second ring resonator are staggered to each other, and are set so that a transmission spectrum of a double ring corresponding to a synthetic spectrum of the transmission spectrum of the first ring resonator and the transmission spectrum of the second ring resonator has a highest first peak at an arbitrary wavelength.

Abstract: The present disclosure relates to an approach for monitoring the output power of a VCSEL or VCSEL array in a relatively compact, low profile package. A VCSEL device or VCSEL package of the present disclosure may generally be configured with a photodiode for monitoring output power of one or more VCSELs. In some embodiments, one or more VCSEL devices may be arranged over or on a photodetector, such that the photodetector is configured to detect light emitted through a bottom of the VCSEL. In such embodiments, the VCSEL device may have a patterned bottom metal layer and/or an etched substrate to allow light to pass below or behind the VCSEL to the photodiode. In other embodiments, a photodetector may be arranged on a submount adjacent one or more VCSELs, and may be configured to detect light reflected via a diffuser in order to monitor output power.

Abstract: In various embodiments, the concentration and deposition of siloxane materials within components of laser systems, such as laser resonators, is reduced or minimized utilizing mitigation systems that may also supply gas having low siloxane levels into multiple different components in series or in parallel.

Abstract: Methods and systems are provided for a light emitting device. In one example, an illumination system comprises a plurality of light sources, each light source of the plurality of light sources comprising a light emitting diode configured to emit a collimated beam of light of a color, a plurality of reflective optical components oriented identically to one another, wherein the plurality of reflective optical components is configured to direct the first collimated beam, the second collimated beam, the third collimated beam, the fourth collimated beam, and the fifth collimated beam along a common axis, and an output positioned to receive light along the common axis, wherein the output is configured to generate an output beam.

Abstract: Optical devices and methods of manufacturing and operating such optical devices. In an embodiment, an optical device includes a substrate, a multi-layer structure having a first surface in contact with a first surface of the substrate, a first mirror disposed over a second surface of the multi-layer structure, a second mirror disposed over a second surface of the substrate, an intermediate mirror within the multi-layer structure, and an optical gain structure within the multi-layer structure. The device may include a first optically resonant cavity within the multi-layer structure, bounded by the first mirror and the intermediate mirror, where the first optically resonant cavity includes the optical gain structure. The device may further include a second optically resonant cavity, bounded by the first and second mirrors, where the second optically resonant cavity includes the first optically resonant cavity, the second optically reflective layer, and the substrate.

Abstract: An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first straight waveguide to receive incoming light and to output outgoing light to be coupled to a photodetector to provide an optical signal for rotational sensing. The gyroscope comprises a first microresonator ring proximate to the first straight waveguide. Light evanescently couples from the first straight waveguide to the first microresonator ring and experiences propagation loss while circulating as a guided beam within the first microresonator ring. The guided beam evanescently couples back from the first microresonator ring to the first straight waveguide to provide the optical signal for rotational sensing after optical gain is imparted to guided beam to counter the propagation loss. In a coupled-ring configurations, the first microresonator ring acts as a loss ring, and optical gain is imparted to a second microresonator ring which acts as a gain ring.

Abstract: One illustrative device disclosed herein includes a micro-ring modulator that comprises an inner ring, an outer ring and a doped waveguide ring positioned between the inner ring and the outer ring. The device also includes an upper bus waveguide that is positioned vertically above at least a portion of the doped waveguide ring and at least a portion of the outer ring.

Abstract: Apparatuses, methods, and systems for generating signatures based on sensing one or more gas concentration conditions are disclosed. One method includes sensing, by one or more sensors, levels of a gas over time for a plurality of gas concentration conditions, receiving, by a controller, the sensed levels of gas over time for the plurality of gas concentration conditions, and generating, by the controller, a plurality of signatures, wherein one or more signatures is generated for one or more gas concentration conditions based on the sensed levels of gas over time, and determining whether to take action or not to take action.

