Abstract: A three-dimensional measurement method comprises: converting a total number of levels of sawtooth fringes into a Gray code and acquiring a sawtooth slope coefficient; fusing the coefficient into a sawtooth fringe image to generate a target sawtooth fringe pattern; projecting each target sawtooth fringe pattern to a surface of a to-be-measured object through a projector, and collecting a deformed target sawtooth fringe pattern on the surface through a camera; solving a Gray code of each sawtooth fringe collection pattern at each pixel point according to a differential property of adjacent pixels in each sawtooth fringe collection pattern and solving a fringe level and a wrapped phase at each pixel point; calculating an absolute phase at each pixel point according to the fringe level and the wrapped phase at each pixel point, and reconstructing a three-dimensional point cloud through triangulation ranging to obtain a three-dimensional model of the to-be-measured object.

Abstract: A multi-passage cavity made up of the assembly of a planar mounting and first and second reflective optical elements each having a main face arranged opposite one another, the main face of at least one of the optical elements being microstructured to modify the phase of incident luminous radiation that is reflected several times on each of the optical elements to form transformed radiation, the multi-passage cavity includes precisely three assembly interfaces.

Abstract: A transmission device includes: a first wavelength conversion circuit configured to convert a wavelength band of a wavelength multiplexed signal light based on a wavelength of a second excitation light by performing four-wave mixing on the second excitation light and the wavelength multiplexed signal light inputted to a second nonlinear medium; and a second wavelength conversion circuit configured to convert the wavelength band of the wavelength multiplexed signal light based on a difference between frequencies of a third excitation light and a fourth excitation light by performing four-wave mixing on the third excitation light and the fourth excitation light and the wavelength multiplexed signal light inputted to a third nonlinear medium.

Abstract: A system and method are disclosed for providing time reversal situational awareness. An input filter receives an input signal at a first frequency and a pump signal at a second frequency and blocks signals at a third predetermined frequency. A non-linear medium performs a second order operation or a third order operation on the filtered input signal and the filtered pump signal to produce an output signal at the third frequency, the third frequency lower than the first frequency and the second frequency. An output filter is coupled to receive the output signal from the non-linear medium and blocks signals at the first frequency and at the second frequency such that a filtered output signal is generated that is a phase conjugate signal which provides time reversal situational awareness.

Abstract: Display devices can be used to provide display functionality in dynamic autostereoscopic displays. One or more display devices are coupled to one or more appropriate computing devices. These computing devices control delivery of autostereoscopic image data to the display devices. A lens array coupled to the display devices, e.g., directly or through some light delivery device, provides appropriate conditioning of the autostereoscopic image data so that users can view dynamic autostereoscopic images. Methods and systems for calibrating a hogel display are also described, including generating calibration hogel data corresponding to a calibration pattern; generating a hogel light field from the calibration hogel data; detecting the hogel light field; and determining calibration data by analyzing a set of hogel properties in response to detecting the hogel light field.

Abstract: An optical network is suggested, comprising a first set of optical fibers, a multimode multiplexer, a multimode amplifier, a multimode demultiplexer, and a second set of optical fibers, wherein the first set of optical fibers is connected via the multimode multiplexer to the multimode amplifier and wherein the multimode amplifier is connected via the multimode demultiplexer to the second set of optical fibers. Accordingly, an optical network element is provided.

Abstract: A system for optical wireless power transmission to a power receiving apparatus generally situated in a mobile electronic device. The transmitter has an optical resonator with end reflectors and a gain medium positioned between them, such that an optical beam is generated. The frequency of the beam is selected such that it is absorbed by almost all transparent organic materials in general use. A beam steering unit on the transmitter can direct the beam in any of a plurality of directions, and the beam is absorbed on the receiver by means of an optical-to-electrical power converter, through a low reflection surface. The band gap of this power converter is selected to be smaller than that of the gain medium. The receiver has a voltage converter including an inductor, an energy storage device and a switch. A beam steerer controller ensures that the beam impinges on the receiver.

