Abstract: A laser using a stimulated Brillouin scattering (SBS) mirror and a moving grating eliminates frequency walkoff of the reflected beams. A laser using a double-SBS mirror prevents frequency walkoff by having the other side of the SBS mirror act as a conjugate moving grating.

Abstract: Disclosed is an optical device producing single mode laser emission. The device includes a semiconductor laser which would normally emit a number of closely spaced longitudinal modes and a filter which receives light from the laser active layer and reflects light back to the active layer. The filter includes at least one thin, optically absorbing layer, a dielectric layer, and a reflecting layer. The thickness and refractive indices of the layers are such that the filter reflectivity has a number of narrow maxima, but only one which lies within the gain bandwidth of the laser. The width of the peak and the background amplitude between peaks is such that only a single longitudinal mode of the laser is allowed to oscillate.

Abstract: An improved folded cavity laser having particular application to holographic imaging is disclosed. The laser includes a lasing medium, such as for example a ruby rod, which is optically or electronically "pumped" in order to provide laser light. The medium includes first and second optical surfaces disposed at opposite ends of the lasing medium. A retro-reflecting roof mirror is disposed in optical alignment with the second optical surface of the lasing medium. A transverse mode selector is provided in optical alignment with the first surface of the lasing medium in order to surpress all transverse modes except those of a desired character. In the present embodiment, the transverse mode selector includes two apertures of approximately two millimeters diameter in order to obtain a laser output with a TEM.sub.00 mode.

Abstract: A picosecond short cavity dye laser utilizes a piezoelectric translator to vary the length of the optical cavity in the laser to allow continuous tuning of the output wavelength. The laser includes a pair of closely spaced generally flat mirrors forming an optical cavity. A laser dye solution is inserted into the cavity. The short cavity laser is pumped by pulses from another laser to produce picosecond output pulses. The piezoelectric translator, which is attached to one of the mirrors, moves the mirror to tune the laser as an applied DC voltage is varied. The piezoelectric tuning of the dye laser allows the laser to operate in a tunable single axial mode.

Abstract: The use of a Galilean telescope, situated in between the two lasing mediums that are located within the resonant cavity of a single longitudinal mode hybrid laser, increases the effective mode volume and, hence, the amount of lasing energy that can be derived from such a hybrid laser.

Abstract: Single longitudinal mode operation is achieved and maintained under CW and high speed (Gbps) current modulation conditions by a short coupled cavity laser including a short cavity semiconductor laser having two parallel mirror facets and a reflective surface spaced apart from and in predetermined relationship with one of the mirror facets. A short external cavity resonator is formed between the one mirror facet and the reflective surface. In general, the laser cavity length is related to the external cavity resonator length by the equation, nL=md, where nL is the effective optical length of the injection laser, d is the length of the external cavity resonator, and m is a positive number preferably between 2 and 10.

Abstract: In an optical system such as a ring laser gyroscope cavity, oscillations occur in many transverse modes. The desired modes are allowed to exist by suppressing undesired modes utilizing a light stop apparatus. One light stop is made by treating a dielectric mirror with an electron beam causing a phase change to occur to the undesired reflected waves. An alternative light stop is made by depositing an absorptive material on a dielectric mirror for absorbing some of the energy of the undesired modes. Both light stop embodiments are adjustable with respect to a laser wave in a resonant cavity.

Abstract: A distributed feedback semiconductor laser which has, in an active layer or an adjoining layer, first corrugations causing periodic refractive index variations in the travelling direction of light and performs laser oscillation by the injection of a current into said active layer portion. In accordance with the present invention, second corrugations are formed to be aligned obliquely to said first corrugations, thereby causing additional loss to the TM mode to permit oscillation in the TE mode alone.

Abstract: A waveguide laser having a square bore and an external modulator has its power doubled by proper relationship of a coupled cavity external to a cavity in the waveguide medium.

