Abstract: The present invention provides a wavelength converter with wideband four-wave-mixing, which includes a laser diode, an optical modulator, a first and a second polarization controllers, a first, a second and a third tunable lasers, an optical coupler, a semiconductor optical amplifier (SOA) and a multiplexer. The present invention utilizes an assist beam that can improve the recovery rate and saturation power of the SOA. While the SOA is operated at a bias current close to the transparent condition for the assist beam, it does not influence the gain of the SOA wavelength converter.

Abstract: There are disclosed a nonlinear optical crystal 1 which can generate a THz wave by a parametric effect; a pump light incidence apparatus 12 for allowing a pump light 2 to be incident upon the nonlinear optical crystal; and a seed light injection apparatus 14 for injecting a seed light 5 having a variable frequency in a generation direction of an idler light 3 generated by the pump light. The seed light injection apparatus 14 comprises angle dispersion compensation means 16 set so that an incidence angle ?IN of the seed light upon the nonlinear optical crystal 1 substantially equals to a desired phase matching condition regardless of a wavelength.

Abstract: A method of patterning and fabricating poled dielectric microstructures in dielectric materials comprising the following steps. A poled dielectric microstructure within a dielectric material is provided. The poled dielectric microstructure is then segmented into a plurality of independent sub-structures. The poled dielectric microstructures are then fabricated within each of the plurality of independent sub-structures. Additional processes and a novel poling setup for improving and implementing this patterning and fabrication method are also disclosed.

Abstract: A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>103 pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.

Abstract: A higher intensity eye safe laser is provided for long range target designation or illumination as well as long range eye safe communications by providing a single beam line combination of an optical parametric oscillator and optical parametric amplifier which are used to double the output of the optical parametric oscillator while limiting beam spread to less than 1.2 milliradians assuming a 20 mm clear aperture. The OPO/OPA combination requires no conditioning, isolation or synchronization optics and provides a factor of two improvements in beam quality as compared to an equivalent optical parametric oscillator, with the subject system providing a compact robust configuration. The high conversion is provided by the use of a simple optical parametric oscillator seeding an optical parametric amplifier without double passing the pump pulse in the optical parametric oscillator.

Abstract: A monolithic non-linear transmission line and sampling circuit with reduced shock-wave-to-surface-wave coupling are presented herein. In coplanar-waveguide (CPW) technology, this reduced coupling is achieved by selecting properly the thickness of the semiconductor substrate, and by elevating the center conductor of the CPW above the substrate surface. The elevated center conductor is supported by means of conducting posts, and may be backed by a low-loss dielectric such as polyimide or silicon nitride. In coplanar-strip (CPS) technology, the reduction in coupling between shock waves and surface waves is achieved by controlling the substrate thickness as in the CPW case, and by elevating the coplanar strips above the substrate surface. The elevated strips are supported by a low-loss dielectric. The reduced coupling in both guiding media enhances the high-frequency performance of nonlinear-transmission-line-based circuits.

Abstract: The invention concerns a device for generating, by interaction(s) with three or four waves from one or several incident optical radiation(s), one or several emergent radiation(s) tuneable at least in frequency. The invention is characterized in that it consists essentially of a crystal with non-linear optical property whereof the surface defines a cylindrical volume with complete revolution, or truncated on at least two opposite faces symmetrical relative to its axis of revolution, or partial on one of two said faces. Said device is particularly designed for applications in spectroscopy, remote sensing, long-distance transmission, remote guiding. The invention also concerns a method using said device.

Abstract: A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

Abstract: An optical parametric circuit for separating an input signal light and a wavelength-converted light even when the wavelength difference is small is provided. The optical parametric circuit includes: a nonlinear Mach-Zehnder interferometer which includes a first optical path and a second optical path; optical dispersive mediums and second-order optical nonlinear mediums provided in the first and second optical paths; wherein optical dispersive medium and second-order optical nonlinear medium in the first optical path are placed in the reverse order of optical dispersive medium and second-order optical nonlinear medium in the second optical path.

