Abstract: An apparatus comprises a laser system and a light sensor system. The laser system is associated with a housing and configured to generate a first laser beam and direct the first laser beam toward a surface of an object in which the surface has a plurality of quantum dots. The first laser beam is configured to cause the plurality of quantum dots to generate light. The laser system is further configured to generate a second laser beam and direct the second laser beam toward the light generated by the plurality of quantum dots. The second laser beam is configured to amplify a portion of the light generated by the plurality of quantum dots. The light sensor system is associated with the housing and configured to detect the portion of the light to form data.

Abstract: A radiation source that provides high order harmonic radiation (HHG radiation) in an UV or XUV wavelength range comprising a resonant cavity that guides laser light pulses that includes at least two cavity mirrors, a first non-linear medium that provides the HHG radiation by harmonic generation based on an interaction of the laser light pulses with the first non-linear medium, wherein the first non-linear medium is arranged in the resonant cavity in an environment of reduced pressure, and a second non-linear medium arranged in the resonant cavity and adapted for at least one of amplifying the laser light pulses and phase locking longitudinal modes of the laser light pulses in the resonant cavity.

Abstract: In a frequency-tripled fiber-MOPA, a pre-amplified plane-polarized seed-pulse having a fundamental frequency is divided into two pulse-components, plane-polarized in polarization-orientations at 90-degrees to each other. The fundamental-wavelength pulse-components are amplified in a common amplifier-fiber. The amplified components are separately propagated on different optical paths. One of the amplified components is frequency-doubled. The frequency-doubled component on one path and fundamental-frequency component on the other path are then combined on a common-path and sum-frequency mixed to provide a frequency-tripled pulse.

Abstract: The specification and drawings present an apparatus and a method for intra-cavity harmonic generation in lasers such as solid-state lasers using a multi-resonance cavity with meniscus lenses for focusing corresponding wavelength radiation components on non-linear optical elements such as non-linear optical crystals using type I or type II phase-matching for significantly increasing efficiency of the harmonic conversion and output powers of generated harmonics. Using only type I or only type II phase-matching for all non-linear crystals may eliminate the requirement of linear-polarization on the fundamental laser wavelength generation. For example, a highly efficient UV Nd:YAG laser at 355 nm (a third harmonic of the fundamental wavelength of 1064 nm for the Nd:YAG laser) using intra-cavity triple resonance cavity and meniscus lenses has been developed using embodiments described herein.

Abstract: Prior art techniques for converting the wavelength of electromagnetic radiation by non-linear interactions such as sum frequency generation SFG produces blurred images when applied to polychromatic images. The invention provides an improved arrangement (15) for up-converting incoming electromagnetic radiation with dissimilar first wavelengths (?,) distributed in a first wavelength interval (??,) into up-converted electromagnetic radiation comprising corresponding dissimilar up-converted wavelengths (?3), smaller than the first wavelengths (?1). The arrangement applies a nonlinear crystal (5) and a laser (16) for providing a laser beam (10) of second wavelength, different from the first wavelengths (?1) inside the nonlinear crystal, and a Fresnel zone plate (17) for focusing or converging the incoming radiation inside the nonlinear crystal in spatial overlap with the laser beam.

Abstract: Optical systems operable to emit an output beam having fast-switched wavelengths are provided. In one embodiment, an optical system includes a laser and a wavelength conversion device. The laser emits a pump beam that switches between at least two fundamental spectral peaks at different wavelengths at a wavelength cycling period that is shorter than a response time of the human eye. The wavelength conversion device includes a non-linear optical medium configured to phase match the frequency doubling of the at least two switched fundamental spectral peaks such that an output beam that switches between at least two frequency-converted spectral peaks at different converted-wavelengths is emitted from an output facet of the wavelength conversion device when the pump beam of the optical source is incident on an input facet of the wavelength conversion device.

