Abstract: An optical pump may include a polarization element to separate pump light into a first component beam and a second component beam, wherein the polarization element is to separate the pump light such that the first component beam has a first polarization and the second component beam has a second polarization that is different from the first polarization. The optical pump may include a gain medium to absorb a portion of the first component beam and a portion of the second component beam, and transmit an unabsorbed portion of the first component beam and an unabsorbed portion of the second component beam. The optical pump may include one or more optical elements to at least partially isolate a pump source from the unabsorbed portion of the first component beam and the unabsorbed portion of the second component beam.

Abstract: Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

Abstract: A heat exchanger configured to cool an energy output device, and systems, devices, and methods thereof, can comprise a heat exchanger housing and an internal chamber defined in the housing that is configured to be filled with a phase-change material (PCM). The internal chamber can be provided at a first predetermined level inside the housing relative to the top surface of the housing and can extend under a first predetermined portion of the top surface of the housing. The internal chamber can include a plurality of PCM channels configured to be filled with the PCM and to accommodate phase changes of the PCM in multiple phase-change directions. Optionally, the plurality of PCM channels can be defined by a plurality of fins and/or the internal chamber can be accessible to outside the housing via at least one PCM interface configured to receive and pass therethrough the PCM.

Abstract: An optical device may include a package having a first port for receiving signal light, a source for providing pump light, a combiner for combining the signal light and the pump light into combined light, a second port for sending the combined light, a third port for receiving amplified light, and a free-space optical system for filtering amplified signal light from the amplified light, and a fourth port for sending the amplified signal light. The free-space optical system may include beam shaping optics that enlarge a beam size of the amplified light prior to the filtering.

Abstract: An optical assembly maintains 90° polarization rotation. In one aspect, an optical assembly includes a polarization beam splitter a rotational element and a path exchange mirror. The temperature, wavelength and manufacturing dependencies of polarization rotation of this optical assembly are minimal to nonexistent compared to conventional Faraday rotation assemblies as the optical fiber accepts only the desired rotation. As such these optical assemblies have no temperature and wavelength dependencies of the polarization rotation angle over broad temperature and wavelength ranges with minimal additional losses.

Abstract: First and second amplifiers amplify a voltage value of a first signal and generate first and second amplified signals. Third and fourth amplifiers amplify the voltage value of a second signal and generate third and fourth amplified signals. A corrector corrects one of the first amplified signal and the second amplified signal based on a first correction function illustrating a relationship between the voltage value of the first amplified signal and the voltage value of the second amplified signal and generates one of a first corrected signal and a second corrected signal, and corrects one of the third amplified signal and the fourth amplified signal based on a second correction function illustrating a relationship between the voltage value of the third amplified signal and the voltage value of the fourth amplified signal and generates one of a third corrected signal and a fourth corrected signal.

Abstract: In one embodiment, an optical system for amplifying space-multiplexed optical signals includes an input fiber that propagates multiple spatially-separated optical signals and a bulk amplifier formed of a doped material that receives the multiple spatially-separated optical signals and simultaneously amplifies those signals to generate multiple amplified signals.

Abstract: A method for amplifying optical signals includes determining a source optical signal, generating a first resultant signal including a pump signal and the source optical signal, sending the first resultant signal through a non-linear element to generate a second resultant signal including the first resultant signal and an idler signal, and sending the second resultant signal through a non-linear element to perform phase-sensitive amplification. The phase-sensitive amplification results in a third resultant signal including an amplified source optical signal, the pump signal, and the idler signal. The method also includes filtering the third resultant signal to remove the pump signal and the idler signal and outputting the amplified source optical signal.

Abstract: A method and apparatus for providing a high peak power optical beam. The method includes interleaving pulse trains of different wavelengths and spatially and temporally overlapping the different wavelengths to produce an amplified output beam with very high peak power.

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 radial power combination system is provided. The system comprises a radial divider comprising ports in the form of rectangular waveguides on the periphery, a radial combiner superposed on the radial divider, comprising ports in the form of rectangular waveguides on the periphery, a first, input transition transmitting a first signal to the center of the radial divider, a second, output transition capturing the first signal amplified to the output of the radial combiner, at least two amplifying channels comprising a third, input transition capable of interacting with the guides, a fourth, output transition capable of interacting with the guides and at least one amplifier, and means for adjusting the positioning of the amplifying channels, thus making it possible to adjust the phase shift of the various channels.

