Abstract: A fiber laser for producing high energy ultrashort laser pulses, having a positive-dispersion fiber segment and a negative-dispersion fiber segment joined in series with the positive-dispersion fiber segment to form a laser cavity. With this configuration, soliton effects of laser pulse circulation in the cavity are suppressed and widths of laser pulses circulating in the cavity undergo large variations between a maximum laser pulse width and a minimum laser pulse width during one round trip through the cavity. The fiber laser also provides means for modelocking laser radiation in the laser cavity, means for providing laser radiation gain in the laser cavity, and means for extracting laser pulses from the laser cavity.

Abstract: A semiconductor laser (10) having an external cavity used for coherent frequency and time domain reflectometry is provided. The laser (10) provides a very stable single longitudinal mode characteristic, a very narrow lasing linewidth, and a very low noise optical output. The laser (10) includes a semiconductor optical amplifier (14) emitting a coherent light beam from one facet, a phase modulator (22) receiving the coherent light beam and linearly varying an optical frequency of the laser, and an etalon (32) selecting and stabilizing one longitudinal mode of the laser cavity for lasing, narrowing the linewidth and reducing the noise. A computer-controlled and piezoelectric actuated wavelength-selective grating (58) varies the length of the laser cavity and thereby tuning the optical frequency of the selected longitudinal mode to track the transmission frequency of the etalon by maintaining maximum power intensity thereby stabilizing the selected mode.

Abstract: A single-longitudinal-mode laser comprises a laser medium, an etalon, and a resonator. The etalon is located in the resonator in a state such that two light passage end faces of the etalon, which are parallel to each other, may make a predetermined angle with respect to a resonator axis. The longitudinal mode of the etalon coincides with a gain peak wavelength of the laser medium. The single-longitudinal-mode laser is free from the problems in that the threshold value of the pumping power for the oscillation of the laser becomes large, in that the output power of the laser becomes low, in that the profile of the radiated beam becomes distorted, and in that the single longitudinal mode characteristics become bad.

Abstract: The invention relates to a microwave generator which is characterized by a multimode fiber ring laser (1) having associated with it an intermediate-frequency device (22) which generates the microwave frequency by forming the difference of the frequencies assigned to the modes.

Abstract: A self-aligned, monolithic, solid microlaser with passive switching by a saturable absorber and a production process therefor. The cavity for the microlaser has a solid active medium, a saturable absorber, an entrance mirror and an exit mirror, wherein the saturable absorber is a thin film of saturable absorbent material directly deposited on the solid active medium.

Abstract: An active etalon comprising a laser gain chip interposed between an input mirror and an etalon end mirror is provided. In an intracavity frequency-doubled solid-state laser, a pump source emits pump radiation which passes through the input mirror and into the laser gain chip. The laser gain chip lases in response to the pump radiation to produce fundamental laser light. The etalon end mirror reflects a portion of the fundamental laser light back into the laser gain chip and transmits the remaining portion of the fundamental laser light into the laser cavity. The input mirror reflects substantially all of the fundamental laser light into the laser gain chip. The portion of the fundamental laser light which passes through the etalon end mirror may be frequency doubled by a frequency doubler chip and a portion thereof transmitted through the front end of the laser cavity to form the output laser beam.

Abstract: A phase shift device for a laser beam has a circular first area transparent so the laser beam and a second area provided around the first area and transparent to the laser beam. The first and second areas generate a phase difference for example 180.degree. in the passing light beams. The phase shift device is positioned for example at a beam waist of a laser scanning apparatus to form a beam spot of a diameter smaller than that defined by the numerical aperture of the imaging optical system. Structure of a laser apparatus employing such phase shift device is also disclosed.

Abstract: An apparatus and method for producing laser radiation from a vertical cavity semiconductor laser are disclosed. A preferred embodiment includes a quantum-well region formed over a semiconductor substrate. A first reflective surface is formed over the quantum-well region, and a second reflective surface is formed over the substrate, opposite the first reflective surface, forming a laser cavity. The quantum-well region is optically pumped, producing laser oscillation. The absorbed pump power causes a thermal lensing effect within the semiconductor material, stabilizing the transverse spatial mode of the laser cavity. The invention has applications in optical communication and laser printing.

