Abstract: System and method are disclosed for in-situ monitoring of a specimen while undergoing a defined process. The system includes a processing system adapted to perform the defined process on the specimen, and a coherent anti-Stokes Raman scattering (CARS) microscopy system adapted to in-situ monitor the specimen. In another aspect, the CARS microscopy system is adapted to in-situ monitor the specimen simultaneous with the defined process being performed on the specimen by the processing system. In still another aspect, the CARS microscopy system is adapted to perform a measurement of the specimen while the defined process being performed on the specimen is paused or temporarily halted.

Abstract: A method and apparatus for generating and transmitting high energy optical pulses are described. Distributed temperature sensors usually use Raman scattering in optical fibers as the means to determine the temperature. Here, light from a laser source is sent down a fiber and the small amount of light that is scattered back towards the source is analysed. As the fiber length increases, the resolutions of the temperature and loss measurements become poorer. This is because losses in an optical fiber attenuate the signal. An obvious solution to this problem is to launch more light into the fiber to compensate for the losses but stimulated Raman scattering limits how much light may be launched. The present invention solves this problem by using a pulse conversion method to maximize the resultant pulse energy while the power is kept below SRS threshold.

Abstract: The present invention relates to a light source apparatus that has a base structure capable of generating SC light and further having a structure that enables the shaping of the spectral waveform of the SC light, power adjustment of the SC light, or adjustment of the frequency of repetition of the pulse train that contains the SC light. For example, a light source apparatus that enables shaping of spectral waveforms comprises a seed light source that emits seed light which is a pulse train or continuous light; an optical fiber that generates SC light from the seed light, and spectrum shaping means for completely or partially changing the spectral waveform of the SC light. The shaping of the spectral waveform changes the maximum power of the seed light by changing the optical coupling efficiency of the seed light source and optical fiber, for example, thereby suitably deforms the spectrum of the SC light.

Abstract: An apparatus and method that reduces laser speckle by using stimulated Raman scattering in an optical fiber. The fiber core diameter and length are selected to achieve a desired output color. An adjustable despeckler is formed by combining two optical fibers in parallel and adjusting the amount of light in each path.

Abstract: Fiber-laser light is Raman shifted to eye-safer wavelengths prior to spectral beam combination, enabling a high-power, eye-safer wavelength directed-energy (DE) system. The output of Ytterbium fiber lasers is not used directly for spectral beam combining. Rather, the power from the Yb fiber lasers is Raman-shifted to longer wavelengths, and these wavelengths are then spectrally beam combined. Raman shifting is most readily accomplished with a “cascaded Raman converter,” in which a series of nested fiber cavities is formed using fiber Bragg gratings.

Abstract: Apparatus and methods are described for efficiently transporting and using incident radiation falling on photosensitive devices and structures supporting photosensitive devices. For example, an apparatus includes a low-absorption medium capable of passing and absorbing incident radiation; a scattering material disposed over at least a portion of or within the low-absorption material, the scattering material permitting a portion of incident light to pass therethrough; and a reflective surface disposed adjacent to the low-absorption medium to reflect radiation towards or within the medium.

Abstract: An apparatus and methods for generating a substantially supercontinuum-free widely-tunable multimilliwatt source of radiation characterized by a narrowband line profile. The apparatus and methods employ nonlinear optical mechanisms in a nonlinear photonic crystal fiber (PCF) by detuning the wavelength of a pump laser to a significant extent relative to the zero-dispersion wavelength (ZDW) of the PCF. Optical phenomena employed for the selective up-conversion in the PCF include, but are not limited to, four-wave mixing and Cherenkov radiation. Tunability is achieved by varying pump wavelength and power and by substituting different types of PCFs characterized by specified dispersion properties.

Abstract: A surface-enhanced Raman scattering substrate includes a carbon nanotube film structure and a plurality of metallic particles disposed on the carbon nanotube film structure. The carbon nanotube film structure includes a number of carbon nanotubes joined by van der Waals attractive force therebetween. The carbon nanotube film structure is a free-standing structure.

Abstract: An optical antenna collects, modifies and emits energy at light wavelengths. Linear conductors sized to correspond to the light wavelengths are used. Nonlinear junctions of small dimension are used to rectify an alternating waveform induced upon the conductors by the lightwave electromagnetic energy. The optical antenna and junctions are effective to produce harmonic energy at light wavelengths. The linear conductors may be comprised of carbon nanotubes that are attached to a substrate material, which may then be connected to an electrical port.