Abstract: Laser linewidth is controlled by reflecting a certain portion of the laser light back into the laser cavity. This control is accomplished by aligning the active layer on an electroabsorptive cell with the active layer of a semiconductor laser on a single substrate with a first waveguide therebetween. Light from the laser is guided by the first waveguide to the electroabsorptive cell whose light absorption is electronically controlled. The laser light propagates through the active region in the electroabsorptive cell and then is guided by a second waveguide to a reflection facet. The laser light is reflected by this reflection facet back through the waveguide-cell-waveguide-laser light path. The foregoing device can be formed using either a monolithic or a hybrid design.

Abstract: A high power, fundamental (TEMoo) mode gaseous laser is described having a discharge-confining bore tube which is provided with spaced-apart annular, inwardly-extending, radial projections or rings, which have inside diameters which match the fundamental mode diameter along the tube.

Abstract: A generator of a TE.sub.O mode wave beam, particularly adapted for confining plasmas, comprises a laser device for generating an electromagnetic wave having at least a TM.sub.O mode component. The TM.sub.O mode component is filtered by parallel sided plates or refractive surfaces disposed at the Brewster angle for the TM.sub.O component to derive an intermediate wave beam. A TM.sub.O -TE.sub.O mode converter shifts the TM.sub.O mode intermediate wave polarization vector by an angle of .pi./2 radians.

Abstract: A pulsed or CW laser is rapidly switched to operate at one or more selectable wavelengths by means of intracavity insertion of beam dispersion and focussing elements and an apertured focal plane mask and shutter assembly. The laser beam has an axis and is dispersed into components or sub-beams having different axes and representing different wavelengths, the sub-beams being focussed to substantially reduced diameters on the focal plane mask at points, respectively, at which apertures are formed. Movable shutters adjacent to the respective apertures control alternate opening of and closing of the apertures and selectively permit the laser to resonate at at least one of a plurality of wavelengths corresponding to that of the sub-beam passing through an open aperture. Mask apertures having very small diameters (<50 microns) and separations are achieved enabling switching between different operating wavelengths in milliseconds.

Abstract: A laser system for providing a rapidly steerable laser output beam. The laser system includes a phase conjugate reflector, laser gain medium and its associated pump source, an output coupling device, and an optical element which selectably controls the transverse lasing mode of the laser system. The components are arranged to form a laser oscillator between the phase conjugate reflector and the optical device, and is operated in such a manner that each selected transverse mode of laser operation generates an output beam from the system which has a different wavefront tilt. Accordingly, the output beam is steerable and is dependent upon the selected transverse mode which is currently lasing in the oscillator.

Abstract: There is provided a gain medium capable of radiating spectral lines differing in intensity as a function of position along a selected, gain-medium axis. A first resonator is arranged along a first optical axis that crosses the gain medium in a first region along the selected, gain-medium axis; the first resonator is adapted to establish a first optical mode that selectively lases one group of the spectral lines of the gain medium, namely a group thereof having high intensity within the volume in which the first mode is established. A second resonator is arranged along a second optical axis that crosses the gain medium in a second region along the selected, gain-medium axis; the second resonator is adapted to establish a second optical mode that lases a second group of spectral lines differing at least in part, from the first group. The second group of spectral lines has high intensity within the volume in which the second mode is established.

Abstract: A laser control apparatus for use with a laser having output radiation including an intermodal beat frequency and electric signal responsive means for controlling the light frequency from the laser; radiation responsive electric signal means adapted for association with said radiation for providing an electric signal having a frequency as a function of said beat frequency; and means for sensing changes in phase of the aforementioned signal and providing a second electric signal varying as a function thereof and being adapted for connection to the electric signal responsive means. The apparatus also includes a phase comparator and circuitry providing a phase lock of the first-named and reference signals.

Abstract: A semiconductor diode laser system with microwave mode locking. The system includes a semiconductor laser diode and an external reflector positioned to receive radiation that emits from the diode and reflects the same back into the diode, the microwave mode locking serving to modulate the radiation and the external reflector being properly positioned to return the radiation to the diode at a return time equal to the period of the drive signal or a submultiple thereof.