Abstract: There is provided a turbo blower for lasers which is capable of effectively cooling a shaft and bearings thereof. Oil held in a shaft support member is drawn up via an oil inlet port by a centrifugal force generated by rotation of the shaft, and passes through a cooling oil passage extending through the shaft to be discharged from an oil outlet port provided below an upper one of rolling bearings as the bearings. The oil discharged from the outlet port returns via an oil return passage to an oil sump. While passing through the oil return passage, the oil is cooled by a coolant circulating through an coolant passage. Further, part of the oil discharged from the oil outlet port is supplied to the upper one of the bearings for lubrication. On the other hand, part of the oil held within the shaft support member is drawn up along a tapered portion of an oil suction head by the centrifugal force generated by rotation of the oil suction head for lubrication of a corresponding one of the rolling bearings.

Abstract: A solid-state laser comprises a pump diode for generating pump radiation and transmitting the pump radiation into a laser cavity. The pump radiation passes through an entrance mirror and enters a laser gain chip which lases to produce fundamental laser light. The fundamental laser light passes through a harmonic reflector and a first dispersive element and is frequency doubled by a frequency doubler chip to produce harmonic laser light. The harmonic laser light passes through a second dispersive element and impinges on a mirrored surface. A portion of the harmonic laser light passes through the mirrored surface to form the output beam of the laser. The remaining portion of the harmonic laser light is reflected back into the laser cavity. First and second dispersive elements control the phase of the harmonic laser light in the laser cavity such that substantially all of the harmonic laser light is in-phase when the harmonic laser light impinges upon the mirrored surface.

Abstract: A semiconductor light emitting device has a light emitting layer portion comprising AlGaInP layers formed on a GaAs substrate. A light reflecting layer portion comprising alternately laminated layers with different refractive indices is provided between the GaAs substrate and the light emitting layer portion. The light reflecting layer portion comprises Al.sub.w Ga.sub.1-w As.sub.1-v P.sub.v layers (where: 0.ltoreq.w.ltoreq.1, 0<v.ltoreq.0.05 w). An active layer which constitutes the light emitting layer portion comprises an (Al.sub.y Ga.sub.1-y).sub.0.51 In.sub.0.49 P layer (where: 0.ltoreq.y.ltoreq.0.7).

Abstract: A CPM mode-locked fiber ring laser including an ion-implanted semiconductor saturable absorber providing sub-picosecond pulses at rapid repetition rates. The laser provides compact, turn-key capability and is polarization insensitive.

Abstract: In an optical wavelength converting apparatus, a fundamental wave impinges upon a crystal of a nonlinear optical material, the type II of phase matching between the fundamental wave and its second harmonic is effected, and the second harmonic of the fundamental wave is thereby radiated out of the optical wavelength converting apparatus. Two crystals constituted of the same material are employed as the crystal. The two crystals have equal lengths and are located in orientations such that corresponding optic axes may be shifted 90.degree. from each other. The optical wavelength converting apparatus yields the second harmonic having the maximum possible output power and yet can be kept small in size and low in cost.

Abstract: A hollow member or an envelope 7 housing a laser medium 3 having a reflective coating 31 on one surface thereof, a non-linear optical crystal 4 and an output mirror 5 having a reflective coating 51 on one surface thereof has a thin-walled portion 71 in its center portion. The air-tightly sealed envelope 7 is evacuated through an exhausting pipe 9 and, after sealing the pipe 9, a laser resonator unit 70 is obtained. By arranging a laser diode unit 10 on the reflective coating 31 of the laser medium 3 and integrating it by a connecting member 17, a long life-time, compact solid state laser excited by laser diode is obtained.

Abstract: A semiconductor light emitting element has a semiconductor laminating structure formed on a semiconductor substrate and having a junction portion formed in parallel with a semiconductor substrate face; a light generating portion formed in the vicinity of the junction portion such that an electric current can be injected into the light generating portion; a light emitting end face approximately perpendicular to the junction portion and approximately having an arc or hyperbolic shape in a direction parallel to the semiconductor substrate face; and an electrode for electric current injection formed in an upper portion of the semiconductor laminating structure and arranged in a position separated from at least a center of curvature of the arc light emitting end face. The semiconductor light emitting element has a shape of the light emitting portion and a layer structure capable of controlling a radiant angle of light.

Abstract: A stripline laser has its HF voltage distribution optimized by grounding springs. A grounded electrode is connected to an outside wall with electrically conductive connector elements, and is preferably connected thereto at a plurality of locations along its axial extent.