Abstract: A hologram layer (13) is irradiated by light from an optical element (10). The hologram layer (13) is provided with a first hologram (14) that diffracts in a predetermined direction, from among incident light from the optical element (10), X-polarized light in which the polarization component is in a specific direction and emits the light as X-polarized light of a first phase state (P1), and a second hologram (15) that both diffracts in the same direction as the X-polarized light of the first phase state (P1) and moreover at an equal radiation angle, from among incident light from the optical element (10), Y-polarized light in which the polarization component is in a direction orthogonal to that of the X-polarized light and converts it to X-polarized light, and emits the light as X-polarized light of a second phase state (P2) that differs from the first phase state (P1).

Abstract: An apparatus, comprising a substrate with a planar surface an optical power splitter on the surface, and an optical power combiner on the surface. The apparatus also comprises pairs of optical waveguides located on the planar surface, each waveguide of the pairs connecting a corresponding output of the optical power splitter to a corresponding input of the optical power combiner. The apparatus also comprises a plurality of optical resonators located on the surface, each of the resonators of the plurality being evanescently coupled to a corresponding one of the waveguides. For each particular one of the pairs, resonant frequencies of the optical resonators coupled to the waveguides of the particular one of the pairs are about the same. Resonant frequencies of each pair of the optical resonators coupled to two of the waveguides in different ones of the pairs are different.

Abstract: A readout circuit for an image sensor is disclosed. At least one column amplifier (CA) generates a CA reset signal when the column amplifier is reset. A capacitor and a switch are configured to receive a column of the image sensor. A multiplexer is coupled between (a) the capacitor and the switch and (b) an input of the column amplifier. A correlated double sampling (CDS) circuit is used for controllably receiving an output of the column amplifier.

Abstract: An improved method and apparatus for passively conjugating the phases of a distorted wavefronts resulting from optical phase mismatch between elements of a fiber laser array are disclosed. A method for passively conjugating a distorted wavefront comprises the steps of: multiplexing a plurality of probe fibers and a bundle pump fiber in a fiber bundle array; passing the multiplexed output from the fiber bundle array through a collimating lens and into one portion of a non-linear medium; passing the output from a pump collection fiber through a focusing lens and into another portion of the non-linear medium so that the output from the pump collection fiber mixes with the multiplexed output from the fiber bundle; adjusting one or more degrees of freedom of one or more of the fiber bundle array, the collimating lens, the focusing lens, the non-linear medium, or the pump collection fiber to produce a standing wave in the non-linear medium.

Abstract: There is provided an optical device including a plurality of polarizers that are arranged along a propagation direction of incident light, where the plurality of polarizers have transmission axes of substantially the same direction, a phaser that is provided between the plurality of polarizers, where the phaser has a retarded-phase axis forming a predetermined angle with the transmission axes of the plurality of polarizers, and a phase modulator that is provided adjacent to the phaser along the propagation direction, where the phase modulator has a retarded-phase axis of substantially the same direction as the retarded-phase axis of the phaser. Here, a phase difference generated in the incident light by the phase modulator is temporally adjusted such that the optical device transmits light in different wavelength ranges at different timings.

Abstract: A guiding nonlinearity cell. The novel nonlinearity cell includes a nonlinear medium and a waveguide adapted to guide input electromagnetic energy through the nonlinear medium. In an illustrative embodiment, the cell includes a thin layer of a liquid or solid nonlinear medium disposed between two parallel plates adapted to guide energy through the length of the medium by total internal reflection. The plates can be made from a material having a refractive index less than a refractive index of the medium to provide total internal reflection within the liquid, or they can be made from a material matching the refractive index of the medium such that outer walls of the plates provide total internal reflection, allowing energy to leak into the plates.

