Abstract: A wavelength conversion laser has: an exciting LD1, a solid state laser including a resonator, and a wavelength conversion element 7 disposed in the resonator. The solid state laser includes a first laser medium and a second laser medium as at least two types of laser media, and is configured to oscillate the solid state laser beams of the first emission wavelength and the second emission wavelength in the resonator as a result of the excitation light entering a region 3 configured from the first laser medium, thereafter entering a region 4 configured from the second laser medium, and subsequently entering a region 5 configured from the first laser medium. The wavelength conversion element 7 simultaneously generates a second harmonic and a sum frequency of the first emission wavelength and the second emission wavelength.

Abstract: A nonlinear optic article for difference frequency generation is provided. The article comprises a wave mixer configured to generate a difference frequency mixing signal, the wave mixer comprising a compound made from one or more noncentrosymmetric crystal-glass phase-change materials comprising one or more chalcogenide compounds that are structurally one dimensional and comprise a polymeric 1?[PSe6?] chain or a polymeric 1?[P2Se62?] chain, wherein the one or more chalcogenide compounds are capable of difference frequency generation.

Abstract: A method of operating a digitally modulated solid state laser is disclosed. The laser is optically pumped by a current-supply driven diode-laser radiation and with output-power stabilized at a desired value by a light regulator cooperative with a power monitor and the current source is disclosed. When the laser is turned on, the current-source is enabled and the light-regulator is disabled. A current regulator allows current from the current-supply to increase until the monitored power reaches the desired value. At this point, the light regulator is enabled and the light regulator assumes control of the current-supply for maintaining the output-power at the desired level.

Abstract: A wavelength conversion laser light source includes a fundamental wave laser light source (1) to generate a fundamental wave; a first mirror and a second mirror (4, 5), arranged so as to oppose each other; a wavelength conversion element (3) which is arranged between the first mirror and the second mirror and converts the wavelength of the fundamental wave; and a temperature control portion (8) to control the temperature of the wavelength conversion element.

Abstract: The invention relates to a fiber laser device 100. In the preliminary pumping state, the laser light is not output from the seed laser light source 10, the pumping light is output from the pumping light source 10, and the pumping light has such an intensity that the wavelength of the laser light emitted and output from the amplification optical fiber 30 is not converted by the wavelength converter 71. In the output state, the laser light is output from the seed laser light source 10, the pumping light is output from the pumping light source 20, and the laser light and the pumping light have such intensities that the wavelength of the laser light amplified and output by the amplification optical fiber 30 is converted by the wavelength converter 71.

Abstract: A laser light source device includes a pump light source which emits transverse-multimode light; a plurality of resonator mirrors which define a resonator, at least part of the resonator mirrors outputting light to the outside, where the output light having plural wavelengths; a laser medium arranged in the resonator, the laser medium being pumped with the transverse-multimode light emitted from the pump light source; and a wavelength conversion element arranged in the resonator, the wavelength conversion element being irradiated with a transverse-multimode line beam of fundamental wave obtained by oscillation at the laser medium and outputting a line beam of converted wave.

Abstract: Optical systems operable to emit multiple frequency-converted spectral peaks are provided. In one embodiment, an optical system includes an optical source and a wavelength conversion device. The optical source may include a laser configured to emit a pump beam having at least two fundamental spectral peaks. The wavelength conversion device may include a non-linear optical medium configured to phase match the second harmonic generation of each of the at least two fundamental spectral peaks and sum-frequency generation of the at least two fundamental spectral peaks such that an output beam comprising at least three frequency-converted spectral peaks having approximately equal power 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: Techniques and devices based on optical resonators made of nonlinear optical materials to form triple-oscillator devices for generating a single optical tone, a radio frequency (RF) oscillation signal and an optical frequency comb signal having different optical frequencies.

Abstract: A laser device with frequency conversion, the device comprising a complex optical cavity comprising two cavity parts with two different levels of circulating intracavity power wherein there is placed at least one non-linear crystal (30) is placed within the cavity part of higher circulating power and an active medium (21) in the cavity part of lower circulating power, the power enhancement achieved in two steps and the total enhancement being the product of the enhancement factors in each step, providing additional freedom in design allowing both the condition for high enhancement of the interacting laser power inside the intracavity non-linear crystal and the condition for maximum power output from the laser to be satisfied simultaneously and wherein said complex optical cavity the first cavity part provides the initial step of power enhancement and comprises at least a laser cavity back mirror (20), highly reflective about a laser radiation fundamental frequency .omega., and an active (gain) medium.