Abstract: A laser light source includes a fundamental laser generator that generates a fundamental laser light, a wavelength conversion element that is made of a ferroelectric crystal with a periodically poled structure and converts the fundamental laser light to a laser light having a different wavelength, a holding member that holds at least a part of an element surface of the wavelength conversion element that crosses a polarization direction of the periodically poled structure, and an insulation layer that is provided between the holding member and the element surface. Electric resistivity of the insulation layer is 1×108 ?·cm or higher.

Abstract: A terahertz wave generating apparatus 2 includes an excitation light source 10, a transmission-type diffraction grating 32, a variable imaging optical system 61, and a nonlinear optical crystal 70. The transmission-type diffraction grating 32 inputs pulsed excitation light output from the excitation light source 10, and diffracts and outputs the pulsed excitation light. In the transmission-type diffraction grating 32, its orientation is variable with a straight central axis, that is parallel to the grooves and passing through an incident position of a principal ray of the pulsed excitation light. The variable imaging optical system 61 is configured to input the pulsed excitation light diffracted to be output by the transmission-type diffraction grating 32, to form an image of the pulsed excitation light by the transmission-type diffraction grating 32, and its imaging magnification is variable.

Abstract: A monolithic laser cavity device includes an input mirror coating, a birefringent crystal quarter waveplate such as sapphire, a birefringent crystal gain medium such as neodymium-doped vanadate, a Type-II second-harmonic-generation crystal such as potassium titanyl phosphate, and an output mirror coating. The optical axes of the Type-II second-harmonic-generation crystal and birefringent crystal gain medium are aligned with each other and aligned 45° relative to the optical axis of the birefringent crystal quarter waveplate.

Abstract: A solid state-gain medium is in the form of a thin disk backed by a reflective coating. A laser resonator is formed by the reflective coating and another mirror. Optical pump radiation is directed into the thin-disk gain-medium for energizing the gain-medium and generating a standing wave of fundamental-wavelength radiation in the resonator. The pump-radiation is directed into the gain-medium at an angle to the resonator axis and pump-radiation fringes are formed by interference between incident and reflected pump-radiation. The pump-radiation angle is selected such that the pump-radiation fringes are aligned with antinodes of the fundamental-wavelength standing wave.

Abstract: A high-power diode end-pumped solid-state UV laser comprises high-power fiber-coupled end pumping laser diodes, a specially designed fundamental laser cavity and multiple high-power high-efficiency harmonic generations. Nonuniform fundamental laser cavity has to be used, i.e. the beam size of the fundamental laser cannot be uniform in the fundamental cavity. Thermal transfer inside the laser crystal and harmonic crystal has to be specially and carefully treated, and special crystal mounts were designed to optimize the thermal contact and maximize the heat transfer. In addition, harmonic crystal mounts were specially designed to minimize the loss and protect the hydroscopic crystals.

Abstract: Disclosed herein are architectures for an external cavity laser. In some embodiments, the external cavity laser includes vertical cavity surface emitting laser (VCSEL) elements, a Brewster plate, frequency doubling chips, and a microlens array. The Brewster plate is arranged at an angle relative to the light path, and is configured to polarize at least the light received from the VCSELs and propagating on the light path in a first direction, and extract, from the external cavity, frequency-doubled light propagating on the light path in a second direction opposite to the first direction. The doubling chips are operable to receive the light and double the frequency of a portion of the received light. The microlens array is aligned with the VCSEL elements. A mount may be employed to mount the side stack of doubling chips by either side mounting or end mounting.

Abstract: A system includes: a first nonlinear crystal arranged to receive to a first laser beam having a first wavelength ?1 and operable to generate, by frequency doubling of the first laser beam, a second laser beam having a second wavelength ?2, in which the second beam propagates collinearly with the first beam; a second nonlinear crystal arranged to receive the first and second laser beams from the first crystal, in which the second crystal is operable to generate, by frequency mixing of the first and second laser beams, a third laser beam having a third wavelength ?3; and one or more lenses between the first and second crystals, in which the one or more lenses are operable to spatially separate the first and second beams. The first and second laser beams propagate at an offset and/or titled with respect to an optical axis in order to cause the spatial separation.

