Abstract: The present invention relates to acousto-optic applications of parametric optical apparatuses that use the mechanical energy of elastic oscillations to convert light over a wide range of wavelengths and amplitudes and to generate coherent light.

Abstract: A tunable fiber optic parametric oscillator includes a nonlinear optical loop mirror or fiber Sagnac interferometer NFSI with a dispersion shifted fiber portion. The oscillator is synchronously pumped to amplify a signal wave, while reflecting the depleted pump pulse back towards the pump. The amplified signal wave and simultaneously generated idler waves are directed to a spectral filter. The spectral filter may be a diffraction grating, a Faraday mirror or other optical filter that is tunable to change the signal wavelength that is reflected back to the NFSI. The fiber optic parametric oscillator is tunable over substantially the entire gain bandwidth and is insensitive to the polarization of the pump pulses. The fiber optic parametric oscillator may be used as a tunable source of short pulses for high speed optical communication systems. The fiber optic parametric oscillator may also be used for synchronization and clock recovery.

Abstract: An optical wavelength converter, particularly useful in a wavelength-division multiplexing communication system, including a semiconductor junction in one arm of a Mach-Zehnder interferometer through which a data signal at a first wavelength and a probe signal at a second wavelength counter propagate. The junction is reversed biased into avalanche to selectively absorb the data signal and thereby phase modulate the probe signal according to the data impressed on the data signal. The phase modulated probe signal is beat against an unmodulated probe signal, thereby converting the wavelength of the optical carrier. A tunable laser may produce a probe signal of selectable wavelength. The data signal may first be converted by cross-gain modulation to a third wavelength out of band from the other signals before it is interacts with the probe signal.

Abstract: An apparatus for generating three or more optical signals. The apparatus generally comprises a coherent source, an optical parametric generation device and a sum frequency generator. The coherent source generates a first optical signal having a first free-space wavelength. The optical parametric generation device interacts the first optical signal to produce an idler signal and a second optical signal having a second free-space wavelength while transmitting a portion of the first optical signal to the sum frequency generator. The sum frequency generator non-linearly combines part of the second portion of the first optical signal with the idler signal to produce a third optical signal characterized by a third free-space wavelength. The first, second, and third optical signals may comprise collinear red green and blue beams that may be modulated and scanned to produce an image. Furthermore, the optical parametric generation device and the sum frequency generator may be fabricated as a single monolithic device.

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: A method of and apparatus for creating a second order non-linearity profile along a waveguide. The method comprises: thermally poling a waveguide structure to generate a second order non-linearity; placing a mask adjacent to the waveguide structure; and exposing the waveguide structure with UV light through the mask to selectively erase the second order non-linearity along the waveguide structure. The mask may be an amplitude mask or phase mask. In a preferred embodiment an amplitude mask is used in combination with an incoherent UV light source to produce selective erasure of a thermally poled second order non-linearity. Apparatus for carrying out this method and devices based on waveguide structures fabricated using the method are also described.

Abstract: A wavelength of pump is set to an anomalous dispersion area of an optical fiber for wavelength conversion and pump power is set to be larger than a predetermined threshold of MI so that wavelength conversion capable of flattening conversion efficiency spectrum within a wide bandwidth is permitted. A pumping source can oscillate a lightwave having a wavelength in the anomalous dispersion region of the optical fiber for wavelength conversion and intensity which can flatten the conversion efficiency spectrum over the wide bandwidth.

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 pump resonant optical parametric oscillator (PROPO) is optimized for noise suppression of pump radiation of wavelength &lgr;p. The PROPO generally comprises a parametric amplifier disposed within a resonant cavity having input and output couplers. The parametric amplifier has a gain G that increases with increasing power at a pump wavelength &lgr;p. The cavity resonates at both pump wavelength &lgr;p and signal wavelength &lgr;s. The parametric amplifier transfers noise on the pump radiation to the signal radiation. Input coupler transmission TIC, output coupler pump transmission TP, signal transmission TS, and gain G are chosen such that a resonated pump power at &lgr;p is nearly clamped at a threshold level. By setting these parameters such that the PROPO has a threshold slightly lower than the available power at a wavelength of the optical pump, noise on the pump radiation may be reduced by greater than about a factor of 10.