Abstract: A Raman shifter is provided with improved optical efficiency and robustness, particularly for high power applications. In one embodiment, a source system (100) includes a source pump laser (102) and a seed laser (104). Beams from the pump laser (102) and seed laser (104) combine for transmission into a Raman cell (112). Folding optics define a multi-pass pathway through the Raman cell (112). Such folding optics may include an internal reflectance element. An entry window into the Raman cell, an exit window from the Raman cell, and the internal reflectance elements include surfaces disposed at a Brewster angle relative to the incident beam. The Raman cell medium is circulated in a direction transverse to the beam pathways through the cell. In this manner, improved optical efficiency and robustness is achieved as well as improved performance over a significant wavelength band.

Abstract: The present invention relates to a fabrication method for a quasi-phase-matched waveguide. The method includes the steps of forming a metal etch mask on a ferroelectric single crystal substrate, etching the substrate by using the etch mask, removing the etch mask, forming conductive layers on the etched substrate, forming polarization regions by applying an electric field to the conductive layers, and flattening the substrate after removing the conductive layers. Accordingly, the present invention is advantageous in that it can be applied to various fields employing a ferroelectric substrate, such as LiNbO3, LiTaO3, Mg:LiNbO3 or Zn:LiNbO3, it can obtain more accurate and uniform periodic domain inversion devices with a high quality and can fabricate devices that are cheaper and have a better performance.

Abstract: The invention concerns a laser system with a frequency comb generator for generating a comb of optical frequencies having an offset frequency and a plurality of equidistant modes. The laser system further preferably includes at least one stabilizer for stabilizing the frequency comb onto a certain offset frequency and/or onto a certain mode spacing. The laser system further includes an optical amplifier for amplifying the frequency comb coupled out of the frequency comb generator, the amplification factor of this amplifier being variable; and the amplifier is followed by a Raman medium for generating a Raman shift of the frequency comb.

Abstract: A medical device includes an insertable portion capable of being inserted into an orifice associated with a body of a patient. The insertable portion comprising an automated head unit capable of being manipulated in at least two axes of motion based at least in part on one or more control signals. The medical device further includes one or more controllers coupled to the automated head unit. In one particular embodiment, the one or more controllers generate the one or more control signals based at least in part on an input signal.

Abstract: An optical antenna collects, modifies and emits energy at light wavelengths. Linear conductors sized to correspond to the light wavelengths are used. Nonlinear junctions of small dimension are used to rectify an alternating waveform induced upon the conductors by the lightwave electromagnetic energy. The optical antenna and junctions are effective to produce harmonic energy at light wavelengths. The linear conductors may be comprised of carbon nanotubes that are attached to a substrate material, which may then be connected to an electrical port.

Abstract: A laser system (10) for use in photonic excitation investigation of a target object, in which the target object interacts with incident photons and emits a corresponding photon which is detected and used to generate an image of the target object. The laser system (10) includes a pulsed fiber laser (14) for producing a laser beam, and a non-linear photonic crystal fiber (16) for carrying the laser beam from the laser (14) to an instrument (18) for photonically exciting the target object. The photonic crystal fiber (16) allows for switching, or tuning, the wavelength of the laser beam. In two-photon microscopy, the laser system (10) allows for providing multiple wavelengths for exciting a plurality of different fluorophores simultaneously. In coherent Raman imaging and spectroscopy, the laser system (110) allows for using a single laser to provide two laser beams of different wavelengths.

Abstract: Various methods of using Raman-active or SERS-active probe constructs to detect analytes in biological samples, such as the nucleic acid and/or protein-containing analytes in a body fluid are provided.

Abstract: A wavelength converter for binary optical signals includes an interferometer structure (110) for generating an output signal by modulating a received local signal (LS) according to the modulation of a fUrther received first input signal (IS 1). When such interferometer structures (110) are operated in a standard mode it is known in the art to control the power of the input signal such that the extinction ratio of the output signal is kept minimal. The invention also controls the power of the input signals to achieve the minimal extinction ratio when the wavelength converter and in particular the interferometer structure (110) is operated in a differential mode receiving two input signals.

Abstract: This invention pertains to a scene projection system and a method for projecting a scene that can simulate light temperature of above 2000 K. The system comprises of a light source part for generating light at a lower wavelength; a means part for individually controlling dynamic range, contrast, brightness, temporal characteristics and temporal dynamics of the light; a rare earth doped fiber part that re-emits the output light at a higher wavelength; and a means part for conveying light between its parts. The method comprises steps of generating light at a lower wavelength; individually controlling temporal characteristics, temporal dynamics, brightness and contrast of the light; passing the light through a rare earth-doped fiber; and re-emitting the light at a higher wavelength.

