Abstract: An external-cavity laser, suitable for producing a coherent and highly-polarized optical emission, particularly at communication wavelengths, is enabled by a novel wavelength selective element based on a waveguide technology that supports a long-range plasmons polariton mode. These external-cavity lasers leverage the inherent properties of the novel wavelength selective elements, which are materials agnostic, providing easier means for tunability, laser stability, and low cost of fabrication, high output power and a highly polarized output. Tunable versions are also disclosed.

Abstract: A wavelength selective filter device is presented suitable for use as a part of a laser cavity for processing light output of a gain section of the laser cavity. The filter structure comprises a resonator structure including at least one closed-loop resonator; and defines an optical coupler structure for coupling light from an input/output of the gain section to propagate through said resonator structure, and a light reflector structure for reflecting light filtered by said resonator structure to propagate through said resonator structure to said input/output of the gain section. The filter structure is configured so as to define two optical paths of substantially the same lengths for light propagation in the resonator structure from and to the coupler structure.

Abstract: A solar filter assembly combines a high-precision Fabry-Perot etalon with a variety of conditioning filters judiciously selected to effectively block completely all radiation except for the spectral line of interest. In addition, a tuning mechanism is provided to precisely control the peak frequency of the filter's output by varying the optical length of the etalon's cavity.

Abstract: A temperature-stable and temperature-tunable composite etalon with an increased field of view is constructed by partially filling the cavity with a transmissive parallel-plate filler. The coefficient of thermal expansion and the index of refraction of the filler material are selected so as to produce the desired rate of change of the optical length of the cavity as a function of temperature. The filler plate is preferably chosen to be significantly thicker than the remaining air gap in the etalon cavity. As a result, the fact that the filler plate occupies a large part of the cavity space increases the acceptance angle of the etalon of the invention in comparison with corresponding conventional air-spaced etalons.

Abstract: A laser device which can be used as a light source for an exposure device, can be downsized, and is easy to maintain. A laser beam (LB6) emitted from a DFB (Distributed feedback) semiconductor laser, for example, and amplified by an optical fiber amplifier is passed through non-linear optical crystals (502, 503, 504) to be sequentially doubled in frequency to thereby generate an ultraviolet-region laser beam (LB5) consisting of an octuple wave. A GdYCOB, that is, GdxY1?xCa4O(BO3)3 crystal (0?×?1) is used for the non-linear optical crystal (503) for a double wave-to-quadruple wave conversion, and a KAB, that is, K2Al2B4O7 crystal for the non-linear optical crystal (504) for a quadruple wave-to-octuple wave conversion. The non-linear optical crystals (502-504) are all fine-tuned in phase match angle by temperature controllers (521-523) respectively.

Abstract: A tunable optical resonator for use as a tunable laser or optical filter comprising a cavity in which the cavity is delimited by a reflection grating and a reflector in which the reflection grating is fixed to a flexible support, the resonator also comprising means for flexing the flexible support for causing the grating to mimic rotation about a selected point. A micro-mechanical tunable resonator as above providing mode-hop free tuning.

Abstract: The invention relates to a device for generating terahertz (THz) radiation comprising a short pulse laser (1) with mode coupling to which a pump beam (3) is supplied, and comprising a semiconductor component equipped with a resonator mirror (M4). This semiconductor component serves to derive the THz radiation based on incident laser pulses. The resonator mirror (M4), preferably a resonator end mirror, is provided with a semiconductor layer (8), which is partially transparent to the laser radiation of the short pulse laser (1), whose absorption edge is lower than the energy of the laser radiation of the short pulse laser (1) and on which the electrodes (9, 10) that can be connected to a bias voltage source are placed in order to generate and radiate the THz radiation in the electric field.

