Abstract: Disclosed is a laser system including a first laser and a second laser. The first laser includes a laser cavity, and a gas phase molecular gain medium disposed in the laser cavity, the gain medium having an absorption band. The second laser is a solid state laser configured to be continuously tunable, with respect to an emission wavelength of the second laser, over the absorption band of the gain medium, and the second laser is tuned to pump rotational vibrational transitions in the gain medium to achieve a rotational population inversion.

Abstract: External cavity laser systems are described that can operate with essentially no mode hopping. One example configuration of the laser system includes a semiconductor laser device, a folded cavity external to the semiconductor laser device, where at the semiconductor laser device is positioned at a fold in the folded cavity. In this configuration, at least one mirror is positioned in the folded cavity to enable sustained propagation of light within the folded cavity, and at least two polarization elements are positioned in the folded external cavity. The polarization elements cause a polarization state of the light that impinges in different directions on each semiconductor laser device that is positioned at a fold to be orthogonal to one another, thus eliminating or substantially reducing mode hopping in the laser output.

Abstract: The present invention relates to a system and method for generating wavelength-tunable laser output pulses using parametric processes, wherein a simultaneous and tuned tuning of the pump pulse wavelength and repetition rate ensures a temporal overlap between pump and seed pulses in a parametric gain medium. Based on this parameter coupling, lasers with a wide tunable wavelength range can be obtained, which can be fully fiber-based and which are also suitable for modern nonlinear microscopy or fluorescence microscopy due to a particularly fast response.

Abstract: A sensor receiver may include a Rydberg cell configured to be exposed to a radio frequency (RF) signal, and a probe source configured to generate a plurality of spaced apart pulsed probe beams within the Rydberg cell. The pulsed probe beams may be offset in time from one another. A plurality of excitation sources may be coupled to the Rydberg cell. A detector may be positioned downstream from the Rydberg cell.

Abstract: An apparatus and a method for measuring a microwave electric field at continuous frequencies based on an alternating current (AC) Stark effect of Rydberg atoms. A cesium vapor cell is used as an atomic sample cell. A cesium atom is excited to a Rydberg state by using detection light and coupling light that are emitted by two laser light sources, an electromagnetically induced transparency spectrum is generated. Further, a strong electric field is used as a local field EL, to cause AC Stark frequency shift and splitting of a Rydberg energy level. ES of to-be-detected signal electric field is applied. In this case, the Rydberg atom serves as a frequency converter, to directly read a beat frequency signal ?f of the local field and the signal field. From the beat signal, the strength of Es of signal filed can be directly read out.

Abstract: A method employs a device with a heterostructure as a resonator for electrons of an electrical circuit or for a terahertz electromagnetic wave. The heterostructure comprises at least one dielectric layer and at least one ferroelectric layer. The at least one ferroelectric layer comprises a plurality of ferroelectric polarization domains. The plurality of ferroelectric polarization domains forms a polarization pattern. The polarization pattern is adapted to perform an oscillation with a resonance frequency in a terahertz frequency range. The method comprises functionally coupling the oscillation of the polarization pattern and an oscillation of the electrons of the electrical circuit or of the terahertz electromagnetic wave by the device.

Abstract: An optical receptacle optically couples a light emitting element and an optical transmission member when disposed between the light emitting element and the optical transmission member, and includes a first optical surface that allows incidence of light emitted from the light emitting element; a second optical surface that emits, toward the optical transmission member, light emitted from the light emitting element and advanced inside the optical receptacle; and a diffraction grating disposed on the first optical surface, on the second optical surface, or on a light path between the first and second optical surfaces. The diffraction grating is configured such that zero-order diffraction light of the light emitted from the light emitting element reaches an end portion of the optical transmission member, and that primary diffraction light of the light emitted from the light emitting element does not reach the end portion of the optical transmission member.

Abstract: A method for tuning the frequency of THz radiation is provided. The method utilizes an apparatus comprising a spin injector, a tunnel junction coupled to the spin injector, and a ferromagnetic material coupled to the tunnel junction. The ferromagnetic material comprises a Magnon Gain Medium (MGM). The method comprises the step of applying a bias voltage to shift a Fermi level of the spin injector with respect to the Fermi level of the ferromagnetic material to initiate generation of non-equilibrium magnons by injecting minority electrons into the Magnon Gain Medium. The method further comprises the step of tuning a frequency of the generated THz radiation by changing the value of the bias voltage.

