Abstract: Wavelength conversion devices for converting fundamental waves to light of a different wavelength are provided. The devices have a wavelength converting layer comprising a plate-shaped body of a non-linear optical crystal having a first main face and a second main face. A supporting body is joined with the first main face of the wavelength converting layer. An additional supporting body may also be joined with the second main face of the wavelength converting layer.

Abstract: A remote sensing apparatus includes an optical system device, a frequency converter, and a frequency analyzer. The device transmits laser light generated from a laser light source toward an optical pattern rotary plate to receive its reflection light by an optical receiver. The plate is a measurement object. The converter converts a reception signal obtained by the receiver into a signal in a frequency domain. The analyzer analyzes a frequency component of the signal obtained by the converter, selects candidate values of sideband wave frequencies from the signal in the frequency region, obtains an approximate value of a rotational frequency by decision of a majority of intervals of the sideband wave frequencies, obtains candidate values of the carrier frequency from the approximate value, and selects the rotational frequency on the basis of the candidate values of the rotational frequency from among the candidate values of the carrier frequency.

Abstract: The present invention relates to a method and apparatus for clearly imaging samples such as fingerprints on substrates of forensic samples. The present invention overcomes the problems of the Laser-Induced-Fluorescence (LIF) technique to distinguish fluorescence from the sample from that of the substrate. The method of the present invention uses either a homodyne- or a heterodyne-assisted phase resolving method, or both, to suppress the contribution of the substrate fluorescence. The resulting image of the sample will then be sufficiently clear for forensic purposes. The present invention may also be used on histological and biochemical samples to visualise latent images.

Abstract: Scanning probe apparatus, comprising: a) a tip-electrode which is coupled to be maintained at a first potential; b) a counter-electrode which is positioned in proximity with the tip electrode and which is coupled to be maintained at a second potential differing from the first potential by a value greater than approximately 150 volts; and c) positioning instrumentation, which is adapted to maintain the tip-electrode at a distance from a surface while scanning the tip-electrode parallel to the surface, and controls the position of the tip-electrode in a scanning direction parallel to the surface to within a resolution sufficient so that the apparatus can be used as a scanning probe microscope.

Abstract: Techniques for recovering optical spectral features include receiving a detected time series that represents a temporally varying intensity of an optical signal. The optical signal is formed in response to an interaction between a target optical spectrum and a chirped optical field. The chirped optical field is an optical field that has a monochromatic frequency that varies in time. The target optical spectrum is an optical frequency dependent optical property of a material or device. A phase correction factor is determined based only on one or more properties of the chirped optical field. The detected time series is corrected based on the phase correction factor to produce an output time series that reproduces in time a shape of the target spectrum in frequency. These techniques allow for fast measurement of spectral features and eliminate the need for prior knowledge of the target optical spectrum to adjust the chirp rate.

Abstract: The manufacture of optical devices by reversing domains in specific patterns in ferroelectric crystal material is practiced using a segmented electrode rather than a continuous electrode on at least one of the surfaces of the ferroelectric crystal material. Independent poling voltages are selectively applied to the segments to create various electric fields inside the ferroelectric crystal material. In this manner, portions of the desired domain-reversed pattern are individually established in the ferroelectric crystal material in high fidelity with their respective electrode segments so that upon completion of poling, the entire domain-reversed structure is established in the ferroelectric crystal material in high fidelity relative to the entire electrode. Parameters of the electrode segment that may be varied singly or in combination to achieve a desired degree of fidelity include the overall size of the electrode segment, as well as the shape and size of the features included in the electrode segment.

Abstract: In a wavelength converting method, an ambient that is in contact with a surface of a non-linear optical crystal from which wavelength-converted light is outputted is a gas that is lower in content of nitrogen than air. A wavelength converting device includes a device for controlling the ambient in contact with a surface of the non-linear optical crystal from which the wavelength-converted light is outputted so the ambient is lower in nitrogen than air. A laser machining device includes the wavelength converting device.