Abstract: The present invention relates to an amplifying medium for solid-state dye lasers and to a solid-state dye laser provided with an amplifying medium of this type. The amplifying medium according to the invention comprises an essentially solid active medium which contains at least one type of activatable particle which can be excited to emit laser light in a certain wavelength range, and optical feedback means which define a resonator for the laser light, where the feedback means comprise an essentially solid feedback medium which has a periodic structure. The feedback medium in the amplifying medium is a polymeric dispersion film having a crystalline structure which comprises, in particular, core/shell particles which can be formed into a film.

Abstract: An optical device includes an optical waveguide through which light propagates and a micro-resonator structure including an optical sensor. The micro-resonator is configured to resonate at a wavelength of light that may be transmitted through the optical waveguide. When light at that wavelength is transmitted through the optical waveguide, it resonates in the resonator and is detected by the optical sensor to produce an electrical signal. The optical resonator may be a micro-cylinder, disc or ring resonator and may be coupled to the waveguide via evanescent coupling or leaky-mode coupling. Multiple resonators may be implemented proximate to the waveguide to allow multiple wavelengths to be detected. When the waveguide is coupled to a tunable laser, signals provided by the optical sensor may be used to tune the wavelength of the laser.

Abstract: An optoelectronic package (10) includes a base substrate (40), a plurality of solder pads (21) and a can (30). The base substrate includes a mounting seat (41) laminated first and second layer (421,422). The solder pads (21) respectively attach to a top surface (412) and a bottom surface (4212) of the base substrate and are electrically interconnected with each other via conductive material filled the through-holes (411,4223,4213) and conductor trace (45,45?). Optoelectronic components (not shown) are attached to the top surface of the base substrate and make electrical connection with the solder pads. The can includes a transparent device (31), an metal enclosure (32) and a housing (33), which hermetically seals to the base substrate protecting the optoelectronic components.

Abstract: A surface emitting semiconductor laser system having an outcoupling aperture on a central waveguide. At either end of the central waveguide are means for reflecting a plurality of different wavelengths of light such that multiple wavelengths are outcoupled through a single outcoupling aperture. Means are provided by which the different wavelengths can be independently modulated.

Abstract: A tuneable laser having an active section, a phase section and a Bragg reflector comprising a plurality of descrete grating units, at least two of which gratings have a discrete pitch, wherein at least two of the gratings having a different pitch are each provided with a plurality of independently actuable electrodes.

Abstract: Provided is a fiber grating laser for optical communication which can be used as a light source regardless of the occurrence of mode hopping. The laser module comprises a semiconductor optical amplifier device, an optical waveguide such as an optical fiber, and a diffraction grating such as a fiber grating. The semiconductor optical amplifier device has first and second end surfaces. The optical waveguide is optically coupled to the semiconductor optical amplifier device. The diffraction grating is optically coupled to the optical waveguide. The semiconductor optical amplifier device and the diffraction grating constitute an external cavity. An optical cavity length of the external cavity is in a range of 13 millimeters or more but 27 millimeters or less.

Abstract: When a piezoelectric element 3 applies an external force to a plastic photonic crystal, the photonic crystal deforms, and accordingly, the photonic band gap easily changes. When the photonic band gap changes, transmission of light with a specific wavelength is limited. Therefore, light with a desired wavelength is outputted from the photonic crystal 2 upon sufficient tuning, and extracted to the outside through an output window 6. In the present invention, a plastic photonic crystal 2 which can achieve sufficient wavelength tuning although it is small is used, and elements are unitized, so that the entire wavelength tunable light source unit is downsized.

Abstract: The invention is directed to a photonic crystal defect structure for a vertical cavity surface emitting laser (VCSEL). In accordance with the invention, a set of holes is formed in a pattern with one or more missing holes forming a defect in the pattern of the photonic crystal, according to a proscribed depth, hole diameter, and pattern pitch which will insure operation in a single transverse mode.