Abstract: Apparatus and methods for generating mid-IR frequency combs using intra-pulse DFG. A mode-locked pulse generation laser generates near-IR pulses which are amplified. The amplified pulses are spectrally broadened by a nonlinear element, for example a normal dispersion highly nonlinear fiber (ND-HNLF) to generate broadened pulses. The nonlinear spectral broadening element is a transparent dielectric material having a cubic nonlinear response. Broadened pulses are temporally compressed to generate short, high-power pulses which few-cycle conditioned pulses which are ready for the intrapulse DFG process. The DFG block generates a mid-IR comb by difference frequency generation. It might comprise an orientation patterned GaP (OP-GaP) crystal or a poled lithium niobate (PPLN) crystal.

Abstract: A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness ‘t’ supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

Abstract: A laser-based method of removing a coating from a surface comprises directing a laser pulse to a first position on the surface, removing the coating from the first position by rapidly elevating a surface temperature of the first position using the laser pulse and thereby disassociating the coating from the surface and collecting the disassociated coating. In some embodiments, the coating comprises an environmentally harmful substance such as Hexavalent Chromium. In some embodiments, the coating comprises Diamond-Like Carbon (DLC), Vitrified Contaminant Material (CMAS). The disassociated coating is collected by a waste collector.

Abstract: Compact laser systems are disclosed which include ultrafast laser sources in combination with nonlinear crystals or waveguides. In some implementations fiber based mid-IR sources producing very short pulses and/or mid-IR sources based on a mode locked fiber lasers are utilized. A difference frequency generator receives outputs from the ultrafast sources, and generates an output including a difference frequency. The output power from the difference frequency generator can further be enhanced via the implementation of large core dispersion shifted fibers. Exemplary applications of the compact, high brightness mid-IR light sources include medical applications, spectroscopy, ranging, sensing and metrology.

Abstract: There are provided using deuterium oxide as a media for transmitting high power lasers to perform laser operations, such as cutting, boring and drilling, a target material. High power laser beams are transmitted through a deuterium oxide beam path to a target material, including material in a pressure containment vessel.

Abstract: The closed cycle solid state optically pumped gas hybrid (chemical recovery) system utilizes a laser diode excited solid state, fiber or bulk, laser as a pump for a molecular gas, or gas mix, medium. The existence of efficient high power laser diode excited solid state fiber or bulk lasers, output spectrally matched to suitable principle and excited level 1st and 2nd overtones of relevant gases, is the enabling system technology. The utilization of such in combination with suitable gases introduces a range of viable, in principle sourcing on laser diodes and thus effectively laser diode pumped, gas laser systems with access to the approximately 4.5 ?m to approximately 5.4 ?m spectral region. Continuous wave or pulsed operation, with significant energy capability courtesy of solid state storage, is admitted.

Abstract: Solid state devices are provided for advantageously generating substantially coherent electromagnetic radiation. Electromagnetic waves in one or more desired frequency ranges, including terahertz, infrared, or visible light, can be generated using the ring-down mode of a splint-ring resonator (SRR). Present devices can offer tunable output frequencies by employing a biasing voltage to vary the carrier concentration of the dielectric of a capacitor for the SRR.

Abstract: A pulsed smaser includes at least one optical resonator and an optical pump. The at least one optical resonator includes opposing mirrors, a solid state gain medium having a masing frequency in a range of from about 50 GHz to about 1 THz, and a Q-switch, wherein the solid state gain medium and the Q-switch are optically arranged between the opposing mirrors. The optical pump is arranged to provide optical pump power to the solid state gain medium. The optical pump and the Q-switch are configured to generate pulsed masing in the solid state gain medium at the masing frequency at room temperature to provide output electromagnetic radiation at the masing frequency.

Abstract: An ultraviolet laser device, includes: a first laser light output unit outputs a first infrared laser light; a second laser light output unit outputs a second infrared laser light; a first wavelength conversion optical system generates a first ultraviolet laser light of a fifth harmonic of the first infrared laser light; and a second wavelength conversion optical system to which the first ultraviolet laser light and the second infrared laser light enter, wherein the second wavelength conversion optical system includes a first wavelength conversion optical element which generates a second ultraviolet laser light by sum frequency generation of the first ultraviolet laser light and the second infrared laser light, and a second wavelength conversion optical element which generates a deep ultraviolet laser light by sum frequency generation of the second ultraviolet laser light and the second infrared laser light.