Abstract: A thermal nonlinear cell and method. The cell includes a substantially planar nonlinear medium and a mechanism for removing thermal energy from the medium in a direction substantially orthogonal to said medium. In one embodiment, the mechanism for removing thermal energy is a thermally conductive window mounted adjacent to the medium. Preferably, the mechanism includes plural thermally conductive windows between which the nonlinear medium is disposed. In the best mode, the windows are sapphire and the nonlinear medium is a fluid. The windows and the medium are transmissive with respect to first and second beams that interfere with each other and create an interference pattern in the cell. The interference pattern is sampled by a sampling hologram created within the multiple layers of the medium. The interference pattern is used via a sampling hologram to create a phase conjugate of a signal beam. The windows move thermal energy from the medium in a direction transverse to the longitudinal axis of the medium.

Abstract: Simultaneous amplitude and phase control of ultrafast laser pulses using a single, linear (one-dimensional) liquid crystal spatial light modulator is described. Amplitude shaping is accomplished by writing a high-frequency phase grating having a spatial period much smaller than the spectral focus (over-sampling), onto the modulator, and diffracting away selected frequencies in a controllable manner, while spectral phase control is imparted by adding an appropriate slow phase bias to the modulator. The close pixel spacing, large number of pixels, and small footprint of the reflective spatial light modulator employed with an angular wavelength dispersive element in a folded Martinez stretcher, enables a simple and compact apparatus to be achieved. The high reflectivity of the spatial light modulator results in a highly efficient pulse shaper when either a prism or diffractive grating is used for the angular dispersive element.

Abstract: An adaptive optics system is provided. The system includes a light source, a pair of deformable mirrors and a detection module. The light source is configured to provide an outgoing beam. The outgoing beam has an amplitude and a phase. The first deformable mirror is configured to reflect the outgoing beam and adjust its associated amplitude. The second deformable mirror is configured to reflect the outgoing beam reflected from the first deformable mirror and adjust its associated phase. The detection module is configured to detect an incoming beam and the reflected outgoing beam from the second deformable mirror and generate certain signals. The signals are used to control the first and second deformable mirrors such that the amplitude of the outgoing beam is the same as that of the incoming beam and the phase of the outgoing beam is opposite that of the incoming beam.

Abstract: A high extraction efficiency laser system. The novel laser system includes a master oscillator for providing a laser beam, an amplifier adapted to amplify the laser beam, and an aberrator for aberrating the laser beam to prevent the formation of caustic intensity patterns within the amplifier. In an illustrative embodiment, the laser system also includes a depolarizer disposed between the master oscillator and the amplifier to reduce the contrast of speckle intensity patterns in the amplifier, and a mechanism adapted to rotate or otherwise move the aberrator to time-vary the aberrations in the beam in order to increase the spatial homogenization of saturation and extraction patterns in the amplifier. In a preferred embodiment, the coherence length of the beam is also shortened to reduce interference fringes in the amplifier.

Abstract: Terahertz radiation generation systems and methods are implemented using a variety of methods and devices. According to an example embodiment of the present invention, method for generating terahertz radiation is implemented where the wavelength of an optical pulse is controlled, and where the wavelength is controlled as a function of the group velocity dispersion in a nonlinear crystal. The optical pulse is then directed through consecutively-inverted parallel domains in the nonlinear crystal.

Abstract: An optical amplification apparatus includes a polarizing beam splitter for reflecting a portion of an incident light and transmitting a remaining portion of the incident light, depending upon a polarized state of the incident light, at least two optical amplification means each including a first polarizing plate which makes polarized states of the light before and after the light reflected from the polarizing beam splitter reciprocatingly passes through the first polarizing plate, to be orthogonal to each other, an amplitude division plate for amplitude-dividing the light having passed through the first polarizing plate, into first and second lights, and optical amplifiers for respectively amplifying the first and second lights which are amplitude-divided by the amplitude division plate. The optical amplification means are located such that the light output from upstream optical amplification means is incident upon the polarizing beam splitter included in downstream optical amplification means.