Abstract: A laser is disclosed which includes a gain medium, a switch element, and a pulse controller. In one embodiment laser light of differing polarizations pass along respective paths and a pulsed laser output is generated via an electro-optical element. In another embodiment light of differing polarizations passes in differing directions through a cyclical path. The invention can make use of a prism-shaped polarizer having a polarization selection face and two further faces. Yet further initial pulses can be controlled to reduce energy, for example by progressively increasing the period or amplitude of successive pulses. As a result an efficient and high power laser apparatus is realized.

Abstract: A laser device, comprising a laser beam emitter having an optical resonator, wherein the optical resonator has a resonator and a reflection mirror, and at least one of a length of the resonator or a curvature of the reflection mirror is determined so as to satisfy condition that a parameter M2 of beam quality of a projected laser beam is within a range of 8?M2?22, where M2=?W·?/? (W is a beam waist of a laser beam; ? is a spreading angle; and ? is a wavelength of the laser beam).

Abstract: A system, method and apparatus provide the ability to detect a chemical in an analyte. To detect the chemical, the invention utilizes a laser having an open cavity. A photonic crystal lattice structure having a defect defines a suitable geometry for such a cavity. The analyte is introduced directly into a high optical field of the cavity. Thereafter, the cavity is pumped and an emission from the laser is used to detect the presence of the chemical in the analyte.

Abstract: An integrated optical parametric oscillator, having an optical parametric oscillation region to convert a pump source into a signal beam and an idler beam, and a fine-steering region to adjust optical path of the signal beam in order to finely select a required wavelength component of the signal beam. The optical parametric oscillator is contoured with a plurality of exterior planes with specific reflective characteristics to form a resonator of the idler beam while reflecting and diffracting the signal beam with a desired wavelength.

Abstract: A multi-function combat laser is described that uses single or multiple laser sources (laser diodes) in a configuration such that when it is coupled with a dichroic substrate the laser sources outputs are coupled to produce a single desired output. The multi-function combat laser consolidates multiple laser functions for the dismounted soldier into a single package with shared power supplies, optics and laser sources.

Abstract: A thin-film organic laser, that includes: a substrate; a bottom mirror provided on the substrate; at least one active region deposited on the bottom mirror, wherein the at least one active region includes organic gain material; an external mirror provided at a predetermined distance from the at least one active region such that the bottom mirror combined with the external mirror forms a laser resonator; and an optical pumping means for exciting the organic gain material to produce a laser beam with a wavelength ? and at least one lateral laser mode in the laser resonator and an output of laser light.

Abstract: An external cavity laser having a set atmosphere is disclosed. In an embodiment, the laser system includes a gain medium to emit light in response to an applied current, a wavelength selective reflector configured to resonate the light that is emitted from the gain medium, and a chamber containing a set atmosphere, the chamber being optically connected to the gain medium and the wavelength selective reflector such that the light that is emitted from the gain medium passes through the chamber.

Abstract: The invention relates to a new configuration for a laser resonator for use in combination with a solid-state laser gain medium contained within the core of a planar waveguide. The resonator has a substantially confocal negative branch unstable resonator configuration in a lateral direction, a low loss waveguide resonator configuration in a transverse direction, and the focal point of the unstable resonator is disposed outside the planar waveguide to avoid optical damage or breakdown in the gain medium. The preferred embodiment includes an effective means of transverse mode selection for the case when the planar waveguide is of the multi-mode type. The invention also provides a new low loss waveguide resonator configuration which may be used with planar waveguide gas lasers.

Abstract: A Raman ring resonator based laser and wavelength converter method and apparatus. In one aspect of the present invention, the disclosed method includes directing a first optical beam of a first wavelength and a first power level into a first ring resonator defined in a semiconductor material. Emission of a second optical beam of a second wavelength is caused in the first ring resonator by propagating the first optical beam around the first ring resonator. The first power level is sufficient to cause the emission of the second optical beam. The first optical beam is directed out of the first ring resonator after a round trip of the first optical beam around the first ring resonator. The second optical beam is recirculated around the first ring resonator to further stimulate the emission of the second optical beam in the first ring resonator.