Abstract: An apparatus confocally delivers to an object an infrared CO.sub.2 laser beam and a highly visible (e.g., blue-green) aiming beam. The beams from the two lasers are coaxially superimposed by means of a plate which transmits visible light and reflects infrared light. The resulting two coaxial beams are then guided to the object by means of reflective surfaces. Reflective beam guidance provides coincident focus of the infrared and aiming beams with unprecedented precision and also permits the combination of an infrared beam with a highly visible aiming beam.

Abstract: A frequency tunable waveguide extended cavity laser formed with a laser diode, a channel waveguide comprising an electro-optic material, a frequency tunable Bragg grating reflector formed in or on the channel waveguide and a pair of conducting electrodes. The frequency of radiation produced by the frequency tunable waveguide extended cavity laser is adjusted so as to be at a desired frequency by applying a voltage to the conducting electrodes. The device further incorporates a waveguide nonlinear optical frequency converter to produce frequency convened radiation at a higher frequency. Feedback means are included for dynamically controlling the desired frequency so as to be at a frequency for optimum frequency conversion.

Abstract: A laser capable of generating polychromatic or whim light radiation is realized by employing a diffraction grating and reflecting element as the ends of a simple laser resonator cavity. The dispersive element either solely or in combination with an intracavity lens is arranged such that each wavelength component of the white light radiation is amplified by a different portion of the active medium. Forced oscillation or positive feedback for each wavelength component is achieved by operating the diffraction grating in an auto-collimation configuration.

Abstract: A laser light beam generating apparatus includes at least one light beam source, first and second reflectors, a non-linear optical crystal element and an actuator. The light beam source emits a light beam. The non-linear optical crystal element is provided between the first reflector and the second reflector. A light beam emitted from the light beam source is incident on the non-linear optical crystal element through the first reflector. The actuator actuates at least one of the first and second reflectors along an optical axis of the light beam emitted from the light beam source.

Abstract: Optical guiding of intense laser pulses over a distance of more than one Rayleigh length in a plasma is discussed herein using a multi-pulse technique. The first pulse or pulse sequence prepares a shock-driven, axially-extended radial electron density profile which guides a second pulse or sequence of pulses. The profile is also capable of guiding x-rays. The channel will support mode structure exactly analogous to that of an optical fiber waveguide. The method provides a means for guiding of a high intensity optical laser pulse or x-rays over distances well in excess of a Rayleigh length. The distances over which guiding occurs is limited only by the length of the preformed plasma and absorption and possible backscattering of the guided EM radiation. Applications of the method allow for compact x-ray laser devices and electron particle accelerators.

Abstract: Controlled, high-power laser oscillator. A single laser gain medium is used to efficiently generate high-power, controlled laser light without exposing the control elements to high-power radiation. The control element or elements are separated from the oscillator gain volume by a separator optic which permits only a portion of the energy from the gain volume to enter the region of the control elements, laser light having the desired characteristics being returned to the gain volume through the separator optic. Energy not entering the control region exits the laser as oscillator output energy in order to obtain high efficiency.

Abstract: A laser apparatus includes an unstable resonator having a total reflection mirror and a take-out mirror, and further includes shading means for shading a disturbed phase portion of a laser beam so as to derive exclusively a light having a uniform phase by shading the disturbed phase portion of the beam emitted from the resonator or the beam in the resonator.

Abstract: A laser is capable of working at a wavelength L.sub.2 from an active material capable of generating radiating emissions at at least two wavelengths L.sub.1 and L.sub.2, through the presence of a semiconductor plate in the laser cavity. Notably, the laser can generate wavelengths ranging from 1.4 .mu.m to 2 .mu.m, a range in which the optical damage threshold of the eye is high, from an Nd.sup.3+ doped YAG having numerous radiating emission wavelengths ranging from 0.946 .mu.m to 1.8 .mu.m.

Abstract: The optical modulator of the invention comprises an electro-optic material or magneto-optic material EOD which modulates optical energy in accordance with an applied electromagnetic waveform. The electromagnetic waveform impressed in the EOD is controlled by a light activated switch, or switches, which varies the magnitude of the electromagnetic waveform to the EOD by switching portions of a transmission line (of which the EOD forms all or at least a part of the dielectric) in or out. The switch, or switches, may be configured between segments of one of the conductors of the transmission line and may overlay the electro-optic dielectric material. The transmission line may include a plurality of sections, each charged to a selected voltage, so that when switched by said light activated switches, the electromagnetic waveform to the EOD is controlled. When used in a laser cavity, the optical modulator can control the output of the laser cavity in response to optical input control signals.