Abstract: The wavelength converter comprises (1) an optical multiplexer for multiplexing an amplitude-modulated first light and reference light, which is continuous light having a wavelength different from the wavelength of the first light, (2) an optical fiber for propagating the multiplexed light therethrough to generate a third light by a non-linear optical phenomenon, and (3) an optical filter having a pass wavelength range set such that a pulse time width of the third light is 20% or more narrower than a pulse time width of the first light after the third light has passed through the optical filter, or (3?) an optical filter having a pass wavelength range set such that a cross point of an eye pattern of the third light is lower than a cross point of an eye pattern of the first light after the third light has passed through the optical filter.

Abstract: Optical Fourier transform is executed over a wide time range. A quadratic function type optical pulse generator (7) generates a control light pulse of a shape expressed by a quadratic function or a parabola according to a clock signal based on a signal light pulse from an optical coupler (1). The signal light pulse inputted is multiplexed by a multiplexer (9) with the control light pulse optically delayed by an optical delay element (8) so that the timing is matched with the signal light pulse, and introduced into an optical Kerr medium (10). In the optical Kerr medium (10), the signal light pulse inputted by the mutual phase modulation between the signal light pulse and the control light pulse is subjected to a linear phase modulation (frequency chirp) over the entire pulse or a wide time range.

Abstract: A semiconductor based Raman laser and/or amplifier with reduced two-photon absorption generated carrier lifetimes. An apparatus according to embodiments of the present invention includes optical waveguide disposed in semiconductor material and a diode structure disposed in the optical waveguide. The optical waveguide is to be coupled to a pump laser to receive a first optical beam having a first wavelength and a first power level to result in emission of a second optical beam of a second wavelength in the semiconductor waveguide. The diode structure is to be biased to sweep out free carriers from the optical waveguide generated in response to two photon absorption in the optical waveguide.

Abstract: A light source includes a wavelength shifter that is capable of shifting a shorter optical signal wavelength to a longer optical signal wavelength based at least in part on a Raman effect in a waveguide. The wavelength shifter includes a pump laser that operable to produce the shorter optical signal wavelength. The wavelength shifter also includes an intermediate stage that is coupled to the pump laser and capable of producing an intermediate optical signal wavelength. The intermediate optical signal wavelength is longer than the shorter optical signal wavelength. The wavelength shifter further includes a final stage capable of generating the longer optical signal wavelength. The final stage includes at least in part a ZBLAN waveguide and wherein the longer optical signal wavelength is greater than 1.7 microns and is greater than the intermediate pump signal wavelength.

Abstract: A photonic bandgap assembly used in a laser device for generating a near-diffraction-limited optical beam that comprises simultaneous multiple wavelengths. The photonic bandgap fiber assembly has a plurality of serially connected segments each having a photonic crystal fiber each being designed to efficiently perform Raman conversion on a pump wavelength to a near-diffraction-limited output wavelength. A first segment of the assembly is connected to a pump laser, and the output wavelength generated by each segment is output to the following segment to serve as a pump beam of the photonic crystal fiber thereof. Therefore, the pump beam is converted in a plurality of output beams with different wavelengths. The output beams can then be selectively recombined and coupled out as a multiple-wavelength optical beam.

Abstract: Fiber Bragg writing devices comprising solid state lasers are provided. The solid state lasers comprise optical parametric oscillators and emit moderate peak-power output beams at wavelengths which are suitable for efficient production of fiber Bragg gratings without causing embrittlement of the optical waveguide. These solid state lasers generate output beams with wavelengths of approximately 240 nm, in order to match the primary absorption peak in the ultraviolet range for a typical optical waveguide. Some of these solid state lasers generate tunable wavelength beams using an optical parametric oscillator (“OPO”), then generate harmonics of these tunable beams. Other lasers mix the tunable beam with fixed wavelengths derived from the pump laser to reach the desired output wavelength.

Abstract: A direct-view optical microscope system is provided which uses high-energy light from a phenomenon known as non-resonant Raman scattering to illuminate a living biological specimen. One embodiment of the system combines two discrete light sources to form a combined incident light source for the microscope. The system includes a method and apparatus for modulating the intensity of the scattered light when two light waves are combined to produce the incident light. By varying the frequency of the two source light waves, the intensity of the combined Raman-scattered light can be modulated to achieve finer resolution.

