Abstract: Systems and methods for optically pumping alkali-metal atoms using Coherence Population Trapping (CPT) resonances are disclosed. An illustrative push-pull optical pumping system for inducing CPT resonances in a resonance cell containing an admixture of alkali-metal atoms and one or more buffer gasses may include a laser assembly adapted to produce alternating orthogonally polarized light, and at least one DC current source adapted to output a constant-intensity carrier current signal for inducing laser emission from the laser assembly at a carrier wavelength of the alkali-metal atoms. An RF modulated signal outputted from an RF modulation source can be rectified, split, and phase-shifted for inducing a time-dependent polarization of the laser light that can be used to enhance CPT resonances.

Abstract: In harmonic-generating laser apparatus, plane-polarized fundamental radiation of a laser is converted to harmonic radiation by an optically nonlinear crystal. The power of harmonic radiation generated by the apparatus is selectively varied by selectively rotating the plane of polarization of fundamental radiation entering the optically nonlinear crystal.

Abstract: A laser light source device includes: a laser light source that emits a laser light; and an optical wavelength conversion section that includes a ferroelectric material carrying therein a plurality of polarization inversion rows in which a polarization inversion area and a polarization non-inversion area are alternately formed in a predetermined direction, and converts the laser light directed in the predetermined direction into a second harmonic. In the laser light source device, the laser light source is disposed at a fixed position to allow any one of the polarization inversion rows to be positioned on an optical path of the laser light.

Abstract: Methods and apparatus for optical isolation in high peak power fiber-optic systems prevent damage to a facet within a fiber-optic isolator caused by back-reflected light from, for example, an optical amplifier. Preventing damage to the facet may include expanding a mode area of the back-reflected light and/or reducing a change in refractive index.

Abstract: An efficient technique for producing deterministically polarized single photons uses liquid-crystal hosts of either monomeric or oligomeric/polymeric form to preferentially align the single emitters for maximum excitation efficiency. Deterministic molecular alignment also provides deterministically polarized output photons; using planar-aligned cholesteric liquid crystal hosts as 1-D photonic-band-gap microcavities tunable to the emitter fluorescence band to increase source efficiency, using liquid crystal technology to prevent emitter bleaching. Emitters comprise soluble dyes, inorganic nanocrystals or trivalent rare-earth chelates.

Abstract: Disclosed is a spin-based semiconductor laser source capable of generating a completely circularly polarized laser light by injecting current into p-type and n-type half-metal magnetic semiconductor layers. Each of the p-type and n-type half-metal magnetic semiconductor layers is prepared by doping a magnetic semiconductor with a transition metal atom and optionally with an acceptor or donor. Alternatively, each of the p-type and n-type half-metal magnetic semiconductor layers is prepared by providing a gate to a magnetic semiconductor and adjusting/controlling its ferromagnetic state according to the field effect. The present invention can solve the problem concerning the insufficient degree of circular polarization in conventional circular-polarization semiconductor laser sources.

Abstract: A photonic-crystal fiber provides dispersion compensation in a soliton fiber laser. The anomalous dispersion provided by the photonic-crystal fiber permits construction of a femtosecond fiber laser at 1 ?m wavelength without prisms or diffraction gratings. The laser produces ˜100-fs pulses with 1 nJ energy, and is a major step toward environmentally-stable all-fiber devices at 1 ?m.

Abstract: A method of operating a stretched-pulse Raman fiber laser includes producing laser radiation gain in a laser cavity using predominantly Raman amplification. Such a stretched-pulse Raman fiber laser has a laser cavity that includes a Negative Group Velocity Dispersion Fiber connected in series with a Positive Group Velocity Dispersion Fiber, a polarization controller and an isolator. In some examples, the Negative Group Velocity Dispersion Fiber is a Dispersion Compensating Fiber. In other examples, the Negative Group Velocity Dispersion Fiber is replaced by a Raman Specialty Fiber.