Abstract: A laser light generating apparatus is provided with a laser light source, a phase modulator, a signal generating unit for applying a modulating signal to the phase modulator, and resonators. A nonlinear optical element is provided in the resonator, and an optical path length varying means for changing length of an optical path of each of the resonators is provided. Error signals are obtained using detection signals of photodetectors for receiving light from the resonators, respectively, and the optical path length varying means is controlled by a sideband method, whereby a control circuit having a negative feedback configuration for controlling length of the resonators is formed. Laser light is subjected to phase modulation and then inputted to the resonator, and light generated by the nonlinear optical element is inputted to the resonator so that the plurality of resonators are simultaneously held in a resonant state.

Abstract: An arrangement (10) for efficiently generating tunable pulsed laser output at 8-12 microns. The arrangement (10) includes a laser (12), a first optical parametric oscillator (14) of unique design, and a second optical parametric oscillator (22). The first oscillator (14) is constructed with an energy shifting crystal (20) and first and second reflective elements (16) and (18) disposed on either side thereof. Energy from the laser (12) at a first wavelength is shifted by the crystal and output at a second wavelength. The second wavelength results from a secondary process induced by a primary emission of energy at a third wavelength, the third wavelength resulting from a primary process generated from the first wavelength in the crystal. Mirror coatings are applied on the reflective elements (16 and/or 18) for containing the primary emission and enhancing the secondary process.

Abstract: A method and a nonlinear frequency mixer employing the method to generate at least one output light from at least one input light with the aid of a quasi-phase-matching (QPM) grating for quasi-phase-matching the input and output light involved in a nonlinear frequency mixing operation such as three-wave mixing, four-wave mixing or other nonlinear operation mediated by a susceptibility of the nonlinear optical material. The QPM has a beam-modifying pattern with features for wave front shaping. More specifically, the features shape the wave fronts of the output light by diffraction or phase front shaping to thereby modify its propagation. This modification of propagation can be used to steer, focus, defocusing, split and/or collimate the output light.

Abstract: An apparatus for generating laser radiation, the apparatus comprising: a pumping device comprising a resonant cavity; and a laser radiation generation element that is substantially Poynting vector walk-off compensated, the laser radiation generation element being located within the resonant cavity.

Abstract: A synchronously pumped optical parametric oscillator generates pulses with duration 25 ps and repetition rate of 10 Hz. The bandwidth of the radiation is 1.36 cm−1, close to the Fourier limit. A single pulse from each oscillator is further amplified with an optical parametric amplifier obtaining pulse energies up to 3.7 mJ. This source can be tuned between 410 nm-2000 nm. The system is not a laser but an optical parametric oscillator where amplification is obtained in a parametric process rather than by population inversion. The oscillator is pumped by a pulse train from a Nd:Yag laser. In each roundtrip the bandwidth of the radiation is reduced by a grating-mirror assembly. After a number of roundtrips a close to ideal pulse is obtained. This single pulse is then amplified by an optical parametric amplifier obtaining a single tunable narrow bandwidth pulse with a duration of about 25 ps.

Abstract: A wavelength converter implements high speed, high efficiency, low noise wavelength conversion without performing high voltage poling of a crystal, and enables switching and modulation of converted light in response to an electric field. A KLTN crystal, includes a deposited-gold electrode within its incidence plane, and is connected to a DC power supply via a copper wire. The crystal material is composed of KTa1-xNbxO3 and/or K1-yLiyTa1-xNbxO3. A polarizer controls the polarization of the fundamental wave in the direction parallel to the electric field, and launches it into the electrode of the KLTN crystal. The KLTN crystal, rotating on an axis in the direction of the electric field, launches only part of the generated SHG light with the same polarization direction as that of the incident light into a photo multiplier tube through a polarizer.

