Abstract: A high brightness optical parametric amplifier array uses energy--scaleable optical parametric amplifiers that provide high brightness output. The leability in energy is achieved by using an array of parallel crystal amplifiers to handle high laser energies. High brightness is obtained by using an optical phase conjugator to keep the phase front of the array coherent.

Abstract: One manner of construction of robust, thin film materials with large second-order optical nonlinearities is the covalent self-assembly of aligned arrays of high-.beta. molecular chromophores into multilayer superlattices. the dispersion of the large second harmonic generation (SHG) response in a self-assembled (SA) film containing stilbazolium chromophore building blocks is disclosed, as well as the fabrication of SHG waveguides with such materials.

Abstract: The design and synthesis of a family of calix[4]arene-based nonlinear optical (NLO) chromophores are discussed. The calixarene chromophores are macrocyclic compounds consisting of four simple D-.pi.-A units bridged by methylene groups. These molecules were synthesized such that four D-.pi.-A units of the calix[4]arene were aligned along the same direction with the calixarene in a cone conformation. These nonlinear optical super-chromophores were subsequently fabricated into covalently bound self-assembled monolayers on the surfaces of fused silica and silicon. Spectroscopic second harmonic generation (SHG) measurements were carried out to determine the absolute value of the dominant element of the second-order nonlinear susceptibility, d.sub.33, and the average molecular alignment, .PSI.. A value of d.sub.33 =60 pm/V at a fundamental wavelength of 890 nm, and .PSI..about.36.degree. was found with respect to the surface normal.

Abstract: A solid state laser beam generating system includes a solid state laser which produces a laser beam having a wavelength outside the eyesafe range of 1.5 .mu.m to 1.8 .mu.m. A converter including a non-linear structure is used to convert the laser beam to a beam having a wavelength within the eyesafe range. The non-linear structure has three defined principal axes and the input laser beam to the structure travels in a direction offset from one of the principal axes by an angle greater than 2.degree..

Abstract: The present invention relates generally to the field of optical devices and particularly to embodiments of a four-stage PPLN optical parametric oscillator/difference-frequency generator configuration. The present invention allows simultaneously and colinear generation of four wavelengths in efficient use of the pump signal. A first embodiment comprises a singly resonant cavity having an internal monolithic non-linear optical medium disposed in the cavity. The cavity is bounded by an input mirror and an output mirror. The monolithic non-linear optical medium is divided into four regions each having its own grating period. A second embodiment of the present invention comprises a monolithic non-linear optical medium divided into four separate regions. The entrance facet and exit facet of the monolithic non-linear optical medium includes a coating which acts as the cavity mirrors.

Abstract: It is an object of the present invention to provide a multi-wavelength laser apparatus and a continuous variable wavelength laser apparatus capable of simultaneously outputting laser beams with a plurality of wavelengths and generating up to a high laser output without causing any optical damage. To achieve this object, a multi-wavelength laser apparatus including an optical parametric oscillator having a nonlinear optical crystal and an excitation laser light source includes mirrors for dividing a laser beam emitted from the excitation laser light source into at least three optical axes, and a ring type resonator which simultaneously inputs the laser beams divided by these mirrors at different angles to the nonlinear optical crystal, thereby making the nonlinear optical crystal generate laser beams with at least six different wavelengths, and which does not cause any optical damage up to a high laser output.

Abstract: An optical parameter oscillator system is proposed for use in a continuous wave pump laser system having a single-frequency pump source. The system comprises a single-resonance resonator having a nonlinear medium to produce a first and second parametrically generated wave in response to the pump wave from the single-frequency pump source. The system includes means for controlling the cavity length of the resonator, means for controlling the pump frequency of the pump source and means for controlling the temperature of the nonlinear medium. The system provides for a reliable singly-resonant optical parametric oscillator capable of emitting laser light with high spectral purity and frequency stability over a wide spectral range and is resistant to mode hopping.