Abstract: A tunable laser comprises multiple reflectors defining a resonant cavity, and an optical gain medium positioned within the resonant cavity. One of the reflectors is a programmable micromirror array that acts as a tunable blazed diffraction grating providing continuous tuning of a single resonant mode over a wavelength gain region of the gain medium. The continuous tuning is provided by altering the micromirror array to shift, in synchrony, a resonant mode wavelength of the resonant cavity and a reflection filtering peak of the array. The array comprises a plurality of micromirror elements that can be controlled to independently move in a direction perpendicular to the plane of the array. In one embodiment, each element has a V-shaped movable mirror. In another embodiment, each element has a flat or slightly-tilted horizontal mirror and a vertical or nearly-vertical mirror orthogonal to the horizontal mirror producing a corner-cube-like reflection.

Abstract: A tunable laser source of a Littman arrangement type has a wavelength selection mirror rotating around a position where a mode hop is suppressed in a wavelength variation, a feed screw receiving a driving force of a motor at one end to be rotated, in which another end is disposed at a predetermined position, and which is larger in coefficient of thermal expansion than the optical base, a first nut feedably fitted to the feed screw, a flat spring in which one end is fixed to the first nut; and a mirror arm having a rotation shaft disposed at a rotation center of the wavelength selection mirror, and first and second arm portions formed in a V-like shape and elongating from the rotation shaft. The wavelength selection mirror is fixed to the first arm portion, and another end of the flat spring is fixed to the second arm portion.

Abstract: A laser is disclosed which includes a gain medium, a switch element, and a pulse controller. In one embodiment laser light of differing polarizations pass along respective paths and a pulsed laser output is generated via an electro-optical element. In another embodiment light of differing polarizations passes in differing directions through a cyclical path. The invention can make use of a prism-shaped polarizer having a polarization selection face and two further faces. Yet further initial pulses can be controlled to reduce energy, for example by progressively increasing the period or amplitude of successive pulses. As a result an efficient and high power laser apparatus is realized.

Abstract: An arrangement for optical beam transformation, having at least one light source which can emit at least one light beam, with the at least one light beam having a greater divergence in a first direction (Y) than in a second direction (X) at right angles to it, a collimation means, which can at least reduce the divergence of the at least one light beam in the first direction (Y), an apparatus for optical beam transformation, which is arranged downstream from the collimation means in the propagation direction (Z) of the at least one light beam, with the apparatus being such that the divergence of the at least one light beam passing through the apparatus in the first direction (Y) is interchanged with the divergence in the second direction (X) at right angles to it, and such that the cross-sectional area of the at least one light beam is reduced in the apparatus for optical beam transformation.

Abstract: An active region of a VCSEL at one (i.e., n doped) end having an expanded effectively undoped region, and another (i.e., p doped) end having a significantly doped region up to or even including a portion of the active region. A previous way had heavy doping of the n and p doped regions up to the active region, at least close to it or even partially into it.

Abstract: Selectively oxidized vertical cavity lasers emitting at about 1290 nm using InGaAsN quantum wells that operate continuous wave below, at and above room temperature are reported. The lasers employ a semi-insulating GaAs substrate for reduced capacitance, high quality, low resistivity AlGaAs DBR mirror structures, and a strained active region based on InGaAsN. In addition, the design of the VCSEL reduces free carrier absorption of 1.3 ?m light in the p-type materials by placing relatively higher p-type dopant concentrations near standing wave nulls.