Abstract: A wavelength converter for converting wavelength of a signal beam combined to a pump beam. The wavelength converter comprises a mode converting region for converting mode of the pump beam; a direction combining region for combining the signal beam to the pump beam; and wavelength converting region for converting the wavelength of the signal beam combined to the pump beam. The mode converting region and the wavelength converting region are formed as integrated by nonlinear polymeric material to construct a polymeric waveguide extended along propagation direction. The wavelength converting region includes the nonlinear polymer poled to a predetermined direction. According to the present invention, a DFG device, a cascade wavelength converting device, and second harmonic generation device of higher energy converting efficiency can be developed.

Abstract: An optical parametric device for broadband parametric processes involving first and second frequencies &ohgr;1 and &ohgr;2. The device comprises an optical fiber comprising a core and a cladding, the cladding being microstructured with holes for providing waveguiding confinement of at least one optical mode in the core. The optical fiber is poled lengthwise with a non-linearity profile having a period that satisfies a quasi phase matching (QPM) condition including the first and second frequencies. Through the use of a poled holey fiber of suitable hole structure, it is possible to increase the second harmonic (SH) efficiency in comparison with poled conventional (non-holey) fiber. This is achieved by a combination of a low mode overlap area between the fundamental and SH waves, a low absolute value of the mode area, and a large SH bandwidth per unit length of the fiber, all of which can be provided together in a poled holey fiber.

Abstract: An optical parametric amplifier pumped by ultrashort optical pulses provides time-gated image amplification or time-gated image frequency conversion, resulting in optical sectioning of an object under test and/or background rejection of improperly timed light. An ultrashort laser pulse of one frequency is used to illuminate an object under test. An ultrashort pulse light beam at a signal frequency transmitted through or scattered from the object is optically mixed with an ultrashort laser pulse at a pump frequency in a nonlinear optical medium. This mixing produces an amplified image of a particular optical section of the object at the signal frequency in addition to producing a frequency converted image of the same optical section at an idler frequency. This time-gated amplification can be used in conjunction with a confocal imaging system, or a conventional imaging system.

Abstract: Provided are nonlinear optical materials that can be used for a number of optical applications including, but not limited to, second harmonic generation (SHG), sum-frequency generation (SFG), difference-frequency generation (DFG) and optical parametric amplification (OPA). The nonlinear optical materials of the present invention are formed from divalent metal ions and borate anions to form a complex borate framework, with the B:O ratio of the framework being about 10:17. The present NLO materials generally satisfy Formula 1: Ba2−xMxB10O17  Formula 1 wherein M is a divalent metal ion; wherein x ranges from 0 to 0.3. M of Formula 1 is independently selected from Groups IIA and IIB metals, preferably strontium, barium, and lead. Other charged species that charge balance the B10O17 species may also be used to form compounds satisfying Formula 1 as long as these compounds also exhibit NLO properties.

Abstract: An optical parametric oscillator includes a nonlinear element for converting an incident pump beam of angular frequency &ohgr;p into a combination of a signal wave of angular frequency &ohgr;s and an idler wave of angular frequency &ohgr;i at an arbitrary angular frequency ratio, a beam splitter for splitting the combination exiting the nonlinear element into the signal wave of angular frequency &ohgr;s and the idler wave of angular frequency &ohgr;i, a signal optical resonator for resonating the signal wave of angular frequency &ohgr;s at a resonator optical length Ls between an input mirror and an end mirror, and an idler optical resonator for resonating the idler wave of angular frequency &ohgr;i at a resonator optical length Li between an input mirror and an end mirror. The resonator optical length Ls of the signal optical resonator and the resonator optical length Li of the idler optical resonator are set to satisfy the relationship Li/Ls=&ohgr;i/&ohgr;s.

Abstract: A dispersion compensating module which can compensate the chromatic dispersion of an optical transmission line and which suppresses wavelength distortions ascribable to nonlinear phenomena, is provided. Signal light inputted from a light input portion (19 in FIG. 1) is caused to enter the nonlinear medium (3) of phase conjugate wave generation means (15) by passing it through a light input waveguide (2), a beam splitter (22) and a light input/output waveguide (18) in succession. The nonlinear medium (3) is pumped by pumping light emitted from a pump LD (4), thereby to generate a phase conjugate wave. The generated phase conjugate wave is passed through the light input/output waveguide (18), is reflected by the beam splitter (22) and is passed through a light output waveguide (6) so as to be outputted from a light output portion (20). The light input waveguide (2) is provided with a first isolator (7) which restrains any light from retroceding onto the input side of the signal light.