Abstract: There is disclosed a solid-state laser resonator capable of outputting a high power linearly polarized laser beam, in which a laser beam subjected to the birefringence in the laser resonator is effected to minimize a component of the laser beam which is orthogonal with the direction of polarization definable by a Brewster plate upon traversing a quarter-wave plate, to enable the linear polarization output distribution of the laser beam to become uniform. With this, the emission efficiency and the output power of a linearly polarized laser beam are much improved.

Abstract: An excimer laser apparatus is provided with a compact high efficiency dust particle removal means which is capable of maintaining the windows clean with only a small volume of purging gas, and which prevents deterioration of aperture masks without having to increase the cavity length or risking the possibility of leakage from piping connections. The excimer laser apparatus uses, as dust particle removal means, filters (13a and 13b) made of metal or ceramic which is non-reactive with fluorine. A ground potential dust collector can be provided at a downstream side of a static dust particle remover, having an anode and a cathode, for collecting any dust particles which have passed through the static dust particle remover.

Abstract: Light beams output from active layer stripes of a semiconductor laser array are individually collimated in a GRIN lens array and are converged, in a aspheric lens, into a beam spot, to thereby end-pump a solid state laser with high efficiency.

Abstract: A method is disclosed for establishing an optical link between two lasers via an optical fiber by directing the output from one laser through an optical fiber and into a second laser and vice vera. Before insertion into the lasers, the output from the respective fibers is phase conjugated in a double phase conjugate mirror. Thus, the disclosed method and apparatus provide a combination of fiber optics, used to transport the light from the lasers, and optical phase conjugation, used to compensate for fiber-induced distortions.

Abstract: A laser light beam generating apparatus includes at least one light beam source, first and second reflectors, a non-linear optical crystal element and an actuator. The light beam source emits a light beam. The non-linear optical crystal element is provided between the first reflector and the second reflector. A light beam emitted from the light beam source is incident on the non-linear optical crystal element through the first reflector. The actuator actuates at least one of the first and second reflectors along an optical axis of the light beam emitted from the light beam source.

Abstract: A first gas in a laser cavity is ionized by an electrical discharge in the cavity as a step in producing an energy radiation. Debris (particulates) is produced during the formation of the energy radiation. The radiation and the debris move toward an optical element in the cavity. The optical element may be a window or a mirror. The debris tends to deposit everywhere in the cavity, including on the optical element, thereby dirtying the optical element. This inhibits the efficiency in the laser operation. A clean gas is directed into the cavity through a passage at a position displaced from the optical element. The clean gas then passes in the cavity through an orifice further from the optical element than the passage. The flow of the first gas through the orifice creates a venturi effect on the clean gas to insure that the clean gas will move away from the optical element. In this way, the clean gas inhibits the first gas and the debris from moving to the optical element.

Abstract: A high output, compact laser having a multi-line spectral output and an internal mirror, integral resonator design is disclosed. The laser structure comprises a laser tube containing a resonant cavity, an output coupler and an active medium. A power supply and coolant assembly are coupled to the laser tube. The coolant assembly is a hybrid coolant scheme wherein one portion of the tube is cooled by circulating water coolant, while another portion or portions are cooled by circulating air. In one aspect, the laser tube includes a ceramic bore surrounded by a sheath sealed at a first end and a second end of the ceramic bore, and coolant is provided between the sheath and the bore. In a further aspect, forced air is directed over a reservoir portion of the tube. The reservoir portion may be manufactured from a metallic alloy comprised of nickel iron cobalt with copper cooling fins brazed to the reservoir to increase thermal cooling efficiency and isothermal distribution of heat.

Abstract: Lasing threshold for a whispering mode laser is reduced by appropriate placement of a reflector. A reflector parallel to, and within a wavelength distance of, the disk decreases radiation loss due to imperfect internal reflection. Enhancement is calculable on the basis of destructive interference between reflected and direct radiation.

Abstract: A coherent light source, such as a laser oscillator and a monolithic MOPA device, and a broad area light amplifying device, all characterized by having a leaky waveguide beam expander coupled thereto for expanding a single mode beam into a wide light beam in a coherent manner. The beam expander comprises an elongated antiguide core of a first refractive index and a radiated-wave receiving region of a higher refractive index to receive lightwaves laterally radiated from the antiguide core. This beam expander can be located at an output end of a single mode laser oscillator to receive and expand the beam, at an input end of a broad area optical power amplifier to allow the amplifier to accept a narrow input beam, or between the laser oscillator and power amplifier in a MOPA device. The beam expander elements can also be located partially or entirely within the resonant optical cavity of a laser oscillator.