Abstract: A first pump pulse and a signal pulse are injected into a first optical parametric amplifier. This produces a first amplified signal pulse. At least one additional pump pulse and the first amplified signal pulse are injected into at least one additional optical parametric amplifier producing an increased power coherent optical pulse.

Abstract: Method and system for providing laser light that is tunable over a relatively wide mid-infrared wavelength range, such as 2-17 &mgr;m. A first noncritically phase matched nonlinear crystal receives a laser light beam and converts the light to a first cavity beam having a first selected wavelength, using optical parametric oscillation techniques. A second noncritically phase matched nonlinear crystal receives the first cavity beam and converts the light to a second cavity beam having a second selected wavelength. Where the first wavelength is tuned (e.g., by temperature change or effective path length change) over a wavelength range of 2-5 &mgr;m, the second wavelength can vary over a higher and broader wavelength range, such as 3-17 &mgr;m.

Abstract: A device for optical parametric amplification utilizing four mirrors oriented in a nonplanar configuration where the optical plane formed by two of the mirrors is orthogonal to the optical plane formed by the other two mirrors and with the ratio of lengths of the laser beam paths approximately constant regardless of the scale of the device. With a cavity length of less than approximately 110 mm, a conversion efficiency of greater than 45% can be achieved.

Abstract: A high-gain preamplifier based on optical parametric amplification. A first nonlinear crystal is operatively connected to a second nonlinear crystal. A first beam relay telescope is operatively connected to a second beam relay telescope, to the first nonlinear crystal, and to the second nonlinear crystal. A first harmonic beamsplitter is operatively connected to a second harmonic beamsplitter, to the first nonlinear crystal, to the second nonlinear crystal, to the first beam relay telescope, and to the second beam relay telescope.

Abstract: An optical wavelength converter that includes an optical sum frequency generator (SFG) and an optical difference frequency generator (DFG). The SFG receives part of both an input beam and a continuous-wave (CW) beam. The DFG receives part of the input beam as well as the output of the SFG. The output of the DFG represents the signal of the input beam modulated or carried on a beam having the frequency of the CW beam. Both single-channel and multi-channel configurations are integrally realized in similar numbers of components.

Abstract: A fiber optical parametric oscillator is formed using photonic crystal fibers, also known as microstructure fibers or holey fibers. The optical parametric oscillator includes only a few meters of microstructure fiber. In one embodiment, the microstructure fiber is disposed between a highly reflective mirror and a diffraction grating in a simple Fabry-Perot configuration wherein the diffraction grating is tuned to reflect a particular wavelength of the signal wave back to the microstructure fiber. In another embodiment, the microstructure fiber is disposed in a ring cavity and the parametric oscillator is synchronously pumped. The parametric oscillator may be implemented with free space optics or use all fiber optic components.

Abstract: Conventional short pulse optical parametric oscillator systems have relatively low repetition rates and cannot be pumped by continuous-wave lasers. The invention describes passively mode locked parametric oscillators, consisting of a continuous-wave laser pump source, an optical resonator which is resonant for only one of the two parametrically generated waves, a non-linear medium, and a saturable absorber or a medium for formation of a Kerr lens and an aperture. The repetition rate of such an oscillator system can be selected within a large range through selection of the resonator length. Fields of use are measuring technology and optical spectroscopy.

Abstract: A low-finesse, tri-etalon optical parametric oscillator includes an optical cavity bounded by two coupling mirrors, and a narrow-linewidth pump laser which supplies pump energy to the optical cavity at a pump wavelength. A pair of walk-off compensated, non-linear optical crystals (but not limited to walk-off compensated) is disposed with the cavity and converts energy at the pump wavelength to energy at longer signal and idler wavelengths. The mirrors are configured such that each of the three beams (pump, signal and idler) is approximately 70% to 100% reflected at one end of the cavity and approximately 10% to 30% reflected at the other end of the cavity. This configuration causes partial resonance of each of the beams and generates an etalon effect which enhances the fluence in the leading and trailing edges of pulses in the cavity, thereby enhancing the energy conversion efficiency from the pump wavelength to the signal and idler wavelengths.