Abstract: A thermal nonlinear cell and method. The cell includes a substantially planar nonlinear medium and a mechanism for removing thermal energy from the medium in a direction substantially orthogonal to said medium. In one embodiment, the mechanism for removing thermal energy is a thermally conductive window mounted adjacent to the medium. Preferably, the mechanism includes plural thermally conductive windows between which the nonlinear medium is disposed. In the best mode, the windows are sapphire and the nonlinear medium is a fluid. The windows and the medium are transmissive with respect to first and second beams that interfere with each other and create an interference pattern in the cell. The interference pattern is sampled by a sampling hologram created within the multiple layers of the medium. The interference pattern is used via a sampling hologram to create a phase conjugate of a signal beam. The windows move thermal energy from the medium in a direction transverse to the longitudinal axis of the medium.

Abstract: A deformable mirror according to the invention comprises a substrate, a reflector which is supported by said substrate and the shape of whose reflecting areas is variable, and a plurality of drive units for independently driving a plurality of regions of the reflector and thereby controlling the distances between said plurality of regions and said substrate. Each of the plurality of drive units comprises a plurality of electrodes disposed over said substrate, a tilt member which is rotated round the axis of tilt by being attracted by the selected one of the plurality of electrodes, and an action member for varying the distance between a specific region of the reflector and said substrate following the motion of the tilt member.

Abstract: A system and method for recovery of phase information from recorded intensity values is disclosed. In one aspect, a phase filter is placed in a plane, which may be the back focal plane (BFP) of a lens used for observing an object. The phase filter changes the phase of a wave front distribution in the BFP in a known manner. Amplitude stops or combinations of phase and amplitude filtering patterns can also be used to capture N different sets of intensity data in a conjugate diffraction plane. The N intensity images are used to obtain an estimate of the wave front at the first plane. This wave front estimate is then used to generate N modified estimates of the wave front at the conjugate plane, each modified estimate corresponding to one of N filtering patterns. In one implementation, the N modified IP estimates are corrected by replacing the estimated amplitudes with the actually measured ones for that image.

Abstract: Distortion optics are used to efficiently couple a spiral color wheel and an orthogonal modulator. Light 602 from a light source enters an aperture in a reflective end of a recycling integrator rod 604. The light travels through the rod and exits the end of the rod adjacent a sequential color filter 606, shown as a spiral color wheel. The shape of the light beam 608 exiting the integrator rod 604 is determined by the shape of the exit aperture of the integrating rod 606. The exit aperture of the integrating rod 606 typically is formed by a reflective exit aperture on the exit face. A cross section of the light beam 608 exiting the sequential color filter includes several bands of filtered light, one for each of the filter segments of the color wheel illuminated by the light beam. The curvature of the color bands makes it difficult for a row addressed spatial light modulator to efficiently use the light.

Abstract: A phase conjugate laser mirror employing Brillouin-enhanced four wave mixing allows multiple independent laser apertures to be phase locked producing an array of diffraction-limited beams with no piston phase errors. The beam combiner has application in laser and optical systems requiring high average power, high pulse energy, and low beam divergence. A broad range of applications exist in laser systems for industrial processing, especially in the field of metal surface treatment and laser shot peening.

Abstract: An optical storage system, which includes a temporary buffer and an optical storage medium, allows the practical combination of phase-conjugation and hologram multiplexing. The temporary buffer receives an object light beam and a first reference light beam, and records a first hologram at an intersection of the object light beam and the first reference light beam. The temporary buffer then receives a second reference light beam that is phase-conjugate to the first reference light beam and that illuminates the first hologram, thereby generating a phase-conjugate object light beam. The optical storage medium receives the phase-conjugate object light beam and a third multiplexed reference light beam, and records a second hologram for long-term storage at an intersection of the phase-conjugate object light beam and the third reference light beam.

Abstract: A system for summing RF modulated optical signals. In order to compensate for performance degradation at the summing junction, the system utilizes four-wave mixing elements to provide the phase conjugates of each of the modulated RF signals. The phase conjugates of the RF modulated optical signals are summed at the summing junction. The use of the phase conjugates of the RF modulated optical signals compensates for optical phase errors known to degrade performance when summing RF modulated optical signals.