Abstract: This invention covers apparatus for providing a compact, high resolution waveguide optical demultiplexer or spectrometer for application in optical communications. With this invention, incoming light composing many discrete wavelengths or optical channels is spectrally resolved by the waveguide demultiplexer such that the wavelength channels are separated spatially. The two major elements of this invention are a waveguide having a partial mirror along its length to reflect optical frequencies therein, and an optical resonator where one of its resonating mirrors is the partial mirror of the waveguide. Selected frequencies are then extracted from the waveguide and resonated in the resonator.

Abstract: An assembly for use in a laser instrument which produces a plane of laser light by reflection from a cone. The assembly includes a weak focusing lens which improves the control over the planarity of the plane of light produced. Because it is weak, the weak focusing lens can be positioned over a relatively large distance to produce slight changes in the focus of the beam which is reflected to produce the plane of light. Critical, time consuming, and expensive manufacturing requirements can be relaxed, while improved performance results in superior laser instruments.

Abstract: A control system for a laser includes a resonator cavity having a displaceable control mirror, a drive for displacing the control mirror, sensor devices located to sense the position of the outputted laser beam, and a control circuit connected to the sensor devices for measuring the positional deviation of the outputted laser beam from a reference position and for controlling the drive in response thereto to angularly displace the control mirror to correct the positional deviation.

Abstract: A pulsed laser utilizing an oscillating or rotating intra cavity photon deflector means to extract a beam transverse to the long axis of the resonator from intracavity power. The moving photon deflector is supported and set into motion either mechanically or electromagnetically within the resonator and in the path of lasing photons, thereby intercepting and deflecting photons out of the resonator.Movement of the deflector within the path of lasing photons results in the circumferential deflection of photons with the most intense concentration being deflected from that portion of the surface of the deflector which first intercepts the circulating intracavity photon stream. As lasing photons are deflected from the leading edge of the deflector, lasing action is instantaneously reestablished after the trailing edge moves through the photon stream. Wherever the deflector does not intersect the normal trajectory of photons in the laser cavity, lasing action is automatically reestablished.

Abstract: A laser source arrangement is provided for use in a laser instrument of a kind used to transmit a scan pattern to a target which is spaced from the laser instrument and to detect light reflected from the target. The laser source arrangement preferably comprises a laser diode for producing a laser beam used to form the scan pattern. The laser diode is characterized by astigmatism which is subject to variation with the temperature of the case of the diode. The arrangement further includes drive apparatus for driving the laser diode in a pulsed mode having a duty cycle which reduces the astigmatism and substantially controls the temperature dependence of the astigmatism. Optics are also provided for statically correcting the astigmatism of the laser diode.

Abstract: A diode laser and optical system uses the minimum number of elements to obtain a small diameter beam (1 mm). A large numerical aperture lens collimates the full energy from the diode and the oval shaped output of the collimator is corrected for astigmatism by means of a cylinder lens and made circular by two identical prisms arranged to receive the corrected, collimated beam directly at a right angle surface of the first prism and transmit the beam after deflection to the second prism further which demagnifies the beam producing the round (.ltoreq.1 mm diameter) beam spot output of the laser. The output beam is well collimated (1 mRad) and wave front aberration is diffraction limited. The spot size at 50 feet distance is maintained. In order to hold total Gaussian distribution energy, the prisms are coated with a multilayer dielectric thin film eliminate reflection and to transmit the TE mode wave without loss at the Brewster angle.

Abstract: An object of this invention is to provide a pulsed laser beam source device which is easy to handle and is operative stably. Pumping light is irradiated to a laser medium from a light source for optical pumping. The stimulated laser medium pumps radiation of a set wavelength. This radiation is stimulated to be amplified while reciprocating between resonator mirrors. A multi layer film is inserted in an optical path of the radiation. Feeble light of the radiation from the laser medium is absorbed by the multi-layer to be weaker, and that part of the radiation having intensities above a set intensity is compressed in terms of time to be emitted outside. The emitted radiation has a very short pulse duration.

Abstract: A method and apparatus for pumping a coolant through a laser cavity to cool the laser. The apparatus has a titanium housing and a casing containing a rotatable titanium hollow shaft. A titanium impeller is located at one end of the shaft within the housing and rotates with the shaft to pump the fluid through a laser. Disposed within casing and attached to the shaft are a plurality of permanent magnets. External to the casing are stator windings through which current flows to create a magnetic field that rotates the permanent magnets, shaft and impeller. When the impeller is rotated, the coolant is passed through the housing and to the laser. The impeller also forces the fluid passing through the shaft and into the casing to cool and lubricate the pump. The magnets are encased in a titanium sleeve attached to the titanium shaft to prevent the coolant from contacting with the magnets.

