Abstract: A semiconductor laser device (5) comprising at least one semiconductor laser chip (7) is provided, wherein the semiconductor laser chip (7) contains an active layer that emits electromagnetic radiation. Further, at least one corner reflector (1) is formed in the semiconductor laser chip (7). The corner reflector (1) has a first and a second reflective surface (14, 15), wherein the first and the second reflective surface (14, 15) are arranged at an angle of less than 90 degrees with respect to one another. This results in an improved emission characteristic of the radiation emitted by the semiconductor laser device (5).

Abstract: Through the use of a relatively inexpensive third mirror on a novel folded hybrid unstable resonator configuration, the optimum output coupling for a given laser design can be explored quickly and easily with a minimum of intracavity mirror alignment. No changes in either the radii of curvature of the three cavity optics or their spacing are required for this exploration. In addition to providing techniques for purposefully and systematically introducing mirror edge effects or avoiding edges effects altogether, the invention provides that output beams of different width can be advantageously explored in a relatively simple and straightforward manner. The invention provides that higher geometric magnification cavity designs may be made compatible with low diffraction output coupling in a configuration that uses only three totally reflecting optics.

Abstract: A system for producing a laser light pulse is disclosed. The system includes a travelling wave or ring laser incorporating a gain medium with polarizing means for introducing substantially polarized radiation having a first polarization state into the travelling wave laser and output coupling means to substantially output couple radiation having an output polarization state from the travelling wave laser. The system further includes polarization changing means incorporated into the optical path of the travelling wave laser for changing the polarization of radiation having the first polarization state to a seeding polarization state, wherein radiation with the seeding polarization state seeds the gain medium, and radiation intensity modulation means for modulating the intensity of radiation in the travelling wave laser to vary the feedback of radiation into the gain medium, wherein the radiation intensity modulation means also modulates the radiation with respect to the output coupling means.

Abstract: A waveguide retroreflector consists of an end cap with curved output surface attached to a waveguide such as optical fiber. The radius of curvature of the output surface of the end cap matches the length of the end cap so as to retro-reflect a substantial portion of radiation exiting the waveguide, back into the waveguide. A method of fabricating the waveguide retroreflector includes steps of splicing an end cap to a waveguide, heating the free flat surface of the end cap, so that surface tension changes the shape of the end cap to a convex shape due to surface tension, monitoring amount of light reflected off the surface being heated, and stopping applying the heat when the amount of the reflected light approaches a maximum value.

Abstract: A robust scalable laser. The laser includes plural fiber laser resonators. A cavity that is external to the fiber laser resonators combines plural laser beams output from the plural fiber laser resonators into a single output laser beam. In a specific embodiment, the plural fiber laser resonators are eye-safe double-clad Er:YAG laser resonators that are pumped via laser diode arrays.

Abstract: In a semiconductor lasers using quantum well gain medium, a quantum well stack is mounted in an epi-down configuration. The epitaxial side of the device may be directly bonded to an efficient heat transport system so that heat may more easily leave the quantum well stack layers and be disposed at a heatsink. Such a device runs cooler and exhibits reduced loss mechanisms as represented by a laser system loss-line. External cavity systems using this configuration may permit a high degree of tunability, and these systems are particularly improved as the tuning range is extended by lowered cavity losses.

Abstract: A laser assembly is suitable for coupling laser light into at least one optical fiber. The laser assembly contains a plurality of laser light sources disposed spaced from a light entrance surface of the at least one optical fiber. The laser light sources are divided into at least one group of first laser light sources and at least one group of second laser light sources. An aperture is provided and is suitable for spatially confining the laser light emitted during operation of the laser light sources before being coupled into the at least one optical fiber. A coupling device is provided and is suitable for coupling the laser light during operation of the first and second laser light sources before it enters into the at least one optical fiber.

Abstract: A laser source (10) for generating a continuously wavelength tunable light (12) includes a gain media (16), an optical output coupler (36F), a cavity collimator (38A), a diffraction grating (30), a grating beam (54), and a beam attacher (56). The diffraction grating (30) is spaced apart from the cavity collimator (38A) and the grating (30) cooperates with the optical output coupler (36F) to define an external cavity (32). The grating (30) includes a grating face surface (42A) that is in a grating plane (42B). The beam attacher (56) retains the grating beam (54) and allows the grating beam (54) and the grating (30) to effectively pivot about a pivot axis (33) that is located approximately at an intersection of a pivot plane (50) and the grating plane (42B).