Abstract: An apparatus and a method for generating an optical carrier is disclosed. The apparatus includes: a light source generating a pump light; a SBS generator for stimulated Brillouin scattering the pump light to generate a stokes light from the light source; an attenuator for controlling an amplitude of the pump light from the light source to generate an amplitude controlled pump light; and a detector for heterodyne beating the stokes light and the amplitude controlled pump light to generate an optical carrier.

Abstract: A dispersion compensator and method of dispersion compensation in which an input light is converted to a selected second wavelength, the converted light beam having the second wavelength is dispersion compensated in an amount dependent upon the second wavelength, and the compensated light beam having the second wavelength is converted to the first wavelength.

Abstract: A method and apparatus for transferring information of an optical information-bearing signal from a first wavelength to a second wavelength. The method is implemented in an all-optical wavelength converter circuit which includes a laser diode in communication with a polarization controller. An information-bearing signal having a first wavelength is input to the circuit. A polarization controller adjusts the polarization of the information-bearing signal. The laser diode receives the polarization-adjusted information-bearing signal and generates a converted information-bearing signal by transferring the information of the polarization-adjusted information-bearing signal from the first wavelength to the second wavelength. The polarization controller receives the converted information-bearing signal from the laser diode, and polarizes the converted information-bearing signal.

Abstract: A method for thermally stabilizing an optical parametric oscillator (OPO) 10 to maintain constant optical path length for stable high power output places a beam dump 32 outside an OPO cavity 18. The OPO 10 has a nonlinear crystal 22 within cavity 18 for splitting a single input pump beam 14 into lower energy signal and idler beams 16, 18. The method includes providing a cavity exit port for unconverted pump and generated idler beams, and absorbing unconverted beams in beam dump 32. The method includes athermalization by actively cooling surfaces used as an optics mounting base, and athermalization by constraining the size of cavity 18 by using thermally stiff members, guiding pins or rails, or by using bimetallic materials with different expansion.

Abstract: Crystal housing apparatus for adjustably positioning cooperating non-linear optical crystals in a laser beam generating system, includes a housing (50) with entry (60) and exit (62) windows for respective laser beams, respective holder means (72, 74, 76) to retain respective crystals within the housing in optical alignment with the windows, and means (86) mounting the respective holder means for individual fine rotational adjustment of the crystals about respective axes. Individual temperature control elements (120) are mounted in association with the respective holder means for controlling the temperature of the respective crystals and means (110, 114) is provided for effecting the fine rotational adjustment of the crystals.

Abstract: An optical frequency converter that can use a low-amplitude, high-frequency signal for converting a wide range of optical frequencies. The optical frequency converter includes a device for modulating a lightwave of a preset frequency with a modulation signal to generate a group of sidebands thereof, a device for selecting sidebands from among the group of sidebands, and a device for changing modulation signal frequencies and selecting specific sidebands.

Abstract: A device and method for processing a signal e.g. equalizing a signal, is disclosed. Such processing involves dividing a signal into two portions that each traverses a wavepath and then are combined. The respective wavepaths impose a non-linear frequency-versus-phase dependency on a signal portion. The frequency-versus-phase dependencies that characterize the respective wavepaths are similar in shape but inverted from each other. A processed signal has significantly improved signal-to-noise ratio.

Abstract: A method of irradiating ultraviolet light onto an object. The method includes generating pulse light having a single wavelength within a range from 1.51 ?m to 1.59 ?m from a laser generating portion, amplifying the pulse light plural times with an optical amplifier that includes a plurality of fiber optical amplifiers, wavelength-converting the amplified pulse light into ultraviolet light with a wavelength converting portion that includes a plurality of non-linear optical crystals, and irradiating the ultraviolet light onto the object through an optical system.