Abstract: A therapeutic laser with a source of pulsed electromagnetic radiation, a control device for controlling the intensity and/or the duration of the therapeutic laser applied to the tissue, and a detection device for detecting optoacoustic signals triggered by irradiating the living tissue with the pulsed electromagnetic radiation. The therapeutic laser is characterized by an evaluation device that acts on the control device and is used for calculating a degree of quality B(t) from the optoacoustic signals detected by the detection device for individual laser pulses applied to a predetermined laser spot and determining a fit function f(t) at a predetermined point in time ?t1, the fit function f(t) approximating the mean curve of B(t) for 0?t??t1. The intensity and/or the irradiation time of the therapeutic laser is defined by the parameters for the predetermined laser spot, the parameters being determined for the fit function f(t).

Abstract: The present invention provides a laser processing method comprising the steps of attaching a protective tape 25 to a front face 3 of a wafer 1a, irradiating a substrate 15 with laser light L while employing a rear face of the wafer 1a as a laser light entrance surface and locating a light-converging point P within the substrate 15 so as to form a molten processed region 13 due to multiphoton absorption, causing the molten processed region 13 to form a cutting start region 8 inside by a predetermined distance from the laser light entrance surface along a line 5 along which the object is intended to be cut in the wafer 1a, attaching an expandable tape 23 to the rear face 21 of the wafer 1a, and expanding the expandable tape 23 so as to separate a plurality of chip parts 24 produced upon cutting the wafer 1a from the cutting start region 8 acting as a start point from each other.

Abstract: A laser system for semiconductor inspection includes a fiber-based fundamental light source for generating fundamental light that is then converted/mixed by a frequency conversion module to generate UV-DUV laser light. The fundamental light source includes a nonlinear chirp element (e.g., a Bragg grating or an electro-optic modulator) that adds a nonlinear chirp to the seed light laser system prior to amplification by the fiber amplifier(s) (e.g., doped fiber or Raman amplifiers). The nonlinear chirp includes an x2 or higher nonlinearity and is configured to compensate for the Self Phase Modulation (SPM) characteristics of the fiber-based amplifiers such that fundamental light is generated that has a spectral E95 bandwidth within five times that of the seed light. When multiple series-connected amplifiers are used, either a single nonlinear chirp element is provided before the amplifier string, or chirp elements are included before each amplifier.

Abstract: Downhole cutting systems, devices and methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena. Systems and devices for the laser cutting operations within a borehole in the earth. These systems and devices can deliver high power laser energy down a deep borehole, while maintaining the high power to perform cutting operations in such boreholes deep within the earth.

Abstract: A method of manufacturing a photo-semiconductor device that has a photoconductive semiconductor film provided with electrodes and formed on a second substrate, the semiconductor film being formed by epitaxial growth on a first semiconductor substrate different from the second substrate, the second substrate being also provided with electrodes, and the electrodes of the second substrate and the electrodes of the photoconductive semiconductor film being held in contact with each other.

Abstract: An apparatus including: an element configured to generate or detect a terahertz wave; a semi-spherical lens configured to guide the terahertz wave outgoing from the element or entering the element; and a holder configured to hold the semi-spherical lens and the element in a state in which a flat surface of the semi-spherical lens and the element are in contact with each other or in a state in which the flat surface of the semi-spherical lens and the element clamp a substance which allows the terahertz wave to pass therethrough and the flat surface of the semi-spherical lens and the element are in contact with the substance, wherein the holder includes: a resiliently deformable portion; and a position adjusting unit configured to adjust a relative position between the semi-spherical lens and the element in a direction parallel to the flat surface of the semi-spherical lens by resiliently deforming the resiliently deformable portion.

Abstract: Compact laser systems are disclosed which include ultrafast laser sources in combination with nonlinear crystals or waveguides. In some implementations fiber based mid-IR sources producing very short pulses and/or mid-IR sources based on a mode locked fiber lasers are utilized. A difference frequency generator receives outputs from the ultrafast sources, and generates an output including a difference frequency. The output power from the difference frequency generator can further be enhanced via the implementation of large core dispersion shifted fibers. Exemplary applications of the compact, high brightness mid-IR light sources include medical applications, spectroscopy, ranging, sensing and metrology.