Abstract: A photonic band gap (PBG) device is provided for frequency up and/or down-converting first and second photonic signals incident on the device to produce a down-converted output photonic signal. When the first and second incident photonic signals have respective first and second frequencies &ohgr;3 and &ohgr;2, the down-converted photonic signal has a third frequency &ohgr;1=&ohgr;3−&ohgr;2. When the first incident field has a frequency &ohgr;1, the first up-converted photonic signal has a second frequency &ohgr;2. The second up-converted photonic signal has a third frequency &ohgr;3=&ohgr;1+&ohgr;2. Thus, the PBG device can be used to generate coherent near- and mid-IR signals by frequency down-converting photonic signals from readily available photonic signal sources, or red, blue, and ultraviolet signals by up-converting the same readily available photonic signal sources.

Abstract: In one aspect of the invention, an apparatus operable to convert wavelengths of a plurality of optical signals includes a coupler operable to receive a pump signal and a plurality of input signals each input signal comprising at least one wavelength different than the wavelengths of others of the plurality of input optical signals. The apparatus further includes an optical medium operable to receive the pump signal and the plurality of input signals from the couplet, wherein the pump signal and each of the plurality of input signals are synchronized to overlap at least partially during at least a part of the time spent traversing the optical medium to facilitate generation of a plurality of converted wavelength signals each comprising a wavelength that is different than the wavelengths of at least some of the plurality of input signals. Various embodiments can result in low cross-talk and/or low polarization sensitivity.

Abstract: The apparatus for generating at least three visible light beams of different output wavelengths for display purposes comprises a passively mode-locked solid-state thin-disk laser and means for at least partially converting said primary light beam into electromagnetic radiation characterized by said at least three different output wavelengths including an optical parametric oscillator (OPO). The OPO is preferably an optical fiber feedback OPO. An optical fiber feedback OPO comprises a nonlinear optical element and feedback means for feeding back at least a proportion of the radiation emitted by the nonlinear medium to the nonlinear element, wherein the feedback means comprise an optical fiber.

Abstract: A method and apparatus are provided for increasing the energy of chirped laser pulses to an output in the range 0.001 to over 10 millijoules at a repetition rate 0.010 to 100 kHz by using a two stage optical parametric amplifier utilizing a bulk nonlinear crystal wherein the pump and signal beam size can be independently adjusted in each stage.

Abstract: A multiple-wavelength ultrashort-pulse laser system includes a laser generator producing ultrashort pulses at a fixed wavelength, and at least one and preferably a plurality of wavelength-conversion channels. Preferably, a fiber laser system is used for generating single-wavelength, ultrashort pulses. An optical split switch matrix directs the pulses from the laser generator into at least one of the wavelength conversion channels. An optical combining switch matrix is disposed downstream of the wavelength-conversion channels and combines outputs from separate wavelength-conversion channels into a single output channel. Preferably, waveguides formed in a ferroelectric substrate by titanium indiffusion (TI) and/or proton exchange (PE) form the wavelength-conversion channels and the splitting and combining matrices. Use of the waveguide allows efficient optical parametric generation to occur in the wavelength-conversion channels at pulse energies achievable with a mode-locked laser source.

Abstract: A chemical sensing system and method. The system (10) includes a transmitter having a laser for providing a collimated beam of electromagnetic energy at a first frequency and a Q switch in optical alignment with the beam. The system further includes a crystal for shifting the frequency of the beam from the first frequency to a second frequency. A mechanism is included for shifting the beam from the second frequency to a third frequency in the range of 8-12 microns. The system includes a mechanism for switching the polarization state of the second beam and providing third and fourth beams therefrom. The third beam has a first polarization and the fourth beam has a second polarization. The second polarization is orthogonal relative to the first polarization. The frequency shifted third and fourth beams are combined to provide an output beam in the range of 8-12 microns. The output beam is transmitted and a return signal is detected by a receiver in the illustrative chemical sensing application.