Abstract: An apparatus for optically shifting the frequency of an input signal beam includes a first Raman medium that receives an input signal beam, a first pump beam, and a first reference beam to responsively generate an intermediate signal beam comprising a Raman sideband of the first Raman medium. A second Raman medium is optically coupled in series with the first Raman medium. The second Raman medium receives the intermediate signal beam, a second pump beam, and a second reference beam to responsively generate an output signal beam comprising a Raman sideband of the second Raman medium. The generated output signal represents the input signal that is shifted in frequency by a frequency shift that corresponds to the frequency difference between the first and second reference beams.

Abstract: A direct-view optical microscope system is provided which uses high-energy light from a phenomenon known as non-resonant Raman-scattering to illuminate a biological specimen. One embodiment of the system combines two discrete light sources to form a combined incident light source for the microscope. The system includes a method and apparatus for modulating the intensity of the scattered light when two light waves are combined to produce the incident light. By varying the frequency of the two source light waves, the intensity of the combined Raman-scattered light can be modulated to achieve finer resolution. In one embodiment, the system provides illumination and observation of microscopic agglutination events between pathogenic antigens and specific antibodies, for prompt detection and identification in the field.

Abstract: A method and apparatus for high-efficiency stimulated Raman Stokes and anti-Stokes scattering is described. A dual-Raman scattering cell configuration is disclosed. A variable pressure of the first Raman cell causes a controllable pressure shift of the Raman-active two-photon transition. The frequency-shifted Stokes radiation generated in the first Raman cell, along with the residual pump laser radiation, is applied to a second Raman cell whose pressure is adjusted to maximize production of the anti-Stokes sidebands. By the steps of applying the first Stokes sideband “injection” signal, and controlling its frequency via the pressure difference of the two Raman cells, and its intensity by appropriate focussing, the process of Raman scattering may be significantly enhanced over the techniques of the prior art. These techniques are of especial interest to the production of intense, coherent, short-wavelength radiation, especially when only a single pump laser frequency is available.

Abstract: A system for converting a single input beam of light into a plurality of spatially or angularly shifted output beams, each having a different wavelength supplies the single input beam of light to the first of a plurality of cascaded acousto-optical and/or stimulated Brillouin scattering (SBS) wavelength-shifting devices in optical communication with each other. This causes the first wavelength-shifting device to produce a first output beam having a wavelength shifted from that of the input beam. The output beam from each of the cascaded wavelength-shifting devices is supplied to the next such device to cause each successive wavelength-shifting device to produce an output beam having a wavelength shifted from the wavelength of the input beam to that device. Thus, variations in the wavelength of the input beam or in temperature or strain of the wavelength-shifting devices will cause the wavelengths of the output beams to uniformly vary, thus maintaining constant intra-wavelength spacings among the output beams.

Abstract: A direct-view optical microscope system is provided which uses high-energy light from a phenomenon known as non-resonant Raman scattering to illuminate a living biological specimen. One embodiment of the system combines two discrete light sources to form a combined incident light source for the microscope. The system includes a method and apparatus for modulating the intensity of the scattered light when two light waves are combined to produce the incident light. By varying the frequency of the two source light waves, the intensity of the combined Raman-scattered light can be modulated to achieve finer resolution.

Abstract: The present invention is directed to a three-dimensional memory apparatus for storing information in a volume comprising of an active medium. The active medium is capable of changing from a first to a second isomeric form as a response to radiation of a light beam having an energy substantially equal to a first threshold energy. The concentration ratio between a first and a second isomeric form in any given volume portion represents a data unit. The active medium in the memory apparatus comprises of diarylalkene derivatives, triene derivatives, polyene derivatives or a mixture thereof. The invention is further directed to means for reading the data units from the isomeric states of the active medium in different portions of said active medium where the two isomeric forms have a substantially different absorption coefficient for absorbing energy of a second threshold energy. Reading may also be carried out by measuring the scattering pattern of the two isomeric forms.

Abstract: A compact apparatus and a method for generating wavelength-tunable short optical pulses, which apparatus and method can change the wavelength of generated pulses without adjustment of an optical system and enable generation of ideal femtosecond soliton pulses. The apparatus includes a short-optical-pulse source, an optical characteristic regulation unit for regulating characteristics of light output from the short-optical-pulse source, and an optical fiber for receiving input pulses from the optical characteristic regulation unit and for changing the wavelength of output pulses linearly. Short optical pulses are input to the optical fiber, so that new soliton pulses are generated in the optical fiber due to its nonlinear effect. Further, the nonlinear effect enables the wavelength of the soliton pulses to shift linearly in accordance with the intensity of input light.