Abstract: A compact, optically-pumped solid-state microchip laser device uses efficient nonlinear intracavity frequency conversion for obtaining low-cost green and blue laser sources. The laser includes a solid-state gain medium, such as Nd:YVO4, and a nonlinear crystal. The nonlinear crystal is formed of periodically poled lithium niobate or periodically poled lithium tantalate, and the crystal is either MgO-doped, ZnO-doped, or stoichiometric to ensure high reliability. The nonlinear crystal provides efficient frequency doubling to translate energy from an infrared pump laser beam into the visible wavelength range. The laser device is assembled in a package having an output aperture for the output beam and being integrated with an optical bench accommodating a laser assembly. The package encloses and provides heat sinking for the semiconductor diode pump laser, the microchip laser cavity assembly, the optical bench platform, and electrical leads.

Abstract: It is provided a device oscillating an electromagnetic wave having a target frequency of 0.1 THz to 30 THz. The device includes a main body made of a non-linear optical crystal and a sub-wavelength grating structure formed on the main body. The sub-wavelength grating structure includes protrusions arranged in first direction “X” and second direction “Y” on the main body, first grooves 3X each provided between the adjacent protrusions and extending in the first direction, and second grooves 3Y each provided between the adjacent protrusions and extending in the second direction. Each of the protrusions includes a pair of first faces opposing in the first direction “X” with each other and a pair of second faces opposing in the second direction “Y” with each other. The width of the first face is made smaller from the main body 7 toward an upper end 2c of the protrusion 2.

Abstract: Technology for detecting an optical data signal carried in a combined optical signal that comprises a carrier optical signal modulated by the optical data signal and also comprises ASE noise. The proposed optical data detector/receiver is provided with an SHG device adapted to generate a second harmonic optical signal of the carrier optical signal modulated by the data signal. In the signal, generated by the SHG, the ASE noise will be essentially reduced.

Abstract: An optical waveguide device includes a ferroelectric layer having a thickness of 4 ?m-7 ?m; a supporting body; and an adhesive layer adhering a bottom face of the ferroelectric layer and supporting body. The ferroelectric layer includes a ridge comprising a channel optical waveguide, first and second protuberances on opposite sides of the ridge, inner grooves between the ridge and protuberances, respectively, and outer grooves outside of the protuberances, respectively. The outer groove is deeper than the inner groove. The ridge portion has a width of 6.6 ?m-8.5 ?m, a distance of an outer edge of the first protuberance and an outer edge of the second protuberance is 8.6 ?m-20 ?m, the inner groove has a depth of 2.0 ?m-2.9 ?m, and the outer groove has a depth of 2.5 ?m-3.5 ?m.

Abstract: It is provided a wavelength converting device oscillating an idler light having a wavelength of 5 to 10 ?m from a pump light. The wavelength of the idler light is longer than that of the pump light. The wavelength converting device includes a wavelength converting layer 5 of a semiconductor non-linear optical crystal and having a thickness of 50 ?m or smaller. The wavelength converting layer 5 includes a crystal orientation inversion structure wherein crystal orientation of the optical crystal is inverted at a predetermined period and at least one flat main face 5b. The device further includes a Peltier device 2 controlling a temperature of the wavelength converting layer 5; and a clad portion 4 joined with the flat main face 5b of the wavelength converting layer 5 and provided between the wavelength converting layer 5 and the Peltier device 2. The pump light, idler light and signal light satisfies a particular phase matching condition.

Abstract: An array of Surface Emitting Laser (SEL) elements can be used to efficiently pump a disk or rod of solid-state laser glass or crystal, or harmonic-generating crystal. Placing the laser array chip against or near the surface of this solid-state material provides very high and uniform optical power density without the need for lenses or fiber-optics to conduct the light from typical edge-emitting lasers, usually formed in a stack of bars. The lasers can operate in multi-mode output for highest output powers. Photolithography allows for an infinite variety of connection patterns of sub-groups of lasers within the array, allowing for spatial contouring of the optical pumping power across the face of the solid-state material. The solid-state material may be pumped either within (intra-cavity) or externally (extra-cavity) to the SEL laser array.