Abstract: An improved resonator and optical cavity is adapted for use with a chemical laser that has a nozzle upstream of the resonator that emits a gain medium in a flow direction, and a pressure-recovery system downstream of the resonator. The optical resonator comprises first and second optical elements that are spaced apart from one another along an optical axis. Each of the optical elements has a selected geometry and a selected optical transmissivity to permit transmissive outcoupling of a beam of laser radiation from the resonator, the outcoupled beam being transmitted about the optical axis. The transmissivity and geometry of each optical element is selected to define an unstable region between the optical elements and around the optical axis, and a stable region in a region surrounding the unstable region and spaced apart from the optical axis.

Abstract: In the manufacture and application of a PLC-ECL type wavelength tunable light source, provided is a wavelength tunable mechanism with improved performance and stability, a light source with improved packaging performance and mass productivity, and a light source applied to a WDM-PON with initialization and stabilization functions. The wavelength tunable light source having a PLC (planar lightwave circuit)-ECL (external cavity laser) structure includes a first housing in which a semiconductor optical gain medium is mounted, a second housing in which a PLC device is mounted, and a third housing in which an optical fiber is mounted. The first, second, and third housings make an optical axis alignment through an optical coupling lens and combined in a laser welding method.

Abstract: A VCSEL (Vertical Cavity Surface Emitting Laser) structure (1), wherein at least one cross-section of the VCSEL structure perpendicular to the optical axis (2) of the VCSEL structure comprises a mode selecting shape (10) promoting output of the fundamental transverse mode of the resonator while suppressing output of the higher modes. According to the present invention, the mode selecting shape (10) comprises a longitudinal portion (101) being directed past the optical axis (2) and having a one-sided broadening (102) forming a central area (103) around the optical axis, the geometry of the mode selecting shape being chosen to concentrate the fundamental mode in the central area while guiding the possible higher modes away from the optical axis through the longitudinal portion.

Abstract: [Project] To provide a microphase-separated structure which comprises a vast and visible structure showing a structural color with the use of the phase separation due to the self-assembly of a block copolymer, enables the design of a definite structural color by a convenient method and shows temperature response. [Means for Solving Problems] A microphase-separated structure comprising a block copolymer, which contains at least a block chain A consisting of a monomer A as a repeating unit and a block chain B consisting of a monomer B as a repeating unit, and a solvent, wherein the solvent has a temperature zone 1 where the block chain A and the block chain B are soluble and a temperature zone 2 where the block chain A is insoluble but the block chain B is soluble, and a structural period thereof varies by changing temperature between the temperature zone 1 and the temperature zone 2.

Abstract: A laser module has an optical amplifier, a first etalon and a wavelength selectable mirror. The first etalon has wavelength peaks at a given wavelength interval in transmission characteristics and transmits a light from the optical amplifier. The wavelength peaks are tunable. The wavelength selectable mirror acts as an external mirror of an external cavity laser including the optical amplifier, and has a relatively high reflection intensity at a part of wavelength range in an effective gain range of the optical amplifier. The effective gain range of the optical amplifier includes more than one wavelength peak of the first etalon. A reflection bandwidth where the wavelength selectable mirror has a relatively high reflection intensity is less than twice of the wavelength interval of the wavelength peaks of the first etalon.

Abstract: The present invention relates to a wavelength tuneable external-cavity laser module, the laser being tuneable across a predetermined wavelength range and comprising: a thermally stabilised substrate; a gain medium for emitting an optical beam passing through the external cavity along an optical axis, said gain medium being placed in thermal contact with the thermally stabilised substrate; an end mirror for receiving and reflecting the optical beam within the external cavity, and a phase element for controlling the phase of the optical beam and being positioned within the external cavity between the gain medium and the end mirror, wherein said phase element comprises a material having a refractive index that varies in response to changes in temperature and has a transmissivity substantially independent of wavelength across said predetermined wavelength range.

Abstract: A mode-locked laser device includes a Fabry-Perot resonator, a mode-locking element disposed within the resonator, a solid-state laser medium disposed within the resonator, and exciting means for applying excitation light to the solid-state laser medium. The opposite ends of the resonator, the mode-locking element and the solid-state laser medium are disposed to provide an average beam diameter of lasing light of not more than 150 ?m on the mode-locking element and an average beam diameter of the lasing light of not more than 200 ?m within the solid-state laser medium.