Abstract: A laser device comprises a waveguide including a resonance structure for causing electromagnetic waves to resonate. The waveguide by turn comprises a gain medium for generating electromagnetic waves, a first negative permittivity medium arranged electrically in contact with the gain medium, a second negative permittivity medium arranged electrically in contact with the gain medium at the side opposite to the first negative permittivity medium so as to dispose the gain medium between the first and second negative permittivity mediums, and lateral structures of a positive permittivity medium arranged to be in contact with lateral surfaces of the gain medium and sandwiched between the first and second negative permittivity mediums. The waveguide has a section in which the width w of the gain medium sandwiched between the lateral structures is not greater than twice of the thickness h of the lateral structures sandwiched between the first and second negative permittivity mediums.

Abstract: A short light pulse generation device includes: a light pulse generation portion that has a quantum well structure and generates a light pulse; a frequency chirping portion that has a quantum well structure and chirps a frequency of the light pulse; a light branching portion that branches a chirped light pulse; and a group velocity dispersion portion that has a plurality of optical waveguides, on which each of a plurality of the light pulses branched in the light branching portion is incident, and produces a group velocity difference depending on a wavelength with respect to a plurality of branched light pulses, wherein light path lengths of the light pulses in a plurality of light paths before the light pulse is branched in the light branching portion and then incident on the plurality of optical waveguides of the group velocity dispersion portion are equal to each other.

Abstract: An ultraviolet laser device equips a laser beam output unit that includes first, second and third amplifiers that output first through third infrared laser beams, and first through third optical systems into which the first through third infrared laser beams through which the first through third infrared laser beams are propagated. A wavelength conversion unit includes a fourth optical system into which the combined first through third laser beams are incident through which they are propagated. The first optical system wavelength converts and generates the first infrared laser beam to a predetermined harmonic wave as the first laser beam, the fourth optical system includes a first wavelength conversion element that generates an earlier stage ultraviolet laser beam between the predetermined harmonic wave and the second laser beam, and the second wavelength conversion element generates an ultraviolet laser beam between the earlier stage ultraviolet laser beam and the third laser beam.

Abstract: A laser device for emitting waves in a frequency range belonging to the terahertz range, includes the following, in combination: a wave guide extending longitudinally along an axis A-A?; a superconducting coil arranged coaxially to the wave guide and arranged at a first end of the wave guide; a p-Ge p-doped germanium crystal arranged inside the coil such that the turns of the superconducting coil at least partially surround the p-Ge crystal; a cooling device containing a coolant, the superconducting coil and the p-Ge crystal being arranged in the cooling device, and the wave guide partially extending outside the cooling device; and removing the coolant from the wave guide.

Abstract: Methods for utilizing 10 kW or more laser energy transmitted deep into the earth with the suppression of associated nonlinear phenomena to enhance the formation of Boreholes. Methods for the laser operations to reduce the critical path for forming a borehole in the earth. These methods can deliver high power laser energy down a deep borehole, while maintaining the high power to perform operations in such boreholes deep within the earth.

Abstract: A laser device having a wave emission within a frequency range of 0.5 to 5 THz, includes a semiconductor heterostructure having a cylindrical form with a circular cross-section and including: a first optically nonlinear semiconductor material layer including an emitting medium configured to emit at least two optical whispering gallery modes belonging to the near-infrared spectrum, the two whispering gallery modes being confined within the first layer and enabling the generation, within the first layer, of radiation within an electromagnetic whispering gallery mode having a frequency of 0.

Abstract: Systems devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser perforation of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to perforate such boreholes.

Abstract: There is provided a mobile high power laser system and conveyance structure for delivering high power laser energy to and for performing high power laser operations in remote and difficult to access locations. There is further provide such systems with high power laser, handling equipment and conveyance equipment that are configured to avoid exceeding the maximum bending radius of high power optical fibers used with the conveyance structures. There are also provided embodiments of the conveyance structures having channels, lines and passages for delivering materials such as fluids.

Abstract: A laser device for emitting waves in a frequency range belonging to the terahertz range, includes the following, in combination: a wave guide extending longitudinally along an axis A-A?; a superconducting coil arranged coaxially to the wave guide and arranged at a first end of the wave guide; a p-Ge p-doped germanium crystal arranged inside the coil such that the turns of the superconducting coil at least partially surround the p-Ge crystal; a cooling device containing a coolant, the superconducting coil and the p-Ge crystal being arranged in the cooling device, and the wave guide partially extending outside the cooling device; and removing the coolant from the wave guide.