Abstract: Methods and systems are disclosed that dynamically shift the wavelength of an electromagnetic (EM) beam by interacting the beam with a polariton wave having a selected polariton wave frequency.

Abstract: A tunable light source equipped with an optical parametric amplifier (OPA) placed in a cavity for performing an optical parametric oscillation (OPO) driven by a pump beam at a pump frequency selected within a certain range such that the OPO is driven near degeneracy. An adjustment mechanism adjusts the pump frequency within a wavelength tuning range to select a gain spectrum of the OPO and a spectral control mechanism sets a resonant frequency of the cavity within that gain spectrum. Thus, only one of the idler and signal beams within the passband set by the narrowband tuner is supported inside the cavity. Other nonlinear frequency conversion operations can also be performed within the cavity in conjunction with the OPO. The light source can be operated in cw, near-cw and pulsed operation modes as a broadly tunable narrowband source covering a wavelength window of 250 nm.

Abstract: An optical parametric amplifier (OPA) driven with at least two pump waves. The pump waves may be configured such that the OPA produces uniform exponential gain over a range of wavelengths that extends, for example, at least 30 nm on either side of the average pump-wave wavelength. In addition, since the Brillouin scattering limit applies to each pump wave independently, substantially twice the amount of energy may be pumped into an OPA of the present invention compared to that in the corresponding single pump-wave OPA of the prior art. An OPA of the present invention may be used in a WDM communication system and configured for simultaneous signal amplification and wavelength conversion.

Abstract: A THz-wave generator according to the present invention includes a nonlinear optical crystal 1 capable of parametric generation, a first laser device 12 for injecting a single-frequency first laser beam 7 as a pump wave into the nonlinear optical crystal, and a second laser device 14 for injecting a different single-frequency second laser beam 8 to thereby injection-seed a second laser beam 8 in a direction in which an idler wave is generated by the pump wave. By this configuration, it is possible, in generation of a THz-wave by use of the parametric effect in the nonlinear optical crystal under a non-collinear phase matching condition, to greatly increase a power of the THz-wave, to narrow its spectrum width, to make variable the wavelength of a generated THz-wave, and to hold its generation direction almost constant.

Abstract: The present invention relates to an optical parametric oscillator including a non-linear optical crystal and two glass substrates surface contacted to the opposite ends of said crystal. The substrates include mirrors on their outer surfaces so that the combination of the mirrors, substrates and the crystal functions as the parametric oscillator. The invention also relates to the method of producing such an oscillator that overcomes the problems of surface contact bonding and laser damage threshold by use of an alkaline polishing compounds on the crystal ends.

Abstract: A higher intensity eye safe laser is provided for long range target designation or illumination as well as long range eye safe communications by providing a single beam line combination of an optical parametric oscillator and optical parametric amplifier which are used to double the output of the optical parametric oscillator while limiting beam spread to less than 1.2 milliradians assuming a 20 mm clear aperture. The OPO/OPA combination requires no conditioning, isolation or synchronization optics and provides a factor of two improvements in beam quality as compared to an equivalent optical parametric oscillator, with the subject system providing a compact robust configuration. The high conversion is provided by the use of a simple optical parametric oscillator seeding an optical parametric amplifier without double passing the pump pulse in the optical parametric oscillator.

Abstract: The invention features a nonlinear optical crystal assembly and a gas mixture that surrounds the nonlinear crystal. The gas mixture reduces photochemical degradation of the nonlinear crystal caused by exposure of the nonlinear crystal to a high power light source. For example, the nonlinear crystal may be a borate-based nonlinear crystal such as BBO and the gas mixture may include a hydrogen and oxygen to repair broken bonds in boron-oxygen rings of the borate-based crystal. The assembly may be incorporated into a light source, and applications requiring such a light source, such as, e.g., applications requiring ultraviolet light. Furthermore, the nonlinear crystal assembly may be placed inside an optical cavity.