Abstract: To compensate a waveform distortion by using a nature that a spectral shape is perfectly retained even if all the linear distortions occur on a time-axis. An optical pulse transmitted from an optical pulse transmitter (1) via an optical fiber transmission line (2) is transmitted. An optical Fourier transformer (3) receives an optical pulse, and optically Fourier-transforms an optical pulse on a time-axis onto a frequency-axis to reproduce the frequency spectrum of an optical pulse on a time-axis be effecting switching between frequency and time, thereby compensating a waveform distortion by a linear effect on the optical fiber transmission line (2). A photodetector (4) receives an optical pulse from the optical Fourier transformer (3) and transforms this into an electrical signal to thereby obtain a pulse waveform before a transmission over the optical fiber transmission line (2).

Abstract: An EUV light generation system and method is disclosed that may comprise a droplet generator producing plasma source material target droplets traveling toward the vicinity of a plasma source material target irradiation site; a drive laser; a drive laser focusing optical element having a first range of operating center wavelengths; a droplet detection radiation source having a second range of operating center wavelengths; a drive laser steering element comprising a material that is highly reflective within at least some part of the first range of wavelengths and highly transmissive within at least some part of the second range of center wavelengths; a droplet detection radiation aiming mechanism directing the droplet detection radiation through the drive laser steering element and the lens to focus at a selected droplet detection position intermediate the droplet generator and the irradiation site.

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 wavelength conversion system includes a Mach-Zehnder interferometer including two optical waveguides, a non-linear medium provided on one of the two optical waveguides, and a branching ratio adjuster for adjusting the branching ratio of multiplexed light produced by multiplexing signal light and pumping light so that the powers of the signal light and the pumping light which are to be emitted from the two optical waveguides are equal to each other. The multiplexed light whose branching ratio is adjusted by the branching ratio adjuster is introduced into the two optical waveguides such that the non-linear medium generates phase conjugation light of the signal light and the light guided through the one optical waveguide and the light guided through the other one of the two optical waveguides interfere with each other so that the phase conjugation light is extracted as wavelength conversion light.

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: An EUV light generation system and method is disclosed that may comprise a droplet generator producing plasma source material target droplets traveling toward the vicinity of a plasma source material target irradiation site; a drive laser; a drive laser focusing optical element having a first range of operating center wavelengths; a droplet detection radiation source having a second range of operating center wavelengths; a drive laser steering element comprising a material that is highly reflective within at least some part of the first range of wavelengths and highly transmissive within at least some part of the second range of center wavelengths; a droplet detection radiation aiming mechanism directing the droplet detection radiation through the drive laser steering element and the lens to focus at a selected droplet detection position intermediate the droplet generator and the irradiation site.

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 method to improve an extinction ratio of an optical device, the method includes positioning at least a majority of a plurality of micro-mirrors in an off-state position. A mirror assembly includes the plurality of micro-mirrors. The method also includes selectively positioning at least one of the plurality of micro-mirrors in an on-state position. In one particular embodiment, the at least one of the plurality of micro-mirrors positioned in the on-state position operates to improve an extinction ratio of an optical device.

Abstract: The present invention provides devices and methods for dispersion compensation. According to one embodiment of the invention, a dispersion compensating device includes a negative dispersion fiber having an input configured to receive the optical signal, the negative dispersion fiber having a length and dispersion sufficient to remove any positive chirp from each wavelength channel of the optical signal, thereby outputting a negatively chirped optical signal; an amplifying device configured to amplify the negatively chirped optical signal; and a nonlinear positive dispersion fiber configured to receive the negatively chirped optical signal. The devices of the present invention provide broadband compensation for a systems having a wide range of variable residual dispersions.

