Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.

Abstract: Optical microcavities based on two dimensional arrays of holes defined in photonic crystals are optimized for maximum Q factors and minimum mode volume. They can also be used for strong coupling between the cavity field and an atom trapped within a defect of the photonic crystals, or for tunable filters if the holes are filled with electro-optical polymers. In one embodiment the Q factor of a cavity is increased by elongation of a plurality of holes in at least one row in a predetermined direction. Modal structures of microcavities, as well as quality factors, mode volumes, symmetry properties and radiation patterns of localized defect modes as a function of the slab thickness and parameters of photonic crystal and defects are illustrated.

Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: A beam delivery system for a laser emitting at a relevant wavelength of less than 200 nm is provided. The system includes a sealed enclosure connected to the laser and surrounding the path of the beam as it exits the laser resonator. The enclosure extends between the laser output coupler and a photodetector sensitive at the wavelength of the relevant laser emission. The interior of the enclosure, and thus the beam path between the output coupler and the detector, is substantially free of species that strongly photoabsorb radiation at the relevant laser emission wavelength. A beam splitting element diverts at least a portion of the beam for measurement by the detector. The beam splitting element preferably includes a beam splitting mirror, holographic beam sampler or diffraction grating. In addition, optics are preferably provided for filtering a visible portion of the diverted beam, so that substantially only a VUV portion of the diverted beam is received at the detector.

Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.

Abstract: In accordance with the invention, there is provided a device having a first portion with at least one quantum well, where the first portion emits light, a spacer layer, and a second portion with an amplifying region with at least one quantum well, where the device is configured so that the spacer layer transmits the light beam emitted by the first portion and the amplifying region increases the intensity of the light beam. In accordance with another aspect of the invention, there is provided a method of manufacturing a vertical cavity surface emitting laser having the steps of, forming a first portion, having at least one quantum well, that emits light, forming a spacer layer made of a material that is transmissive of light emitted from the first portion, forming a second portion having at least one quantum well, where the second portion is positioned over the spacer layer and the spacer layer is positioned over the first portion.

Abstract: A beam delivery system for a laser emitting at a relevant wavelength of less than 200 nm is provided. The system includes a sealed enclosure connected to the laser and surrounding the path of the beam as it exits the laser resonator. The enclosure extends between the laser output coupler and a photodetector sensitive at the wavelength of the relevant laser emission. The interior of the enclosure, and thus the beam path between the output coupler and the detector, is substantially free of species that strongly photoabsorb radiation at the relevant laser emission wavelength. A beam splitting element diverts at least a portion of the beam for measurement by the detector. The beam splitting element preferably includes a beam splitting mirror, holographic beam sampler or diffraction grating. In addition, optics are preferably provided for filtering a visible portion of the diverted beam, so that substantially only a VUV portion of the diverted beam is received at the detector.

Abstract: A single-transverse-mode laser has a gain medium and a single-transverse-mode fiber disposed within a resonance cavity. The single-transverse-mode fiber has a filter portion and a partial reflection portion. The filter portion of the single-transverse-mode fiber is coupled to the gain medium and disposed within the resonance cavity. The partial reflection portion of the single-transverse-mode fiber defines one end of the resonance cavity. The gain medium has a double-tapered structure.

Abstract: A device is provided, the device comprising a first vertical cavity surface-emitting laser (VCSEL) of a monolithic vertical cavity surface-emitting laser (VCSEL) array, the first vertical cavity surface-emitting laser (VCSEL) being tunable to a first plurality of wavelengths. The device also comprises a second vertical cavity surface-emitting laser (VCSEL) of the monolithic vertical cavity surface-emitting laser (VCSEL) array, the second vertical cavity surface-emitting laser (VCSEL) being tunable to a second plurality of wavelengths, wherein at least one wavelength is in both the first plurality of wavelengths and the second plurality of wavelengths.

Abstract: An excimer or molecular fluorine laser includes a gain medium surrounded by a resonator and including a line-narrowing module preferably including a prism beam expander and one or more etalons and/or a grating or grism within the resonator. The material of transmissive portions of the line-narrowing module including the prisms and the plates of the etalons comprises a material having an absorption coefficient of less than 5×1031 3/cm at 248 nm incident radiation, less than 10×10−3/cm at 193 nm incident radiation, and less than 0.1/cm at 157 nm. Preferably the material also has a thermal conductivity greater than 2.0 W/m° C.