Abstract: Apparatuses, methods, and systems for detecting a substance are disclosed. One system includes a light source, an optical cavity, a cavity detector, and a processor. The light source generates a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at multiple wavelengths. The optical cavity receives the beam of electro-magnetic radiation, wherein the physical characteristics of the cavity define a plurality of allowed axial-plus-transverse electro-magnetic radiation modes, wherein only a subset of the allowed axial-plus-transverse electro-magnetic radiation modes are excited when the optical cavity receives the beam of electro-magnetic radiation. The cavity detector senses electro-magnetic radiation emanating from the optical cavity.

Abstract: The laser apparatus includes a master oscillator, an amplifier, a power source, and a controller to control the power source. The controller controls the power source such that an excitation intensity of the amplifier in a burst oscillation period performing the burst oscillation is a first excitation intensity, controls the power source such that, if the predetermined repetition frequency is a first repetition frequency, an excitation intensity of the amplifier in a suspension period suspending the burst oscillation is a second excitation intensity equal to or lower than the first excitation intensity, and controls the power source such that, if the predetermined repetition frequency is a second repetition frequency higher than the first repetition frequency, the excitation intensity of the amplifier in the suspension period is a third excitation intensity lower than the second excitation intensity.

Abstract: A system includes: a first device; a second device connected to the first device via a transmission line; and control devices that are coupled to the first and second devices and control transmission and reception of a data signal and a timing signal between the first device and the second device, wherein the first device: determines a combination of phases with which a range of a voltage of determination as to whether the data signal is acquired is wider than a range of a voltage in which the data signal is acquired in other combinations of phases in information including combinations of phases in which a phase of the timing signal is specified for each data line in the transmission line, when the second device is operated according to the combinations of phases based on the information; and controls the second device based on the combination of the phases.

Abstract: Apparatuses, methods, and systems for detecting a substance are disclosed. One system includes a light source, an optical cavity, a cavity detector, and a processor. The light source generates a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at multiple wavelengths. The optical cavity receives the beam of electro-magnetic radiation, wherein the physical characteristics of the cavity define a plurality of allowed axial-plus-transverse electro-magnetic radiation modes, wherein only a subset of the allowed axial-plus-transverse electro-magnetic radiation modes are excited when the optical cavity receives the beam of electro-magnetic radiation. The cavity detector senses electro-magnetic radiation emanating from the optical cavity.

Abstract: Provided herein are systems and methods of manufacture and operation for a compact laser to achieve high-intensity output pulses. These compact laser resonators and methods rely upon separate and distinct functions of the laser resonator to be operated in balance such that the functions, while deleterious when separate are supportive of laser generation and growth when combined within a small volume laser resonator as described herein. The combined elements of the described laser resonator include a delicate balance that allows the laser to operate between plane-parallel operation and unstable operation. This operation mode further allows distinct methods of construction and operation that allow the compact laser to be reliably assembled and tested during assembly. Therefore, despite requiring a delicate balance of disparate elements, the described laser resonator results in a compact robust laser.

Abstract: The invention describes an array of light sources comprising multiple VCSELs arranged laterally to each other on top of a substrate, wherein each VCSEL comprises a light emitting area surrounded by an electrode structure which does not emit light, wherein a shielding layer is applied on top of at least the electrode structure only covering a surface (of the electrode structure facing towards an average light emitting direction of the VECSELs, the shielding layer is an opaque layer and being adapted to optically match the array in a switched-off state to an outer surface of a housing of a device, where the array of light sources is to be installed. The invention further describes the device comprising such an array and a method for manufacturing an array of light sources.

Abstract: In the examples provided herein, a system has a first racetrack resonant waveguide structure, positioned to enable an input light signal to couple from a first waveguide; and a second racetrack resonant waveguide structure, positioned to enable the input light signal to couple between the first racetrack resonant waveguide structure and the second racetrack resonant waveguide structure, and further positioned to enable an output light signal to couple from the second racetrack resonant waveguide structure to a second waveguide. The system also has a primary heating unit, positioned to heat a primary region including a first portion of the first racetrack resonant waveguide structure and a first portion of the second racetrack resonant waveguide structure, to change a central frequency and a passband width for the system.