Abstract: A device for the optical excitation of laser-active crystals with a diode laser (1) is disclosed. The diode laser (1) generates pump radiation (2), and the laser-active crystal (14) is arranged in a solid-state laser or solid-state laser amplifier. The laser-active crystal (14) has an axis (C) with strong absorption and an axis (A) with weak absorption. The pump radiation (2) from the diode laser (1) is substantially polarised linearly in a privileged polarisation direction. The device is configured in such a way that the pump radiation (2) is injected into the laser-active crystal (14) with a polarisation direction which is oriented parallel to the weak-absorption axis (A). The polarisation of the pump radiation in the vicinity of the laser-active crystal is oriented parallel relative to the weak-absorption axis.

Abstract: A method of controlling the state of polarization of an optical signal includes injecting the optical signal into a laser diode and matching the wavelength of the optical signal to a longitudinal mode of the laser diode. A stabilizer signal can also be injected in to the laser diode. The wavelength of the stabilizer signal is matched a first longitudinal mode of the laser diode a longitudinal mode of the laser diode to the optical signal.

Abstract: A solid state zig-zag slab laser amplifier in which depolarization occurring at total internal reflection from opposed lateral faces of the amplifier slab is controlled by selecting a complex evanescent coating that provides a selected phase retardance that results in minimization of depolarization. Without use of the complex coating, small changes in incidence angles can result in phase retardance changes large enough to increase depolarization significantly, especially when the amplifier is operated at higher powers. Appropriate selection of the complex evanescent coating allows a desired phase retardance angle to be maintained relatively constant over a small range of angles of incidence, at a given wavelength, and therefore permits minimization of depolarization and birefringence effects.

Abstract: An optical module comprises a splitting element that splits light outputted from a light source; a first monitoring means that detects the intensity of light split by the splitting element; a polarization control means that switches the polarization state of light outputted from the splitting element based on a control signal; a filter means that accepts light outputted by the polarization control means as input, and whereof the characteristic changes depending on the polarization state of the input light; and a second monitoring means that detects the intensity of the light transmitted through the filter means.

Abstract: An apparatus for and a method of amplifying Faraday or Voigt rotation by passing light through a sample many times using multiple internal reflections and successive mirrored chambers that repeatedly send the light back through the sample. The sample is placed in a sample chamber that is adjacent to an optical amplifier chamber, and the optical amplifier chamber is adjacent to one or more additional chambers. The sample has a magnetic field applied thereto. The sample chamber receives light from a light source. The light reflects within the sample chamber and the sample to accumulate rotation of the light. The sample chamber transmits the light to the optical amplifier chamber. The optical amplifier chamber transmits the light to the additional chambers and reflects the light back to the sample where the light undergoes further rotation. Each one of the additional chambers transmits the light to the next additional chamber and reflects the light back to a previous chamber.

Abstract: A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Abstract: A laser includes a gain medium located in a laser resonator. The gain medium generates plane polarized radiation plane polarized in a first polarization orientation. An electro-optical switch is located in the resonator. When the switch is activated the polarization plane of the laser radiation is rotated to a second orientation after making a forward and a reverse pass through the optical switch. When the switch is deactivated, the polarization orientation of the forward and reverse transmitted laser radiation remains about the same. A polarization selective device is located in the resonator between the electro-optical switch and the gain medium. The polarization selective device is arranged to permit circulation in the resonator of laser radiation in the first polarization orientation, and to restrict circulation of laser radiation in the second polarization orientation. The Gain medium is energized and the switch activated to allow energy to build in the gain medium.

Abstract: A method and apparatus for generating single polarization fiber laser output are disclosed. A Bragg grating is non-destructively fabricated within the fiber to introduce differential loss between the two polarizations of the laser output. Curvature at the grating site into a tight loop further increases the differential loss between the available polarizations.