Abstract: Techniques for predicting and correcting for optical distortions. A method for correcting optical distortions in a laser system includes operating a laser system at a first time to emit a laser beam. The laser system includes a laser source, a beam transfer assembly, and a lens assembly. The laser beam is capable of traversing from the laser source, through the beam transfer assembly and the lens assembly, to a laser target. Additionally, the method includes retrieving a first correction setting from a memory system. The first correction setting corresponds to the first time. Moreover the method includes adjusting at least one of the beam transfer assembly and the lens assembly in response to the first correction setting and sending the laser beam through the beam transfer assembly and the lens assembly to the laser target.

Abstract: A self-adjusting interferometric outcoupler. In the most general sense, the invention is an optical system (100) comprising a first mechanism (112) for generating a first beam, a second mechanism (122) for receiving the first beam and returning a second beam, and an interferometer (116) positioned to couple the first beam to the second mechanism (122) and to receive and output the second beam, wherein the interferometer (116) is also shared by the first mechanism (112) and/or the second mechanism (122) to control the frequency of the first beam and/or the second beam, respectively. In the illustrative embodiment, the first mechanism (112) is a master oscillator, the second mechanism (122) is a phase conjugate mirror, and the system (100) further includes a power amplifier (118) positioned to amplify the first beam during a first pass and to amplify the second beam during a second pass.

Abstract: A system for directing electromagnetic energy. The inventive system includes a first subsystem mounted on a first platform for transmitting a beam of the electromagnetic energy through a medium and a second subsystem mounted on a second platform for redirecting the beam. In accordance with the invention, the second platform is mobile relative to the first platform. In the illustrative embodiment, the beam is a high-energy laser beam. The first subsystem includes a phase conjugate mirror in optical alignment with a laser amplifier. The first subsystem further includes a beam director in optical alignment with the amplifier and a platform track sensor coupled thereto. In the illustrative embodiment, the second subsystem includes a co-aligned master oscillator, outcoupler, and target track sensor which are fixedly mounted to a stabilized platform, a beam director, and a platform track sensor. In the best mode, the stable platform is mounted for independent articulation relative to the beam director.

Abstract: An optical system for producing high power laser beams has an in/out coupler for receiving an input laser beam from an oscillator. The coupler inputs the beam to a first multiplexer which produces a plurality of beams which are sent to a plurality of fiber amplifiers. A second beam multiplexer receives the thus amplified plurality of beams to combine then into a single amplified beam which is input to a loop PCM (phase conjugate mirror). A multi-mode fiber amplifier is included in the loop PCM. The output of the loop PCM is phase conjugated with the amplified beam input to the loop PCM thereby eliminating any phase and polarization distortions and aberrations occurring in the fiber amplifiers. The output of the loop PCM is supplied in reverse direction through the second multiplexer, the fiber amplifiers and the first multiplexer in that order and then through the in/out coupler as a high power output laser beam.

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: In an optical amplifier evaluation instrument, a rectangular spectrum light source 1 transmits continuous light having a wide-band and flat spectrum shape, a first optical modulator 2 receives and pulse-modulates the continuous light. Further, a second optical modulator 3 operates in the same period as the first optical modulator 2 and performs the on/off pulse operation, thereby providing a sampling window in a time domain for extracting and suppressing an optical signal. A modulation signal generation section 4 performs such control and drive. An optical signal undergoing pulse intensity modulation is input to a measured optical amplifier 6. Post-amplified signal light power for each frequency component and amplified spontaneous emission power for each frequency component in a time domain in which no optical pulse signal exists are measured and operations are performed for each wavelength.

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: The instant invention relates to a laser system for optical free space communications, in particular the generation of amplified laser light under conditions in outer space. In the process, an optical beam (72) to be amplified is conducted via a polarizing beam splitter (71) to a Faraday rotator (70) and brought from there to a neodymium crystal (68). By means of reflection, appropriate diffraction and passage through a quarter-wave plate (67), a multiple passage through the neodymium crystal (68) is forced and amplification is achieved by this.

Abstract: A phase locked phase conjugation system comprises a first (1) and a second (2) stimulated Brillouin scattering (SBS) cell. A laser beam is split into sub beams; one (9) is directed through the first SBS cell as a beam of collimated light and focused into the second SBS cell from which a phase conjugated beam is returned. One or more other sub beams (11, 12) are focused into the first SBS cell so that overlap occurs between focused sub beams and collimated beam. This provides a phase locked phase conjugated beam. Two or more sub beams are directed twice through laser amplifiers to provide an amplified phase locked phase conjugated beam. The second SBS cell may be a simple reflective cell operating on a focused laser sub beam, or may be an SBS loop arrangement having reflectors and lenses for causing optical feedback of the Brillouin scattered light.