Abstract: Methods and apparatus for maintaining a quality of a Raman medium in a Raman conversion cell. In various examples, a flow velocity of the Raman medium is tailored based on a spatial nonuniformity of heat deposition resulting from the Raman conversion in the cell. In particular, in one example, the flow velocity of the Raman medium may be tailored to be higher where the heat deposition/temperature rise is larger and smaller elsewhere in the cell. This type of flow velocity profile reduces the overall required volumetric flow of the Raman medium in the cell without significantly affecting a quality of the Raman medium.

Abstract: A dot termination comprising a disk of thin film resistive material connects a transmission line on a substrate to a DC ground plane in a manner to provide broadband high frequency performance. The dot termination connects to DC ground connections spaced about the perimeter of the disk. Each DC connector includes a ground via passing through the substrate to the ground plane. A metal trace is used for each DC connection, the trace connecting a respective via with the perimeter of the disk. Each metal trace can include a resistive portion connected to the dot region and a metal trace portion connecting the trace to the via. A resistive extension tongue of the disk connects the disk to a transmission line trace.

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 Raman amplifier includes a Raman gain fiber comprising a length of high-dispersion gain fiber and operable to receive at least one optical signal. The Raman amplifier also includes at least one pump source capable of generating at least one pump signal that co-propagates within the Raman gain fiber with at least a portion of the at least one optical signal received by the Raman gain fiber. The length of the high-dispersion gain fiber is at least ten (10) times a walk off length between the at least one pump signal and at least one wavelength of the at least one optical signal received by the Raman gain fiber. In addition, the length of high-dispersion gain fiber is at least two (2) times a walk off length between at least two optical signal wavelengths of the at least one optical signal received by the Raman gain fiber.

Abstract: Opto-electronic devices and techniques using Brillouin scattering to select a sideband in a modulated optical carrier signal for amplification. Two lasers respectively provide a carrier signal beam and a Brillouin pump beam which are fed into an Brillouin optical medium in opposite directions. The relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillouin gain on the sideband. This effect can be used to implement photonic RF signal mixing and conversion with gain, conversion from phase modulation to amplitude modulation, photonic RF frequency multiplication, optical and RF pulse generation and manipulation, and frequency-locking of lasers.

Abstract: A dot termination composed of a circular thin film resistive material connects a transmission line to a DC ground plane in a manner to provide a broadband high frequency performance. The termination uses resistive traces provided around the perimeter of the dot with vias connecting the traces to ground to provide multiple DC paths to ground. The use of these multiple DC paths enhances the high frequency performance of the dot termination, and maintains a desired impedance. The dot termination can be used in a shunt configuration with an optical modulator to provide broadband voltage biasing for the optical modulator. To maximize the biasing voltage, a DC blocking capacitor is placed between the dot termination and ground. Biasing current can be applied between the dot termination and the blocking capacitor to maximize performance.

Abstract: In a light unit that converts a false linear light into which a light from a point light source has been converted by a columnar light guide, into a planar light by a plate-shaped light guide, the point light source is arranged only at an end of the columnar light guide at which an angle between a longitudinal direction of the columnar light guide and ridge lines of recesses and projections forming a prism surface is obtuse. Thus, a positional relationship between the point light source and the ridge lines is set so that a main irradiation direction of band-shaped light emitted from the columnar light guide and which has been obtained by converting the light from the point light source to a false linear light is not substantially orthogonal to the ridge lines of the recesses and projections forming the prism surface of the plate-shaped light guide. Consequently, light obtained by totally reflecting this band-shaped light is unlikely to be viewed.

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: Opto-electronic devices and techniques using Brillouin scattering to select a sideband in a modulated optical carrier signal for amplification. Two lasers respectively provide a carrier signal beam and a Brillouin pump beam which are fed into an Brillouin optical medium in opposite directions. The relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillouin gain on the sideband. This effect can be used to implement photonic RF signal mixing and conversion with gain, conversion from phase modulation to amplitude modulation, photonic RF frequency multiplication, optical and RF pulse generation and manipulation, and frequency-locking of lasers.