Abstract: A pulsed optical parametric oscillator comprising a spectrally pure source or emitting pumping wave pulses, a non-linear crystal to which the pumping wave is applied, a resonant cavity for the complementary wave defined by two same-axis mirrors situated on opposite sides of the crystal, a cavity for the signal wave defined by two same-axis mirrors situated on opposite sides of the crystal, and means for adjusting the length of one or both cavities, wherein the oscillator is a monomode pulsed parametric oscillator and wherein one of the two mirrors for each cavity is situated between the two mirrors of the other cavity.

Abstract: An object of the present invention is to speed up a wavelength tuning speed thereby varying both wavelengths of signal light and idler light at high speed.

Abstract: A wavelength conversion device employs an axicon lens to form Bessel beams of signal light and pump light, which are directed into an anisotropic nonlinear optical crystal. The signal light and pump light are both polarized parallel to the uniquely determined Z-axis of the anisotropic nonlinear optical crystal, the Z-axis being oriented perpendicular to the beam axis. The axicon lens is configured to refract the signal light and pump light at angles such that a phase matching condition is satisfied in the anisotropic nonlinear optical crystal, and converted light, also polarized parallel to the Z-axis and having a new wavelength, is generated.

Abstract: An optical parametric diffuser is provided with an optical mixer which receives inputs of a probe light of a wavelength .lambda..sub.1 and a pumping light of a wavelength .lambda..sub.2, multiplexes them, and generates an output signal light including a wavelength .lambda..sub.5 which is apart from the pumping light wavelength on the opposite side of the probe light wavelength by n.DELTA..lambda. (.DELTA..lambda.=.vertline..lambda..sub.1 -.lambda..sub.2 .vertline., n.gtoreq.2). The signal of a wavelength .lambda..sub.5 is then extracted by a band-pass filter. The optical mixer is made to have a peak in output signal generation efficiency at the wavelength .lambda..sub.5 so that an output light beam of the wavelength .lambda..sub.5 can be obtained from the probe light and the pumping light.

Abstract: A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media.

Abstract: A coherent white light source generates a uniform and continuous coherent white light spectra over 200 nm at a low pump power. The source is based on a pump light source which produces pump optical pulses at a wavelength .lambda..sub.0 and an optical waveguide to receive a pump optical pulse at .lambda..sub.0 to generate a white pulse having a wavelength spread of .DELTA..lambda.. The optical waveguide is characterized by having dispersion properties such that four-wave mixing light having a wavelength spread of .lambda..sub.0 .+-..DELTA..lambda./2 is produced, and the power gain of the four-wave mixing light is greater than 1. These properties of the waveguide are defined by: the path length of the waveguide device ln G.sub.0 /(2.vertline..gamma..vertline.P) in units of ?km!, an absolute value of the dispersion slope to be not more than 16(.vertline..gamma..vertline.E)(.DELTA..lambda..sup. ln G.sub.0) in units of ?ps/nm.sup.2 /km! and an absolute value of the dispersion at the wavelength .lambda..sub.

Abstract: A source of narrow-band coherent radiation has a first optical parametric oscillator (OPO 1) for producing seed radiation, and a second optical parametric oscillator (OPO 2), into which the seed radiation is input after passing through a wavelength-selective element (G). In order to stabilize and adjust the bandwidth of the radiation (14) emitted by the second optical parametric oscillator (OPO 2), radiation of this type is also input into the wavelength-selective element (G) and thereby analyzed, in order, in accordance with the analysis, to adjust the wavelength-selective element or the OPO 2.

Abstract: In an optical parametric oscillator including a laser medium (3) for producing a fundamental wave, a pair of optical elements (4 and 8) constituting a resonator exhibiting resonance for the fundamental wave, and a nonlinear optical crystal (7) between the optical elements for carrying out wavelength-conversion on the fundamental wave to produce a wavelength-converted wave so that one (8) of the optical elements transmits the wavelength-converted wave as an oscillator output wave, a saturable absorber (10) is located between the optical elements. The saturable absorber has a saturable absorption characteristic for the fundamental wave to allow transmission of the fundamental wave of a higher intensity higher than a predetermined intensity and to disallow transmission of the fundamental wave of a lower intensity hot higher than the predetermined intensity.