Abstract: Method and apparatus for creating a clone relationship between two or more optical-frequency comb sources (OFCSs). In one embodiment, the invention is an apparatus having (i) first and second OFCSs, each adapted to generate a respective frequency comb, and (ii) means for locking the phases of two comb lines of the first OFCS and the phases of the respective two comb lines of the second OFCS to create a full or partial clone relationship between these two OFCSs. In one system configuration, the locking of the phases of the first and second OFCSs is achieved by locking the phases of two selected comb lines generated by each of these OFCSs to the phases of the respective comb lines generated by the same (third, reference) OFCS.

Abstract: In one version, the present invention provides an all optical device for wavelength conversion, reshaping, modulating, and regenerating, including: a splitting device having first, second, third, and fourth terminals; a nonlinear element, and an attenuator; the third and fourth terminals being associated with an optical loop including the attenuator and the nonlinear element, the nonlinear element being displaced from a center of the optical loop, wherein the splitting device is arranged to receive a modulated signal from one of the first and second terminals and a continuous beam from one of the first and second terminals and to generate based on the continuous beam a patterned signal at one of the first and second terminals, and wherein the widths of pulses of the patterned signal are proportional to the widths of pulses of the modulated signal. In an alternative version according to the present invention, the optical loop includes a nonlinear element and a coupling device for receiving chopped signals.

Abstract: Quasi-phasematching design to provide an approximation to a desired spectral amplitude response A(f) is provided. An initial phase response ?(f) corresponding to A(f) is generated. Preferably, d2?(f)/df2 is proportional to A2(f). A function h(x) is computed such that h(x) and H(f)=A(f)exp(i?(f)) are a Fourier transform pair. A domain pattern function d(x) is computed by binarizing h(x) (i.e., approximating h(x) with a constant-amplitude approximation). In some cases, the response provided by this d(x) is sufficiently close to A(f) that no further design work is necessary. In other cases, the design can be iteratively improved by modifying ?(f) responsive to a difference between the desired response A(f) and the response provided by domain pattern d(x). Various approaches for binarization are provided. The availability of multiple binarization approaches is helpful for making design trades (e.g., in one example, fidelity to A(f) can be decreased to increase efficiency and to increase domain size).

Abstract: A nonlinear optical conversion device includes a nonlinear crystal having entrance and exit surfaces allowing input and output laser beams to propagate in the phase-matching plane for a desired nonlinear generation process. The nonlinear generation process involves a nonlinear interaction in the nonlinear crystal and resultant conversion of power in one or two input beams into power in the output beam. The nonlinear crystal is characterized by absorption and resultant modification of the crystal properties by the power in the output beam, the modification with the potential for reducing the efficiency of the nonlinear process in the crystal, and the nonlinear process involving critical phase-matching in the nonlinear crystal in which the powers in the output beam and input beam or beams propagate in different directions through the process of Poynting vector walk-off. The input beam or beams are of a sufficiently small beam dimension in the phase-matching plane.

Abstract: An optical fiber wavelength converter inputs signal light and pumping light into an end of the highly nonlinear optical fiber to obtain converted light of the signal light from the other end of the highly nonlinear optical fiber. In the optical fiber wavelength converter, a wavelength ?p of the pumping light is set within a range from ?0?1 nanometers to ?0+1 nanometers, where ?0 is a zero-dispersion wavelength of the highly nonlinear optical fiber, an absolute value of a dispersion slope of the highly nonlinear optical fiber with the wavelength ?p is not more than 0.02 ps/nm2/km, a nonlinear coefficient ? of the highly nonlinear optical fiber with the wavelength ?p is not less than 10/W/km, and a change in a conversion bandwidth D defined as D=|?p??s2| is not more than 30 percent at variable environmental temperatures ranging from 0° C to 40° C.