Abstract: Disclosed herein are architectures for VCSEL systems. By using high power IR VCSEL element(s), a bulk doubling material can be used to double the IR light and generate visible light (red, green, blue, or UV light) in a cavity, in either continuous wave (CW) or pulsed mode. The reflectivity of the output distributed Bragg reflector (DBR) of these VCSELs can be designed to increase the power in the cavity, rather than the power in the VCSEL laser. By enabling the use of a bulk doubling material in the cavity and directly doubling the VCSEL the device can be inexpensive, simpler, high efficiency, better reliability, and vastly improved manufacturing and alignment tolerances. There are a number of cavity architectures that can be used to double the IR light from the VCSEL(s). The VCSEL(s) can be single elements, or arrays with high intensity elements.

Abstract: A light conversion module includes a coupler for combining two light beams to form a combined light beam, a nonlinear crystal arranged to receive the combined light beam and configured to include a plurality of poling regions for performing successive nonlinear frequency mixing processes, a first optical device configured to focus the combined light beam onto the nonlinear crystal, a first moving stage carrying the nonlinear crystal and moving the nonlinear crystal for an adjustment of a focus position of the combined light beam on the nonlinear crystal, and an optical detector configured for measuring a power level of the light beam from the nonlinear crystal for the adjustment of the focus position of the combined light beam on the nonlinear crystal.

Abstract: Provided is a light emitting device improved in safety to an eye. The light emitting device includes: a semiconductor laser element for emitting laser light; an optical conversion member for converting coherent laser light which is emitted from the semiconductor laser element into incoherent light, and for emitting the incoherent light; and a safety device for preventing the coherent laser light from exiting to an outside.

Abstract: The present invention provides a radiation source apparatus which can generate a DUV radiation beam having a wavelength of 193.4 nm efficiently.

Abstract: A laser device for intra-cavity frequency conversion, in particular, for the second harmonic generation, the device comprising a laser cavity, formed by the first and the second laser cavity end reflectors wherein the said laser cavity end reflectors are highly reflective for the radiation about the laser fundamental frequency and as such provide for a predetermined level of circulating inside the cavity fundamental frequency power; an active medium provided within the said laser cavity; at least one non-linear crystal, in particular, for the second harmonic generation provided within the same laser cavity; tuning means adapted for tuning at least one of laser cavity end reflectors; wherein at least one of the laser cavity end reflectors comprises an interferometric layout providing spectrally selective reflection for the radiation about the laser fundamental frequency with the value of reflectivity nearly to 100% within a spectral range close to the free spectrum range of the laser cavity and with a sufficie

Abstract: An optical parametric oscillator including a nonlinear crystal pumped by a laser source and an optical resonator, including an optical interferometer, which determines a level of output coupling of the oscillator, allowing high stability, broad wavelength tuning, and output power level optimization.

Abstract: In a frequency-tripled fiber-MOPA, a pre-amplified plane-polarized seed-pulse having a fundamental frequency is divided into two pulse-components, plane-polarized in polarization-orientations at 90-degrees to each other. The fundamental-wavelength pulse-components are amplified in a common amplifier-fiber. The amplified components are separately propagated on different optical paths. One of the amplified components is frequency-doubled. The frequency-doubled component on one path and fundamental-frequency component on the other path are then combined on a common-path and sum-frequency mixed to provide a frequency-tripled pulse.

Abstract: A semiconductor laser module is disclosed, comprising a module carrier (20) having a mounting area (21), a pump device (1) arranged on the mounting area (21), a surface emitting semiconductor laser (40) arranged on the mounting area (21), and a frequency conversion device (6) arranged on the mounting area (21), wherein the mounting area (21) of the module carrier (20) has an area content of at most 100 mm2.