Abstract: A method for generating a quantum-entangled photon pair is such that a biexciton in such a state that the angular momentum is 0 is generated through two-photon resonance induced by irradiating a semiconductor substance, e.g., CuCl, with two parent photons (angular frequency ?i). A photon pair is then generated by splitting the biexciton thus generated simultaneously into two photons (angular frequencies ?s and ?s?). Since the photon pair is generated by splitting such biexciton having an angular momentum of 0, it has a quantum entanglement with regard to polarization. Since the photon thus generated has a wavelength substantially equal to that of the parent photons, photons of shorter wavelength in a quantum entangled state can be generated.

Abstract: A surface light emitting semiconductor laser element, comprises a substrate, a lower reflector including a semiconductor multi-layer disposed on the substrate, an active layer disposed on the lower reflector, an upper reflector including a semiconductor multi-layer disposed on the active layer, a compound semiconductor layer having a first opening for exposing the upper reflector and extending over the upper reflector, and a metal film having a second opening for exposing the upper reflector disposed inside of the first opening and extending over the compound semiconductor layer, wherein the metal film and the compound semiconductor layer constitute a complex refractive index distribution structure where a complex refractive index is changed from the center of the second opening towards the outside. A method of emitting laser light in a single-peak transverse mode is also provided.

Abstract: A resonator sensing device having an optics coupler device for communicating light between light source(s) and sensor(s) and a hollow core fiber resonator. Light from one resonator fiber tip is coupled to a second resonator fiber tip via a graded index (GRIN) lens having the appropriate pitch such that the maximum coupling efficiency is achieved and having two angled surfaces. The angled surfaces are coated with an appropriate coating having a reflectance R in order to achieve the desired degree of coupling. Light reflected by the second angled surface is captured with another lens (such as a microlens) and coupled to a third fiber segment (coupled port). The optical parameters for the GRIN lens and the microlens are tailored to have the least loss.

Abstract: The invention concerns a gallery mode microdisc system for an electrically pumped optical source, the microdisc (1) being formed on one face of a substrate (2), the lower part of the microdisc being provided with an electrical contact referred to as the lower contact (4), the upper part of the microdisc being provided with an electrical contact referred to as the upper contact (6), the upper part of the microdisc being covered with a protective layer (3) of electrically insulating material, the central part (5) of the microdisc being electrically neutralised in order to prevent the passage of an electric current in said central part.

Abstract: A lasing method including the steps of providing a laser resonator; utilizing birefringence compensation in said resonator whereby said resonator is induced to operate in a Laguerre-Gaussian higher order mode; and utilizing polarized outcoupling of lasing energy at said higher order mode from said resonator. In the illustrative application, the laser resonator is a high-power, solid-state laser resonator. In the specific embodiment, the inventive method further includes the step of changing an outcoupling preference for a non-degenerate high-order Laguerre-Gaussian mode. In one embodiment, the step of changing outcoupling preference includes the step of changing an outcoupling polarization. In another embodiment, the step of changing outcoupling preference includes the step of changing an orientation of a roof edge of a prism in the laser resonator.

Abstract: At least either of the light entering plane or the light exiting plane is parallel to the (111) crystal face of the CaF2 crystal and the laser beam entering from the entering plane passes through the plane located between the [111] axis and the first azimuth axis in the locus of rotation of the [001] axis around the [111] axis and including the [111] axis and the first azimuth axis, the plane located between the [111] axis and the second azimuth axis in the locus of rotation of the [010] axis around the [111] axis and including the [111] axis and the second azimuth axis or the plane located between the [111] axis and the third azimuth axis in the locus of rotation of the [100] axis around the [111] axis and including the [111] axis and the third azimuth axis and exits from the exiting plane.

Abstract: A high power laser processing system is disclosed that includes a laser source and at least one optical element. The laser source provides a high power laser illumination of a first wavelength. The optical element includes a substrate that is substantially transparent to the first wavelength illumination, at least one highly reflective coating on a first side of the substrate, and at least one anti-reflective coating on a second side of the substrate.

Abstract: An optical coupling device for coupling light with an optical waveguide comprises a mirror formed within an optical waveguide. The mirror comprises a first material, a first reflective end, and a second reflective end. The first material is light conducting and has a first refractive index. The first and second reflective ends reflect and transmit light. The mirror has an axis line. The optical coupling device is useful for extracting light from a waveguide and providing a backlight for a liquid crystal display.

Abstract: The present invention provides a ring laser system comprising forming an optical core by an epitaxial layer overgrowth over an intermediate layer, forming multi-quantum wells adjacent to the optical core and forming an outer structure further comprising a total internal reflector, wherein forming photons within the multi-quantum wells further comprises circulating the photons within the ring laser structure comprising the outer structure, the multi-quantum wells, and the optical core.