Abstract: An external cavity laser system includes an in-line optical filter and a reflection suppressor that efficiently suppresses back-reflected light while allowing light to resonate within the laser cavity. The reflection suppressor may include a polarizer that polarizes light within the cavity and polarization rotators that rotate the polarization state of the polarized light such that back-reflected light is suppressed by the polarizer. Because back-reflected light is suppressed, use of an in-line filter becomes viable in an external cavity laser system.

Abstract: A laser polarization control apparatus includes a polarization modifying device, such as a liquid crystal variable retarder, and a controller. The polarization modifying device receives a laser beam and modifies the polarization of the laser beam. The controller, which is connected to the polarization modifying device, adjusts an input to the polarization modifying device in order to control modification of the polarization of the laser beam based on alignment of a structure to be processed by the laser beam. For example, the polarization of the laser beam may be rotated to correspond with the alignment of a link in a semiconductor device to be cut by the laser beam. The polarization modifying device is configured for incorporation into a laser processing system that produces the laser beam received by the polarization modifying device and that focuses the laser beam modified by the polarization modifying device onto a workpiece that includes the structure to be processed by the laser beam.

Abstract: A method and apparatus for reducing speckle uses polarization averaging. A polarizing beam splitter divides a first polarized laser output into a second polarized laser output and a third polarized laser output. A plurality of mirrors creates an optical path difference between the second and third polarized laser outputs. The optical path difference is at least about a coherence length for the first polarized laser output. The second and third polarized laser outputs are combined into a fourth laser output, which illuminates a depolarizing screen. If a human eye or an optical system having a intensity detector views the depolarizing screen, the eye or the intensity detector will detect reduced speckle, which results from uncorrelated speckle patterns created by the second polarized laser output and the third polarized laser output. A first alternative embodiment of the invention functions without the optical path difference being at least about the coherence length.

Abstract: There is provided a millimeter wave band frequency optical oscillator predicted to be used as a millimeter wave oscillating frequency signal source in a base station of a millimeter wave wireless transmission system. The optical oscillator has a double resonator structure in which a pair of wavelength tunable fiber grating mirrors are inserted into a unilateral fiber-ring laser resonator in order to internally and additionally form a linear laser resonator. The double resonator structure composed of the two stable laser resonators can oscillate laser of two modes. Due to a beat phenomenon occurring between the two modes, received laser is modulated to an ultra-speed frequency of 60 GHz or greater. A variation in the gain within a resonator is induced by a polarization controller using the dependency of laser modes upon polarization. A modulation frequency is consecutively changed from 60 GHz to 80 GHz by controlling the wavelength of light reflected by the fiber grating mirrors.

Abstract: A distributed feedback laser device inhibiting beam coupling coefficient variation resulting from fabrication dispersion and improving fabrication yield. The distributed feedback laser device includes cladding layers provided on an InP substrate and located on both sides of an active layer and a diffraction grating having grating bars, different in refractive index from the cladding layers, in either cladding layer and extending in a direction perpendicular to a light emission direction at a prescribed pitch in the emission direction, as well as at least one light distribution control layer, located in the cladding layer, spaced from the diffraction grating and having the same composition as the diffraction grating.

Abstract: A compressive strain GRIN-SCH-MQW active layer and a tensile strain GRIN-SCH-MQW active layer are laminated, and there are provided a diffraction grating formed in the vicinity of the compressive strain GRIN-SCH-MQW active layer and a diffraction grating formed in the vicinity of the tensile strain GRIN-SCH-MQW active layer, between the radiation end face and the reflection end face of the laser beam. A laser beam obtained by polarization-multiplexing a laser beam in the TE mode generated in the compressive strain GRIN-SCH-MQW active layer and a laser beam in the TE mode generated in the tensile strain GRIN-SCH-MQW active layer, and having a plurality of oscillation longitudinal modes of not larger than a predetermined output value is output by the wavelength selection characteristic of the diffraction gratings.