Abstract: An EUV light source of the present invention is capable of using a saturable absorber stably and continuously in a high heat load state. A saturable absorber (SA) device is disposed on a laser beam line to absorb feeble light, such as self-excited oscillation light, parasitic oscillation light or return light. SA gas from an SA gas cylinder and buffer gas from a buffer gas cylinder are mixed to be a mixed gas. The mixed gas is supplied to an SA gas cell via a supply pipeline, and absorbs the feeble light included in the laser beam. The mixed gas is exhausted via an exhaust pipeline, and is sent to a heat exchanger. The mixed gas, cooled down by a heat exchanger, is sent back to the SA gas cell by a circulation pump.

Abstract: Pulses from a mode-locked Yb-doped laser are spectrally broadened, and temporally compressed, then frequency-doubled and used to pump an optical parametric oscillator (OPO). The OPO output is tunable over a wavelength range from about 600 nm to about 1100 nm.

Abstract: A wavelength conversion element 20 has a periodic polarization reversal structure formed in a non-linear optical crystal, wherein positive/negative polarity is periodically alternated in period d expressed by the following formula (1), outputs light having frequency of 2? from the incident light having frequency of ?, and is characterized in that the non-linear optical crystal is a nitride single crystal: d=m?/[2(n2??n?)]??(1) where, m represents the order of phase matching, ? represents the wavelength of the incident light, n? represents the refractive index of the nitride single crystal such as AlN for the light having frequency of ?, and n2? represents the refractive index of the nitride single crystal such as AlN for the light having frequency of 2?.

Abstract: Phase-matched high-order harmonic generation of soft and hard X-rays is accomplished using infrared driving lasers in a high-pressure non-linear medium. The pressure of the non-linear medium is increased to multi-atmospheres and a mid-IR (or higher) laser device provides the driving pulse. Based on this scaling, also a general method for global optimization of the flux of phase-matched high-order harmonic generation at a desired wavelength is designed.

Abstract: A wavelength conversion laser light source having: a laser medium which generates a fundamental wave light; a laser resonator for causing laser oscillation of the fundamental wave light; a wavelength convertor which is provided with a wavelength converting region to convert the fundamental wave light under the laser oscillation by means of the laser resonator into converted light of a different wavelength; and an excitation laser light source for exciting the laser medium, wherein the laser resonator has at least one reflecting surface which reflects the fundamental wave, and a first reflecting element which is provided on an end surface of the wavelength convertor to reflect the fundamental wave light; the wavelength converting region is situated between the at least one reflecting surface and the first reflecting element; the wavelength convertor has a periodic first polarization reversal structure formed in the wavelength converting region, and a non-converting region formed between the first reflecting el

Abstract: A cA crystal configured to change a frequency of a laser through an optical parametric oscillation (OPO) process and a difference frequency generation (DFG) process is provided. The crystal includes: an OPO-DFG segment that is quasi-periodically poled to yield (i) a conversion of a laser pump light applied thereto, to a first signal and an idler, and (ii) a conversion of a first signal applied thereto, to a second signal and to the idler, by phase-matching a difference frequency generation (DFG) process and an OPO process therein simultaneously, wherein the laser pump light has a frequency that equals a sum of a frequency of the first signal and a frequency of the idler and wherein the frequency of the first signal equals a sum of a frequency of the second signal and the frequency of the idler.

Abstract: A laser source includes a laser device configured to emit laser light at a given angle with respect to a normal of an output end face; and an optical device configured to include an optical waveguide that guides and outputs the laser light. The output end face of the laser device is parallel to an input end face of the optical device, and the optical waveguide extends in a direction of ?w1 that is given by ?w1=arcsin(sin ?a1/nF), where ?a1 denotes an outgoing angle of the laser light from the laser device, and nF denotes an effective refractive index of the optical waveguide for the laser light.