Abstract: Laser systems and related methods are provided. In this regard, a representative laser system includes: a laser diode array that generates light; a first crystal having a cavity; an optical element operative to focus the generated light onto the first crystal such that the light generates a high-power circulating beam within the cavity; a second crystal positioned with respect to the first crystal such that the frequency of the high-power circulating beam is doubled; and a first coating applied to the first crystal and second coating applied to the second crystal, the first coating and the second coating being operative to cause at least a portion of the beam to be emitted within a particular wavelength range of the generated light.

Abstract: A direct ultrashort laser system is provided. In another aspect of the present invention, a method of measuring laser pulse phase distortions is performed without requiring an adaptive pulse shaper or interferometry. In yet another aspect of the present invention, a system, a method of operating, a control system, and a set of programmable computer software instructions perform Multiphoton Intrapulse Interference Phase Scan processes, calculations, characterization and/or correction without requiring an adaptive pulse shaper.

Abstract: A system and method for optical frequency conversion having asymmetric output include a coherent light apparatus. The coherent light apparatus includes a coherent light source that produces a first coherent light, a frequency converter optically coupled to the coherent light source, and a coupling optic optically coupled between the coherent light source and the frequency converter. The frequency converter converts the first coherent light to a second coherent light at a second frequency and includes an asymmetric frequency converter (AFC) that nonlinearly converts the first coherent light to the second coherent light with the frequency conversion being more efficient in a first direction than in a second direction. A resonant cavity formed about the AFC circulates the first coherent light and transmits the second coherent light propagating in the first direction.

Abstract: The invention is directed to the provision of a wavelength conversion-type ultraviolet light source apparatus that can obtain a stable output. A light source apparatus according to one mode of the invention includes: a laser light source 1 which produces fundamental light L1; at least one nonlinear optical crystal 3 which takes the fundamental light L1 or a harmonic thereof as incident light and outputs wavelength-converted light L2; and polarization adjusting means 2 which is placed in an optical path of the incident light and causes an output of the wavelength-converted light L2 to change by changing its refractive index for a polarized component of the incident light. The polarization adjusting means 2 changes the amount of change of the refractive index in accordance with an electrical signal output from a photodetector 7.

Abstract: A nonlinear optical crystal can be mounted to a mounting block configured to receive the crystal. The crystal can be mounted to the mounting block with a face of the crystal abutting a surface of the mounting block. An adhesive secures the crystal to the mounting block by adhering to the bottom and/or sidewall of the channel and to at least corresponding a portion of the bottom and/or side face of the crystal proximate an edge of the crystal.

Abstract: Crystals of the yttrium/aluminium/borate family are used for producing UV light. To produce UV light with the described crystal family a crystal of the family AxM1-xX3(BO3)4, wherein both A and also M stand for an element from the group Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, A?M and X is selected from the group consisting of Al, Ga, Sc and 0?x?1, is used as a non-linear optical element to produce light of a wavelength of less than 0.450 ?m.

Abstract: A wavelength conversion device includes a laser light source that emits a fundamental wave; a wavelength conversion element that converts the fundamental wave into a second harmonic wave; and an optical system including a wavelength selective mirror that reflects the fundamental wave transmitted through the wavelength conversion element without being converted into the second harmonic wave, while transmitting therethrough the second harmonic wave generated by wavelength conversion, wherein the optical system makes the fundamental wave transmitted through the wavelength conversion element without being converted into the second harmonic wave enter the wavelength conversion element again to be subjected to wavelength conversion once or more than once, while being focused by the wavelength selective mirror, and the conversion efficiency in at least one of the second stage and stages subsequent to the second stage is higher than the conversion efficiency in the first stage, where the conversion efficiency in each

Abstract: A wavelength conversion device has a supporting body, a wavelength conversion substrate, a lower side buffer layer provided on the side of a bottom face of the substrate, a upper side buffer layer provided on the side of a upper face of the substrate, and an adhesive layer adhering the supporting body 8 and the lower side buffer layer. The wavelength conversion substrate is made of a Z-plate of a ferroelectric single crystal and a periodic polarization inversion structure formed therein. The supporting body has a volume resistivity lower than that of the ferroelectric single crystal of the wavelength conversion substrate.