Abstract: A synchronously pumped optical parametric oscillator (OPO) using a temperature tuned 90 degree phase matched LBO crystal is disclosed which provides a broad selection of output wavelengths. In one embodiment a Ti:sapphire pump source having a cavity length matched to the OPO cavity length pumps a cavity with an LBO crystal located at the cavity waist of the cavity mode. Resources are included to, tune the OPO to a desired wavelength, repetitively scan through a series of desired wavelengths, and adjust the cavity length to obtain a synchronous pumping condition and diagnose a wavelength at which the OPO is operating. A frequency doubled beam in the LBO crystal is generated as a substantially collinear alignment beam.

Abstract: The frequency agile OPO device converts a fixed wavelength pump laser beam to arbitrary wavelengths within a specified range with pulse to pulse agility, at a rate limited only by the repetition rate of the pump laser. Uses of this invention include Laser radar, LIDAR, active remote sensing of effluents/pollutants, environmental monitoring, antisensor lasers, and spectroscopy.

Abstract: A multiple-stage optical Kerr gate system for gating a probe pulse of light. In a first embodiment, the system includes at least two optical Kerr gates, each Kerr gate including a polarizer, an optical Kerr cell actuable by a pump pulse, and an analyzer. In a second embodiment, at least one of the Kerr cells may be eliminated by arranging the respective sets of polarizers and analyzers so that they share a common Kerr cell. Gated pulses obtained using the present system typically have a signal to noise ratio that is at least 500 times better than that for gated pulses obtained using a single optical Kerr gate system. The system of the present invention may also include means for causing the pump pulse to arrive at the second Kerr cell (in the case of the first embodiment) or at a single Kerr cell a second time (in the case of the second embodiment) non-synchronously with the arrival of the probe pulse thereat.

Abstract: An optical parametric oscillator which operates with uncoated optics and a non-linear crystal. The pulse length is long relative to the cavity length, and hence the pump is still operating when the crystal flouresces. The fresnel reflection from the uncoated optics is sufficient to maintain the flouresence. Another aspect attenuates one of the idler and signal beams within the cavity, to allow the other one to emerge more dominant.

Abstract: Single-crystal lithium tetraborate (single-crystal Li.sub.2 B.sub.4 O.sub.7 or single-crystal LBO) as an optical converter device which stably operates for a long term, has a long life, and is compact, light and inexpensive, an optical converter device using the single crystal LBO, especially, for emitting light having a wavelength of 500 nm or less, and an optical apparatus using the optical converter device. Coherent light irradiates the light incident face of the single-crystal LBO at a predetermined incident angle, which single-crystal LBO is cut at a predetermined plane to the optical axis in order to satisfy a predetermined phase matching angle, and light having a half wavelength of the incident light is emitted. Preferably, the single-crystal LBO has a refractive index variation of 10.sup.-5 /mm or less and/or a etch-pit density of approximately 1.times.10.sup.3 /cm.sup.2.

Abstract: A laser arrangement for generating narrow-band, tunable coherent radiation has an optical parametric oscillator (10) and a tunable seed oscillator (20) whose emitted seed radiation can be set in a narrow-band fashion by means of at least one wavelength-selective element (30). In order to achieve simple tunability of the output radiation (38) of the OPO in conjunction with a narrow bandwidth, good spatial beam quality and high beam intensity without maladjustment of the OPO resonator, the lineshape, set using the wavelength-selective element (30), of the seed radiation I.sub.seed (.lambda.), and the intensity transmission function T.sub.opo, (.lambda.) of the non-pumped resonator (12, 14) of the OPO (10) are set in such a way that given tuning of the center wavelength .lambda..sub.max seed of the seed oscillator (20) in the middle between two neighboring transmission maxima of the intensity transmission function T.sub.opo (.lambda.) it holds for all wavelengths .lambda. not equal to .lambda..sub.