Abstract: Methods and apparatus for non-collinear optical parametric ampliffication (NOPA) are provided. Broadband phase matching is achieved with a non-collinear geometry and a divergent signal seed to provide bandwidth gain. A chirp may be introduced into the pump pulse such that the white light seed is amplified in a broad spectral region.

Abstract: In a photon pair generating apparatus for generating a pair of correlated photons by hyper-parametric scattering, a light-shaping section irradiates an optical resonator with two beams of light of equal wavelength from different directions, and the optical resonator is configured to emit two correlated photons of different wavelengths in one direction as a pair of correlated photons. This makes it possible to provide a photon pair generating apparatus capable of achieving generation of a pair of correlated photons by a simpler configuration.

Abstract: A phase modulation element according to the present invention has a first area having a first phase value based on a phase modulation unit having a predetermined size and a second area having a second phase value based on the phase modulation unit having the predetermined size, and each phase distribution is defined by a change in area shares of the first area and the second area depending on each position.

Abstract: The present invention relates to a white light source, and particularly to a white light source with crystal fiber and a method for color temperature tuning thereof. The white light source of the present invention comprises a pumping source for providing a first-color light, and a gradient index lens for coupling the first-color light into a crystal fiber. The crystal fiber absorbs a portion of the first-color light and generates a second-color light and a third-color light, and a white light with high color rendering index can be obtained. The crystal fiber is made of a first rare earth element oxide and a second rare earth element oxide co-doped yttrium aluminum garnet. The color temperature of the white light can be tuned by adjusting the position of the focus of the pumping light on the end section of the crystal fiber.

Abstract: Master oscillator power amplifier (MOPA) apparatus includes two seed-pulse sources coupled to a single fiber amplifier including one or more stages of amplification. One of the seed-pulse sources is a single-mode source generating pulses having a duration selectively variable between about 0.1 ns and 10 ns. The other seed-pulse source is a multi-mode source generating pulses having a duration selectively variable between about 1 ns and 10 ?s. Selectively operating one or the other of the seed-pulse sources provides that the apparatus can deliver pulses selectively variable in a range between about 0.1 ns and 10 ?s.

Abstract: A wavelength conversion laser light source includes an element temperature switching section that switches a temperature of the wavelength conversion element according to a harmonic wave output value as set in an output setting device, and the element temperature switching section for switching a temperature of a wavelength conversion element according to a harmonic wave output level as set in the output setting device. The element temperature switch section includes an element temperature holding section that holds the wavelength conversion element at the temperature as switched by the element temperature switching section.

Abstract: An optically pumped semiconductor apparatus having a surface-emitting semiconductor body (1) which has a radiation passage area (1a) which faces away from a mounting plane of the semiconductor body (1), and an optical element (7) which is suitable for directing pump radiation (17) onto the radiation passage area (1a) of the semiconductor body (1).

Abstract: A high index contrast waveguide based source for radiation. In some embodiments, the radiation is in the 0.5-14 Terahertz regime. Waveguides are provided that permit the generation of radiation at the sum and/or difference frequency of two input beams. In order to control the power level within the waveguide, embodiments in which pluralities of similar or identical waveguide are provided, and the input radiation is divided among the plurality of waveguides. The output radiation can be steered by applying phased array methods and principles.

Abstract: Seed light pulses and pump light pulses are generated; the seed light pulses are preferably chirped; and both are directed into an enhancement cavity at a full repetition rate. The enhancement cavity defines a closed optical path that contains a nonlinear medium that provides phase matching at a wavelength different from both the central seed wavelength and the central pump wavelength. The generation of the pump light pulses and the seed light pulses are synchronized to pass the seed light pulses through the nonlinear medium simultaneously with the pump light pulses to parametrically amplify the seed light pulses in the nonlinear medium to produce an amplified signal pulse and idler pulse. Increased conversion with low average pump power can be achieved, as well as gain bandwidth enhancement approaching octave-spanning levels.