Abstract: The invention relates to a device for generating electromagnetic THz radiation with free electron beams, comprising a dynatron tube, where the dynatron tube comprises an electron source, an extraction grid, and, an anode preferably coated with a material composition for high secondary electron emission, arranged in vacuum. The dynatron tube is connected to a voltage supply supplying an extractor voltage and an anode voltage and the extractor voltage is higher than the anode voltage. An oscillator modulates the anode voltage and the anode voltage is set to a work point voltage.

Abstract: Disclosed is a terahertz wave generator which includes a dual mode semiconductor laser device configured to generate at least two laser lights having different wavelengths and to beat the generated laser lights; and a photo mixer formed on the same chip as the dual mode semiconductor laser device and to generate a continuous terahertz wave when excited by the beat laser light.

Abstract: Systems, devices and methods for the transmission of 1 kW or more of laser energy deep into the earth and for the suppression of associated nonlinear phenomena. Systems, devices and methods for the laser drilling of a borehole in the earth. These systems can deliver high power laser energy down a deep borehole, while maintaining the high power to advance such boreholes deep into the earth and at highly efficient advancement rates.

Abstract: A light pointer apparatus and method of use comprising: a substantially flat bottom surface comprising a sufficiently large surface area such that when said substantially flat bottom surface is rested upon a substantially flat horizontal surface, said apparatus remains substantially immobile and stable relative to the substantially flat horizontal surface solely by virtue of the plane of contact formed between said substantially flat bottom surface and the substantially flat horizontal surface; a light source for emitting a low-divergence light beam comprising wavelengths in the visible light spectrum with a beam divergence of at most three degrees, fixed in orientation relative to said substantially flat bottom surface so as to emit said low-divergence light beam at a predetermined emission angle of at least 45 degrees relative to said substantially flat bottom surface; and surfaces other than said substantially flat bottom surface capable of being held and moved by a human hand.

Abstract: Certain embodiments of the invention may include systems, methods, and apparatus for generating terahertz electromagnetic radiation. According to an example embodiment of the invention, a method is provided for generating terahertz electromagnetic radiation. The method includes: coupling a terahertz resonator with an optical resonator, wherein the optical resonator comprises non-linear optical material; directing laser light through the optical resonator to generate terahertz radiation by parametric interaction of the laser light with the optical resonator and the terahertz resonator; and directing the terahertz radiation from the terahertz resonator to an output.

Abstract: A first exemplary aspect of the present invention is a wavelength-tunable optical transmitter including: a semiconductor substrate (101); a wavelength-tunable light source that is formed on the semiconductor substrate (101) and includes at least a first reflector (102) of a wavelength-tunable type and a gain region (104); a semiconductor optical modulator formed on the semiconductor substrate (101); a first semiconductor optical waveguide (105c) that is formed on the semiconductor substrate (101) and smoothly connected to the wavelength-tunable light source; a second semiconductor optical waveguide (105d) that is formed on the semiconductor substrate and smoothly connected to the semiconductor optical modulator; a waveguide coupling region (108) in which the first and second semiconductor optical waveguides are collinearly coupled with a length LC that is not equal to m/2 (m: integer) times a complete coupling length LC0; and a second reflector (113) formed at an end of the waveguide coupling region (108).

Abstract: Disclosed is a terahertz wave generator which includes a dual mode semiconductor laser device configured to generate at least two laser lights having different wavelengths and to beat the generated laser lights; and a photo mixer formed on the same chip as the dual mode semiconductor laser device and to generate a continuous terahertz wave when excited by the beat laser light.

Abstract: A photo-semiconductor device comprises a photoconductive semiconductor film provided with electrodes and formed on a second substrate, the semiconductor film being formed by epitaxial growth on a first semiconductor substrate different from the second substrate, the second substrate being also provided with electrodes, the electrodes of the second substrate and the electrodes of the photoconductive semiconductor film being held in contact with each other.

Abstract: A compact high average power mid infrared range laser for ultrasound inspection. The laser comprises one of a Nd:YAG or Yb:YAG laser pumped by a diode at 808 nm to produce a 1 micron output beam. The 1 micron output beam is directed to an optical parametric oscillator where the beam wavelength is converted to 1.94 microns and conveyed to a mid infrared emission head. The emission head comprises one of a Ho:YAG or Ho:YLG laser optically coupled with a second optical parametric oscillator. The second optical parametric oscillator forms a generation output beam for creating ultrasonic displacements on a target. The generation output beam wavelength ranges from about 3 to about 4 microns, and can be 3.2 microns.