Abstract: Provided is a laser resonator for generating a laser light by absorbing energy from outside. The laser resonator includes a metal body and a gain medium layer having a ring shape. The gain medium layer of a ring shape may be provided on the metal body and may generate the laser light by a plasmonic effect.

Abstract: A chip-scale ultrasensitive ring laser gyroscope that utilizes the physics of exceptional points. By exploiting the properties of such non-Hermitian degeneracies, the rotation-induced frequency splitting becomes proportional to the square root of the gyration speed (?1/2), thus enhancing the sensitivity to low angular rotations by orders of magnitudes. At its maximum sensitivity limit, the measurable spectral splitting is independent of the radius of the cavity rings involved. Binary and ternary systems and associated methods are described.

Abstract: The present invention relates to a system for measuring conductivity in a multiphase fluid flow comprising a fraction of water, the system comprising a measuring section including means for emitting electromagnetic signals into a pipe containing said flow within at least one chosen frequency range and means for detecting resonant frequencies within said range. The measuring section comprising features for providing at least two resonanct frequencies within said at least one frequency range, the system also comprising means for based on at least a first resonant frequency and a first Q-factor related to the corresponding resonance peak as well as the Q-factor of a second resonance peak, calculating the conductivity of the water in said flow.

Abstract: An example method for use with a LIDAR system includes assigning a firing time of a laser included in the LIDAR system. The assignment of the firing time includes: (i) receiving a universal clock signal at the LIDAR system, where the universal clock signal common to one or more other LIDAR systems; (ii) synchronizing a system clock of the LIDAR system to the universal clock signal to generate a synchronized clock signal; and determining the firing time based on the synchronized clock signal to reduce interference with the one or more other LIDAR systems. The method also includes firing the laser at the firing time.

Abstract: The line narrowed laser apparatus configured to perform a plurality of burst oscillations including a first burst oscillation and a second burst oscillation next to the first burst oscillation to output a pulse laser beam. The line narrowed laser apparatus comprises a laser resonator, a chamber provided in the laser resonator, a pair of electrodes provided in the chamber, an electric power source configured to apply a pulsed voltage to the pair of electrodes, a wavelength-selecting element provided in the laser resonator, a spectral width varying unit provided in the laser resonator, a wavelength variable unit configured to change a selected wavelength selected by the wavelength-selecting element, and a controller. The controller is configured to control the wavelength variable unit based on an amount of control of the spectral width varying unit in a period from a time of ending the first burst oscillation to a time of starting the second burst oscillation.

Abstract: An optical coupler structure may include a substrate, a waveguide section and an anchored cantilever section. The substrate may include a main body and a sub-pillar structure formed on the main body. The waveguide section may be disposed on the substrate, and may include a core waveguide of a first material surrounded by a cladding layer of a second material. The anchored cantilever section may be disposed on the sub-pillar structure on the substrate, which may be configured to support the cantilever section and separate the cantilever section from the main body of the substrate. The anchored cantilever section may include a multi-stage inverse taper core waveguide and a cladding layer, of the second material, which surrounds the multi-stage inverse taper core waveguide.

Abstract: Apparatuses, systems, and methods for a digital power amplifier (DPA) to generate a monotonic and linear ramp-up and ramp-down for a time division multiple access (TDMA) slot transmission are described. In one aspect, a monotonic and linear amplitude-to-control input code relationship model is generated for the DPA and stored. When the DPA needs to generate a ramp-up or ramp-down, the stored monotonic and linear amplitude-to-control input code relationship model is used to shape the input control code before it is input into the DPA. A new monotonic and linear amplitude-to-control input code relationship model may be generated and stored if the operating conditions change. The apparatuses, systems, and methods described herein may be applied to a multi-standard broadband modem chip capable of 2G transmission.

Abstract: Wavelength-selective external resonators can be used to greatly increase the output brightness of dense wavelength beam combining (DWBC) system beams by stabilizing the wavelengths of the beams emitted by the individual emitters of the DWBC laser source. The present invention pertains to external resonant cavities that utilize thin-film filtering elements as wavelength-selective elements in external resonators. The present invention further pertains to particular embodiments that utilize thin-film filtering elements in DWBC systems as both output beam coupling elements and wavelength selective elements. The present invention provides advantages over the prior art that include decreased cost, increased fidelity of wavelength selection, and increased wall plug efficiency.