Abstract: An imaging system comprises an acousto-optic tunable filter for receiving light at an input end thereof and outputting light at an output end thereof. A control circuit is provided for tuning the filter. A prism is responsive to the light output by the tunable filter. The prism is oriented at an angle with respect to the filter to compensate for dispersion of the output light caused by the tunable filter.

Abstract: An optical parametric oscillator (50) includes a resonator cavity (26) for laser light, and a gain medium (28) disposed in the resonant cavity for converting pump light to the laser light. The oscillator includes an optical arrangement for directing a pulse of the pump light pulse to make generally axially counterpropagating initial and return passes through the gain medium. The optical arrangement includes a pulse return reflector (37) for directing the pulse to make the return pass. The reflector is separated from the gain medium forming a delay line of length sufficient that the initial and return passes are separated in time by greater than about 0.5 FWHM of the pump light pulse. The reflector forms part of a relay imaging system (51) which causes the initial and return passes to propagate through substantially the same volume of gain medium.

Abstract: An optical parametric oscillator or OPO (20) includes an elongated resonant cavity (22) for signal light, having a parametric gain medium (28) disposed therein for converting pump light to signal light. The resonant cavity has a output coupling device (26) at one end thereof and a Porro prism (24) at the opposite end thereof. The OPO includes an optical arrangement (30, 39 and 40) for directing pump light to make counterpropagating initial and return passes longitudinally through the gain medium at an angle (36) to the axis (23) of the resonant cavity.

Abstract: Efficient nonlinear processes in a nonlinear optical medium are achieved by combining the concept of electromagnetically induced transparency (EIT) and a strongly-driven atomic local oscillator. The present method uses a nonlinear optical medium having elementary entities, such as atoms or molecules, in which a ground state .vertline.1> and a second state .vertline.2> are selected such that the transition between the ground state .vertline.1> and the second state .vertline.2> is a dipole forbidden transition. An upper state .vertline.3> selected from among the energy states .vertline.i> above the ground state .vertline.1> such that a two-photon transition between the ground state .vertline.1> and the second state .vertline.2> via the upper state .vertline.3> is allowed.

Abstract: A laser system in which an intense laser beam of a predefined pumping wavelength traverses a non-linear material, such as crystalline lithium niobate, that has been impressed with one or more quasi phase matching (QPM) gratings is disclosed. Quasi phase matching compensates for the dispersion or birefringence in a non-linear material by modulating the non-linearity with the proper period such that the different wavelengths involved in the non-linear process stay in phase over a long interaction length. The first QPM grating promotes the parametric generation of a resonant signal whose wavelength is determined by the grating period. According to the invention, either a second QPM grating impressed in the same medium or a different order of the first QPM grating promotes the non-linear interaction between the resonant signal and another optical signal traversing the non-linear material.

Abstract: The invention relates to an optical parametric oscillator characterized in that it comprises an OPO nonlinear material (18) and two mirrors (24, 26) on either side of said nonlinear material and forming an OPO cavity and a switched microlaser (2, 6, 8, 26) for generating an OPO cavity laser pumping beam.

Abstract: A parametric generator for efficiently converting short duration pump pulses of a first frequency to a signal beam of a desired frequency is described. The parametric generator includes a second order nonlinear parametric medium, a retro-reflector, and an optical re-imaging system. Each optical sub-path through the parametric medium is substantially distinct and non-overlapping. At least two optical sub-paths have a direction within a phase matching acceptance angle of the parametric material which corresponds to the desired wavelength. The parametric generator can be configured to be compact because it utilizes multiple transmissions through the parametric medium and it employs only a single pump beam input.

Abstract: A solid state laser system producing coherent radiations at deep ultraviolet wavelengths includes a solid state laser producing a first beam having a wavelength near 1 micron. The 1 micron beam is passed to both a harmonic generation stage and to a tunable optical parametric oscillator. The harmonic generation stage is configured to produce a fifth harmonic of the 1 micron beam, while the optical parametric oscillator produces a tunable beam in the near infrared spectrum (e.g., approximately 2.075 micron). The fifth harmonic and the near infrared beams are mixed in a sum frequency generator to produce a highly coherent beam in the deep ultraviolet (e.g., between approximately 180 nm to 213 nm).