Abstract: Whenever any laser is interfaced with any type of optics there is always backscatter back into the laser. For diode lasers this backscatter makes it emit chaotic radiation where the frequency spectrum is broad and contains many different frequencies. This means that the laser has limited use as a source of information transfer in fibers. This weakness can be overcome, by driving the laser with an external cavity filled with a Kerr material. The addition of a Kerr material in the external cavity suppresses the chaos, or coherence collapse. Thus the new apparatus of laser plus external cavity filled with a Kerr material increases the stability of the diode laser.

Abstract: A speckle-free display system using coherent light is disclosed. The light is directed through a spinning diffusing element to illuminate a spatial light modulator. The spinning element is operable to move the interference patterns around the screen at a speed where it is undetectable to the human eye. The diffusing element is more than likely comprised of ground glass.

Abstract: An apparatus for wavelength conversion of laser light which can prevent optical destruction of a wavelength conversion element and achieve a high wavelength conversion efficiency. The apparatus for wavelength conversion of laser light has an optical focusing system for focusing the input laser light on the wavelength conversion element in an optical cavity, which optical focusing system makes the cross-sectional shape of a light beam non-circular, for example, elliptical.

Abstract: A phase conjugation mirror (20) for use in a phase conjugation resonator (1). The phase conjugation mirror provides a nonlinear resonance enhancement for a coherent optical signal incident thereon. The phase conjugation mirror is comprised of a semiconductor material having a characteristic bandgap energy selected to be at an absorption bandgap edge, or slightly greater than the absorption bandgap edge, for the coherent optical signal.

Abstract: A laser alignment apparatus is provided for generating a plurality of mutually perpendicular laser beams. The apparatus further includes rotatable beam diverters selectively hingedly moveable into or out of positions for diverting one of the laser beams. The beam diverters may be rotated about an axis coincident with the associated laser beam for sweeping laser planes. The laser planes swept by the respected beam diverters are mutually perpendicular to one another, and each laser plane is parallel to the other beams generated by the apparatus.

Abstract: A tunable laser is described in which the gain element is fabricated to produce wavelength dispersion within the laser resonator cavity. Specifically, the laser gain element has Brewster angled entrance and exit faces which allow it to operate as a wavelength dispersive element while simultaneously performing the functions of an optical gain element within a laser cavity. Wavelength tuning is effected by angular rotation of one of the end reflective elements in the cavity. By using suitable dispersive materials for the laser gain element no additional tuning elements are required providing high efficiency, low threshold laser operation for a variety of optical excitation methods. The laser gain element replaces other discrete intracavity laser tuning means required for tunable lasers, including prisms, diffraction gratings, and birefringent filter elements.

Abstract: A laser light generating apparatus comprises a light source for generating an exciting light beam, a condenser lens for converging the exciting light beam from the light source, a laser medium for generating a laser light of first wavelength by the radiation of the exciting light beam supplied thereto through the condenser lens, a nonlinear optical crystal element for generating a second laser light by the radiation of the first laser light generated from the laser medium, a pair of reflecting means for constituting a laser resonator together with at least the laser medium and the nonlinear optical crystal element, a deflecting element for deflecting an optical axis of the second laser light emitted from reflecting means provided at the emitting side of the pair of reflecting means, detecting means for detecting a part of a light beam output from reflecting means disposed at the output side of the pair of reflecting means, control means for controlling the light source on the basis of a detected output from t

Abstract: A vertical-cavity, surface-emitting semiconductor laser having a substrate, an active layer of a semiconductor material which is adapted to generate light on a surface of the substrate, a pair of mirrors at opposite sides of the active layer and means for expanding the diameter of the output beam. Such means include a spacer layer of an optically passive material between the active layer and at least one of the mirrors, and mirror layers of reduced difference in index of refraction, interface layers having intermediate indices of refraction placed between mirror layers, in either case expanding the effective optical cavity length to at least 100 times the thickness of the active material in the active layer. Another means is anti-waveguiding which directly expands the diameter of the beam. The expanded cavity provides an output beam of larger diameter while maintaining stable single mode emission. The spacer layer may be a separate layer or region over the substrate or at least a portion of the substrate.