Abstract: The invention relates to a laser light source for generating narrow-band laser radiation with high coherence, comprising a laser diode (1), which forms an internal resonator (4), and an external resonator (7) coupled to the internal resonator (4). The object of the invention is to improve a laser source of the kind such that it generates narrow-band and coherent laser radiation with high output power and at the same time with high long-term stability. Furthermore, the laser light source is to be produced in a cost-effective manner. The object is achieved by the invention in that the laser diode (1) runs in an operating mode in which multimode laser radiation is generated, comprising a plurality of spectrally neighboring resonance modes (9) of the external resonator (7). The resonance modes are selected by adapting the spectral characteristics of the external (7) and internal (4) resonators.

Abstract: Application of a modular coaxial package design, compatible with telecommunication passive component packaging, to microchip lasers, in particular to passively Q-switched microlasers, pumped with a fiber-coupled diode, is disclosed. The number of parts is thereby reduced while providing the adequate degrees of freedom for the active or passive alignment of the optical elements within the package.

Abstract: A laser module includes a semiconductor laser element and a feedback optical component forming an external cavity with the semiconductor laser element. Even if a ratio of a current threshold of the laser module changing according to a polarized state of returned light from the feedback optical component to a current threshold of the semiconductor laser element is in an arbitrary range within a predetermined range, a total value of a relative intensity noise occurring between a first frequency determined according to a cavity length of the external cavity and at least equal to or more than a frequency band of using a laser light and a second frequency calculated by multiplying the first frequency by a predetermined number is equal to or more than ?40 dB.

Abstract: An apparatus/method may comprise a line narrowed pulsed lithography laser light source which may comprise: a seed pulse providing laser system which may comprise: a first pulsed seed laser producing seed pulses at a rate of X kHz; a second pulsed seed laser producing seed pulses at a rate of X kHz; an amplification system which may comprise: a first amplifier gain system which may comprise a first and a second pulsed gas discharge amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½ X kHz on output pulses from the first seed laser; a second amplifier gain system which may comprise a first and a second pulsed amplifier gain medium, each with a nominal center wavelength in the UV range, and each operating at ½ X kHz on output pulses from the second seed laser.

Abstract: External-cavity optically-pumped semiconductor lasers (OPS-lasers) including an OPS-structure having a mirror-structure surmounted by a surface-emitting, semiconductor multilayer (periodic) gain-structure are disclosed. The gain-structure is pumped by light from diode-lasers. The OPS-lasers can provide fundamental laser output-power of about two Watts (2.0 W) or greater. Intracavity frequency-converted arrangements of the OPS-lasers can provide harmonic laser output-power of about one-hundred milliwatts (100 mW) or greater, even at wavelengths in the ultraviolet region of the electromagnetic spectrum. These high output powers can be provided even in single axial-mode operation.

Abstract: A collimator lens converts light beams emitted from a low reflectance facet of a semiconductor laser into parallel light beams. A diffraction grating receives and diffracts the light beams at a predetermined incident position and a predetermined angle of a diffraction face. A turnable mirror has a mirror surface which is positioned opposite the diffractance facet of the diffraction grating, makes the diffracted light beams incident in a reverse optical path to the diffraction face, and returns the incident light beams to the laser. A stationary mirror makes the light beams from the collimator lens incident from a predetermined direction to a predetermined position of the diffraction grating at the side of the mirror surface of a virtual plane extending from the mirror surface of the mirror and at the side of the diffraction face of a virtual plane extending from the diffraction face of the diffraction grating.

Abstract: External cavity laser (ECL) systems and methods for measuring the wavelength of the ECL by using a portion of the positional light received by the position sensitive detector (PSD) to determine the position of a wavelength tuning element (such as a diffraction grating or an etalon), for determining the longitudinal laser mode or power output of the laser from a portion of the laser light received by a beam-shearing mode sensor, and by using a non-output beam(s) from a transmissive diffraction grating in the ECL to monitor the external cavity laser.

Abstract: An optical module is configured with a combination of a single-mode oscillating light source and an optical filter. In this optical module, the single-mode oscillating light source outputs a single-mode, frequency-modulated signal. Further, the optical filter converts the frequency modulation to an amplitude modulation. And, the single-mode oscillating light source and the optical filter are packaged without active alignment on the same substrate. Accordingly, it is possible to realize an optical module in a simple and low-cost configuration by packaging the single-mode oscillating light source and the optical filter by passive alignment, without active alignment, on the same substrate, and by using a simple optical filter such as a waveguide ring resonator, which converts a frequency modulation to an amplitude modulation.