Abstract: A pattern electrode having a predetermined pattern and a connecting electrode connected to the pattern electrode are formed on one surface of a single-polarized ferroelectric substance crystal. An electric field is applied across the ferroelectric substance crystal with corona charging or electron beam irradiation from the side of the other surface of the ferroelectric substance crystal. A polarization inversion region having a shape corresponding to the predetermined pattern is thus formed in the ferroelectric substance crystal. The electric field is applied in a state, in which an electrical insulating material is located on the other surface of the ferroelectric substance crystal and at a position corresponding to at least a position of a certain area of the connecting electrode.

Abstract: When forming a periodically-poled structure on a nonlinear optical crystal 1 that permits wavelength conversion and/or optical computing, the group velocity matching conditions are determined to synchronize the group velocity of the incident light L1 with that of the outgoing light L2, and the polarization reversal period of the periodically-poled structure is determined to satisfy quasi-phase matching conditions for the aforementioned wavelength conversion and/or optical computing. As a result, the problems associated with wavelength conversion of the pulsed light due to a difference in the group velocity are suppressed.

Abstract: The present invention discloses a means of the generation of tunable femtosecond pulses from 380 nm to 465 nm near the degenerate point of a 405-nm pumped type-I BBO non-collinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a pumping energy of 75 mJ at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.

Abstract: A low-noise optical frequency converter uses a predetermined microwave electric signal to modulate an input light wave and output a light wave that includes a first-order upper-sideband or lower-sideband and a third-order lower-sideband or upper-sideband. The frequency converter modulates a light wave identical to the input light wave with a signal having a frequency that is three times that of the microwave signal, to form a first light wave having a first-order lower-sideband or upper-sideband. The first light wave is mixed with a second light wave having a first-order upper-sideband or lower-sideband and a third-order lower-sideband or upper-sideband, with a phase of the third-order lower-sideband or upper-sideband reversed to a phase of the first light wave, thereby suppressing third-order sidebands.

Abstract: A signal light pulse to be converted into a two-dimensional space signal and a reference ultra-short light pulse are directed to a dispersion device, a second-harmonic is generated by introducing a one-dimensional frequency light distribution obtained by a one-dimensional Fourier transform lens, the second-harmonic is then subjected to time-to-space conversion through a one-dimensional Fourier transform lens so as to obtain a light wave distribution, and the light wave distribution is then subjected to filtering by a time-frequency filter provided on a filter plane of a one-dimensional space frequency filtering optical system and is further converted into a two-dimensional space signal corresponding to a time-frequency expanded two-dimensional light distribution which represents a relation between time and frequency of the signal pulse light.

Abstract: The light source unit includes a single wavelength oscillation light source, a light generating portion which has an optical modulator converting and emitting light from the light source into a pulse light, a light amplifying portion made up of an optical fiber group in which each fiber has a fiber amplifier to amplify the pulse light from the optical modulator, and a light amount controller. The light amount controller performs a step-by-step light amount control by individually turning on/off the light output of each fiber making up the optical fiber group, and a light amount control of controlling at least either of the frequency or the peak power of the emitted pulse light of the optical modulator.

Abstract: Working with an information system operating an application—are an imager, a coded data source, and a computer-readable signal-bearing medium signal (FIG. 1, 11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 23, 24, 25, 26, 27, 31, 32, 33, 41, 42, 43, 44, 45, 51, 52, 53, 54, 55, 91, 92, 93) connected to the information system where light from the data source—which represents data—is detected by the imager which inputs a signal—which represents the light—to the information system; where a use component of the medium causes the data to be made available to the application with the application being specified by the data; and where: the image can be from a plurality of imagers signal connected to the information system; the coded data source can be from a plurality of coded data sources; the application can be from a plurality of applications operated by the information system; and the medium can have a plurality of components which cause uses of data, management of imagers, and output signals.