Abstract: A technique for correcting wavefront aberrations introduced by large primary optical elements in portions of the electromagnetic spectrum. The aberrations of the primary element are first transferred to a beacon beam and this aberrated beam is interfered with a reference beam in a holographic medium. These beams are then turned off and a beam from a distant object, containing the same aberrations, is allowed to diffract from the hologram. The diffracted beam from the hologram contains the image of the distant object with aberrations removed. Use of this technique permits the construction of large optical elements inexpensively, since surface tolerances of the elements can be substantially relaxed.

Abstract: A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases.

Abstract: An optical communication system compensating for chromatic dispersion and a phase conjugate light generator for use therewith. The system includes an optical transmitter which receives an input signal and transmits signal light over an optical transmission line which is then input to a phase conjugate light generation unit. The phase conjugate light generation unit generates phase conjugate light corresponding to the signal light and outputs the phase conjugate light to an optical receiver which reproduces a demodulated signal corresponding to the input signal. The system compensates for chromatic dispersion by having the phase conjugate light generator generate phase conjugate light corresponding to signal light received over a first optical transmission line and then transmitting the generated phase conjugate light over a second optical transmission line.

Abstract: A loop four-wave mixing phase conjugator that can be used with depolarized signal beams comprises a polarization separator, a polarization mixer, an optical diode, a gain medium and relay optics that together form a unidirectional laser resonator. In operation, the polarization separator separates a signal beam .epsilon..sub.1 into orthogonally polarized signal beam components .epsilon..sub.11 and .epsilon..sub.12 and directs them to a nonlinear medium. The components propagate through the nonlinear medium and emerge as loop beam .epsilon..sub.2, with orthogonally polarized components .epsilon..sub.2 and .epsilon..sub.22. The polarization mixer mixes the energy from the two orthogonally polarized loop beam components, and relay optics direct the loop beam components back to the nonlinear medium at an angle with respect to the input beam. The loop beam components intersect and optically interfere with signal beam components .epsilon..sub.11 and .epsilon..sub.22 in the nonlinear medium to form gratings.

Abstract: A class of rigid rod and latter polymers having light emitting capability is provided. Included in this class of polymers are those having novel repeating structural units. These rigid rod and ladder polymers are employed in light emitting diodes.

Abstract: A compact loop four-wave mixing phase conjugator that can be used in practical optical applications comprises a reflective nonlinear cell, relay optics, an optical gain medium, and an optical diode that together form a unidirectional ring laser resonator. In operation, a signal beam .epsilon..sub.1 is directed to the nonlinear cell, where it passes through a nonlinear medium contained within the cell and is reflected out of the cell as loop beam .epsilon..sub.2. The relay optics direct loop beam .epsilon..sub.2 through the optical diode, optical gain medium, and back to the nonlinear cell, where it intersects and optically interferes with the signal beam .epsilon..sub.1 to form a refractive index grating in the nonlinear medium. The optical diode and gain medium are positioned in the loop so that an oscillation beam .epsilon..sub.3 builds up from optical noise in the resonator and oscillates in a direction counter to the propagation direction of loop beam .epsilon..sub.2. A portion of oscillation beam .

Abstract: An adaptive optics imaging system uses a double pumped phase conjugate mirror (DPCM) to compensate for phase, amplitude or polarization aberrations imposed upon a multi-pixel object beam. A remote reference beam is used to sample an aberrating medium through which the object beam is transmitted, and forms a shared hologram in a two-beam coupling medium with a local reference beam having known phase characteristics, generally plane-wave. An output beam is produced in the phase conjugate direction of the local reference beam, with the pixelized difference in phase characteristics between the output and local reference beams corresponding to the pixelized difference in phase characteristics between the object and remote reference beams; the remote reference beam is also preferably planar.

Abstract: A phase conjugation mirror including a non-linear medium (1) and a focusing lens (2), in which a beam to be reflected (F1) is displaced relative to a non-linear medium. The displacement is obtained through displacement of the focusing lens and has application in the stabilization of the reflectivity of a phase conjugation mirror.