Abstract: “This invention offer optical modulator module with fulfilling the effective and the stable optical modulation, which stabilizes the emission of semiconductor and control the shift of optic axis between the optical component by the temperature change and so on, when using the semiconductor laser. Peculiarly, the optical modulator module includes, in same package, the semiconductor laser (27) as light source, the optical modulation device (28) that has optical waveguide on the surface of the chip made by the element of the electro-optical effect, and the polarization rotating element (40) between said semiconductor laser and said optical modulation device, for bringing plane of polarization of light from said semiconductor laser (27) to optimum plane of polarization in waveguide of the said optical modulation device in line and blocking the returning light from said optical modulation device to said semiconductor laser.

Abstract: An optical resonator supporting two sets of simultaneously co-existent oscillation modes (30 and 31), having polarizations orthogonal to each other. Mode control elements (28 and 29), such as apertures and phase elements, are introduced into the resonator to allow only preferred modes to exist. The placement and orientation of the sets are designed such that the high intensity zones of one set fall on the nodes or low intensity zones of the other set in an interlaced pattern. Thus, in a laser resonator, better utilization of the gain medium (24) is achieved and the beam quality and brightness over multimode lasing are improved. This configuration improves the performance of high Fresnel number resonators, in both pulsed and continuous lasers, for applications such as scribing, drilling, cutting, target designation and rangefinding. An application of the intra-cavity coherent summation of orthogonally polarized modes is described, whereby azimuthally or radially polarized beams may be obtained.

Abstract: A laser apparatus, which generates laser light to be transmitted through an optical transmission system includes a laser that emits light that is substantially linearly polarized, a housing in which the laser is mounted, and a quarter wave retarder plate. The quarter wave retarder plate is disposed so that the emitted laser light passes through the quarter wave retarder plate prior to transmission of the emitted laser light through the optical transmission system. The quarter wave retarder plate causing the emitted laser light to become circularly polarized with a predefined handedness. The quarter wave retarder plate is also disposed so that light reflected by the optical transmission system back toward the laser passes through the quarter wave retarder plate a second time prior to reaching the laser, causing the reflected light to become linearly polarized with a linear polarization that is orthogonal to the polarization state of the light emitted by the laser.

Abstract: A device (10) for producing high frequency radiation using a source of elliptically polarized radiation is disclosed based on: irradiating a frequency multiplication medium having a screw axis (16) symmetry of approximate Nth order symmetry, oriented so that said elliptically polarized radiation propagates in parallel to the screw axis (16). Also, a method for producing high frequency radiation is disclosed based on irradiating a frequency multiplication medium having a screw axis (16) of approximate Nth order symmetry with elliptically polarized radiation so that the elliptically polarized radiation propagates in parallel to the screw axis (16). Furthermore, a method of producing a beam of high frequency radiation composed of only a limited number of wavelengths is disclosed whereby the intensity of a beam (22) interacting with a frequency multiplication medium is selected so that only a limited number of wavelengths is emitted.

Abstract: A laser oscillator comprises a laser medium, an optical excitation laser diode that irradiates the laser medium with light, a polarizer disposed on an optical path of the laser medium at a first end thereof, a first Porro prism disposed with the optical path coinciding with a point on a ridgeline thereof and with the ridgeline parallel or perpendicular to a plane of incidence of the polarizer, and a second Porro prism disposed on the optical path of the laser medium at a second end thereof with the optical path coinciding with a point on a ridgeline thereof. An angle formed by the two ridgelines of the first and second Porro prisms is a predetermined angle other than 0 degrees, 90 degrees, 60 degrees, 45 degrees and 36 degrees, 30 degrees.

Abstract: A Laser arrangement (1) comprising a pump unit (2) containing a pumped laser crystal (3), and means, such as a saturable absorber (15), for passive mode-locking, wherein two separate, alternatively switchable resonator arms (11, 12) are provided, one resonator arm (11) of which, which is active in a pulse forming phase (21), comprises the saturable absorber (15), whereas the other resonator arm (12), which is active in an amplifying phase (22), is free from components that introduce losses.