Abstract: A novel and efficient system and method for providing an output beam of collimated energy in the 8-12 micron range. The solid state system includes a pump laser (210) for providing an input beam and an OPO (250) using an x-cut potassium titanyl arsenate crystal for shifting the input beam from the first wavelength to a second wavelength. A second optical parametric oscillator (271) is included for shifting the beam from a second wavelength to a third wavelength. The second optical parametric oscillator (271) uses a cadmium selenide crystal. A tuning mechanism with an associated controller is provided to tune the oscillator as needed for a particular application.

Abstract: A frequency synthesizer for generating a multiple tone lightwave signal that can be converted into an RF carrier or local oscillator signal. The frequency synthesizer comprises a multiple mode master laser, two slave lasers injection-locked to the master laser, an optical coupler coupling the optical outputs of the two slave lasers, which produces an optical heterodyne output. The frequency synthesizer further comprises a homodyne phase-lock loop providing feedback control over one of the slave lasers and a heterodyne phase-lock loop providing feedback control over the other slave laser. A local oscillator selector is used to select the optical mode to which one of the slave lasers is locked, thus providing selection of the frequencies of the heterodyne output.

Abstract: Achromatic phase-matching (APM) is used for efficiently multiplying the frequency of broad bandwidth light by using a nonlinear optical medium comprising a second-harmonic generation (SHG) crystal and stationary optical elements whose configuration, properties, and arrangement have been optimized to match the angular dispersion characteristics of the SHG crystal to at least the third order. These elements include prisms and diffraction gratings for directing an input light beam onto the SHG crystal such that each ray wavelength is aligned to match the phase-matching angle for the crystal at each wavelength of light to at least the third order and such that every ray wavelength overlap within the crystal.

Abstract: A synchronously pumped optical parametric oscillator generates pulses with duration 25 ps and repetition rate of 10 Hz. The bandwidth of the radiation is 1.36 cm−1, close to the Fourier limit. A single pulse from each oscillator is further amplified with an optical parametric amplifier obtaining pulse energies up to 3.7 mJ. This source can be tuned between 410 nm-2000 nm. The system is not a laser but an optical parametric oscillator where amplification is obtained in a parametric process rather than by population inversion. The oscillator is pumped by a pulse train from a Nd: Yag laser. In each roundtrip the bandwidth of the radiation is reduced by a grating-mirror assembly. After a number of roundtrips a close to ideal pulse is obtained. This single pulse is then amplified by an optical parametric amplifier obtaining a single tunable narrow bandwidth pulse with a duration of about 25 ps.

Abstract: Wavelength stability of an optical oscillator has been enhanced by feedback from an external position-sensing detector to control the position or tilt of an intracavity optical element, such as a mirror. The wavelength stability results from stabilization of the intracavity beam position relative to an aperture in the oscillator. The wavelength selectivity of the aperture results from incorporation of a dispersive element in the oscillator cavity that produces a mapping of wavelength to beam position at the aperture.

Abstract: A method and apparatus for harmonically upconverting a phase and/or amplitude modulated subcarrier signal to a higher frequency through a non-linear optical link is disclosed. The method requires that a bandpass signal, with a carrier frequency at a submultiple of the desired radio transmission frequency, be frequency translated in a non-linear two-port device. To avoid the inherent distortion inflicted on the information signal in harmonic upconversion, a predistortion technique is outlined. This consists of phase compression in the case of a phase modulated signal, amplitude scaling in the case of amplitude only and combined phase-amplitude predistortion for QAM type signals. With predistortion on the subcarrier signal input to the non-linear two-port, the resulting upconverted signal may be transmitted in a standard form suitable for demodulation at the signal destination without special equipment.