Abstract: A novelty filter utilizes self-nulling and self-aligning of reflection and transmission phase conjugate beams. A photorefractive crystal is arranged so that the contributions to the phase conjugate are equal and opposite in the steady state to produce destructive interference when the input image is stationary, and thus no output image is displayed. If the image moves, then the gratings will rewrite and erase themselves, each with their own response times, total destructive interference will not occur, and transient enhancement and surpression of the phase conjugate output signal will indicate the direction of motion of the input image.

Abstract: The phase conjugation device includes at least one non-linear medium and an optical focussing system producing at least two focal points within the non-linear medium and capable of focussing light at these two points.

Abstract: A flexible rejection filter removes coherent radiation from an incoming beam of light. The filter includes a beamsplitter for dividing the transmitted portion into first and second beams. A photorefractive crystal in the paths of the first and second beams couples coherent radiation from the first beam to the second beam. A focal plane detector follows the crystal in the path of the first beam for sensing the incoherent radiation in the first beam, while a beam dump follows the crystal in the path of the second beam for absorbing the coherent radiation of the second beam. Other filter configurations can utilize contradirectional energy coupling or resonator structures in conjunction with photorefractive media.

Abstract: A dye laser amplifier is formed by a stimulated brillouin scattering (SBS) dye cell which receives both dye laser light to be amplified and a pump beam along a common optical path. Phase conjugation and amplification of received energy are reflected from the SBS cell. The cell comprises an SBS medium that is a solvent for the laser dye used. Typical SBS mediums are methanol, acetone, isopropyl alcohol, etc. Typical dyes are Rhodamine 6G, Rhodamine B, Rhodamine 560, Rhodamine 575, Sulphorhodamine B, Kiton Red, DCM, Courrarun 523, etc. A plurality of amplifiers may be connected in series to provide increased amplification. The action of the phase conjugation corrects optical distorsions, thereby preserving beam quality and bandwidth even after multiple amplifications. A typical dye laser beam of 590 nm wavelength, about 1 .mu.J may be amplified to about 120 mJ, with a 17 nsec pulse width, and <500 MHz bandwidth.

Abstract: Optical communication systems, optical computing systems and optical logic elements which rely on the phenomina of cross-phase modulation to alter and control, either or simultaneously, the spectral, temporal or/and spatial properties of ultrashort light pulses for processing information with high speed repetition rates. A weak beam of ultrashort light pulses is modulated by an intense beam of ultrashort light pulses by copropagating both beams through a non-linear medium such that cross-phase modulation effects are realized.

Abstract: Disclosed are an optical interconnection network and process, having a phase-conjugate mirror and input and output side channels. In the network, time-reversed wave, of a light beam propagated through the output side channel, is generated in the phase-conjugate mirror to cause an interconnection between the input side channel and the output side channel. The energy of the time-reversed wave comes from a light beam propagated through the input side channel.

Abstract: A degenerate four-wave mixing arrangement employs a photorefractive crystal as a real time holographic recording medium to record a hologram of the noisy optical signal. The signal passes through the crystal and is phase conjugated by a self pumped barium titanate phase conjugator, and the resulting phase conjugate beam reads out the hologram and multiplicative noise is substantially reduced in the optical output signal.

Abstract: A laser beam with a wavelength .lambda. emitted from a laser beam source is split into first and second pump beams and a probe beam. The first and second pump beams are incident on light incident surfaces of a photo-nonlinear medium from opposing directions on the same optical path. The probe beam is incident on the light incident surface forming an angle with the first pump beam to generate interference fringes in the normal direction of the light incident surface and to form a refractive index grating. A phase conjugate wave is emitted in the reverse direction to an incident optical path of the probe beam by means of irradiating the second pump beam on the refractive index grating.