Abstract: An MO-PA fiber laser having a master oscillator; and a first power amplifier which uses as a gain medium, a rare earth-doped optical fiber which is connected to a later stage of the master oscillator, wherein the MO-PA fiber laser has a wavelength conversion portion between the master oscillator and the power amplifier, and has a wavelength filter between the wavelength conversion portion and the master oscillator which only allows wavelength components of pulse light emitted from the master oscillator to pass, thereby making it possible to prevent breakage to a fiber laser which is caused by reflection light without using high-cost optical components.

Abstract: A wavelength conversion laser is provided with a solid-state laser having a cavity, and a wavelength converting element arranged within the cavity. The solid-state laser includes two or more types of laser crystals and oscillates solid-state laser light of multiple wavelengths. The wavelength converting element converts the solid-state laser light of multiple wavelengths into light of second harmonic waves and sum-frequency wave of multiple wavelengths and simultaneously generates the second harmonic waves and sum-frequency wave of multiple wavelengths. The wavelength conversion laser outputs converted wavelength light having a broad spectral width and low coherency, thereby enabling it to carry out highly efficient and stable high-output oscillation.

Abstract: Because a reflector that reflects a fundamental wave generated from a solid-state laser element and forms an optical resonator is disposed on an exit surface of a wavelength conversion element, the fundamental wave cannot be resonated and amplified in a stage before the wavelength conversion element is joined to the solid-state laser element. As a result, a problem is created in that the solid-state laser element emits low level light output, so that a relative position of the semiconductor laser and the solid-state laser element cannot properly be adjusted. In order to overcome the above problem, even in the stage before joining the wavelength conversion element to the solid-state laser element, the invention enables the semiconductor laser and the solid-state laser element to be joined by properly adjusting the relative position of the laser and the laser element.

Abstract: A device for generating light pulses includes a seed laser source for generating input light pulses. An optical pre-amplifier having variable gain receives the input light pulses from the seed laser source. An optical power amplifier receives the light pulses from the optical pre-amplifier and amplifies and compresses the received light pulses. The light pulses are compressed in the optical power amplifier in such a manner that the pulse duration of the output light pulses of the optical power amplifier is tunable via adjusting the gain of the optical pre-amplifier. Wavelength-tunable light pulses are obtained by supplying the output light pulses of the optical power amplifier to a highly non-linear optical fiber.

Abstract: The invention applies to doubly resonant optical parametric oscillators comprising a non-linear crystal (4) through which pass a pump laser beam (fp), a signal beam (fs), and a complementary beam (fc), and a device (5) that totally or partially reflects said beams emanating from the crystal such that, after reflection, they generate between them a relative phase-shifting value ??ar for a given functioning mode independent of the signal frequency or complementary frequency, and is characterized in that the reflecting device (5) is a metallic minor, or a combination of two scattering mirrors and a multilayer dielectric mirror placed downstream.

Abstract: The present invention relates to a green laser generation device which can be applied to a cellular phone, and more particularly to a green laser generation device which is ultra compact in size having volume of 1 cc or less, despite having a built-in thermo electric cooler, and has sufficient output power, despite having low power consumption, and a portable electronic machine having a laser projection display using the said device. The present invention provides a green laser generation device comprising an LD pump constituted by a photo diode; a fundamental generator generating infrared light laser according to the driving of the LD pump; a second harmonic generator generating green light using the generated infrared light laser; a polarization maintenance unit inserted between the fundamental generator and the second harmonic generator to maintain the polarization of the laser; and a temperature controller controlling an internal temperature of the green laser generation device.

Abstract: Methods, apparatus and systems for an up-converter resonant cavity light emitting diode device includes a semiconductor light source, an up-converter to form the light emitter with up-converting materials and an electrical source coupled with the semiconductor light source for providing electrical energy to the semiconductor light source to provide a desired wavelength emitted light. The semiconductor light source is a resonant cavity light emitting diode or laser that emits an approximately 975 mm wavelength to provide electrical and optical confinement to the semiconductor light source to form a resonant cavity up-converting light emitting diode (UC/RCLED). Rows and columns of electrodes provide active matrix addressing of plural sets of UC/RCLEDs for display devices.