Abstract: A frequency converter can be used, in particular, to generate optical waves in the medium infrared (3.12 .mu.m) range from optical sources in the near infrared range. It comprises a heterostructure semiconductor waveguide formed by an alternation of layers of material M.sub.I and M.sub.II, at least one of these materials being a non-linear semiconductor and the plane of the layers being parallel to the direction of propagation of the electromagnetic waves in the waveguide.

Abstract: A three-color coherent light system includes a laser source for generating a laser beam in the 1000-1100 nm wavelength region; means, responsive to the laser source, for generating the second harmonic of the laser beam; an optical parametric oscillator for providing a signal beam and an idler beam; means for splitting the second harmonic of the laser beam into a first beam for providing a source of coherent green light and a second beam for pumping the optical parametric oscillator to produce the signal and idler beams; means for generating the second harmonic of the signal beam as a source of coherent blue light; and means for generating the second harmonic of the idler beam as a source of coherent red light.

Abstract: An optical phase conjugator includes an optical nonlinear medium for receiving original signal light and pumping light, and generating and outputting phase-conjugate light by a nonlinear optical effect. The optical nonlinear medium contains an element which can be activated upon irradiation of activation light and has an amplification function with respect to at least the pumping light. The optical phase conjugator comprises a first optical coupler for coupling the original signal light and the pumping light and then inputting the coupled light into the medium, and a second optical coupler for inputting the activation light into the medium. An improvement in phase-conjugate light generating efficiency is attained, and phase-conjugate light having a sufficiently high intensity can be obtained by the optical phase conjugator with a simple, compact arrangement.

Abstract: Nonlinear optical materials are described which satisfy Formula 1M.sub.Xl M'.sub.Y (B.sub.3 O.sub.5).sub.Z Formula 1wherein M and M' are mono- or divalent metal ions, X varies from about 0.1 to about 1.9, Y varies from about 1.9 to about 0.1, and Z is 2 or 3. Currently, the best nonlinear optical materials also satisfy Formula 2M.sub.X M'.sub.Y (B.sub.3 O.sub.5)X+Y Formula 2wherein M and M' are monovalent metal ions independently selected from the group consisting of Group IA metals, X varies from 0.1 to about 1.9, and wherein Y varies from about 1.9 to about 0.1. The best results are achieved when compounds satisfying Formula 2 have X=Y=1, and the metal ions are independently selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and francium. One example, without limitation, of a compound that satisfies Formulas 1 and 2 is CsLiB.sub.6 O.sub.10.

Abstract: A tunable source of narrowband coherent radiation comprises a pulsed pump laser (10), an optical parametric oscillator or amplifier (12) and a so-called master oscillator (14). The narrowband output radiation of the master oscillator serves as seed radiation which is injected into the optical parametric oscillator or amplifier (12). In order to obtain a beam profile of the emitted output radiation as homogeneous as possible, optically imaging elements (28) are arranged in an optical delay line (24) for the partial pulses which pump the optical parametric oscillator or amplifier, which transform the spatial beam profile at the output (30) of the pump laser (10) with respect to amplitude, phase and, preferably, the divergence, too, into the crystal of the optical parametric oscillator or amplifier.

Abstract: A tunable narrowband source of a coherent radiation, comprisinga first optical parametric oscillator (OPO1) which includes at least one first optical parametric amplifier medium (K.sub.1) in a resonator (18, 20; 20, 34) or an optical parametric generator;at least one second optical parametric oscillator (OPO2) which includes at least one second optical parametric amplifier medium (K.sub.

Abstract: A tunable, optical, parametric oscillator including at least one non-linear optical crystal (10) comprises a first deflector mirror (18) arranged inside the resonator between the resonator mirror (12) and the crystal (10) to couple in the pump radiation (16) as well as a second deflector mirror (20) arranged outside the resonator behind a second resonator mirror (14) to separate the pump radiation (22) from the radiation (24) generated in the optical parametric oscillator.