Abstract: A wavelength converter comprises a loop of optical fiber having an entry end (14) and an exit end (16). The entry end of the loop forms an input for a pump wavelength and the exit end forms an outlet for a converted signal. The loop is arranged to produce Stokes shifted wavelength components from a pump wavelength by Raman effect. A wavelength selective coupler (18) is provided between the entry and exit end (14, 16) of the loop. The coupler permits exit of a predetermined wanted Stokes shifted wavelength component but causes coupling of lower order Stokes wavelengths to the entry for recirculating in the loop to enhance generation of the predetermined wavelength component.

Abstract: An apparatus and method are described for exploiting almost the full almost 25 THz of bandwidth available in the low-loss window in optical fibers (from 1430 nm to 1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths .lambda..sub.r should lie in close proximity to the zero-dispersion wavelength .lambda..sub.0 of the amplifying fiber.

Abstract: An harmonic generator system for generating at least two output beams (6a, 6b, 6c) of higher order harmonic radiation from an input beam (1) of radiation of frequency .omega. comprises at least two non linear optical crystals (3a, 3b, 3c) arranged in series. Radiation output from each crystal stage has first and higher order harmonic components. Chromatic separators (5a, 5b, 5c) separate beams of radiation output from each crystal and selected beams are then passed through a telescope (9a, 9b) to the next crystal in the series, thereby generating further radiation beams of first and higher order harmonics. Multiple beams of second, 2.omega., third 3.omega., or fourth, 4.omega., harmonic radiation may be output from the system and may be used to pump various stages of a secondary laser system or an optical parametric oscillator. Alternatively, the output beams of higher order harmonic radiation may be coherently combined to form a single output.

Abstract: A high efficiency solid state Raman laser system for shifting the frequency of an input beam emitted by a laser pumping system is described. The laser pumping system suppresses relaxation oscillations in the input beam and emits a constant power, mode-locked pulse train. A solid Raman medium is disposed inside a Raman resonator cavity to shift the frequency of the input beam to produce a Raman beam. The frequency of the Raman beam is finely tuned in the resonator cavity to eliminate high order Raman shifted wavelengths. The polarization of the Raman beam is selected using a polarizing element disposed in the resonator cavity. The Raman beam frequency is shifted using a non-linear medium inside the resonator cavity. The non-linear medium is preferably a frequency doubler. The Raman laser system is particularly suitable for producing high-quality yellow light for guide star applications.

Abstract: An intracavity doubled solid state Raman laser system for converting the frequency of a laser input beam emitted by a laser pumping system is described. A solid Raman medium is disposed within a resonator cavity to shift the frequency of the input beam to produce a Raman beam. The frequency of the Raman beam is tuned in the resonator cavity preferably using an etalon and a birefringent filter. The polarization of the Raman beam is selected using a polarizing element disposed in the resonator cavity. The Raman beam frequency is doubled using a non-linear doubling medium inside the resonator cavity. The Raman laser system is particularly suitable for producing yellow light.

Abstract: Crystals formed of Tl.sub.3 AsS.sub.3 provide very good materials for the nonlinear optical conversion efficiency. The crystals are useful in nonlinear optical devices such as harmonic generators and optical parametric oscillators, and in linear applications such as acousto-optical devices. The method of preparing such crystals is also disclosed.

Abstract: A light source having a solid state laser emitting a beam that is separated into a number of segments. Each segment is frequency shifted by a different amount so that the segments do not substantially overlap in the frequency domain. Each segment passes through a short focal length lens element of a fly's eye array to be dispersed onto a mask plane for evenly illuminating a mask. The lens elements of the fly's eye array are contained within a small region in comparison to the width of the dispersed beam segments, such that each beam segment contributes illumination to the entirety of a common portion of the mask.

Abstract: A laser-diode-pumped solid-state laser includes a solid-state laser rod which is doped with a rare-earth material such as neodium and has a wavelength converting function and a semiconductor laser which pumps the solid-state laser rod. Opposite end faces of the solid-state laser rod are formed into resonator mirrors, and a wavelength-converted wave such as a second harmonic of the laser beam oscillated by the solid-state laser rod or a sum frequency wave of a laser beam oscillated by the solid-state laser rod and a semiconductor laser beam emitted by a semiconductor laser is extracted.

Abstract: An attenuator/filter is disclosed that is inherently tuned and provides for a stimulated Brillouin scattering effect having a predetermined threshold that fixes the output thereof at a predefined power level. The stimulated Brillouin scattering effect is disclosed as being provided by either a fused silica optical fiber or a fiber-optic ring resonator both of which act as a filter to allow selected frequencies to pass. The SBS threshold is selected to improve the sideband to carrier power ratio which, in turn, determines the modulation depth for the modulated signal.