Abstract: The invention provides an optical phase conjugator suitable for use with a repeater, for example, for an optical communication system for a very long distance of up to several thousands kilometers across an ocean as well as an optical reception apparatus and an optical transmission apparatus for use with an optical communication system which employs the optical phase conjugator. The optical phase conjugator comprises an optical phase conjugation section for outputting signal light having a frequency or spectrum inverted from that of input signal light thereto, and a frequency or wavelength conversion section for outputting signal light having a frequency or wavelength converted from that of the signal light inputted thereto from the optical phase conjugation section.

Abstract: A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications.

Abstract: Disclosed is a compact optical source capable of emitting wavelengths (notably in the blue spectrum) which it is difficult for standard laser diodes to achieve. This source has a laser (or laser diode) emitting at a wavelength .lambda.oi, a non-linear medium (NLM) in which the phase matching condition is achieved at a wavelength .lambda.o.sub.a belonging to the set of .lambda.o.sub.i values, a mirror M.sub.l transparent at .lambda.o.sub.i /2 and reflective at .lambda.oi placed at output of the medium (NLM) By reinjecting wavelengths .lambda.oi.noteq..lambda.oa into the laser, it is possible to lock the emission of the laser to .lambda.oa and thus set up a high-powered optical source .lambda.o.sub.a /2. Application: blue sources.

Abstract: Limiting quadratic processing and compansion in photorefractive two beam coupling is disclosed. Two-beam coupling in photorefractive barium titanate employs the imaged intensity of the signal to amplify the reference beam while maintaining the phase of the reference beam. The phase distorted signal beam is converted to that of the controlled phase of the reference beam. The high pump limit of amplification in this two-beam coupling device produces an amplitude compressed output to reduce multiplicative noise. Lost contrast of the image is thereafter restored. Beam clean-up of a non-intelligence bearing beam can be carried out by a similar process; a low pass filter consisting of a pinhole plate can be used in place of the second photorefractive crystal in the Fourier plane and only the planar wavefront portion will pass through the pinhole and may be collimated by a lens to provide a cleaned planar output beam.

Abstract: An optical amplification system and method that allows an optical seed beam to pass through an optical amplifier more than two times, even when the seed beam is highly depolarized. This is accomplished by using a polarizing beamsplitter that separates a highly depolarized seed beam into two diverging orthogonally polarized beams. The orthogonally polarized beams perform a first pass through the amplifier and are re-directed back into the amplifier so that each beam makes a second pass through the amplifier by propagating back along the other beam's first path. Because of the path exchange, the two orthogonally polarized beams diverge from each other when they pass back through the polarizing beamsplitter. The diverging beams are phase conjugated and retrace their respective paths through the system so that each beam performs a third and fourth pass through the amplifier. After the fourth pass, the orthogonally polarized beams are recombined into a single depolarized return beam by the polarizing beamsplitter.

Abstract: A solid-state laser architecture producing a beam of extremely high quality and brightness, including a master oscillator operating in conjunction with a zig-zag amplifier, an image relaying telescope and a phase conjugation cell. One embodiment of the laser architecture compensates for birefringence that is thermally induced in the amplifier, but injects linearly polarized light into the phase conjugation cell. Another embodiment injects circularly polarized light into the phase conjugation cell and includes optical components that eliminate birefringence effects arising in a first pass through the amplifier. Optional features permit the use of a frequency doubler assembly to provide output at twice optical frequencies, and an electro-optical switch or Faraday rotator to effect polarization angle rotation if the amplifier material can only be operated at one polarization.

Abstract: A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation.