Abstract: A tunable narrowband optical parametrical oscillator (OPO) is excited in pulsed fashion to generate tunable narrowband radiation. A wavelength selective means (T, G) disposed outside the resonant cavity (M3, M4) of the optical parametrical oscillator reduces the bandwidth of the OPO radiation generated. A pumping pulse is divided by a beam splitter (DM1) into at least two partial pulses, and the delay between the two partial pulses is adjusted by means of a delay distance (D) in such a mannner that the first partial pulse will pump the crystal of the optical parametrical oscillator, part of the OPO radiation thus generated passing through the wavelength selective means which is arranged outside the resonant cavity, being coupled back into the resonant cavity, and passing through the crystal (C) once again when the second partial pulse (2) pumps the crystal (C).

Abstract: A laser system in which an intense laser beam of a predefined pumping wavelength traverses a non-linear material, such as crystalline lithium niobate, that has been impressed with one or more quasi phase matching (QPM) gratings is disclosed. Quasi phase matching compensates for the dispersion or birefringence in a non-linear material by modulating the non-linearity with the proper period such that the different wavelengths involved in the non-linear process stay in phase over a long interaction length. The first QPM grating promotes the parametric generation of a resonant signal whose wavelength is determined by the grating period. According to the invention, either a second QPM grating impressed in the same medium or a different order of the first QPM grating promotes the non-linear interaction between the resonant signal and another optical signal traversing the non-linear material.

Abstract: An optical wavelength converter apparatus that employs quasi-phase-matched parametric interaction or sum/harmonic frequency generation of electromagnetic radiation within a slab of optical material. The optical wavelength converter apparatus uses a zig-zag electromagnetic beam path in an optically flat and parallel slab on which total internal reflection from upper and lower surfaces provides a phase shift for phase matching for each leg of the zig-zag path.

Abstract: A compact solid state source of coherent laser light in the range of about 298 nm through about 355 nm utilizes a Nd:YAG or Nd:YLF laser to pump a tunable Ti:Al.sub.2 O.sub.3 laser. The beam from the Nd:YAG/Nd:YLF laser is then combined in a nonlinear optical crystal with the tunable beam from the Ti:Al.sub.2 O.sub.3 laser to provide a continuously tunable laser beam in the range of about 298 nm through about 355 nm.

Abstract: A poled dielectric structure, such as is useful as a frequency doubler, is fabricated by creating a uniform potential, such as a ground by means of an electrode surface, adjacent a first surface of a polable dielectric material, such as a piezo-electric or lithium niobate, and then applying an electric field adjacent a second surface of the polable dielectric material, where the electric field is spatially-modulated according to a three-dimensional modulation pattern with a field amplitude level at selected locations sufficient to cause atomic rearrangement within predefined regions in the polable material, and where the modulation amplitude level of the modulation pattern is controlled according to a modulation parameter. The control mechanism of modulation amplitude level may be protrusions of an electrically-conductive material extending toward the polable material or by modulated variations in the dielectric constant of a dielectric material separating the polable material from an electrode plate.

Abstract: Tunable optical parametric amplifiers and oscillators that are pumped by the light from a tunable laser source are disclosed. One possible embodiment uses a tunable solid-state laser pump and an OPA medium or nonlinear crystal, such as potassium titanyl phosphate KTP or barium borate BBO or lithium borate LBO. The second harmonic output from a tunable solid-state laser is also used to pump the OPA medium. A singly or doubly resonant cavity design is preferably used to reduce the oscillation threshold (i.e., the required pump beam power) of the OPO.

Abstract: Optical parametric oscillators using non-linear crystals cut for the type I interaction have an extraordinary pump beam which generates ordinary signal and idler beams. The use of an optical element to rotate the signal beam before sending this signal beam to a grating element allows for the grating element to have its dispersion plane oriented coplanar with the extraordinary crystal plane of the non-linear crystal. In this manner, for non-linear crystals which have relatively narrow acceptance angles, such as BBO crystals, the reduction in angular aperture of the parametric gain in the extraordinary plane will produce a reduction in the linewidth of the produced output. The grating translates the angular variations into variations in wavelength.