Abstract: A UV light generator for receiving a baseband light beam from a baseband light source is provided. The UV light generator includes a first lens unit, a second lens unit, a first frequency doubling crystal and a second frequency doubling crystal. The baseband light beam from the baseband light source passes through the first lens unit. The first lens unit and the second lens unit control a minimum of baseband light spot position and a minimum of second harmonic light spot position. The first frequency doubling crystal is disposed between the first lens unit and the second lens unit, and located on the minimum of baseband light spot position. The second frequency doubling crystal is disposed between the first lens unit and the second lens unit, and located on the minimum of second harmonic light spot position.

Abstract: When a laser light source module includes a heat sink in which a solid laser element, an excitation light source, and a wavelength conversion element are arranged and a stem that supports the heat sink, wherein the heat sink is separated into three blocks, namely a first block including a laser oscillating unit for the solid laser element is arranged, a second block including a semiconductor laser element that emits excitation light for the laser oscillating unit and a first temperature sensor are arranged and on a specific surface of which the first heater is arranged, and a third block including the wavelength conversion element that converts the wavelength of the fundamental laser beam and a second temperature sensor are arranged and on a specific surface of which a second heater is arranged, enabling thus downsizing of the module and improvement of the positioning accuracy of the elements.

Abstract: A light source including a light emitting unit, a nonlinear medium, and a resonant grating. The light emitting unit is arranged to emit a first light into the nonlinear medium. The nonlinear medium is arranged to generate a second light such that an optical frequency of the second light is higher than an optical frequency of the first light. The resonant grating is arranged to stabilize an optical frequency of the first light by providing optical feedback to the light emitting unit.

Abstract: A laser and monitoring system is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and binary pulse shaping (BPS). Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan (hereinafter “MIIPS”) method is used to characterize the spectral phase of femtosecond laser pulses and to correct them. A further aspect of the system of the present invention is employed to monitor environmental chemicals and biological agents, including toxins, explosives, and diseases.

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 method for operating a wavelength-converted light source includes directing a pump beam having a fundamental wavelength from the laser source into an input facet of the wavelength conversion device such that a wavelength-converted output beam is emitted from an output facet of the wavelength conversion device in the field of view of an optical detector. A physical property of the wavelength conversion device is varied within individual ones of a succession of consecutive speckle reduction intervals having durations less than the integration time of the optical detector. The physical property of the wavelength conversion device is varied by an amount that is sufficient to change in a phase-matched (PM) wavelength of the wavelength conversion device. The fundamental wavelength of the pump beam is thereafter adjusted based on the change in the PM wavelength to maintain an efficiency of the wavelength conversion in the wavelength conversion device.

Abstract: In a UV laser system, the problem of deposition of residues of organic substances on the surfaces of optical components is avoided so that the reduction in the laser output can be avoided. A wavelength converting crystal (10) used for the generation of a UV laser light is provided with a reflective plane (14) that selectively reflects the UV laser light (23) to cause the UV laser light to emit from a part of the wavelength converting crystal different from an optical path of a basic wavelength laser light (21). The residues may be deposited on the part of the wavelength converting crystal from which the UV laser light is emitted, but not in the part of thereof through which the basic wavelength laser light passes so that the generation process for the UV laser light is not affected by the deposition of the residues.

Abstract: A GaN-based semiconductor laser (1) emits first laser light of a single polarization and having a first wavelength. An optical resonator (30) includes a solid-state laser medium which is excited by incidence of the laser light and which oscillates second laser light having a second wavelength different from the first wavelength. A polarization switch (6) switches over at least one of polarization directions of the first laser light and the second laser light to thereby change the wavelength of laser light to be emitted from the optical resonator (30) or the intensity ratio between a plurality of laser light to be emitted from the optical resonator (30). With the above arrangement, a plurality of laser light can be used effectively.

Abstract: A wavelength conversion laser light source includes a fundamental wave laser light source; a wavelength conversion element for converting a fundamental wave emitted from the fundamental wave laser light source into a harmonic wave; and an element temperature holding section for holding the wavelength conversion element at a temperature as set, wherein the element temperature holding section includes a magnetic metal formed on at least a part of the surface of the wavelength conversion element via an insulating material, and a magnetic flux application section for heating the magnetic metal with an application of a magnetic flux to the magnetic metal.

Abstract: Surface emitting laser arrays with intra-cavity harmonic generation are coupled to an optical system that extracts harmonic light in both directions from an intra-cavity nonlinear optical material in such a way that the focusing properties of the light beams are matched.