Abstract: The light-emitting device comprises a substrate, an active region and a tunnel junction structure. The substrate comprises gallium arsenide. The active region comprises an n-type spacing layer and a p-type spacing layer. The tunnel junction structure comprises a p-type tunnel junction layer adjacent the p-type spacing layer, an n-type tunnel junction layer and a tunnel junction between the p-type tunnel junction layer and the n-type tunnel junction layer. The p-type tunnel junction layer comprises a layer of a p-type first semiconductor material that includes gallium and arsenic. The n-type tunnel junction layer comprises a layer of an n-type second semiconductor material that includes indium, gallium and phosphorus. The high dopant concentration attainable in the second semiconductor material reduces the width of the depletion region at the tunnel junction and increases the electrostatic field across the tunnel junction, so that the reverse bias at which tunneling occurs is reduced.

Abstract: A diode end-pumped solid state laser is provided which produces improved power output, long term stability and improved conversion efficiency from the pumping power, high as well as low power operation while maintaining certain desirable common characteristics such as TEM00 operation, circular outputs, readily aligned systems and compatibility with long lifetime for all components. The invention intracavity conversion to second, third and higher harmonics in several different spectral regimes. The invention also addresses the aspects of design flexibility, seeking in certain embodiments to provide a single platform for providing several harmonic beams.

Abstract: A photonic crystal-based resonant cavity includes a first dielectric substance having a first dielectric permittivity, a plurality of second dielectric substances having a second dielectric permittivity and arranged in a first periodic structure with respect to at least one or more directions on a plane formed of the first dielectric substance, a plurality of third dielectric substances having a third dielectric permittivity and arranged in a second periodic structure with respect to at least one or more directions on the plane formed of the first dielectric substance, and disposed in unit cells formed by the plurality of second dielectric substances so as to be arranged in a third periodic structure together with the plurality of second dielectric substances, and one or more local defects formed to disrupt either the first periodic structure formed by the second dielectric substances or the second periodic structure formed by the third dielectric substances.

Abstract: The present invention is directed a method of fabricating a VCSEL. First, a substrate with a back surface and a front surface is provided. Then, a first reflector, an active region, and a second reflector are disposed on the front surface. The first reflector is disposed on the front surface. The active region is interposed between the first reflector and the second reflector. Then, anti-reflection features are formed into the back surface of the substrate to reduce specular reflection of light into the active region.

Abstract: The present invention is a Raman laser and methods related thereto. In the preferred embodiments, the Raman laser comprises a laser pump signal in a fiber waveguide which is optically coupled to a micro-resonator through a fiber taper. The micro-resonator is constructed from a material that has a high Q when it is formed into a micro-resonator and is phase matched to the waveguide. The lasing frequency can be determined based upon the pump input or the micro-resonator material. In the preferred embodiments, the micro-resonator is constructed from a fused silica material. The present invention provides a compact laser with improved emissions and coupling efficiencies and the ability to use stimulated Raman scattering effects to create lasers having frequencies that are otherwise difficult to obtain. Alternative configurations include multiple micro-resonators on a single fiber waveguide and/or utilizing multiple waveguides attached to one or more micro-resonators.

Abstract: The present invention contemplates a simplified laser oscillator-amplifier system for deep UV generation. The simplified system employs same type of gain media in both the oscillator and the amplifier and utilizes a single pump pulse split to pump both the oscillator and the amplifier. A short cavity oscillator is operated near lasing threshold to produce a seed pulse with a narrow spectral bandwidth and long pulse duration. A short cavity amplifier is Q-switched to amplify the seed pulse to produce a single short pulse with good energy extraction efficiency. The amplifier is simply a short cavity, Q-switched laser. Short pulse is obtained with short cavity length and high gain of the amplifier. Consequently, the simplified laser oscillator-amplifier system can accommodate a long pump pulse to produce a nanosecond pulse suitable for deep UV laser generation.