Abstract: A slab type laser apparatus has a slab type gas laser medium part formed in a region defined by a pair of electrode flat plates oppositely disposed in parallel with each other in a space to be filled with a gas laser medium which is excited by high-frequency electric power. The apparatus includes an oscillator part including a pair of resonator mirrors oppositely disposed with a part of the gas laser medium part in between, and for amplifying a laser beam to have predetermined light intensity to emit the laser beam, and the amplifier part including a plurality of return mirrors oppositely disposed with a part of the gas laser medium part in between. The incident laser beam goes and returns plural times between the return mirrors, and the laser beam is amplified to have predetermined power.

Abstract: A wavelength conversion device is disclosed. The wavelength conversion device includes at least a fundamental wave light source and an external resonator, where a reflectance Rin of an input coupling element that inputs light from the fundamental wave light source to the external resonator is selected as represented by the equations 1 and 2, when a frequency jitter of the fundamental wave light source is ?fjitter, a resonator length of the external resonator is Lcav, a frequency line width of the external resonator is ??cav, a total internal loss of the external resonator is ?, and a speed of light is c.

Abstract: The present invention includes a laser amplifier and a method of making the same. The laser amplifier of the present invention includes a gain medium layer having a first index of refraction, and a coupling layer optically coupled to the gain medium. In the various embodiments described herein, the coupling layer can have a second index of refraction less than the first index of refraction. The laser amplifier described herein can also include an evanescent layer disposed between the gain medium and the coupling layer. The evanescent layer can have a third index of refraction less than the second index of refraction. The laser amplifier provides high power, efficient laser resonance through frustrated total internal reflection and total internal reflection while simultaneously providing for the minimization of waste heat in the gain medium layer.

Abstract: A semiconductor laser has a reflectance of the front facet coating film or the rear facet coating film dramatically that decreases at wavelengths greater than a predetermined wavelength. This characteristic causes the loss of the semiconductor laser to dramatically increase at wavelengths greater than the predetermined wavelength. As a result, the oscillation wavelength of the semiconductor laser at high temperatures is clamped to around the predetermined wavelength.

Abstract: A light source module for use in display systems is provided herein. According to one exemplary embodiment, the light source module includes a plurality of coherent light sources, and a diffraction grating in optical communication with the coherent light source, the diffraction grating being configured to provide feedback to the coherent light source to produce a plurality of spectra over a broad spectrum.

Abstract: A microresonator sensor apparatus has a microcavity resonator that defines equatorial whispering gallery modes (EWGMs), whose frequencies are separated by the free spectral range (FSR). The EWGMs lie in a plane perpendicular to a microcavity resonator axis. A light source is optically coupled to inject light into the microcavity resonator. The light source produces output light having an output spectrum whose bandwidth is approximately equal to or broader than the FSR of the EGWMs. One or more fluorescent materials are excited using the excitation light coupled into the microcavity resonator. A fluorescent signal arising from fluorescence of the one or more fluorescent materials is then detected.

Abstract: In one embodiment of the invention, in a semiconductor laser in which a first conductivity type lower cladding layer, an active layer that includes a quantum well layer, and a second conductivity type upper cladding layer are formed in this order on a semiconductor substrate, a dopant concentration of the lower cladding layer is not more than 4.0×1017/cm3, and a resonator length is not less than 1500 ?m.

Abstract: A laser processes a workpiece with laser pulses delivered at random time intervals and at substantially constant energy levels by characterizing the laser cavity discharge behavior and utilizing that information for adjusting dummy pulse time periods to compensate for the energy errors. Dummy pulses are laser pulses that are blocked from reaching a workpiece. A second way for providing constant pulse energies employs an AOM for varying amounts of laser energy passed to the workpiece. A third way of providing constant pulse energies entails extending the pulse period of selected pulses to allow additional laser cavity charging time whenever a dummy pulse is initiated.

Abstract: A volume Bragg laser including a resonator comprising photo-thermo-refractive (PTR) volume diffractive elements that can be used in a laser emitting window of transparency of PTR glass to provide control of the lasers spectral and angular parameters, and methods, devices, apparatus and systems related thereto. The high efficiency volume Bragg gratings recorded in photo-thermo-refractive (PTR) glass preferably has an absolute diffraction efficiency exceeding approximately 95% in transmitting and reflecting modes is used for selection of a transverse and longitudinal mode for thermal, optical and mechanical stabilization of the volume Bragg lasers and coherent coupling of different lasers. Robustness, compactness, thermal and laser stability along with the ability to place several elements in the same space allows the use of sophisticated optical system according to the invention in fields of military lasers, optical communications, data storage and processing, and the like.