Abstract: There is provided a wide-band optical amplifier (10) that is capable of amplifying a wide-band signal. The wide-band optical amplifier (10) includes a first amplifier (NOPA1) that emits, based on a to-be-amplified light beam having a predetermined range of wavelengths and a first pump beam (L2) having a first wavelength, the to-be-amplified light beam having a first range of amplified wavelengths, where the first range is a part of the predetermined range, and a second amplifier (NOPA2) that emits, based on the to-be-amplified light beam having the first range of amplified wavelengths and a second pump beam (L3) having a second wavelength different from the first wavelength, the to-be-amplified light beam having a second range of amplified wavelengths, where the second range is different from the first range.

Abstract: The invention relates to a laser system including a nonlinear crystal having a first length portion and a second length portion. The nonlinear crystal disposed to receive input light from the laser for converting the input light into frequency converted light; wherein the nonlinear crystal is configured so that the first length portion of the nonlinear crystal is phase matching for the input light and the frequency converted light, and the second length portion of the nonlinear crystal is phase mismatching for the input light and the frequency converted light. Phase mismatching means may include a temperature controlling board, a clamp, or electrodes.

Abstract: In a branched resonator OPS-laser arrangement, a combination of intra-cavity optical parametric generation and intra-cavity frequency conversion provides output radiation in a range between about 550 nanometers about 800 nanometers from an OPS fundamental wavelength in a range between about 900 nm and about 1100 nm.

Abstract: Apparatus and methods of controlling a frequency-converted diode laser system are disclosed. The diode laser systems can include embodiments of thermally coupled elements facilitating temperature stabilization. Aspects of some methods include monitoring the output of a stabilized diode laser system to reduce noise of the output laser beam. Other aspects of some methods include adjusting the temperature of a frequency converter based on noise in the output beam, and/or the current provided to drive the diode laser. Systems incorporating such control aspects, and others, are also disclosed.

Abstract: A laser-wavelength conversion system with a broad temperature acceptance bandwidth is provided. The laser system includes a broad-band pump laser driving one or several cascaded laser wavelength converters, wherein the pump laser spectrum is broader than the spectral acceptance bandwidth of at least one of the laser wavelength converters. The broad pump laser spectrum allows some temperature variation in the laser wavelength converters, resulting in a broad temperature acceptance for the whole laser system. The laser system provides stable multi-color laser radiation for applications such as the red-green-blue laser projection TV.

Abstract: The present invention provides a laser device having a high wavelength conversion efficiency and a wide wavelength width, and is suitable as a display light source. The laser device includes a fundamental wave generating section including a laser diode which has a plurality of luminous points and a bragg reflection structure, and generating a plurality of fundamental waves which has at least a pair of wavelengths different from each other, and a nonlinear optical element having a periodic polarization inversion structure, and generating harmonics corresponding to the plurality of fundamental waves, respectively.

Abstract: A method for making a microchip laser includes preparing a laser-cavity chip assembly comprising a gain media, a first substantially flat surface, and a second substantially flat surface parallel to the first substantially flat surface. The method also includes forming a first reflective film on the first substantially flat surface to form a first cavity mirror, forming a second reflective film on the second substantially flat surface to form a second cavity mirror, and patterning at least one of the first reflective film or the second reflective film by removing at least a portion of the reflective film in the outer portion to form a center reflective portion in the one of the first reflective film or the second reflective film. The first cavity mirror and the second cavity mirror can suppress higher order transverse modes and produce a single TEM00 mode in the lasing light.

Abstract: An extended cavity surface emitting laser has a first laser die with a first cavity and a first gain element and a second laser die with a second cavity and a second gain element. The first and second gain elements are in series to provide optical gain and optical feedback in an extended optical cavity configuration. The first and second gain elements provide optical gain and optical feedback in a common extended cavity with the first and second gain elements operating serially as a common extended cavity optical mode.

Abstract: A compact optically-pumped solid-state laser designed for efficient nonlinear intracavity frequency conversion into desired wavelengths using periodically poled nonlinear crystals. These crystals contain dopants such as MgO or ZnO and/or have a specified degree of stoichiometry that ensures high reliability. The laser includes a solid-state gain media chip, such as Nd:YVO4, which also provides polarization control of the laser; and a periodically poled nonlinear crystal chip such as PPMgOLN or PPZnOLT for efficient frequency doubling of the fundamental infrared laser beam into the visible wavelength range. The described designs are especially advantageous for obtaining low-cost green and blue laser sources. Also described design of the continuously operated laser with an electro-optic element for modulation of the intensity of the laser output at frequencies up to hundred of megahertz. Such modulation is desired for various applications, including compact projectors with high resolution.