Abstract: A wavelength converter for generating a wavelength tunable laser optical source in itself is disclosed. The wavelength converter includes a first semiconductor optical amplifier for generating an optical noise, generating and outputting a first optical source by amplifying the generated optical noise if an external current is applied, first and second distributed Bragg reflectors for reflecting only a component of a specified wavelength range among components of the optical noise and applying the reflected component to the first semiconductor optical amplifier, and a second semiconductor optical amplifier for receiving an optical source divided from the optical source reflected by and outputted from the first distributed Bragg reflector and an input data optical source, generating and outputting a second optical source by changing a phase of the divided optical source according to a digital signal from the input data optical source.

Abstract: Input light is split by an input-light splitter into first split light and second split light. A multiplex-interference portion performs multiplex interference of the first split light and the second split light to generate intensity-modulated light having a first wavelength. A phase modulation portion is fed with the intensity-modulated light and continuous wave light having a wavelength equal to a second wavelength, and performs cross-phase modulation of the continuous wave light in accordance with phase modulation of the input light.

Abstract: A method and apparatus for controlling an optical gain difference and an optical phase difference in a semiconductor optical amplifier—Mach-Zehnder interferometer (SOA-MZI) wavelength converter having two arms and that outputs probe output signals POH and POL, corresponding to pump input signals of logic high and logic low, respectively. The controlling includes detecting an optical power level of the output probe signals and controlling at least one of an optical gain difference between the two arms and an optical phase difference between the two arms in accordance with a detected optical power level of the probe output signal.

Abstract: The present invention generally provides systems and methods for distribution of radiation among a plurality of optical channels, each of which can include a non-linear optical element. An optical system of the invention can include a source for generating radiation and an optical time-division multiplexer that can deflect, at any given time interval, the radiation into one of a plurality of optical channels.

Abstract: An apparatus and method generating an optical pulse of picosecond class (having a high duty ratio), which accurately and stably operates at an arbitrary repetition frequency, has a high OSNR, and is not restricted by an RF modulation frequency, are provided. New modulation spectrum components are generated by performing phase modulation for light output from a single wavelength laser light source with an optical phase modulator. The phases of the modulation spectrum components are aligned by a phase adjuster, so that a pulse wave in a time domain is generated.

Abstract: An apparatus (8, 14) for wavelength shifting light from a first frequency ?1 to a second frequency ?2 is provided in the form of a semiconductor intersubband laser (8) lasing at its intersubband frequency ?3. The output light is wavelength shifted to a frequency ?2=?1+n?3, where n is a non-zero integer ( . . . , ?2, ?1, 1, 2, . . . ). The wavelength shifted light ?2 may be amplitude modulated and/or frequency modulated to impart information upon it. The wavelength shifting is a coherent process allowing for the possibility of coherent communication techniques to be used.

Abstract: A wavelength conversion device including a nonlinear medium having quantum dots uses a tunable laser as an excitation light source of optical four wave mixing, and performs wavelength conversion for a wide bandwidth signal light with optical four wave mixing by employing a control apparatus for controlling an optical system including an optical path of a signal light and an optical system including an optical path of an excitation light in correspondence with a wavelength of a signal light that is to be wavelength converted.

Abstract: A wavelength conversion device includes a photodetector for generating a photocurrent in response to the detection of radiation at a first wavelength. An avalanche multiplier amplifies the signal photocurrent and feeds this to a light emitting element that produces radiation at a second wavelength shorter than the first wavelength and corresponding to the detected radiation at the first wavelength. The components are assembled together in an integrated stacked arrangement either by epitaxial growth or wafer fusion of the individual components. The device is useful as an image intensifier or thermal imaging device.

Abstract: A device for converting frequency of electromagnetic radiation includes a nonlinear medium that forms a moving grating in the nonlinear medium by introducing at opposite ends of the nonlinear medium a first set of electromagnetic radiation having varying frequencies. Electromagnetic radiation is inputted into the nonlinear medium at a first frequency and extracted at a second frequency from the nonlinear medium. The moving grating in the nonlinear medium allows for electromagnetic radiation to be converted into the second frequency.