Abstract: An excimer or molecular fluorine laser includes a discharge chamber filled with a gas mixture, multiple electrodes within the discharge chamber connected to a power supply circuit for energizing the gas mixture, and a resonator including the discharge chamber and a pair of resonator reflectors for generating an output laser beam. One of the resonator reflectors is an output coupling interferometer including a pair of opposing reflecting surfaces tuned to produce a reflectivity maximum at a selected wavelength for narrowing a linewidth of the output laser beam. One of the pair of opposing reflecting surfaces is configured such that the opposing reflecting surfaces of the interferometer have a varying optical distance therebetween over an incident beam cross-section which serves to suppress outer portions of the reflectivity maximum to reduce spectral purity.

Abstract: A tunable medical laser diode system for activating PhotoDynamic Therapy (PDT) compounds is disclosed. A tunable medical laser diode system for activating PhotoDynamic Therapy (PDT) compounds and other moderate or low energy multiple wavelength applications is disclosed. Interchangeable diode laser cartridges are used. Each cartridge contains a diode laser, which consists of at least one diode or diode array or some combination thereof. Typically, each diode laser cartridge is tuned to a different wavelength. Multiple cartridges, however may be tuned to the same wavelength for some applications One or more cartridges are attached to the system base unit simultaneously. The cartridges may be powered in series or in tandem for different applications. Selectively powering these cartridges causes light to be emitted at a certain wavelength or wavelengths. Selection of cartridges is facilitated by a drug identification scanner which scans drug activation wavelength information into the system.

Abstract: A rotational constructional laser including a light source (3, 33) for emitting a laser beam (L) and located in the laser housing, a laser beam motor-driven deflection device (7; 50; 74; 104) located in a housing unit (10; 51; 73; 93; 103) secured to and at least partially projecting beyond the laser housing (2; 32, 72; 92; 102) and having a least one beam hole (52, 53) for the laser beam, a device (37) for tilting a rotational axis of the deflection device a detection device for detecting a return laser beam (R) reflected from a display mark and entering the housing unit through the at least one beam hole, an evaluation and control unit connected with the detection device and controlling operation of the tilting device, and an automatically actuatable device (40; 75; 107; 108; 109) for adjusting an axial position of the deflection device (50; 74; 104) with respect to initial axial position of the deflection device in accordance with the detection data obtained in the detection device.

Abstract: A high-energy laser Faraday rotator is used in an optical system in which the Faraday rotator absorbs laser light energy of more than 20 mW. The Faraday rotator includes a bismuth-substituted rare-earth iron garnet single crystal film grown as a Faraday rotator by using a liquid phase epitaxial method, and non-magnetic substrate having a side surface on which the bismuth-substituted rare-earth iron garnet single crystal film is formed.

Abstract: An optical resonator type organic electroluminescent element has a multilayered film mirror 30, a transparent electrode 12, an electron hole transportation layer 14 and a luminescent layer 16 configuring an organic layer, and a metallic electrode mirror 20, formed on a glass substrate 10. The optical resonator type organic electroluminescent element amplifies a specific wavelength (especially, in a range of about 30 nm toward a shorter wavelength side from a luminescence peak wavelength of the organic layer) in luminescence light by a minute optical resonator, which comprises the multilayered film mirror 30 and the metallic electrode mirror 20. It is determined that the minute optical resonator has an optical length L which is twice as long as a resonance wavelength, the organic layer has a thickness of 100 nm or more, and the transparent electrode has a thickness of 50 nm or more or a thickness so to have a sheet resistance of 30 &OHgr;/□ or less.

Abstract: An apparatus and method are provided for bandwidth narrowing of an excimer laser to &Dgr;&lgr;≈6 pm or less with high spectral purity and minimized output power loss. Output stability with respect to pulse energy, beam pointing, beam size and beam output location is also provided. The excimer laser includes an active laser medium for generating a spectral beam at an original wavelength, means for selecting and narrowing the broadband output spectrum of the excimer laser, a resonator having at least one highly reflecting surface, and an output coupler. Means for adapting a divergence of the resonating band within the resonator is further included in the apparatus of the invention. The divergence adapting causes the spectral purity to improve by between 20% and 50% and the output power to reduce by less than 10%. A method according to the invention includes selecting and aligning the divergence adapting means.

