Abstract: Reduction of output power of light with a wavelength converted is suppressed, which is caused by a pyroelectric effect that occurs when a temperature of a wavelength conversion element including a ferroelectric substrate is changed.

Abstract: A light-emitting device includes an optical fiber, a first light source unit, and a second light source unit. The optical fiber includes a wavelength converting portion. The wavelength converting portion is provided between a light incident portion and a light emerging portion. The wavelength converting portion contains a wavelength converting material. The wavelength converting material is excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light and amplifies the spontaneous emission of light to produce an amplified spontaneous emission of light. The first light source unit makes the excitation light incident on the light incident portion. The second light source unit makes seed light, causing a stimulated emission of light to be produced from the wavelength converting material that has been excited by either the excitation light or the amplified spontaneous emission of light, incident on the light incident portion.

Abstract: A light-emitting system includes an optical fiber, a first light source unit, a second light source unit, and a light-guiding member. The optical fiber includes a wavelength-converting portion containing a wavelength-converting element. The wavelength-converting element may be excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light and may also be excited by an amplified spontaneous emission of light. The first light source unit makes the excitation light incident on the optical fiber. The second light source unit makes seed light, causing the wavelength-converting element that has been excited by either the excitation light or the amplified spontaneous emission of light to produce a stimulated emission of light, incident on the optical fiber. The light-guiding member guides the light coming from the optical fiber and lets the light emerge therefrom.

Abstract: A radiation-emitting component (1) is specified with a carrier (2) having a cavity (9), a radiation-emitting semiconductor chip (3) which is arranged on a bottom surface delimiting the cavity (9) and which is configured to generate primary electromagnetic radiation, and a first reflector layer (6) arranged above a top surface of the semiconductor chip (3), wherein the carrier (2) is transparent in places to the primary electromagnetic radiation, and the semiconductor chip (3) is spaced apart from at least one side surface delimiting the cavity (9).

Abstract: The invention is a nonlinear Raman optical device generating zig-zag radiation beam paths in a nonlinear medium having dichroic coatings reflecting at a pump radiation wavelength, with a first mirror between an injected beam of pump radiation and a first end of the nonlinear medium and a second mirror at a second end of the nonlinear medium, the second mirror being partially reflecting at a first Stokes wavelength of the pump radiation.

Abstract: An integrated-optics MEMS-actuated beam-steering system is disclosed, wherein the beam-steering system includes a lens and a programmable vertical coupler array having a switching network and an array of vertical couplers, where the switching network can energize of the vertical couplers such that it efficiently emits the light into free-space. The lens collimates the light received from the energized vertical coupler and directs the output beam along a propagation direction determined by the position of the energized vertical coupler within the vertical-coupler array. In some embodiments, the vertical coupler is configured to correct an aberration of the lens. In some embodiments, more than one vertical coupler can be energized to enable steering of multiple output beams. In some embodiments, the switching network is non-blocking.

Abstract: A cylindrical electrode module of a fiber optic laser system includes an inner cylinder having an inner repeating pattern of longitudinally-aligned positive and negative electrodes on an outer surface of the inner cylinder. The cylindrical electrode mode includes an outer cylinder that encloses the inner cylinder. The outer cylinder that has an outer repeating pattern of longitudinally-aligned negative and positive electrodes on an inner surface of the inner cylinder that are in corresponding and complementary, parallel alignment with the positive and negative electrodes of the inner repeating pattern on the outer surface of the inner cylinder. The cylindrical electrode module includes an optical fiber having an input end configured to align with and be optically coupled to a pump laser. The optical fiber is wrapped around the inner cylinder within the outer cylinder to form a cylindrical fiber assembly. The electrodes are activated to achieve quasi-phase matching.

Abstract: An optical waveguide structure comprising a nonlinear optical waveguide, a central region, a first side region, and a second side region. The central region is located within the nonlinear optical waveguide, wherein the central region comprises a nonlinear optical material. The first side region is on a first side of the central region and the second side region is on a second side of the central region. The nonlinear optical material comprising the central region has a first nonlinear coefficient that is larger than a second nonlinear coefficient of a second material comprising the first side region and the second side region.

Abstract: A system and method for applying a time-varying phase shift to an optical signal is described. Such a phase shift results in a frequency shift of the optical signal, which can be useful for instance in sensing applications. The design uses cross phase modulation (XPM) in a nonlinear medium such as optical fiber. The pump producing the XPM experiences a change in energy along the medium, for instance due to loss. The pump and signal have mismatched group velocities such that they walk-off each other in time, and the pump pulse repetition rate is chosen so that it has a specific relationship with respect to the walk-off. The design is compatible with very low signal loss and does not require high fidelity electrical control signals. It is capable of high-efficiency one-directional serrodyne frequency shifts, as well as producing symmetric frequency shifts. It can also be made polarization independent.