Abstract: A laser system using ultrashort laser pulses is provided. In another aspect of the present invention, the system includes a laser, pulse shaper and detection device. A further aspect of the present invention employs a femtosecond laser and a spectrometer. Still another aspect of the present invention uses a laser beam pulse, a pulse shaper and a SHG crystal. In yet another aspect of the present invention, a multiphoton intrapulse interference phase scan system and method characterize the spectral phase of femtosecond laser pulses. Fiber optic communication systems, photodynamic therapy and pulse characterization tests use the laser system with additional aspects of the present invention.

Abstract: Particular embodiments of the present invention relate generally to semiconductor lasers and laser projections systems and, more particularly, to schemes for controlling semiconductor lasers. According to one embodiment of the present invention, a laser having a gain section, a phase section and a wavelength selective section is configured for optical emission of encoded data. The optical emission is shifted across a plurality of laser cavity modes by applying a quasi-periodic phase shifting signal I/V? to the phase section of the semiconductor laser. The amplitude of the quasi-periodic signal transitions periodically between a maximum drive level and a minimum drive level at a frequency that varies randomly over time.

Abstract: A laser light source includes a semiconductor laser, a wavelength converting element made of a non-linear optical crystal for converting excitation light from the semiconductor laser into wavelength converted light having a wavelength different from the wavelength of the excitation light, a photodiode for measuring a part of the wavelength converted light to be emitted from the wavelength converting element as output light, a photodiode for measuring the excitation light to be emitted from the wavelength converting element, and a control circuit, wherein the control circuit simultaneously performs an output constant control of making the intensity of the wavelength converted light constant, using a current driving circuit, and a temperature control of adjusting the temperature of the wavelength converting element, using a heater.

Abstract: The present invention relates to a method and to an arrangement for the frequency conversion of coherent optical radiation with adjustable wavelength by way of a two-stage non-linear optical process. In the method and the arrangement, a frequency doubling is carried out in a first non-linear optical crystal (301, 302) and a sum frequency generation or a frequency doubling is carried out in a second non-linear optical crystal (401, 402) which is connected downstream. A positively birefringent crystal, in which the frequency doubling is carried out during a phase matching of type I from the extraordinary wave of the output frequency according to the <eeo> scheme, is used as the first non-linear optical crystal (301, 302). The second non-linear optical crystal (401, 402) is chosen such that phase matching is made possible by rotating the crystal in the same spatial plane in which the first crystal (301, 302) must also be rotated during a phase matching.

Abstract: A laser apparatus in which the elimination of separate optical components to provide intra-cavity polarization and compensation for thermally induced birefringence, and their associated losses, results in an improvement in efficiency and reduction in complexity over prior art designs.

Abstract: A wavelength-multiplexed polarization entangled photon pair generator (1) includes: a pump light source (2); a polarization entangled photon pair generating body (4) on which pump light (3) outputted from the pump light source (2) falls; and a spectrometer (7) on which a wavelength-multiplexed parametric photon pair (5) outputted from the polarization entangled photon pair generating body 4 falls. The polarization entangled photon pair generating body (4) made of a nonlinear optical crystal (11) generates wavelength-multiplexed photon pairs by subjecting the pump light 3 to type II phase matching. As a nonlinear optical crystal 11, lithium tantalate of periodically poled structure (11A) can be used, and as a spectrometer (7), an arrayed-waveguide grating can be used. Wavelength-multiplexed polarization entangled photon pairs (5) can thus be generated with simple equipment.

Abstract: Key technologies have been developed in realizing single longitudinal mode CW operation with a regular standing-wave cavity for intracavity frequency doubling and intracavity frequency conversions, so as to produce all solid-state, true cw devices with operation over wide spectral ranges including green, blue and UV. In one method laser arrangement, a beam expander (23 or 41) is applied to render a large mode waist and an improved beam divergence so as to greatly reduce the insertion losses for intracavity optical elements (17, 18 or 44). In another method laser arrangement, when spatial hole burning interference effect is minimized by using a pump head (12) with a thin gain zone (2) in contact with an end cavity mirror, then a low resolving-power spectral filter with low loss can be utilized.