Abstract: A laser beam in the ultraviolet region is generated at high power for along period. A green laser beam generated by a laser oscillator comes incident into a resonator from behind a first curved mirror, and circulates there, reflected by each mirror. By passing a barium borate crystal, it causes a secondary harmonic (a laser beam in the ultraviolet region) to be generated, which is taken out of the resonator via a second curved mirror. The beam waist of the laser beam passing the barium borate crystal is set to 46 &mgr;m, about double the conventional thickness, by adjusting the distance between the first curved mirror and a second flat mirror. As a result, the power density of the laser beam in the barium borate crystal is reduced to ¼ of the value according to the related art, and it is made possible to avoid rapid degradation of the barium borate crystal by excessive squeezing of the laser beam.

Abstract: An excimer laser apparatus comprises a container sealing a laser gas including a halogen gas therein, a pair of discharge electrodes disposed in the container for inducing an electric discharge capable of oscillating a laser light, and a circulating fan with a shaft for producing a high-speed laser gas stream between a pair of the discharge electrodes. Both ends of the shaft are rotatably supported by rotor-stator mechanisms, or one end of the shaft is rotatably supported by a rotor-stator mechanism, and the other end of the shaft is supported by a magnetic bearing. The rotor-stator mechanism comprises a rotor attached to the shaft of the circulating fan, a stator provided at a position opposed to the rotor, an electric motor winding provided in the stator for applying torque to the rotor, and a position control winding provided in the stator for producing a magnetic force to levitate and support the rotor.

Abstract: A defect causing a localized state is induced in a chiral structure composed of multiple chiral elements by twisting one element of the chiral structure with respect to the other elements along a common longitudinal axis such that directors of the element molecular layers that are in contact with one another are disposed at a particular “twist” angle therebetween, the twist angle being greater than a shift angle between directors of consecutive layers. The chiral twist structure may be utilized in a variety of applications such as filters, lasers and detectors. The defect caused by the twist may be made tunable by providing a tuning device for ly rotating one or more of the chiral elements with respect to one another to vary the twist angle and thus vary the position of the induced defect within a photonic stop band. Tunable defects may be advantageously utilized to construct wavelength tunable chiral filters, detectors and lasers.

Abstract: A tunable laser is provided having a gain medium and a resonator for generating a laser beam, and an angular dispersion element. The laser further includes a beam expander with adjustable magnification for adjusting an angular dispersion provided by the dispersion element. The adjustable beam expander preferably includes one or two rotatable prisms. When two prisms are used, the prisms are preferably synchronously rotatable according to a preset ratio such that any changes in refraction angle due to the rotation of the first prism are automatically compensated by the rotation of the second prism. A single prism may serve both as a dispersion element and as a beam expansion element. A processor preferably monitors the linewidth and wavelength of the output beam and adjusts an orientation of the prism or prisms of the expansion unit, and the tilt of either a reflection grating or a highly reflective mirror of the resonator in a feedback loop.

Abstract: A molecular fluorine (F2) laser is provided wherein the gas mixture includes molecular fluorine for generating an emission spectrum including two or three closely spaced lines around 157 nm. An optical method and means are provided for selecting an emission line from among the plurality of closely spaced emission lines of the molecular fluorine laser gas volume and broadening the spectrum of said selected emission line. This approach of broadening the spectrum reduces the coherence length of the output beam. As a result, speckle may be reduced or avoided in microlithography applications.

Abstract: A frequency-doubled semiconductor vertical-external-cavity surface-emitting laser (VECSEL) is disclosed for generating light at a wavelength in the range of 300-550 nanometers. The VECSEL includes a semiconductor multi-quantum-well active region that is electrically or optically pumped to generate lasing at a fundamental wavelength in the range of 600-1100 nanometers. An intracavity nonlinear frequency-doubling crystal then converts the fundamental lasing into a second-harmonic output beam. With optical pumping with 330 milliWatts from a semiconductor diode pump laser, about 5 milliWatts or more of blue light can be generated at 490 nm. The device has applications for high-density optical data storage and retrieval, laser printing, optical image projection, chemical-sensing, materials processing and optical metrology.