Abstract: An optical resonator has an internal cavity with an output coupler, an end mirror, and one or more active mirror amplifiers (AMAs) that are arranged in a manner to form a laser radiation propagation path within the cavity which substantially has the form of a star polygon trajectory.

Abstract: A light-emitting element includes a light amplification unit and an external resonator. The light amplification unit has a function of amplifying light. The external resonator is connected to the light amplification unit. The external resonator includes a planar light waveguide and a stress application unit. The planar light waveguide is arranged inside the external resonator. The stress application unit applies stress directly or indirectly to at least a partial region of the planar light waveguide.

Abstract: An optical apparatus includes a substrate comprising a layer of thermally insulating material disposed thereon; an optical resonator disposed on the layer of thermally insulating material; and a trench in the thermally insulating material disposed around at least a portion of the optical resonator. The optical resonator is substantially thermally isolated from the substrate.

Abstract: A small-sized and high-efficiency light emitting device capable of easily emitting green light includes a resonator including a photonic crystal having a refractive-index periodic structure and a point defect member formed in the photonic crystal to disturb the refractive-index periodic structure, and an active member provided inside the resonator and formed by an In containing nitride semiconductor, wherein a wavelength determined by a band gap energy of the active member is included in a photonic band gap range of the photonic crystal, and is set to be shorter than a peak wavelength at a shortest-wavelength side of a resonance mode of the resonator in the photonic band gap range.

Abstract: A laser frequency stabilizing device comprises a laser light producer operative to produce and emit a laser light containing a first and a second longitudinal mode light having different wavelengths; a spectrometer operative to spectrally decompose the laser light into the first longitudinal mode light and the second longitudinal mode light; a first detector operative to detect the light output signal from a absorption cell; a second and third detector operative to detect the signal intensity of the first and second longitudinal mode light; an actuator operative to change the resonant cavity length; a first drive controller operative to detect the saturated absorption signal from the light output signal detected at the first detector and control driving the actuator based on the saturated absorption signal; a second drive controller operative to control driving the actuator such that the signal intensity of the first longitudinal mode light detected at the second detector and the signal intensity of the secon

Abstract: In a semiconductor lasers using quantum well gain medium, a quantum well stack is mounted in an epi-down configuration. The epitaxial side of the device may be directly bonded to an efficient heat transport system so that heat may more easily leave the quantum well stack layers and be disposed at a heatsink. Such a device runs cooler and exhibits reduced loss mechanisms as represented by a laser system loss-line. External cavity systems using this configuration may permit a high degree of tunability, and these systems are particularly improved as the tuning range is extended by lowered cavity losses.

Abstract: A second-order multi-mode partial distributed feedback (p-DFB) laser having increased electrical-to-optical power conversion efficiency, stabilized wavelength and narrowed emission linewidth. The laser includes an abbreviated grating housed in the laser cavity that is separated from both the front-end and the back-end of the laser facets.

Abstract: A laser diode capable of reducing a radiating angle ?? in the vertical direction, an optical pickup device, an optical disk apparatus, and optical communications equipment, all equipped with the laser diode which increases optical coupling efficiency. It has a first cladding layer of the first conductive type formed on a substrate, with an active layer on top of the first cladding layer and a second cladding layer of the second conductive type on top of the active layer. In at least the first or second cladding layer, it is formed of at least one optical guide layer having a higher refractive index than the first or second cladding layer and operating to expand a beam waist in the waveguide. This operation contributes to widening a region in which to shut up light, enabling a radiating angle ?? in the vertical direction to be reduced.

Abstract: Provided is an athermal external cavity laser (ECL), whose output optical power and output wavelength can be kept regular irrespective of temperature changes without using additional temperature controlling components. The ECL comprises: a semiconductor amplifier; an optical fiber comprising a core in which a Bragg grating is formed and a cladding surrounding the core; and a thermosetting polymer that fixes the optical fiber to a ferrule and has a negative thermooptical coefficient, wherein the thickness of the cladding surrounding the core in which the Bragg grating is formed is smaller than the portion of the cladding surrounding the portion of the core where the Bragg grating is not formed, and the thermosetting polymer the negative thermooptical coefficient surrounds the cladding.