Abstract: A laser includes a first region with a first moveguide having a first diffraction grating, a second region with a second waveguide having a second diffraction grating, and a phase controlling region with a third waveguide and a phase control unit for controlling an effective refractive index of the third waveguide. The phase controlling region, the first region and the second region are coupled serially along a light propagation direction in this order, and are constructed such that light to the first region from the phase controlling region is enlarged relatively to light to the phase controlling region from the first region, or constructed such that a coupling coefficient of the first diffraction grating in the first region adjacent to the phase controlling region is smaller than a coupling coefficient of the second diffraction grating in the second region away from the phase controlling region.

Abstract: Light emission methods and light emission devices are described including method and devices capable of emitting light at a plurality of controllable wavelengths. According to one aspect, a light emission method includes providing a control signal and emitting light using a laser operating in a plurality of polarization states. The polarization state of the laser is adjusted responsive to the control signal and the wavelength of the light emitted using the laser is adjusted responsive to the adjustment of the polarization state of the laser.

Abstract: A method of controlling the state of polarization of an optical signal includes injecting the optical signal into a laser diode and matching the wavelength of the optical signal to a longitudinal mode of the laser diode. A stabilizer signal can also be injected in to the laser diode. The wavelength of the stabilizer signal is matched a first longitudinal mode of the laser diode a longitudinal mode of the laser diode to the optical signal.

Abstract: A laser includes a gain medium located in a laser resonator. The gain medium generates plane polarized radiation plane polarized in a first polarization orientation. An electro-optical switch is located in the resonator. When the switch is activated the polarization plane of the laser radiation is rotated to a second orientation after making a forward and a reverse pass through the optical switch. When the switch is deactivated, the polarization orientation of the forward and reverse transmitted laser radiation remains about the same. A polarization selective device is located in the resonator between the electro-optical switch and the gain medium. The polarization selective device is arranged to permit circulation in the resonator of laser radiation in the first polarization orientation, and to restrict circulation of laser radiation in the second polarization orientation. The Gain medium is energized and the switch activated to allow energy to build in the gain medium.

Abstract: A fast current-controlled polarization switching VCSEL with two independent intra-cavity p-contact electrodes and two independent intra-cavity n-contact electrodes positioned along the four sides of the symmetric aperture such that there are two independent p- and n-contact pairs placed on opposite sides of the aperture in a non-overlapping configuration. The anisotropy resulting from the unidirectional current flow causes the light output to be polarized perpendicular to the direction of current flow. A VCSEL driver circuit switches the polarization state of the output light by using the two orthogonal pairs of non-overlapping intra-cavity contacted electrodes to change the direction of current flow into the VCSEL aperture by 90 degrees.

Abstract: A semiconductor pump laser uses a depolarzer to depolarize the pump light entering the fiber amplifier. The depolarized light source is useful for reducing polarization dependent gain of fiber amplifiers. The pump laser includes one or more semiconductor, coherence-collapsed laser sources emitting polarized pump outputs, and one or more depolarizers disposed to depolarize the polarized pump output from the lasers. One or more fiber outputs are coupled to the one or more depolarizers to receive depolarized pump light. The depolarizer may include an N×M polarization preserving coupler having N inputs and M outputs, N and M being at least 2, an input to the depolarizer at a first coupler input, an output port from the depolarizer at a first coupler output. A polarization-controlling optical path is coupled between a second coupler output and a second coupler input.

Abstract: A method for generating polarized laser output radiation utilizes a laser resonator whose active medium exhibits thermally induced birefringence. The radiation fields oscillating in the laser resonator are not subjected to polarization selection, and only the radiation field exhibiting the desired polarization state (p) is partially output. Only a prescribed polarization of the radiation fields of the laser radiation which can oscillate in the resonator can be partially output from the resonator with a prescribed output level and all differently polarized radiation fields remain in the resonator in a completely reflecting fashion.