Abstract: A compact mid-IR laser device utilizes a quantum cascade laser to provide mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another.

Abstract: A mid-infrared system for optical probing is disclosed that comprises a mid-infrared fiber laser based on cascaded Raman wavelength shifting, a sample volume, and a detector or detection system. The cascaded Raman wavelength shifting process in optical fibers involves the emission of a plurality of optical phonons for at least some of the pump photonics involved in the process. As one example, using the cascaded Raman wavelength shifting process a pump laser wavelength between 1 and 2 ?m can be shifted down to between 2.5 to 10 ?m. In one embodiment, the mid-infrared fiber laser comprises a pump laser with a wavelength between 1 and 2 ?m, one or more stages of cascaded Raman oscillators implemented in fused silica fiber, and one or more stages of cascaded Raman oscillators implemented in mid-infrared fiber that transmits beyond 2 ?m. Examples of mid-infrared fibers include chalcogenides, fluorides and tellurite fibers.

Abstract: A weapon system includes a weapon system illuminator laser system and one or more optical fibers. The weapon system illuminator laser system can produce one or more illuminator laser beams to illuminate at least one object outside the weapon system without destroying the object. The weapon system illuminator laser system is located at a first location within the weapon system. The object, or a second object associated with the object, is to be destroyed or damaged by energy. The one or more optical fibers are configured to transport the one or more illuminator laser beams from the first location to a second location within the weapon system. The one or more optical fibers can provide beam containment and beamwalk maintenance in the presence of mechanical or thermal disturbances. The one or more optical fibers and the weapon system illuminator laser system can withstand mechanical or thermal disturbances.

Abstract: A transmission line for propagating a terahertz wave generated based on a carrier generated in a carrier generation layer includes a first region in which the terahertz wave propagates in a first direction and a second region having a different impedance compared to the first region and forming a reflection interface with respect to a terahertz wave which propagates opposite to the first direction. The transmission line is formed so that a distance from an irradiation location at which light is irradiated to the carrier generation layer to the reflection interface is smaller than D, where D is a distance converted from a half width of a time waveform of a terahertz wave which propagates in the first direction without passing through the reflection interface. Accordingly, a terahertz wave can be made to propagate with energetic efficiency, to a direction the terahertz wave is required to propagate.

Abstract: A quantum cascade laser amplifier (12) having an active zone (20) includes a stack of raw layers of semi-conductor materials formed in an epitaxial manner on a substrate layer (16) of indium. phosphide (InP) or gallium arsenide (GaAs) bearing the active zone (20), and a vertical anti-reflection coating (34) that covers an outlet face (28) of the laser radiation made of materials having given refraction indices and a predetermined thickness so that the entire laser radiation can flow through the outlet face. The anti-reflection coating (34) includes a first layer (36) having a first predetermined retraction index (n1) lower than the predetermined refraction index (nD), and at least a second layer (38) having a second refraction index (n2) higher than the predetermined refraction index (nD), wherein the first layer (36) of the anti-reflection coating (34) is made of yttrium fluoride (YF3).

Abstract: Provided is a long wavelength laser of which the operating point is stabilized and the laser oscillation is stabilized. The long wavelength laser comprises a resistor element provided to a portion where the surface current is maximum in a surface plasmon waveguide to stabilize a potential difference between a first cladding and a second cladding in the surface plasmon waveguide.

Abstract: A compact mid-IR laser device utilizes a quantum cascade laser to provide mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another.

Abstract: A wavelength converter comprising an arsenic sulfide (As—S) chalcogenide glass fiber coupled to an optical parametric oscillator (OPO) crystal and a laser system using an OPO crystal coupled to an As—S fiber are provided. The OPO receives pump laser radiation from a pump laser and emits laser radiation at a wavelength that is longer than the pump laser radiation. The laser radiation that is emitted from the OPO is input into the As—S fiber, which in turn converts the input wavelength from the OPO to a desired wavelength, for example, a wavelength beyond about 4.4 ?m. In an exemplary embodiment, the OPO comprises a periodically poled lithium niobate (PPLN) crystal. The As—S fiber can include any suitable type of optical fiber, such as a conventional core clad fiber, a photonic crystal fiber, or a microstructured fiber.