Abstract: A wavelength conversion device 10 comprises a laser device 12 for radiating light beams, a collimeter lens system 18 including lenses 14, 16 for adjusting the wavefront and diameter of a light beam to condense light, a resonator 26 comprising mirrors 22, 24 of the same radius of curvature, and a crystal 20 located inside the resonator 26 near beam-condensing sites and having a large receptive angle. The resonator 26 is a confocal resonator wherein the focus and center of curvature of the mirror 22 are equal to those of the mirror 24 and the radius of curvature of the mirrors 22, 24 exceeds the curvature of the wavefront of light beams from the collimeter lens system 18. Therefore, when a light beam is reflected from the mirrors 22, 24, the curvature of its wavefront is changed and an SHG light comprising only light beams that pass through the forward path is output efficiently.

Abstract: A broadly tunable femtosecond optical parametric generator includes a cavity having a pumping section in which is located a nonlinear crystal selected from the group CTA and RTA, cut for noncritical phasematching. The plane of the optical x axis and or the optical y axis of the crystal is aligned with the axis of the pumping section. A Ti:S laser pumping beam is directed into the pumping section either collinearly or noncollinearly with the pumping section axis and impinges on the crystal to produce signal and idler beams. The laser is tunable to produce OPO output beams between about 1 and 4 .mu.m.

Abstract: A new family of lasers and optical parametric oscillators is based on efficient frequency conversion or doubling in multimode compound optical waveguides. These waveguides exploit specific useful properties of their higher order modes while providing good compatibility with single-mode optical fibers. A mode engineering approach is applied to construct a compound waveguide structure that supports a higher order mode having a sharp peak in its field. This sharp peak simplifies selection of this mode by efficient coupling of its radiation into a single-mode fiber. The lasers and optical parametric oscillators employ wavelength selective properties of this mode field configuration and its unique ability to support efficient frequency conversion and doubling.

Abstract: An optical resonator which is unstable with respect to laser light whose wavelength is to be converted includes a pair of confocal, coaxial curved mirrors. A nonlinear optical medium, e.g., lithium niobate, is disposed between the mirrors. Laser light injected into the optical resonator becomes concentrated in the vicinity of the optical axis, for highly efficient wavelength conversion.

Abstract: A change in the wavelength of a laser beam is achieved by causing the beam to have a conical wavefront and applying it to a nonlinear crystal so that the beam converges along the center axis producing an output beam of a different wavelength. The conical wavefront is achieved in wavefront conversion means by use of lenses, mirrors and crystals with conical surfaces. Adjustability is provided by diverging the beam first and then converging it, with adjustment in the spacing between the divergence means and convergence means of a wavefront conversion means.

Abstract: An optical resonator which is unstable with respect to laser light whose wavelength is to be converted includes a pair of confocal, coaxial curved mirrors. A nonlinear optical medium, e.g., lithium niobate, is disposed between the mirrors. Laser light injected into the optical resonator becomes concentrated in the vicinity of the optical axis, for highly efficient wavelength conversion.

Abstract: A non-linear frequency conversion device is tunable over a wide tuning range. An input source provides a first input beam with a frequency .lambda.1. A first frequency conversion crystal has an input beam face that is cut at a phase matching angle .theta.1 and is positioned on a first stage at a stage angle .alpha.1. The first frequency conversion crystal provides frequency conversion of the input beam of frequency .lambda.1 to a selected frequency .lambda.2 of a first portion of the selected tuning range. A second frequency conversion crystal has an input beam face that is cut at a phase matching angle .theta.2 and is positioned on a second stage at a stage angle .alpha.2. The second frequency conversion crystal provides frequency conversion of the input beam from a frequency .lambda.1 to a selected frequency .lambda.3 of a second portion of the selected tuning range.