Abstract: A surface emitting semiconductor laser capable of controlling the polarization direction of laser light and a surface emitting semiconductor laser array. In a surface emitting semiconductor laser, a resonator is formed on a semiconductor substrate in the perpendicular direction, from which light is emitted in the direction perpendicular to the semiconductor substrate. The surface emitting semiconductor laser includes a columnar portion, which is part of the resonator, and an insulating layer formed in contact with the side of the columnar portion, wherein the insulating layer exhibits anisotropic stress caused by the planar configuration thereof, and the polarization direction of laser light is controlled by the anisotropic stress.

Abstract: A one piece laser assembly including a rod of gain medium with one end-face bonded to a broad end-face on a stack of optical wafers that process light differently and mirrors plated on the remaining exposed end-faces of the rod and the stack of wafers.

Abstract: A laser irradiation apparatus includes a laser light generation element, a splitting element for splitting laser light generated from the laser light generation element, a light interference element for causing a first beam and a second beam of the laser light split by the splitting element to interfere with each other to form a periodic light pattern, and a phase shifting element for electro-optically shifting the phase of the first beam. The laser light generation element is a pulse oscillation laser based on laser diode excitation.

Abstract: A fiber-optic laser source capable of emitting multiple useful wavelengths at the same time, including multiple ITU grid wavelengths, is disclosed. The laser preferably comprises a diode-pumped rare-earth doped fiber amplifier as gain medium, a periodic filter to define a first set of possible lasing wavelengths corresponding to ITU grid lasing wavelengths, and a resonant filter for defining a subset of the first set of wavelengths. The arrangement is enclosed in a ring resonator. The ring resonator may be made, in part or in total, with polarization-maintaining optical fiber. The resonator may also comprise in-line optical isolators to ensure unidirectional operation and to eliminate undesired reflections. A gain-flattening filter may also be included within the resonator depending on the desired output characteristics of the laser. The laser may be designed to operate in a set of single cavity longitudinal modes.

Abstract: A low noise laser includes a birefringent gain crystal arranged so that polarization is not constant within the gain crystal. The gain crystal and an intracavity optical element each have a nonzero polarization retardance. The total single-pass retardance is approximately equal to an odd multiple of one-half wave; for example each may provide one quarter wave retardance. In one embodiment the optical element comprises a nonlinear crystal situated within the laser cavity for Type II frequency doubling. The principal crystal axis of the gain crystal is offset from the principal axis of the nonlinear crystal at an offset angle for example about 45°. In one embodiment a gain crystal and frequency-doubling crystal are coupled together to form a monolithic laser component. An alternative embodiment is described in which the optical element comprises a quarter-wave plate and the laser output includes substantially two linear polarizations at the fundamental wavelength.

Abstract: The present invention is an active optical system for beam-steering an incoming laser beam. It includes a first control optics assembly for receiving an incoming laser beam and adjusting that incoming laser beam in accordance with first desired wavelength, polarization and beam propagation parameters. A driver element produces a driver laser beam. A second control optics assembly receives the driver laser beam and adjusts that driver laser beam in accordance with second desired wavelength, polarization and beam propagation parameters. A second order non-linear optical element (SONOE) receives an output from the first control optics assembly and an output from the second control optics assembly. The SONOE provides a non-linear optical interaction between the outputs such that a propagation direction modified laser beam is provided that propagates at a different angle than the incoming laser beam and at a difference wavelength thereof.

Abstract: An optical arrangement for direction dependent coupling out of light comprises a first and a second polarization converter each for converting the state of polarization of light received in a predetermined way. A polarization dependent coupling device is adapted for coupling out a portion of the light received, whereby the ratio of the coupled out portion substantially depends on the state of polarization of the light received. The polarization dependent coupling device is arranged between the first and the second polarization converters, and the optical arrangement receives from different sides light beams propagating in different directions. The characteristics of the first and the second polarization converters are adapted such that the polarization dependent coupling device receives light beams propagating with different states of polarization in the different directions.