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 specially cut uncoated birefringent crystal having three Brewster-cut faces with adjacent coated Brewster-cut coupling prisms are used for optical frequency conversion. Two input frequencies are used to obtain a third frequency by sum-frequency generation. The uncoated birefringent crystal permits high power input beams.

Abstract: A photon beam generating apparatus comprises an incident pump beam generation section 1 and a photon pair generation section including a non-linear optical medium 3. The angle between the optical axis of the medium 3 and an incident pump beam is set to a value such that tuning curves become tangent to a line corresponding to a wavelength a in order to generate two photon beams including paired photons generated simultaneously and having a wavelength a. Another photon beam generating apparatus comprises an incident pump beam generation section 1 and a photon pair generation section including a non-linear optical medium 3. The angle between the optical axis of the medium 3 and the incident pump beam is set to a value such that tuning curves become tangent to different lines corresponding to wavelengths a and b respectively, in order to generate two photon beams including paired photons generated simultaneously and having wavelengths a and b respectively.

Abstract: This improved Frequency Agile Optical Parametric Oscillator provides near on-axis pumping of a single QPMC with a tilted periodically poled grating to overcome the necessity to find a particular crystal that will permit collinear birefringence in order to obtain a desired tuning range. A tilted grating design and the elongation of the transverse profile of the pump beam in the angle tuning plane of the FA-OPO reduces the rate of change of the overlap between the pumped volume in the crystal and the resonated and non-resonated wave mode volumes as the pump beam angle is changed. A folded mirror set relays the pivot point for beam steering from a beam deflector to the center of the FA-OPO crystal. This reduces the footprint of the device by as much as a factor of two over that obtained when using the refractive telescope design.

Abstract: Nonlinear optical materials, methods of crystal growth, and devices employing such materials satisfy the general formula (&Sgr;i=1-3M&agr;i1)(&Sgr;j=1-3M&bgr;j2)(&Sgr;k=1-6M&ggr;k3)B14O25  Formula 1 wherein M1, M2, and M3 are mono-, di, or tri-valent metal ions respectively; wherein (&Sgr;i=1-3&agr;i)=X and ranges from 0 to 2, (&Sgr;j=1-3&bgr;j)=Y and ranges from 0 to 4, and (&Sgr;k=1-6&ggr;k)=Z and ranges from 0 to 2, and wherein X+Y+Z=4.0. Other nonlinear optical compounds according to this invention also generally satisfy Formula 2 through 7 below: (&Sgr;j=1-3M&bgr;j2)B14O25, where (&Sgr;j=1-3&bgr;j)=4  Formula 2 M42B14O25  Formula 3 (&Sgr;i=1-3M&agr;i1)(&Sgr;k=1-6M&ggr;k3)B14O25  Formula 4 where (&Sgr;i=1-3&agr;i)=2, and (&Sgr;k=1-6&ggr;k)=2.

Abstract: A passively Q-switched laser is pumped by a first optical input signal to produce a train of optical pulses at a first wavelength. These pulses are then fed into a gain-switched laser. The absorption of energy at the first wavelength induces gain in the cavity of the gain-switched laser at a second wavelength, resulting in the spontaneous generation of an optical output pulse at a preferred eye-safe wavelength.

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: An arrangement (10) for efficiently shifting energy received at a first wavelength and outputting the shifted energy at a second wavelength. The arrangement (10) includes a laser (12) and an optical parametric oscillator (14) of unique design. The oscillator (14) is constructed with an energy shifting crystal (20) and first and second reflective elements (16) and (18) disposed on either side thereof. Light from the laser (12) at a fundamental frequency is shifted by the crystal and output at a second wavelength. The second wavelength is a secondary emission of energy induced by a primary emission generated by the first wavelength in the crystal. A novel feature of the invention is a coating applied on the reflective elements (16 and/or 18) for containing the primary emission and enhancing the secondary emission. This constrains the energy to be output by the arrangement (10) at the wavelength of the desired secondary emission.

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: 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 an 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: A high gain optical parametric amplifier is implemented in a LiNbO3 waveguide fabricated by a combination of periodic electric field poling and proton exchange techniques. The device is capable of amplification in the whole transmission window of silica optical fibers with gains up to 90 dB. The high nonlinearity and resultant high gain of the waveguide-amplifier permits the use of essentially standard power (milliwatt to 10 watt) fiber laser pump sources.