Abstract: Methods and compositions for using an up-conversion phosphor as an emitting material in a reflective displays and Polymer compositions for display mediums, and blue green red (BRG) display mediums. Roles of the pumping duration and character on the temperature and the efficiency of the up-conversion process in (Ytterbium, Erbium or Thulium) co-doped fluoride crystals are set forth. Methods, compositions and display mediums for using up-conversion phosphors in both reflective and transmissive displays in which the substrate and pixel shapes are designed to maximally remove heat deposited in the emitting material and thereby improve the efficiency of up conversion.

Abstract: According to at least one embodiment, a system comprises a Sagnac interferometric loop and a semiconductor optical amplifier (SOA) located at an asymmetric position on that loop, wherein the Sagnac interferometric loop and the SOA are operable to perform signal conversion on an input signal.

Abstract: An optical system includes an InGaAsP photodiode having a bandgap and configured to operate in Gieger mode, a first light source configured to emit an optical signal of a first wavelength less than the bandgap at a first intensity, a second light source configured to emit light of a second wavelength greater than the bandgap at a second intensity, a beam combiner configured to combine the first and second wavelengths to simultaneously irradiate the photodiode with the first and second wavelengths, an electric field applied across the photodiode greater than a breakdown voltage thereof and configured to result in avalanching of electrons in the photodiode when the optical signal from the first light source is incident thereon and resulting in a photorefractive response within the photodiode, and an image capture device in optical communication with and configured to capture modulated light of the second wavelength reflected from the photodiode.

Abstract: A wavelength converter using difference frequency generation (DFG) is disclosed. In one embodiment, the wavelength converter comprises (a) a first optical filter configured to filter out one or more lightwaves requiring wavelength conversion from wavelength-division multiplexed (WDM) lightwaves, and (b) a broadband multi-channel simultaneous wavelength conversion portion comprising a pump source that generates pump light for use in the process of the DFG, a first optical combiner for combining said pump light with said filtered lightwaves, a high non-linear medium configured to generate wavelength converted lightwaves from said filtered lightwaves using the DFG, and a second optical filter for filtering said wavelength converted from said filtered lightwaves.

Abstract: A multi-frequency light producing method and apparatus multiplies the number of optical channels present in an incident wavelength division multiplexed (WDM) signal light source by four-wave mixing (FWM) the WDM signal with at least one pump lightwave at least one time. By FWM the WDM light and a pump lightwave multiple times, wherein each FWM process is executed with a pump lightwave having a different frequency, either in series or parallel, the number of optical channels produced as a result of FWM effectively increases the number of optical channels present in addition to those from the WDM signal. The light producing method and apparatus can be employed in a telecommunications system as an inexpensive light source producing a plurality of optical frequencies.

Abstract: A ring cavity laser has at least two facets and a mechanism is provided to produce unidirectional propagation and light emission at a first wavelength. A source of laser light at a second wavelength is injected into the cavity to reverse the direction of propagation and to produce emission at the second wavelength.

Abstract: A wavelength conversion element which can set the wavelength of a pump light to a wavelength longer or shorter than the wavelength of a plurality of signal lights and a wavelength of a plurality of conversion lights present in an optical communication band, and a method for using such a wavelength conversion element are provided. A first pump light with a wavelength ?1 of 1.51 ?m, a second pump light with a wavelength ?2 of 1.57 ?m, and a signal light with a wavelength of ?S of 1.55 ?m are multiplexed in a multiplexer and introduced as an incident light into an optical waveguide of a wavelength conversion element. In the optical waveguide, an SF light with a wavelength ?SF of 0.77 ?m is generated by the SFG of the first pump light with a wavelength ?1 of 1.51 ?m and the second pump light with a wavelength ?2 of 1.57 ?m, the signal light is wavelength converted as a DF light (wavelength 1.53 ?m) by the DFG of the SF light and signal light, and this DF light is outputted as the converted light (wavelength ?C=1.