Abstract: A passively mode-locked solid-state laser for emitting a continuous-wave train of electromagnetic-radiation pulses, the fundamental repetition rate of the emitted pulses exceeding 1 GHz, without Q-switching has an optical resonator, a solid-state laser gain element placed inside the optical resonator, an exciter for exciting said laser gain element to emit electromagnetic radiation having the effective wavelength, and a saturable absorber for passive mode locking. The laser gain element preferably consists of a laser material with a stimulated emission cross section exceeding 0.8×10−18 cm−2 at the effective wavelength. Typically, the laser gain element is made of Nd:vanadate. The saturable absorber is preferably a semiconductor saturable absorber mirror device. The laser is simple, robust, compact, efficient, and low-cost.

Abstract: A method and apparatus are provided for temporally stretching and smoothing of the pulses of an output beam of excimer and lithography lasers. The method and apparatus are based upon providing an optical delay line or circuit having a plurality of optical reflectors and a plurality of beam recombiners or splitters so arranged as to divide the pulse into numerous portions which vary in their travel time through the circuit. As a result, the energy of the incident pulse is greatly stretched and smoothed.

Abstract: An efficient frequency-converted solid state laser that outputs a single beam utilizing an angled reflector situated within the laser cavity. The laser comprises an optical cavity including a first reflector and a second reflector. A gain medium situated within the optical cavity is energized by a pump source to excite a laser emission at a fundamental wavelength. A nonlinear material is arranged within the optical cavity to convert the laser emission to a second wavelength. The angled reflector, which is reflective of the second wavelength and transmissive of the first wavelength, is situated within the optical cavity between the first reflector and the nonlinear material. In operation, the forward-propagating converted beam is reflected from the second reflector, and then combines with the reverse-propagating converted beam. The angled reflector reflects the combined beam so that it exits from the optical cavity at a nonzero exit angle.

Abstract: In a solid-state laser in which a gain crystal is polished to have the Brewster angle or a solid-state laser comprising a dichroic concave mirror to which light enters at an incidence angle which is not zero, astigmatism generally occurs in pumping light. By tilting a focusing lens for pumping light with respect to the optical axis of the pumping light, the astigmatism is compensated. The tilting angle is determined in such a manner that synthetic focusing points in the sagittal and tangential planes, of a series optical system of a focusing lens, a dichroic concave lens, and a gain crystal are calculated and the focusing points almost coincide with focusing points in a cavity mode.

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: A solid laser produces a laser beam of a 1 &mgr;m wavelength band with an Nd-doped solid laser medium. An oscillation mode is brought to a single longitudinal mode with a Fabry-Pérot etalon located within a resonator. An etalon thickness, an etalon reflectivity, an etalon inclination, and a resonator longitudinal mode interval satisfy the relationships, 1.2%≦RN≦15% and 0.5°≦&thgr;≦2.0°, in which RN represents an effective reflectivity of the etalon with respect to wavelengths &lgr;=&lgr;0±&Dgr;&lgr;c deviating by a resonator longitudinal mode interval &Dgr;&lgr;c from a resonance wavelength &lgr;0 of the etalon, and &thgr; represents an inclination of an etalon optical axis with respect to a resonator optical axis.

Abstract: A current confinement region located proximate to a pair of Bragg reflectors in a semiconductor laser and an epitaxial lateral overgrowth layer grown through an aperture in the current confinement region allows a desirable current flow in the laser. The placement of the current confinement region having an aperture formed therein allows the desired current flow through an active layer of the laser. This current flow allows the laser to achieve a single spatial mode output. Furthermore, the ability to place a pair of Bragg reflectors in close proximity to each other achieves a short optical cavity resulting in a single longitudinal mode output. Together, the single spatial mode and single longitudinal mode result in a desired single frequency output. The single frequency output is particularly useful for high speed, high rate optical and telecommunications.

Abstract: A sub-nanosecond passively Q-switched microchip laser is disclosed. It combines an optically pumped, passively Q-switched, high-frequency, microchip laser producing short pulses with an optically end-pumped amplifier producing high small-signal gain while pumped at low power. The microchip laser for emitting pulsed laser radiation is a monolithic body comprising two reflective elements defining an optical resonator for laser radiation, a laser gain medium, e.g., Nd:YAG, and a saturable absorber medium, e.g., Cr4+:YAG placed inside said resonator. The optical amplifier stage for amplifying the laser radiation comprises an amplifying medium, e.g., Nd:YVO4. The microchip laser and the amplifier are optically end-pumped, preferably by high-brightness diodes. This entirely passive laser system directly produces &mgr;J pulses at repetition rates of about 45 kHz.