Abstract: A laser light source includes an inner ring and an outer ring. The inner ring includes a semiconductor optical amplifier (SOA), a pair of optical circulators, a first optical filter, and a first optical waveguide connecting those in series. The outer ring includes the SOA, a pair of optical circulators, a second optical filter, an output port, and a second optical waveguide connecting those in series except for a portion shared. The inner ring operates as a gain-clamped SOA with a feedback control light defined by the first optical filter. The outer ring generates a laser output in a gain region of the clamped SOA, and with multiple peak wavelengths defined by the second optical filter, in a range from L Band to U band, applicable to WDM network systems. A WDM network system and a method of controlling the laser light source are also disclosed.

Abstract: In a general aspect, a communication system comprises a first station and a second station. The first station includes a photonic crystal maser, a laser subsystem, and a tracking subsystem. A photonic crystal structure of the photonic crystal maser is formed of dielectric material and has an array of cavities and an elongated slot. The elongated slot is disposed in a defect region of the array of cavities. The photonic crystal maser also includes a vapor disposed in the elongated slot and operable to emit a target RF electromagnetic radiation in response to receiving an optical signal. The array of cavities and the elongated slot define a waveguide configured to form the target RF electromagnetic radiation, when emitted, into a beam. The second station includes a receiver configured to couple to the beam of target RF electromagnetic radiation.

Abstract: Disclosed herein is a super resolution imaging method and system for obtaining an image in a crystal material and/or device.

Abstract: Structures with waveguide cores in multiple levels and methods of fabricating a structure that includes waveguide cores in multiple levels. The structure includes a first waveguide core and a second waveguide core positioned in a different level than the first waveguide core. The first waveguide core includes a longitudinal axis and a plurality of segments having a spaced arrangement along the longitudinal axis. The second waveguide core is aligned to extend across the plurality of segments of the first waveguide core.

Abstract: A cylindrical electrode module of a fiber optic laser system includes an inner cylinder having an inner repeating pattern of longitudinally-aligned positive and negative electrodes on an outer surface of the inner cylinder. The cylindrical electrode mode includes an outer cylinder that encloses the inner cylinder. The outer cylinder that has an outer repeating pattern of longitudinally-aligned negative and positive electrodes on an inner surface of the inner cylinder that are in corresponding and complementary, parallel alignment with the positive and negative electrodes of the inner repeating pattern on the outer surface of the inner cylinder. The cylindrical electrode module includes an optical fiber having an input end configured to align with and be optically coupled to a high power pump laser. The optical fiber is wrapped around the inner cylinder within the outer cylinder to form a cylindrical fiber assembly. The electrodes are activated to achieve quasi-phase matching.

Abstract: A light-emitting device includes: a laser light source that radiates blue-based light as primary light; a wavelength converting member that emits secondary light, the secondary light including wavelength-converted light, the wavelength-converted light being the primary light converted into light having more long-wavelength components than the primary light; a first light-guiding member that transmits the secondary light emitted by the wavelength converting member; and a second light-guiding member which includes a resin material, and transmits the secondary light transmitted by the first light-guiding member, and the first light-guiding member and the second light-guiding member are connected by a connector, the connector including a numerical aperture (NA) converting member that optically connects a transmission path in the first light-guiding member and a transmission path in the second light-guiding member.

Abstract: Structures for an optical coupler and methods of fabricating a structure for an optical coupler. A coupling section has a plurality of segments arranged with a pitch, a first waveguide core has a section extending longitudinally over the first plurality of segments of the coupling section, and a second waveguide core has a section extending longitudinally over the coupling section. The section of the second waveguide core laterally spaced from the section of the first waveguide core by a given distance.

Abstract: A method for extending and enhancing bright coherent high-order harmonic generation into the VUV-EUV-X-ray regions of the spectrum involves a way of accomplishing phase matching or effective phase matching of extreme upconversion of laser light at high conversion efficiency, approaching 10?3 in some spectral regions, and at significantly higher photon energies in a waveguide geometry, in a self-guiding geometry, a gas cell, or a loosely focusing geometry, containing nonlinear medium. The extension and enhancement of the coherent VUV, EUV, X-ray emission to high photon energies relies on using VUV-UV-VIS lasers of shorter wavelength. This leads to enhancement of macroscopic phase matching parameters due to stronger contribution of linear and nonlinear dispersion of both atoms and ions, combined with a strong microscopic single-atom yield.

Abstract: There is set forth herein an integrated photonics structure having a waveguide disposed within a dielectric stack of the integrated photonics structure, wherein the integrated photonics structure further includes a field generating electrically conductive structure disposed within the dielectric stack; and a heterogenous structure attached to the integrated photonics structure, the heterogenous structure having field sensitive material that is sensitive to a field generated by the field generating electrically conductive structure.