Abstract: An arrangement (10) for efficiently shifting energy received at a first wavelength and outputting the shifted energy at a second wavelength. The arrangement (10) includes a laser (12) and an optical parametric oscillator (14) of unique design. The oscillator (14) is constructed with a energy shifting crystal (20) and first and second reflective elements (16) and (18) disposed on either side thereof. Light from the laser (12) at a fundament frequency is shifted by the crystal and output at a second wavelength. The second wavelength is a primary emission and induces a secondary emission of energy in the crystal. A novel feature of the invention is a coating applied on the reflective elements (16 and/or 18) for minimizing the secondary emission. This constrains the energy to be output by the arrangement (10) at the wavelength of the desired primary emission. In the alternative, the arrangement (10) may be optimized to output one or more of the secondary emissions.

Abstract: A wavelength conversion apparatus and method uses four wave mixing of a first wavelength and a control wavelength in an optical fiber to convert the first wavelength to a desired wavelength. Four wave mixing is produced by operating the optical fiber at a predetermined input power density and by using a fiber length which provides substantial Raman gain. The first wavelength is converted to a higher wavelength by using the higher wavelength four wave mixing signal and converted to a lower wavelength by using the lower wavelength four wave mixing signal.

Abstract: A laser device comprises a non-collinear optical parametric generator (OPG) and a pump wave source (4). The OFG comprises a non-linear crystal (1) fixedly mounted within the generator wherein the relative orientations of the pump wave (3) and each generated wave (5) to an optic axis (2) of the non-linear crystal (1) are substantially such that a point of inflexion is produced in a tuning curve of wavelength versus pump wave orientation of one of the generated waves, such that a broadband spectral output is obtained. This device has many applications including an amplifier for an input seed wave in which the crystal dose not have to be rotated to match the wavelength of the seed wave; or as part of a continuously tuneable narrowband source.

Abstract: A channel-obtaining device takes the desired channel and uses a resonant semiconductor device to mix the channel to a different frequency. The dropped channel is sufficiently removed from the other channels in frequency that it can be effectively separated.

Abstract: The present invention provides a cesium-lithium-borate crystal, which can be used as a high-performance wavelength converting crystal, having a chemical composition expressed as CsLiB6O10, and substituted cesium-lithium-borate crystals expressed by the following formula: Cs1−xLi1−yMx+yB6O10 or Cs2(1−z)Li2LzB12O20 (where, M is an alkali metal element, and L is an alkali earth metal element); a method for manufacturing same by heating and melting; and an optical apparatus using such crystals

Abstract: An optical parametric oscillator for converting the wavelength of a laser pump beam into a signal wavelength and an idler wavelength. A co-linear double resonance cavity is created with a right angle prism serving as a maximum reflector for both the pump beam as well as the signal and idler beams. A non-linear crystal is positioned within said resonance cavity and is pivoted to tune the oscillator. A pump beam deflector is positioned to deflect the pump beam into the resonance cavity. The deflector preferably is a mirror with a multi-layer coating configured to provide maximum reflection at the wavelength of the pump beam and maximum transmittal of the signal and idler beams over their ranges. The pump beam passes twice through said non-linear crystal and is efficiently converted into said signal and idler beams in said non-linear crystal. The deflector can be placed inside or outside the cavity. In a preferred embodiment the output coupler is an uncoated window.

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. Stationary optical elements whose configuration, properties, and arrangement have been optimized to match the dispersion characteristics of the SHG crystal to at least the second order. These elements include a plurality of prismatic elements 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 second order and such that every ray wavelength overlap within the crystal.

Abstract: An optical parametric amplifier pumped by ultrashort optical pulses provides time-gated image amplification or time-gated image frequency conversion, resulting in optical sectioning of an object under test and/or background rejection of improperly timed light. An ultrashort laser pulse of one frequency is used to illuminate an object under test. An ultrashort pulse light beam at a signal frequency transmitted through or scattered from the object is optically mixed with an ultrashort laser pulse at a pump frequency in a nonlinear optical medium. This mixing produces an amplified image of a particular optical section of the object at the signal frequency in addition to producing a frequency converted image of the same optical section at an idler frequency. This time-gated amplification can be used in conjunction with a confocal imaging system, or a conventional imaging system.