Abstract: A mode-locked gallium arsenide crystal laser has a cavity length equal to one-half its principal noise resonance wavelength and an electrode overlying a portion of the crystal, the remaining portion being a self-aligned region diffused or implanted with impurities comprising saturable absorbing centers. An anti-reflective coating is placed on a crystal facet facing an external mirror defining one end of the laser cavity. The resulting laser has improved power, frequency and temporal stability.

Abstract: An electronically switchable multiwavelength laser system comprises a lasing medium capable of generating a beam having at least two different wavelengths, an anisotropic birefringent component in optical alignment with the medium for refracting the beam into spatially separate polarized rays containing both wavelengths, and another electrically controllable anisotropic electrooptically active element, such as a Pockels' cell, having electrodes aligned with the respective rays and selectively energizable to block either ray to permit the laser to oscillate at the wavelength and polarization of the unblocked ray. The laser system includes highly reflective and partially transmissive mirrors defining the laser cavity and assisting in wavelength discrimination, the birefringent component and Pockels' cell being disposed in series between the lasing medium and the highly reflective mirror.

Abstract: An interferometrically tuned laser resonator for selectively resonating at desired wavelength or fluorescent line. A dielectric reflector having reflectance characteristics which shift toward shorter wavelengths at incident angles not normal thereto is rotatably mounted at one end of a laser cavity along its axis. Rotation of the reflector permits adjustment of the incidence angle to obtain maximum cavity gain at a desired fluorescent line over adjacent competing lines.

Abstract: Radiation at the frequency of a preselected absorbing resonance is produced by use of split and recombined interfering optical paths, arranged to produce near white light interference effects, and a preselected absorption medium disposed in one path of the interfering configuration. By association of this configuration with a laser oscillator, the regeneration characteristic of the laser oscillation can be determined by a peak in the reflected or transmitted wave produced by the cooperation of the optical interference system and the absorption medium. Use with standing wave, ring, and gain-switched transient lasers all can produce radiation essentially confined to the narrow absorption profile of a selected gas. Improved methods of laser chemistry and remote and close range gas detection are made possible by the new system.

Abstract: An output coupler for a high power laser employs the nonlinear effect of the 4-wave mixing process. The coupler adapts so that the coupling efficiency is dependent on the amplitude of the circulating fields within the optical cavity.

Abstract: The lasing action in an unstable optical resonator is controlled as to frequency by limiting frequency selectivity to an axis-near beam. The control is provided preferably outside the cavity by means of active or passive elements. A passive element returns a frequency-controlled beam into the cavity, an active element injects a control beam at the desired frequency.

Abstract: Apparatus is provided which includes a laser oscillator for providing light along a first optical path, and a laser amplifier for amplifying light along a second optical path. Means for coupling light between the first and second optical paths is disposed at one end of the laser amplifier, and a nonlinear medium disposed at the other end thereof for intercepting light provided along the first and second optical paths. The laser oscillator provides a single-mode laser beam along the first optical path which is made incident upon the nonlinear medium from substantially opposite directions. A portion of the beam from the laser oscillator is coupled through the laser amplifier, which forms a probe beam that samples the laser amplifier system. This beam further impinges upon the nonlinear medium and interacts with the counter-propagating laser beams therein.

Abstract: An optical beam mode controlled high power laser system having a resonator which incorporates therein as one of the reflective elements a high efficiency diffraction grating. Impinging upon the diffraction grating is not only the high power resonator laser beam, but also an injected mode controlling laser beam of preselected wavelength. Each beam is directed at the diffraction grating at a predetermined angle in order for the grating to direct away therefrom a combined beam of radiant energy having high power and being locked to the preselected wavelength of the injected laser beam. It is this high power laser beam of preselected wavelength which is output from the laser system.