Abstract: A monolithically integrated wavelength converted photonic integrated circuit (PIC) is fabricated by forming a trench in the PIC's insulating layer to expose a portion of an output waveguide that transmits a photonically processed optical signal at frequency ?1. A non-linear waveguide formed of a non-linear material with non-linear susceptibility at frequency ?1 and a transmission bandwidth spanning both ?1 and m*?1 where m is an integer of at least two is fabricated in direct physical contact with the exposed portion of the output waveguide. A patterned structure is fabricated in or on the non-linear waveguide to enhance non-linear susceptibility to generate an optical signal at frequency m*?1, which may be emitted directly or coupled to an optical antenna.

Abstract: A generating device includes at least one pulsed laser source that delivers primary photons having at least one wavelength in a single spatial mode and in pulses having a high pump energy, forming means that act on the primary photons to deliver an input beam, and at least one optical fiber having at least ten modes between which the pump energy is initially distributed, and able to relocate the latter via a non-linear effect into a fundamental mode, before generating secondary photons of various wavelengths by wavelength conversions from the wavelength of the primary photons in the fundamental spatial mode.

Abstract: There is described a method of tuning an output optical pulse. The method generally has: generating a seed optical pulse, the seed optical pulse having a tunable parameter; propagating the seed optical pulse into and along one of a plurality of optical fibers each having a hollow core extending along a given length, the optical fibers having a parameter being different from one another; pumping a gas inside the hollow core of the one of the optical fibers, said pumping having a tunable parameter; the propagation of the seed optical pulse into and along the one of the optical fibers modifying the seed optical pulse into the output optical pulse; and tuning the output optical pulse by modifying the tunable parameter of the seed optical pulse, modifying the one of the optical fibers along which the seed optical pulse is propagated and modifying the tunable parameter of said pumping.

Abstract: This disclosure provides systems, methods and apparatus related to an ultrasonic receiver for detecting ultrasonic energy received at a first surface of the ultrasonic receiver. The ultrasonic receiver includes an array of pixel circuits disposed on a substrate, each pixel circuit in the array including at least one thin film transistor (TFT) element and having a pixel input electrode electrically coupled to the pixel circuit. The ultrasonic receiver is fabricated by forming a piezoelectric layer so as to be in electrical contact with the pixel input electrodes. Forming the piezoelectric layer includes coating a solution containing a polymer onto the array of pixel circuits, crystallizing the polymer to form a crystallized polymer layer and poling the crystallized polymer layer.

Abstract: A terahertz-wave generating element includes a waveguide including an electro-optic crystal; an optical coupling member that extracts a terahertz wave, which is generated from the electro-optic crystal as a result of light propagating through the waveguide, to a space; and at least two electrodes that cause a first-order electro-optic effect in the electro-optic crystal by applying an electric field to the waveguide so as to change a propagation state of the light propagating through the waveguide. A crystal axis of the electro-optic crystal of the waveguide is set such that the terahertz wave generated by a second-order nonlinear optical process and the light propagating through the waveguide are phase-matched.

Abstract: A distributed acoustic sensing cable package having a polymer composite extruded over an optical waveguide to encase the waveguide and to form a crystalline matrix layer acoustically coupled to the waveguide. The crystalline matrix includes reinforcement fibers to further enhance transmission of a cable strain to the optical waveguide. During manufacture of the cable, the polymer composite may be extruded over the optical waveguide and subsequently subjected to heat treatment to increase the crystallinity of the polymer composite and increase the elastic modulus. Both axial and radial strain fields are effectively interact with cased fiber waveguide for producing measurable phase shift signal for distributed acoustic noise detection.

Abstract: A light modulator (e.g., for terahertz radiation) may be constructed using a prism in which light undergoes total internal reflection (TIR) at one surface. A tunable conductive layer is disposed on the TIR surface. The tunable conductive layer can have a conductivity that is dynamically controllable, e.g., by applying a voltage across the tunable conductive layer or by optically pumping the tunable conductive layer. The tunable conductive layer can absorb a portion of the reflected light beam, attenuating the beam, with the attenuation being a function of the electrical conductivity of the tunable conductive layer. The phase of the reflected light beam can also be altered as a function of electrical conductivity of the tunable conductive layer.

Abstract: Materials and lightguides formed thereof that are suitable for use in lighting units to impart a color filtering effect to visible light. At least a portion of such a lightguide (16) is formed of a composite material comprising a polymeric matrix material and an inorganic particulate material that contributes a color filtering effect to visible light passing through the composite material, and the particulate material comprises a neodymium compound containing Nd3+ ions.