Abstract: The present invention comprises an optical parametric oscillator for down-conversion of coherent light to longer wavelengths. The present invention comprises an optical pump source for providing a pump beam at a primary wavelength. The pump source is coupled into a singly-resonant cavity through an input mirror positioned at the input end of said cavity. The inputed pump beam is directed into a monolithic non-linear optical medium having multiple regions formed on a single substrate. An optical parametric oscillation occurs at each stage of the optical medium; however, the signal (resonated) frequency is identical at each stage of the optical medium. The single frequency produced at each stage of the optical medium results in a sequential gain of the signal, which is resonated by an output mirror which is adapted to reflect and oscillate the signal frequency within the cavity, and allow the idler frequency to pass through the cavity.

Abstract: An object is to provide an optical transmission apparatus, an optical repetition apparatus and an optical transmission method in which the chirp polarity applied to an output signal light can be modified easily in accordance with the wavelength dispersion characteristics of a transmission path. Therefore, for example, with the optical transmission apparatus according to the invention a signal light of optical frequency fsig generated by a signal light generating device, and a probe light of optical frequency fp generated by a probe light generation device are input to a four wave mixing generation device having a nonlinear optical effect to generate various signal lights with optical frequencies of fsig, fp, 2×fsig−fp and 2×fp−fsig. One of the signal lights output from the four wave mixing generation device is selected by a signal light selection device and output to the transmission path.

Abstract: A system is provided that delivers sub-picosecond pulses. The system includes a source that produces an output beam of sub-picosecond pulses at a wavelength no greater than 1.27 microns. A photonic crystal fiber is coupled to the source to receive the output beam. The photonic crystal fiber delivering pulses at the target with a pulsewidth less than 2 times a pulsewidth of the source. A first optical device is positioned between the source and the fiber. The first optical element couples the output beam into an input end of the fiber. A second optical device is positioned at an output end of the fiber that delivers the output beam to a selected target.

Abstract: In a process and an apparatus for generating at least three light bundles of different wavelength for displaying color images, one of these light bundles having a longest wavelength and another of the light bundles having a shortest wavelength, which light bundles are obtained by an OPO and further nonlinear optical component elements from a signal beam and/or idler beam of the OPO and/or a primary light bundle, from which a beam exciting the OPO is also derived, it is provided that at least a partial light bundle is separated from the primary light bundle for exciting the OPO, in that the light bundle with the longest wavelength and the light bundle with the shortest wavelength are obtained from the signal beam and/or idler beam of the OPO by way of frequency multiplication and/or frequency mixing with another partial light bundle of the primary light bundle by excluding components of light bundles other than the generated light bundles with the shortest and longest wavelengths for image display.

Abstract: A method and device for frequency conversion of the radiation of a pulsed optical parametric oscillator (OPO) through sum or difference frequency mixing of a pulsed laser pump radiation with an OPO radiation, where the frequency mixing is integrated into the OPO resonator (1). The method permits the use of OPOs with high conversion efficiency in spectral ranges for scientific, technical and medical applications.

Abstract: Apparatus for providing a laser source optically coupled to an optical waveguide, such as an optical fiber, having a reflective grating positioned from the output facet of the laser source a distance equal to or greater than the coherence length of the laser source providing a portion of reflective feedback into the laser source optical cavity to maintain wavelength operation of the laser source in spite of changes in the laser operating temperature or drive current based upon coherence collapse in the laser operation. In cases where the fiber grating is positioned in the fiber within the coherence length of the laser source, intermittent coherence collapse, as opposed to continuous coherence collapse, is unavoidable. In cases where such a laser source is a pumping source for a solid state gain medium, such as an optical amplifier or laser having an active gain element, e.g.

Abstract: The present invention relates generally to an apparatus that increases the conversion efficiency of optical parametric oscillators. The apparatus comprises an intracavity difference-frequency mixing optical parametric oscillator structure which receives a pulsed-pump beam from an optical pump source. The pump beam is received through an input mirror of a singly resonant cavity having an input and output end. Located within the singly resonant cavity are first and second nonlinear crystals for receiving the pump beam. The first crystal produces signal and idler waves which are received into the second crystal which produces additional idler frequency and a difference-frequency. An output mirror positioned at the output end of the cavity is totally reflective to the signal frequency and fully contains the signal frequency within the resonator cavity.