Abstract: A technique for increasing the lifetime of optical components that are used in a laser for laser shock peening. The technique employs a properly sized iris or a gradient reflector within a laser oscillator to produce a single-transverse-mode laser beam. This technique eliminates hot spots that significantly reduce the lifetime of optical components. Utilization of the present invention can increase the lifetime of components by a factor of ten of their conventional lifetime.

Abstract: A passive mode-locked linear-resonator fiber laser using polarization-maintaining fibers and a saturable absorber to produce ultra short pulses and a long-term reliable operation with reduced maintenance. Such a fiber laser can be configured to produce tunable pulse repetition rate and tunable laser wavelength.

Abstract: The optical transmission device comprises a transmitter which emits radiation vertically with respect to a covering surface. A reflection surface reflects a portion of the emitted radiation back onto an optically sensitive reception zone of a monitor receiver which is disposed on the same side as the transmitter. An intermediate body with a reflecting circumferential surface is disposed between the reflection surface and the reception zone. At least a portion of the reflected radiation passes from the circumferential surface to the reception zone, which significantly increases the yield of the reflected portion used for monitoring purposes.

Abstract: An intracavity, frequency-doubled, external-cavity, optically-pumped semiconductor laser in accordance with the present invention includes a semiconductor multilayer surface-emitting gain-structure surmounting a Bragg mirror. An external concave mirror and the Bragg-mirror define a stable laser-resonator including the gain-structure. A birefringent filter is located in the resonator, inclined at an angle to the resonator axis, for selecting a fundamental frequency of the laser-radiation within a gain bandwidth characteristic of semiconductor structure. An optically-nonlinear crystal is located in the laser-resonator between the birefringent filter and the gain-structure and arranged to double the selected frequency of laser-radiation. The gain-structure is coated with a dichroic coating which reflects the frequency-doubled radiation and transmits the fundamental radiation and optical pump-light.

Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: A quantum absorber is provided having transitions that include a first transition between a first lower quantum state and an upper quantum state, and a second transition between a second lower quantum state and the upper quantum state. The first transition and the second transition have energies that correspond to frequencies of &ohgr;1 and &ohgr;2, respectively. The lower quantum states differ in energy by an energy difference subject to a total a.c. Stark shift. Incident electro-magnetic radiation is generated. The incident electro-magnetic radiation includes main frequency components and additional frequency components. The main frequency components are at frequencies of &OHgr;1 and &OHgr;2, equal to &ohgr;1 and &ohgr;2, respectively, and differ in frequency by a frequency difference. The additional frequency components collectively have a spectrum. The quantum absorber is irradiated with the incident electro-magnetic radiation.

Abstract: A detection signal that quantifies a resonant interaction between a quantum absorber and incident electro-magnetic radiation is generated. The quantum absorber is irradiated with the incident electro-magnetic radiation. The quantum absorber absorbs a portion of the incident electro-magnetic radiation and generates fluorescent electro-magnetic radiation in response to it. The quantum absorber additionally transmits the unabsorbed portion of the incident electro-magnetic radiation. The unabsorbed portion of the incident electro-magnetic radiation is detected to generate a first signal that has a first signal-to-noise ratio. The fluorescent electro-magnetic radiation is detected to generate a second signal that has a second signal-to-noise ratio. The first signal and the second signal are combined to generate the detection signal. The detection signal has a signal-to-noise ratio greater than the first signal-to-noise ratio and the second signal-to-noise ratio.

Abstract: According to the invention, a variable power laser beam delivery apparatus is provided. The apparatus includes a generator for delivering a preselected wavelength beam preferably an ultraviolet (UV) beam along a beam path. A dichroic mirror, desirably two (2) or more preferably four (4) dichroic mirrors, for transmitting the preselected UV wavelength beam at P-polarization and for highly reflecting the preselected UV wavelength beam at S-polarization are located along the preselected wavelength beam path delivered from the laser beam generator. A beam polarization rotator is mounted along the beam path of the laser beam provided from the laser beam generator. The beam polarization rotator is located between the laser beam generator and the dichroic mirror along the laser beam path. A beam output is provided by directing the beam transmitted by the dichroic mirror or reflected by the dichroic mirror to a preselected location as the output of the device.

Abstract: A wavelength conversion laser for generating sum frequency laser beam comprising a laser resonator, a solid-state laser active medium, a second harmonic generation wavelength conversion crystal and a sum frequency generation wavelength conversion crystal, wherein the length of the second harmonic generation wavelength conversion crystal along the optical axis is set to be shorter than that of the sum frequency generation wavelength conversion crystal.