Abstract: A semiconductor laser module includes a semiconductor laser element outputting a laser light; an optical fiber; an optical component disposed at an outer periphery of the optical fiber and fixing the optical fiber; a first-fixing agent fastening the optical component and the optical fiber; a light-absorbing element disposed at an outer periphery of the optical component and fixing the optical component; a first light-blocking portion disposed between an end into which the laser light is incident of the optical fiber and the optical component; and a housing accommodating therein the semiconductor laser element, an end into which the laser light is incident of the optical fiber and the first light-blocking portion. The optical component has an optical transmittance at a wavelength of the laser light, and the light-absorbing element has an optical absorptivity at a wavelength of the laser light.

Abstract: A method of calibrating a tunable laser includes shifting a filter output peak defined by a tunable optical feedback filter of the tunable laser in an optical spectral domain to align with a target etalon output peak of a plurality of spaced etalon output peaks defined by an etalon of the tunable laser. The method also includes shifting a cavity frequency grid defined by cavity modes of the tunable laser to align a target cavity mode of the cavity frequency grid with the filter output peak and shifting the spaced output peaks defined by the etalon to align a target etalon output peak with a target wavelength of an output wavelength grid. The method includes modifying a bias current and a modulation current of a gain section of the tunable laser to achieve a defined output modulation amplitude and a defined extinction ratio.

Abstract: An optical ring resonator sensor array module for a passive SONAR system. The module includes a supporting structure; a silicon substrate mounted on the supporting structure, and a top plate mounted over the silicon structure. The silicon substrate includes an optical waveguide having an input and an output and a plurality of optical ring resonators distributed across the silicon substrate to form a two-dimensional pattern. Each optical ring resonator is positioned adjacent to the optical waveguide and each has a different predetermined diameter. The top plate includes a plurality of diaphragms, one for each of the plurality of optical ring resonators. The diaphragms are distributed on the top plate such that each of the plurality of diaphragms is positioned over an associated one of the plurality of optical ring resonators. In addition, each of the diaphragms is configured to flex in response to externally applied acoustical pressure.

Abstract: The present invention relates to an optically pumped solid state laser device, comprising a solid state laser medium (300-302) in a laser resonator. Several pump laser diodes (100) are arranged to optically pump said solid state laser medium (300-302) by reflection of pump radiation at a mirror element (200) arranged on the optical axis of the laser resonator. The mirror element (200) is designed to direct said pump radiation to the solid state laser medium (300-302) and to form at the same time one of the resonator mirrors of the laser resonator. With this design of the solid state laser device an easy alignment of the pump optics is achieved. The proposed solid state laser device can be realized in a compact form.

Abstract: A transmission device that receives an optical signal on which a frequency modulated signal is superimposed includes: an optical filter configured to filter the optical signal; a filter controller configured to control a passband of the optical filter based on a change of power of the optical signal; and a signal detection unit configured to detect the frequency modulated signal based on the change of the power of the optical signal filtered by the optical filter.

Abstract: The wavelength of fundamental wave light emitted from a semiconductor laser is converted by a wavelength conversion element, and the wavelength-converted light is emitted. A power supply circuit feeds electric power to the semiconductor laser. A control part controls an amount of electric power to be fed to a heater such that the wavelength conversion element becomes a temperature that optimizes the wavelength conversion efficiency. Temperatures detected by an element temperature detector and a light source part temperature detector are introduced to the control part, and the control part takes a wavelength conversion element temperature, at which a temperature detected by the light source part temperature detector is minimum, as a set temperature that makes the wavelength conversion efficiency optimal, and feedback-controls the wavelength conversion element temperature such that the wavelength conversion element temperature is at the set temperature by controlling the heating quantity of the heater.