Abstract: A method and apparatus for obtaining multiple wavelengths of varying temporal format from a single solid state laser are provided. Accordingly, the output from the solid state laser can either be sent through a series of non-linear crystals to obtain UV radiation or through an OPO cavity to obtain IR radiation. In order to provide the different wavelengths in the temporal formats commonly used for various medical procedures, the laser source may be operated in two different modes. When the laser system produces UV radiation a pulse of short duration is desired and the laser source is operated in the standard Q-switched mode or is mode locked. Conversely, when the laser system produces IR radiation, a pulse of long duration is desired and the laser source is operated in the free running mode.

Abstract: Use of quasi-phase-matched (QPM) materials for parametric chirped pulse amplification (PCPA) substantially reduces the required pump peak power and pump brightness, allowing exploitation of spatially-multimode and long duration pump pulses. It also removes restrictions on pump wavelength and amplification bandwidth. This allows substantial simplification in pump laser design for a high-energy PCPA system and, consequently, the construction of compact diode-pumped sources of high-energy ultrashort optical pulses. Also, this allows elimination of gain-narrowing and phase-distortion limitations on minimum pulse duration, which typically arise in a chirped pulse amplification system. One example of a compact source of high-energy ultrashort pulses is a multimode-core fiber based PCPA system. Limitations on pulse energy due to the limited core size for single-mode fibers are circumvented by using large multimode core.

Abstract: The present invention relates generally to an apparatus that increases the conversion efficiency of optical parametric oscillators and also reduces overall system size and susceptibility to vibration. The first embodiment of the present invention incorporates a PPLN OPO architecture which includes mirrored coatings on the entry surface area and exit surface area of a monolithic nonlinear optical medium. The coatings act as mirrors, however, the mirrors are actually affixed to the PPLN element. In the first embodiment of the present invention, the PPLN element is a dual grated element. The second embodiment of the present invention uses a single grated PPLN element.

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 more efficient class of optical parametric oscillators is made possible by introducing means for reducing signal losses due to backconversion of signal photons in the nonlinear optical medium.

Abstract: A light modulation system, wherein a light source provides light of a certain wavelength to be modulated by a material layer, which forms part of a specifically configured plate assembly. The modulation layer is placed in the optical path of the light source. Further, the modulation layer is switched between first and second states, and cooperates with the light source to produce a train of pulses at a given pulse rate. The resulting optical pulses transmitted through the modulation layer are converted from the original certain wavelength to a lower wavelength by a frequency converting device.

Abstract: An optical parametric oscillator comprising two meniscus mirrors disposed on opposite sides of a nonlinear medium that forms a confocal unstable resonator. A reduced-to-practice embodiment uses concave-convex mirrors in a confocal arrangement disposed on opposite sides of a KTP crystal used as the nonlinear medium. The optical parametric oscillator and confocal unstable resonator of the present invention exhibits improved beam divergence angles.

Abstract: The present invention relates generally to the field of optical devices and particularly to embodiments of a three-stage PPLN optical parametric oscillator/difference-frequency generator configuration. The present invention allows simultaneous generation of three wavelengths in efficient use of the pump signal. The structure of the first embodiment of the present invention comprises a first PPLN element having first and second grating regions, and a second PPLN element having its own grating period. An input coupler is positioned at the input and exit ends of a resonator cavity and the first PPLN element is positioned between the input coupler and the second PPLN element. A second embodiment of the present invention includes a single PPLN element having three separate grating regions. The single PPLN element is positioned between input and output coupler mirrors. A third embodiment of the present invention includes a single PPLN element having three grating regions.

Abstract: A method for producing electromagnetically induced transparency (EIT) in atoms with hyperfine structure. EIT is the phenomenon in which a material (e.g. lead vapor) becomes transparent to a first electromagnetic frequency (a probe beam) when exposed to a second electromagnetic frequency (a coupling beam). In the present invention, the atom has hyperfine split energy levels. In the method of the present invention, the coupling and probe beams are tuned to transitions between the centers of gravity (COGs) of the hyperfine split levels. This allows high transparencies to be achieved in high opacity materials. Also, the present method can produce EIT in isotopically mixed materials. This is because the COGs of hyperfine split levels (in nuclear spin.notident.0 atoms) are generally coincident with nonhyperfine split levels (in nuclear spin=0 atoms). The method of the present invention is directly applicable to nonlinear sum and difference frequency generation.