Abstract: The integrated-optics coupling component is designed to cooperate with a transverse multimode power laser diode (2) with semi-conductor to form a transverse multimode power laser. It comprises an input zone (4) connected to at least one output waveguide (6) by at least two adiabatic tapering zones (5). At least two filtering windows (7) form the inputs of the adiabatic tapering zones (5) at the end of a diffraction zone defined by the input zone. Reflecting elements, for example a Bragg grating (12), can be arranged on the output waveguide. An emitting face (3) being antiglare-treated, an extended laser cavity oscillating on a single predetermined mode is thus defined between a reflecting rear face (11) of the laser diode and the reflecting elements (12).

Abstract: A mirror of known type comprises a stack of pairs of dielectric material layers of alternating high and low refractive indices and a metal layer, preferably gold, capping one end of the stack. For improvising the adherence of the metal layer to the stack, the metal is directly contiguous with a layer of tin oxide. In different mirror structures, the tin oxide can be an extra layer added between the end-most pair of layers and the metal layer; or the tin oxide layer can comprise one layer of only the end-most pair of dielectric layers in the stack; or all of the pairs of dielectric layers in the stack can comprise a layer of tin oxide as one of the pair layers.

Abstract: A photonic-crystal distributed-feedback laser includes a laser cavity with a waveguide structure that has a cavity length Lc and is bounded by two mirrors; an active region for producing optical gain upon receiving optical pumping or an input voltage; at least one layer having a periodic two-dimensional grating with modulation of a modal refractive index, the grating being defined on a rectangular lattice with a first period along a first axis of the grating and a second period along a second perpendicular axis of the grating, and wherein the grating produces three diffraction processes having coupling coefficients ?1?, ?2?, ?3?; and a lateral gain area contained within a second area patterned with the grating that has substantially a shape of a gain stripe with a width W, with the gain stripe tilted at a first tilt angle relative to the two mirrors.

Abstract: A quasi-monochromatic light beam carrier for a particular telecommunication channel is likely to experience drift because of age, temperature, or other factors, and may cause the centroid wavelength of the carrier to shift. Temperature adjustments by wavelength lockers to compensate for drift on one channel may affect the performance of other channels. Embodiments of the present invention couple a quasi-monochromatic light beam through a substrate-based grating, diffract the light beam from the edge of the substrate to free space, and detect the light beam from free space at a position detector to determine the centroid wavelength based on a position of the light beam incident on the detector. The diffracted light beam may be reflected within the substrate a number of times prior to exiting the substrate towards the detector.

Abstract: A GaN series surface-emitting laser diode and a method for manufacturing the same are provided. The GaN series surface-emitting laser diode includes: an active layer; p-type and n-type material layers on the opposite sides of the active layer; a first-distributed Bragg reflector (DBR) layer formed on the n-type material layer; an n-type electrode connected to the active layer through the n-type material layer such that voltage is applied to the active layer for lasing; a spacer formed on the p-type material layer with a laser output window in a portion aligned with the first DBR layer, the spacer being thick enough to enable holes to effectively migrate to a center portion of the active layer; a second DBR layer formed on the laser output window; and a p-type electrode connected to the active layer through the p-type material layer such that voltage is applied to the active layer for lasing.

Abstract: Optical filters having at least two coupled whispering-gallery-mode (WGM) optical resonators to produce a second order or higher order filter function with a desired spectral profile. At least one of the coupled WGM optical resonators may be tunable by a control signal to adjust the filtering function.

Abstract: The specification describes an optical filter wherein long period gratings (LPGs) are used in a new configuration to provide in-line bandpass filtering of optical signals. In the basic embodiment, two dissimilar LPGs are installed in the optical fiber transmission line. The first LPG converts light, over a broad wavelength range, being transmitted in the fundamental, or LP01, mode of the optical fiber transmission line into light in a higher order mode (HOM) of the optical fiber. The mode-converted signal, with mode LPm,n, is then coupled to a second waveguide, the second waveguide having transmission characteristics different from those of the first. The second waveguide supports propagation of light in a LPm,n mode. The mode-converted signal is then transmitted through a second LPG where the signal over a selected narrow band of wavelengths that is accepted by the second LPG is converted back to a LP01 mode.