Abstract: One embodiment is a wide stripe semiconductor waveguide, which is cleaved at a Talbot length thereof, the wide stripe semiconductor waveguide having facets with mirror coatings. A system provides for selective pumping the wide stripe semiconductor waveguide to create and support a Talbot mode. In embodiments according to the present method and apparatus the gain is patterned so that a single unique pattern actually has the highest gain and hence it is the distribution that oscillates.

Abstract: An optical device is described. This optical device includes multiple components, such as a ring resonator, an optical waveguide and a grating coupler, having a common etch depth (which is associated with a single etch step or operation during fabrication). Moreover, these components may be implemented in a semiconductor layer in a silicon-on-insulator technology. By using a common etch depth, the optical device may provide: compact active devices, multimode ultralow-loss optical waveguides, high-speed ring resonator modulators with ultralow power consumption, and compact low-loss interlayer couplers for multilayer-routed optical links. Furthermore, the single etch step may help reduce or eliminate optical transition loss, and thus may facilitate high yield and low manufacturing costs.

Abstract: Ultra compact DBRs, VCSELs incorporating the DBRs and methods for making the DBRs are provided. The DBRs are composed of a vertical reflector stack comprising a plurality of adjacent layer pairs, wherein each layer pair includes a layer of single-crystalline Group IV semiconductor and an adjacent layer of silicon dioxide.

Abstract: In order to prevent non-uniformity in emission wavelength among different sites along an optical axis direction, provided is a resonator portion including: a waveguide which includes at least two areas where an effective refraction index varies in the optical axis direction; and diffraction gratings formed along the optical axis direction of the waveguide. The diffraction grating that is formed in one of the at least two areas of the waveguide where the effective refraction index is large has a pitch narrower than a pitch of the diffraction grating that is formed in another of the at least two areas of the waveguide where the effective refraction index is small.

Abstract: Wavelength-selective external resonators can be used to greatly increase the output brightness of dense wavelength beam combining (DWBC) system beams by stabilizing the wavelengths of the beams emitted by the individual emitters of the DWBC laser source. The present invention pertains to external resonant cavities that utilize thin-film filtering elements as wavelength-selective elements in external resonators. The present invention further pertains to particular embodiments that utilize thin-film filtering elements in DWBC systems as both output beam coupling elements and wavelength selective elements. The present invention provides advantages over the prior art that include decreased cost, increased fidelity of wavelength selection, and increased wall plug efficiency.

Abstract: A photonic device and methods of formation that provide an area providing reduced optical coupling between a substrate and an inner core of the photonic device are described. The area is formed using holes in the inner core and an outer cladding. The holes may be filled with materials which provide a photonic crystal. Thus, the photonic device may function as a waveguide and as a photonic crystal.

Abstract: A laser source based on a quantum cascade laser array (QCL), wherein the outputs of at least two elements in the array are collimated and overlapped in the far field using an external diffraction grating and a transform lens.

Abstract: A laser diode assembly includes: a mode-locked laser diode device; a diffraction grating that configures an external resonator, returns primary or more order diffracted light to the mode-locked laser diode device, and outputs 0-order diffracted light outside; and an imaging section provided between the mode-locked laser diode device and the diffraction grating and imaging an image of a light output end face of the mode-locked laser diode device on the diffraction grating.

Abstract: A nitride semiconductor structure of the present invention is obtained by growing an h- or t-BN thin film (12) and a wurtzite-structure AlxGa1-xN (x>0) thin film (14) as buffer layers and forming a single-crystal wurtzite-structure AlGaInBN thin film (13) thereon. While GaN, AlGaN, AlN, and the like have the wurtzite structure with sp3 bonds, h-BN or t-BN has the graphite structure with sp2 bonds, and has a completely different crystal structure. Accordingly, it has heretofore not been considered that a wurtzite-structure AlGaInBN thin film can be grown on a graphite-structure h-BN thin film. However, when a wurtzite-structure AlxGa1-xN (x>0) thin film (14) is formed as a buffer layer on a graphite-structure boron nitride thin film (12), a wurtzite-structure AlGaInBN (13) nitride semiconductor structure such as GaN can be grown on the buffer layer.