Abstract: A semiconductor laser device includes a semiconductor laser element configured to emit a fundamental wave; a transducer configured to receive the fundamental wave incident thereon and convert a wavelength of the fundamental wave to emit wavelength converted light; a filter configured to selectively transmit wavelength range light having a desired wavelength range of the wavelength converted light; a sealing member including a light-transmitting member and configured to enclose the semiconductor laser element, the light-transmitting member being configured to receive the wavelength range light transmitted through the filter and incident on the light-transmitting member, specularly reflect part of the wavelength range light, and substantially transmit the remaining part of the wavelength range light; and a photoreceptor configured to receive the specularly reflected light from the light-transmitting member.

Abstract: An optical source including a laser source and a waveguide is provided. The laser source includes a laser cavity having a laser optical path length extending from a DBR grating to a reflective laser output facet, and emits an output beam at a fundamental wavelength. The waveguide has an input facet and an output facet, and extends along a waveguide optical length from the input facet of the waveguide to the output facet of the waveguide. The input facet and the output facet of the waveguide are approximately normal with respect to an optical path of the output beam. The waveguide and the laser source are proximity coupled, and the waveguide optical length is an integer multiple of the laser optical path length.

Abstract: CdSiP2 crystals with sizes and optical quality suitable for use as nonlinear optical devices are disclosed, as well as NLO devices based thereupon. A method of growing the crystals by directional solidification from a stoichiometric melt is also disclosed. The disclosed NLO crystals have a higher nonlinear coefficient than prior art crystals that can be pumped by solid state lasers, and are particularly useful for frequency shifting 1.06 ?m, 1.55 ?m, and 2 ?m lasers to wavelengths between 2 ?m and 10 ?m. Due to the high thermal conductivity and low losses of the claimed CdSiP2 crystals, average output power can exceed 10 W without severe thermal lensing. A 6.45 ?m laser source for use as a medical laser scalpel is also disclosed, in which a CdSiP2 crystal is configured for non-critical phase matching, pumped by a 1064 nm Nd:YAG laser, and temperature-tuned to produce output at 6.45 ?m.

Abstract: Fundamental-wavelength pulses from a fiber a laser are divided into three or more pulse portions and the three or more portions are separately amplified. Two or more of the amplified fundamental-wavelength pulse-portions are combined and frequency-doubled. The frequency doubled portion is sum-frequency mixed with one or more of the other amplified fundamental wavelength pulse-portions to provide third-harmonic radiation pulses.

Abstract: First and second laser beams are incident on a difference frequency mixing unit, and the two laser beams overlap in the difference frequency mixing unit, thereby generating a terahertz wave whose frequency is a frequency difference between the two laser beams. Each laser beam has a spatial spread in a frequency gradient direction, and a spatial frequency distribution of each laser beam is a distribution in which a magnitude of a frequency gradually increases in the frequency gradient direction. A frequency difference between the two laser beams is equal in each position in an overlapping region of the two laser beams. A terahertz wave of a single frequency is generated from this overlapping region. By spatially shifting the first laser beam and the second laser beam with respect to each other in the frequency gradient direction, the frequency difference in the overlapping region is changed, which changes the single frequency.

Abstract: A single-pass optical parametric amplifier is provided. The single-pass optical parametric amplifier comprises a light source emitting a fundamental wave having a wavelength range; a nonlinear material, which the fundamental wave passes therethrough to form a second harmonic generation wave having a light path; a supercontinuum generator extending the wavelength range of the fundamental wave to form a supercontinuum generation seed; and an optical parametric wavelength transformer transforming the supercontinuum generation seed and the second harmonic generation wave into a signal wave and an idler wave.

Abstract: A QPM waveguide includes an optical substrate having periodic domain-inverted regions and non-inverted regions which are arranged alternately, and a waveguide part passing through the domain-inverted regions and non-inverted regions. The substrate is divided into at least two sections each of which has a wave input facet and a wave output facet. At least one band-pass filter layer is disposed on the wave input facet of one section to filter out a signal wave for preventing back conversion so that the energy of the conversion wave can increase. A method for preventing the back conversion is also disclosed.