Abstract: A solid laser apparatus is provided comprising a semiconductor light emitter 1, an optical fiber 3 having a grating part 6 provided therein, and a wavelength converter 5 for receiving an input of light from an optical resonator composed of the semiconductor light emitter 1 and the optical fiber 3 and releasing its harmonic light, wherein the distance D between the grating part 6 and the wavelength converter 5 is equal to or greater than ½ of the coherent length of the input light.

Abstract: This invention relates to a laser cavity with passive triggering by saturable absorbent and with controlled polarization, and to a laser and in particular to a microlaser containing the said cavity and means of pumping this cavity. The invention also relates to a process for manufacturing the said microlaser. The laser cavity with controlled polarization comprises a substrate made of Y3Al5O12 (YAG) active laser material that may or may not be doped, on which a monocrystalline layer of saturable absorbent doped YAG material is deposited directly by liquid phase epitaxy or by a similar process, in which the said active laser material has a [100] orientation, and in which the said monocrystalline layer of saturable absorbent material is deposited with the same [100] orientation.

Abstract: A planar wafer-level packaging method is provided for a laser and a monitor photo detector. The laser and photo detector are affixed to a planar substrate. The planar substrate provides electrical connections to the components. A lens cap with a microlens is formed and affixed to the substrate with a seal. The lens cap forms a hermetically sealed cavity enclosing the laser and photo detector. The inside surface of the lens cap has a reflective coating with a central opening over the emitting aperture of the laser. The central opening has an anti-reflective coating. Light from the laser is directed and shaped by the lens cap to couple into an external light guide. Residual light from the edge of the laser reflects off the inside surface of the lens cap and is incident upon the photo detector. In an alternate method, the laser may be packaged using flip-chip assembly.

Abstract: An optically pumped laser has a gain medium positioned inside of an optical resonator cavity and disposed about a resonator optical axis. An optical pumping source is positioned outside of the optical resonator cavity. A reflective coupler with a coupler body, and an interior volume passing therethrough is positioned proximal to the optical pumping source. Light from the pumping source passes into an entrance aperture of the reflective coupler to an exit aperture of the reflective coupler positioned distal to the optical pumping source. The interior volume of the reflective coupler is bounded by a reflective surface, an entrance aperture and the exit aperture, and is substantially transparent to radiation from the optical pumping source. The reflective surface has a high reflectivity matched to radiation from the optical pumping source.

Abstract: An optical device has at least one waveguide with at least one adjacent resonator, where the distance between the resonator and the waveguide can be controllably adjusted to change the optical coupling between the resonator and the waveguide. When implemented as part of an interferometer, the ability to adjust the waveguide/resonator distance—and thereby the optical coupling between them—provides a mechanically tunable interferometer.

Abstract: External cavity laser with reflector in optical wave guide, particularly HDBR laser, with an active element comprising a semiconductor optical amplifying cavity having a low-reflectivity facet (3), for example a Semiconductor Optical Amplifier (SOA) with a facet (30) opposite to said low-reflectivity facet treated with a reflecting coating, or a Fabry-Perot laser, and an external reflector comprising a Bragg grating (70) formed in an optical wave guide (4) near a termination (5), facing said facet, of a segment (5, 6, 7) of said optical wave guide coupled with the facet. The grating has a spatial profile of modulation of the refraction index such that a corresponding optical reflectivity spectrum (A) has an optical bandwidth (W) sufficiently small around a prescribed laser oscillation mode wavelength (?c) for the laser to oscillate only on the prescribed mode and not on other oscillation modes even in conditions of high-frequency direct modulation.

Abstract: Fiber gratings (5), (6) having substantially the same reflection center wavelength are provided in an optical fiber (4). The fiber gratings (5), (6) reflects to the semiconductor laser element (1), only a component at the reflection center wavelength of laser light emitted from the semiconductor laser element (1).