Abstract: The invention relates to a photorefractive device made of single crystal of which the chemical composition substantially is Ba.sub.1-x Sr.sub.x TiO.sub.3 (0.01<x<0.1 BST) The method for manufacturing said device comprises: growing BST single crystal by Czochralski technique; annealing said crystal in oxidizing atmosphere; machining said crystal into cuboid with polished surfaces; poling said cuboid mechanically and electrically into single-domain state. Said device may ba a piece of said single-domain crystal, or an optoelectronic assembly including at least one of said crystal as the core part. Performances of said device are similar to the one made of BaTiO.sub.3. A reflectivity as high as 52% has been reached using said device as a self-pumped phase conjugator. Compared to BaTiO.sub.

Abstract: A process for making a custom phase-conjugated circular mirror to be used in a laser resonator that will suit specifications of a user is provided. The mirror reverses wavefront of one particular input beam .PSI..sub.o (x) determined by the user, the input beam .PSI..sub.o (x) having a given wavelength, the laser resonator including the mirror and an output coupler cooperating with the mirror and separated therefrom by a laser gain medium, the mirror being at a distance L from the output coupler. The process comprises steps of (a) determining the input beam .PSI..sub.o (x) that will suit need of the user; (b) calculating equation of .PSI..sub.L (x) which is a value of the input beam .PSI..sub.o (x) that is propagated through said laser gain medium at distance L; (c) calculating phase .PHI..sub.o (x) of the input beam, which is a phase of the input beam .PSI..sub.o (x) at distance L, the phase .PHI..sub.

Abstract: A polarization independent energy exchanger transfers optical energy from a first coherent beam of optical energy to a second coherent beam of optical energy where the second beam is coherent with respect to the first beam, the second beam is counterpropagating with respect to the first beam, and the second beam possesses substantially the same polarization as the first beam. The energy exchanger includes a nonlinear optical uniaxial crystal having electro-optic coefficients r.sub.13 and r.sub.23 of equal magnitude and having a sufficiently large photorefractive charge density to achieve efficient contradirectional two-beam coupling, independent of the polarization states of the first and second beams. The crystal is oriented to receive the first and second beams therein such that the optic axis of the crystal is aligned parallel to the propagation directions of the first and second beams.

Abstract: Enhanced energy transfers are achieved between optical beams by operating at wavelengths in the near-bandgap region of a photorefractive material, and employing an electrorefractive effect previously proposed only for single beams. An electric field is applied across a photorefractive medium of sufficient intensity to induce an electrorefractive coupling and consequent energy transfer between the beams. Gain enhancements are possible by orienting the photorefractive medium to obtain an electro-optic as well as an electrorefractive effect, and by a moving grating technique. The direction of energy transfer between the beams is controlled by the electric field direction, and can be reversed by reversing the field. Operation in the infrared region is made possible with semi-insulating materials. Applications include optical switches, amplifiers and phase conjugators.

Abstract: Apparatus for selectively limiting the response of an auxiliary liquid crystal light valve which is used in a dual liquid crystal light valve laser optics system for correcting inherent liquid crystal light valve distortion by isolating an atmospheric reference beam from the main laser beam in the auxiliary correction system. Two types of isolation are provided: dual bandwith and dual polarization. In the former, the response bandwidth of the auxiliary liquid crystal light valve is shifted to prevent overlap with the bandwidth of an atmospheric reference wavefront. In the dual polarization form of isolation, provision is made for rotating the polarization of only one of the two interacting beams.

Abstract: An optical input beam is transmitted through a non-linear medium capable of two-wave mixing gain by photorefractive, Brillouin, Raman, or other non-linear optical mechanism. A psuedo-conjugator retroreflects the input beam which has passed through the medium, back into the medium. The retroreflected beam acts as a seed, which lowers the threshold for producing a self-pumped conjugate reflected beam in the medium by stimulated scattering. The pseudo-conjugator may be a flat array of retroreflecting elements in the form of spheres or corner reflectors. A mosaic pattern of conjugating elements can be phase-locked to yield larger apertures and/or energy scaling, in a master-oscillator, power-amplifier (MOPA), or a four-wave mixer (FWM) configuration. The retroreflected beam can be modulated to temporally encode information onto the conjugate beam, and/or polarized to increase the system efficiency. The input and self-pumped conjugate reflected beams can be used as reference or pump beams in a FWM configuration.