Abstract: A feature of a wavelength conversion device of this invention is the board range of selection of wavelengths which can be obtained by conversion. A wavelength conversion device of this invention comprises an SC light generation portion 12, which receives an excitation light pulse output from an excitation light pulse source and generates SC light, and an optical wavelength filter 14 which filters the SC light. An excitation light pulse source generates an excitation light pulse, of central wavelength ?S. When the excitation light pulse generated by the excitation light pulse source is incident on the SC medium, SC light having a flat spectral shape over the range from wavelength ?L to wavelength ?H (where ?L<?H) is generated. The optical wavelength filter has a characteristic such that the filtering transmitted central wavelengths are ?1, ?2, ?3, . . . , ?n (where n is a natural number). A further feature is that the following conditions (1) and (2-1), (2-2), . . .

Abstract: Disclosed are an apparatus and method for converting the wavelength of an optical signal using a multi-mode Fabry-Perot laser diode. The apparatus controls polarization of an external pump optical signal to output a TE polarized pump optical signal, and controls polarization of a probe optical signal to output a TM polarized probe optical signal. The apparatus couples the TM polarized probe optical signal and TE polarized pump optical signal irrespective of the polarization of the optical signals. The apparatus finely controls the polarization of the pump optical signal and the polarization of the probe optical signal such that they conform to TE and TM modes of the Fabry-Perot laser diode, respectively.

Abstract: A wavelength converter or demultiplexer device comprising first and second stages (30, 40). For wavelength converter action, the first stage impresses an intensity modulation (IM) and phase modulation (PM) on a CW input signal (?1) carried by an input DATA signal (?2) using cross phase modulation in a non-linear optical element (46). The first stage in an embodiment is a semiconductor laser amplifier loop optical mirror (SLALOM) which has a semiconductor optical amplifier (SOA) as the non-linear optical element. The second stage has a non-linear transfer function and impresses a further IM on the optical signal responsive to the PM impressed in the first stage. In an embodiment, the second stage is a polarization maintaining fiber (PMF) optical loop. The transfer function of the overall device is thus improved by making it steeper and more time confined.

Abstract: The invention concerns an optical resonant frequency converter comprising two mirrors and a non-linear crystal in a ring resonator arrangement for converting laser radiation into frequency-doubled radiation. Because of the refractive effect of the prism-shaped, non-linear crystal two mirrors are sufficient to form a ring resonator with a total of three optical elements. A suitable choice of the orientation of the crystal axes in relation to the laser beam direction reduces scatter in the crystal. In one embodiment the entry surface of the crystal is at the Brewster angle while the exit surface is perpendicular to the beam and has an antireflection coating. In another embodiment the converted beam is coupled out through a polarisation beam splitter layer on one of the crystal surfaces. In a further embodiment the crystal surfaces are cylindrically curved. That produces an elliptical beam profile in the crystal, which reduces the walk-off effect.

Abstract: An ultraviolet laser apparatus having a single-wavelength oscillating laser generating laser light between an infrared band and a visible band, an optical amplifier for amplifying the laser light, and a wavelength converting portion converting the amplified laser light into ultraviolet light using a non-linear optical crystal. An exposure apparatus transfers a pattern image of a mask onto a substrate and includes a light source having a laser apparatus emitting laser light having a single wavelength, a first fiber optical amplifier for amplifying the laser light, a light dividing device for dividing or branching the amplified laser light into plural lights, and second fiber optical amplifiers for amplifying the plural divided or branched lights, respectively, and a transmission optical system for transmitting the laser light emitted from the light source to the exposure apparatus.

Abstract: A nonlinear optical chromophore having the formula D-?-A, wherein ? is a ? bridge including a thiophene ring having oxygen atoms bonded directly to the 3 and 4 positions of the thiophene ring, D is a donor, and A is an acceptor.

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