Abstract: A hybrid chirped pulse amplification system wherein a short-pulse oscillator generates an oscillator pulse. The oscillator pulse is stretched to produce a stretched oscillator seed pulse. A pump laser generates a pump laser pulse. The stretched oscillator seed pulse and the pump laser pulse are directed into an optical parametric amplifier producing an optical parametric amplifier output amplified signal pulse and an optical parametric amplifier output unconverted pump pulse. The optical parametric amplifier output amplified signal pulse and the optical parametric amplifier output laser pulse are directed into a laser amplifier producing a laser amplifier output pulse. The laser amplifier output pulse is compressed to produce a recompressed hybrid chirped pulse amplification pulse.

Abstract: A first pump pulse and a signal pulse are injected into a first optical parametric amplifier. This produces a first amplified signal pulse. At least one additional pump pulse and the first amplified signal pulse are injected into at least one additional optical parametric amplifier producing an increased power coherent optical pulse.

Abstract: An apparatus for generating laser radiation, the apparatus comprising: a pumping device comprising a resonant cavity; and a laser radiation generation element that is substantially Poynting vector walk-off compensated, the laser radiation generation element being located within the resonant cavity.

Abstract: An optical parametric oscillator and a laser system including an optical parametric oscillator is provided for producing widely tunable coherent light over about 6 &mgr;m, such as in the range of at least about 7 &mgr;m to 18 &mgr;m range. Optical parametric oscillators in accordance with the invention advantageously include CdGeAs2 (CGA) crystals. Such crystals, in accordance with the invention can exhibit exceptionally small (<0.1 cm−1) losses in intensity. Laser systems in accordance with the invention can include frequency-doubled CO2 lasers as the pump beam and frequency doublers or changers, based on CGA crystals.

Abstract: A light wavelength converting element having a periodic polarization inversion structure is produced in the following manner: a comb-shaped electrode and a plate electrode are attached to both surfaces of an MgO—LN substrate, and the MgO—LN substrate is immersed in an insulating liquid. In a state in which substrate temperature is at room temperature, the plate electrode is grounded and a pulse voltage of +0.75 kV, for example, is applied for one second such that the comb-shaped electrode has positive potential. Then, the comb-shaped electrode is grounded and a pulse voltage of −3.25 kV, for example, is applied for ten seconds such that the plate electrode has negative potential.

Abstract: Device for performing a parametric process, comprising a substantially periodic photonic crystal structure comprising a plurality of unitary cells each comprising

Abstract: A nonlinear optical mixer produces coherent vacuum ultraviolet radiation. A cell contains a gas mixture of xenon and a phase-matching gas. A pump laser beam selectively excites the two-photon transition in the xenon gas. A mixing laser beam is also directed towards the gas mixture. Coherent vacuum ultraviolet radiation is produced by four wave mixing of the pump and mixing laser beams. The phase-matching gas, for example mercury vapor, is used to achieve phase matching of the four wave mixing. The coherent vacuum ultraviolet radiation preferably has a wavelength of approximately 157.6 nm (the molecular fluorine line) or 121.6 nm (the Lyman-&agr; hydrogen line). In a preferred embodiment, the two laser beams are loosely-focused.

Abstract: Disclosed herein is a method including the steps of wavelength division multiplexing a plurality of optical signals having different wavelengths to obtain resultant WDM signal light; transmitting the WDM signal light by an optical fiber transmission line; supplying reference light having a predetermined wavelength to the optical fiber transmission line; generating four-wave mixing in the optical fiber transmission line by the interaction of the WDM signal light and the reference light; detecting the power of light generated as the result of the four-wave mixing; and controlling the power of the WDM signal light to be supplied to the optical fiber transmission line according to the power detected. According to this method, the effect of four-wave mixing can be suppressed.