Abstract: This disclosure discusses techniques for obtaining wavelength selected simultaneously super pulsed Q-switched and cavity dumped laser pulses utilizing high optical damage threshold electro-optic modulators, maintaining a zero DC voltage bias on the CdTe electro-optic modulator (EOM) so as to minimize polarization variations depending on the location of the laser beam propagating through the CdSe EOM crystal, as well as the addition of one or more laser amplifiers in a compact package and the use of simultaneous gain switched, Q-switched and cavity dumped operation of CO2 lasers for generating shorter pulses and higher peak power for the hole drilling, engraving and perforation applications.

Abstract: A nonlinear optical crystal allowing type 2 phase matching multiplexes a fixed wavelength light having an angular frequency &ohgr;D and a variable wavelength light having an angular frequency &ohgr;S, with the polarization directions thereof being perpendicular to each other, so as to produce a sum frequency light having an angular frequency &ohgr;D+&ohgr;S. When multiplexing the fixed wavelength light and the variable wavelength light through the nonlinear optical crystal, a controlling section controls the polarization direction of the fixed wavelength light so as to be parallel to a predetermined reference axis within a plane vertical to a phase matching direction of the nonlinear optical crystal. Even when the wavelength of inputted light is changed, the predetermined reference axis is a single axis which maintains parallelism with the crystal axis of the nonlinear optical crystal.

Abstract: A third harmonic laser system includes a fundamental wave resonator for generating fundamental laser beam, a second harmonic laser generator for converting fundamental laser beam to a second harmonic laser beam, and a third harmonic laser generator for mixing the second harmonic laser beam with the fundamental laser beam so as to produce a third harmonic laser beam. Multi-pass tripling is used for producing the third harmonic laser beam by means of reflecting and polarizing mirrors, and that the outputted third harmonic laser beam has a high efficiency of about 51% and a high power up to 8.6 W.

Abstract: The present invention provides a semiconductor laser module. A semiconductor laser module (1A) comprising a semiconductor laser element (2a) and an optical fiber (3a) optically coupled by an optical coupling means (2b) is provided, wherein on the optical fiber (3a), a reflective portion (4) and a birefringence fiber (3a) are provided, the birefringence fiber (3a) is provided at least from the incident end on the side of the optical coupling means (2b) to immediately before the reflective portion (4), a connection portion (6) is provided at least at one point in the longitudinal direction of the birefringence fiber (3a), and in the connection portion (6), two eigen axes of X axes and Y axes are connected so that the eigen axes intersect each other at an established angle &thgr;.

Abstract: The invention concerns a light reflecting element comprising a substrate (10), a multilayer mirror (20) and optical coupling means (32, 40) comprising a diffraction grating (40); whereby the reflection coefficient of one polarization is damped without damping the reflection coefficient of the orthogonal polarization over a broad wavelength range and with a large tolerance on the optogeometrical parameters of the device.

Abstract: The efficiency of wavelength conversion of laser light can be improved by allowing incident laser light to pass through nonlinear optical crystals a multiple of times. In converting the wavelength of laser light to generate second- and higher harmonic waves, a returning mirror, a polarizer and nonlinear optical crystals are combined and the rotation of polarized light is utilized to allow the incident laser light to undergo multiple passes through the nonlinear optical crystals so that it can be converted in wavelength with higher efficiency.

Abstract: In order to facilitate control of the polarization plane of a laser beam emerging from a surface-emitting-type semiconductor laser in a specific direction and to suppress occurrence of fluctuations and switching of the polarization plane depending on the optical output and the environmental temperature, a strain generating section (19) is arranged adjacent to a resonator (10B) of a semiconductor laser. The strain generating section (19) impresses anisotropic stress to the resonator (10B) to generate strain, resulting in birefringence and dependence of the gain on the polarization in the resonator (10A). This enables stabilized control of the polarization plane.

Abstract: A method and apparatus for generating single polarization fiber laser output are disclosed. A Bragg grating is non-destructively fabricated within the fiber to introduce differential loss between the two polarizations of the laser output. Curvature at the grating site into a tight loop further increases the differential loss between the available polarizations.