Abstract: An F2-excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF2 and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost.

Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: Disclosed herein is an external resonant laser that comprises a laser oscillator and an external resonator. The laser oscillator emits a laser beam of a specific wavelength. The external resonator resonates the laser beam emitted from the laser oscillator. The external resonator contains a photopolymer volume hologram. The photopolymer volume hologram diffracts the laser beam emitted from the laser oscillator, applies the laser beam into an optical system provided in the external resonator and allows the passage of a laser beam of a prescribed wavelength. The laser beam of the prescribed wavelength is output from the external resonant laser.

Abstract: A calcium fluoride crystal in which the light transparency does not deteriorate with consecutive irradiation by high output short wavelength light over long time periods. A calcium fluoride crystal in accordance with the present invention has an internal transmittance of 70% or more for light of a 135-nm wavelength or more. A calcium fluoride crystal contains any one of strontium, aluminum, silicon and magnesium, with the strontium content ranging from 1 ppm to 600 ppm, the aluminum content ranging from 1 ppm to 50 ppm, the silicon content ranging from 1 ppm to 50 ppm, or the magnesium content ranging from 1 ppm to 10 ppm. A calcium fluoride crystal has an internal transmittance of 70% or more for light of a 135-nm wavelength or more and contains 1 ppm or less of La and 10 ppm or less of Y. An optical system for an excimer laser in accordance with the present invention comprises a lens comprising any calcium fluoride crystal set forth above.

Abstract: An optical beam deflector in which a crosssection of an incident optical (e.g., laser) beam is divided into a first plurality of portions (micro crosssections) by an array of first lenses, a plurality of phases of the optical beam in the first micro crosssections are respectively modified by an array of first optical phase modulators so that a desired phase distribution is realized over the crosssection of the optical beam, and thereafter the crosssection of the optical beam is further divided into a plurality of second micro crosssections, and a plurality of phases of the optical beam in the second micro crosssections are respectively modified by an array of second optical phase modulators. An array of second lenses is provided corresponding to the second optical phase modulators to collect a plurality of portions of the optical beam output from the second optical phase modulators.

Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: An improved stepped etalon comprises a transparent body having a stepped surface. The lands of the steps are separated by a non-abrupt or softened transition region. This reduces the diffraction of light caused by the step transitions, thereby reducing the dead spot behind the step transition portions where interference prevents accurate measurements of light transmission from being made. Methods for producing a smoothly stepped etalon and for smoothing the step transitions in an abruptly stepped etalon are also disclosed.

Abstract: A solid state laser comprises a cavity resonator in the form of a generally cylindrical body and, located within the resonator, an active region which generates lasing light when suitably pumped. The resonator has a relatively high effective refractive index (n>2 and typically n>3) is sufficiently deformed from circularity so as to support at least one librational mode (e.g., a V-shaped or a bow-tie mode, the latter being presently preferred for generating relatively high power, directional outputs). Specifically described is a Group III-V compound semiconductor, quantum cascade (QC), micro-cylinder laser in which the resonator has a flattened quadrupolar deformation from circularity. This laser exhibits both a highly directional output emission and a three-order of magnitude increase in optical output power compared to conventional semiconductor micro-cylinder QC lasers having circularly symmetric resonators.

Abstract: A tuner for optical signals comprises a surface acousto-optic tunable filter utilized to provide signals indicative of the wavelength of the optical signals, a tunable filter, and a processor responsive to the wavelength indicating signals to control the tunable filter such that the tunable filter passes only optical signals at a predetermined wavelength.

Abstract: A free space external cavity multi-wavelength laser that includes a free space external cavity and a two-dimensional laser array is described. The two-dimensional laser array includes a plurality of optical gain elements where each optical gain element generates optical radiation having a unique wavelength and a unique free space optical path. The laser also includes a two-dimensional dispersive optical system that spatially and angularly overlaps each of the free space optical paths in two dimensions. The laser also includes a partially reflecting element that is positioned to intercept each of the free space optical paths. The partially reflecting element, a reflector on each gain element, and the two-dimensional dispersive optical system together form a free space laser cavity that defines the unique wavelengths. The partially reflecting element transmits an overlapping beam comprising radiation having the unique wavelengths.