Abstract: Apparatus and a related method for generating a second harmonic frequency optical output from a fundamental frequency input beam, without significant birefringence. The apparatus includes two Type II doubler crystals of equal length arranged with their corresponding axes parallel to each other, and a polarization rotator positioned between the doubler crystals, to rotate the polarization angle of a residual fundamental frequency component of an output beam from one of the crystals by 90.degree. or an odd multiple of 90.degree.. Random birefringence introduced into one of the doubler crystals is virtually canceled in the other, and the assembly of the two crystals and the polarization rotator may be angularly adjusted as needed for phase matching or tuning, without detracting from the birefringence compensation capability. The invention is also disclosed in the context of a phase conjugated master oscillator power amplifier (PC MOPA) system.

Abstract: A method and apparatus is provided for propagating photoelectrons in a semiconductor material and for controlling the direction of photoelectrons produced in a semiconductor material. A selected region of the semiconductor material is irradiated with two beams of light that overlap in space and time. The two interfering light beams have a predetermined phase relationship and are harmonically related such that the frequency of one is approximately a multiple of two of the other. Each of the beams of light produce substantially a same number of photoelectrons in the semiconductor material. As the phase relationship between the two beams is varied, the direction of propagation of the photoelectrons produced, varies.

Abstract: The present invention provides an apparatus and method for performing polarization-insensitive four-photon mixing of optical signals. The polarization-insensitive optical mixer includes a polarization splitter for splitting an optical signal into parallel and perpendicular polarization components, different mixing paths for mixing a pump signal of like polarization with each of the parallel and perpendicular components in a nonlinear mixing device, and a polarization combiner for combining the resulting mixing products. Certain of the mixing products represent phase conjugates of the input optical signal, and are therefore useful in compensating for chromatic distortion in optical fiber.

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 energy transfers, via stimulated scattering, to a seed beam from a pump beam that has a non-uniform optical intensity distribution are made with an enhanced spatial uniformity of amplification by spatial mixing of the pump beam within the medium where amplification takes place. In a stimulated Brillouin scattering (SBS) phase conjugate mirror (PCM) having an amplifier and a phase conjugating oscillator, beam mixing elements are provided on opposite sides of the amplifier to mix both the input and return phase conjugated beams within the amplifier, and to restore the beams after they have exited. The preferred mixing mechanism is a plurality of cylindrical lenses that are spaced along the beam path, and/or have unequal focal lengths to produce a series of foci within the amplification medium that are rotated with respect to each other. Amplitude replication as well as high fidelity phase conjugation are enhanced using SBS.

Abstract: A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer.

Abstract: A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations.

Abstract: An optical beam amplification and delivery system and method employs a central station with a laser oscillator, a laser amplifier and a phase conjugate mirror (PCM). Low power, near diffraction limited laser beams are delivered to each of a plurality of local stations through single-mode polarization preserving fibers. From the local stations the low power beams are transmitted back to the central station through high power multi-mode optical fibers. At the central station the received beams are amplified, phase conjugated and transmitted back through the amplifier and multi-mode fibers to their respective local stations. Distortions imposed upon the beams by the multi-mode fibers during transmission back to the central station, and by the amplifier, are compensated during the return path, providing high power yet near diffraction limited beam quality at the local stations.

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: This invention is drawn to heavy metal oxide glasses exhibiting high nonlinear susceptibility and infrared transmission consisting essentially, in weight percent, of 42-48% PbO, 33-44% Bi.sub.2 O.sub.3, 10-15% Ga.sub.2 O.sub.3, and up to 15% total of at least one member of the group consisting of up to 5% SiO.sub.2 and/or GeO.sub.2 and up to 15% Tl.sub.2 O. This invention also comprehends the fabrication of light guiding fibers from those glasses.

Abstract: A master oscillator power amplifier (MOPA) system which isolates the master oscillator (MO) from the return amplified beam by dividing the return beam into two components, introducing a phase shift between the components, and recombining the phase shifted beam components through constructive interference into an output beam directed away from the MO. A destructive interference return output is directed back towards the MO, but is held to a negligible level by making the phase shift approximately equal to an odd number of half-wavelengths at the return beam wavelength. In the preferred embodiment a stimulated Brillouin scattering phase conjugate mirror (PCM) is used to direct the amplified beam for a second amplification pass, while a Mach-Zender interferometer transmits the beam both before and after double amplification.