Abstract: A tool and related method for removing unwanted gas hydrates from the surface of equipment used in subsea exploration and production. The tool includes a main vessel and a power cable linked together by a connector. Inside the vessel a laser device is connected to an adjustable focus collimator by a cable, with the wavelength emitted by the laser being between 200 nm and 930 nm. When the radiation reaches the subsea exploration equipment it causes the heating thereof, which in turn heats the hydrate through conduction, breaking down the hydrate formation from the inside out. The front lid of the tools includes a window fitted with anti-reflection film that forms an interface between the vessel and the aqueous medium.

Abstract: Methods and systems are provided for wavelength shift elimination during spectral inversion in optical networks. The method includes receiving an input optical signal, and generating a combined optical signal by combining, by Bragg scattering, the input optical signal having an input wavelength with a first pump signal having a first wavelength. The method further includes converting the combined optical signal into an output optical signal, by phase-conjugation, using a second pump signal having a second wavelength. The output optical signal has the same wavelength as the input optical signal.

Abstract: An opto-electrical oscillator includes, in part, first and second optical phase modulators, a coupler, an optical-to-electrical signal conversion circuit, and a control circuit. The first optical phase modulator modulates the phase of a first optical signal in response to a first feedback signal to generate a first phase modulated signal. The second optical phase modulator modulates the phase of a second optical signal in response to a second feedback signal to generate a second phase modulated signal. The first and second optical signals travel through first and second optical paths respectively and are generated from the same optical source. The optical-to-electrical signal conversion circuit receives an optical signal from the coupler and in response generates an electrical signal applied to the control circuit. The output signals of the control circuit cause the first and second feedback signals to be out of phase.

Abstract: A method and system for delivering laser pulses achieves the delivery of high quality laser pulses at the location of an application. The method includes the steps of: generating laser pulses, amplifying the laser pulses, temporally stretching the amplified laser pulses, and propagating the amplified laser pulses through an optical delivery fiber of desired length, wherein the laser pulses are temporally compressed in the optical delivery fiber and wherein the laser pulses undergo nonlinear spectral broadening in the optical delivery fiber.

Abstract: An opto-electrical oscillator includes, in part, first and second optical phase modulators, a coupler, an optical-to-electrical signal conversion circuit, and a control circuit. The first optical phase modulator modulates the phase of a first optical signal in response to a first feedback signal to generate a first phase modulated signal. The second optical phase modulator modulates the phase of a second optical signal in response to a second feedback signal to generate a second phase modulated signal. The first and second optical signals travel through first and second optical paths respectively and are generated from the same optical source. The optical-to-electrical signal conversion circuit receives an optical signal from the coupler and in response generates an electrical signal applied to the control circuit. The output signals of the control circuit cause the first and second feedback signals to be out of phase.

Abstract: An optical amplifier module is configured as a multi-stage free-space optics arrangement, including at least an input stage and an output stage. The actual amplification is provided by a separate fiber-based component coupled to the module. A propagating optical input signal and pump light are provided to the input stage, with the amplified optical signal exiting the output stage. The necessary operations performed on the signal within each stage are provided by directing free-space beams through discrete optical components. The utilization of discrete optical components and free-space beams significantly reduces the number of fiber splices and other types of coupling connections required in prior art amplifier modules, allowing for an automated process to create a “pluggable” optical amplifier module of small form factor proportions.

Abstract: A tunable parametric mixer comprising a pump laser, a nonlinear waveguide, and a refractive index tuner. The pump laser is configured to generate pump photons. The nonlinear waveguide comprises a cladding and a core. The core is made of nonlinear optical material and the cladding in made of a material with a tunable index of refraction. The nonlinear waveguide is configured to convert the pump photons into signal and idler photons. The refractive index tuner is configured to change the refractive index of the cladding to dynamically tune the dispersion properties of the nonlinear waveguide in order to alter a spectral location of a gain band of the parametric mixer.

Abstract: A method and system for delivering laser pulses achieves the delivery of high quality laser pulses at the location of an application. The method includes the steps of: generating laser pulses, amplifying the laser pulses, temporally stretching the amplified laser pulses, and propagating the amplified laser pulses through an optical delivery fiber of desired length, wherein the laser pulses are temporally compressed in the optical delivery fiber and wherein the laser pulses undergo nonlinear spectral broadening in the optical delivery fiber.

Abstract: A femtosecond laser based laser processing system having a femtosecond laser, frequency conversion optics, beam manipulation optics, target motion control, processing chamber, diagnostic systems and system control modules. The femtosecond laser based laser processing system allows for the utilization of the unique heat control in micromachining, and the system has greater output beam stability, continuously variable repetition rate and unique temporal beam shaping capabilities.

Abstract: The light-synthesizing laser device includes a plurality of collimating lenses that are arranged in a one-to-one relationship with a plurality of laser light sources which exhibit anisotropy in a laser light emission angle, and that convert laser light beams emitted from the laser light sources into parallel light; a condensing lens that condenses the laser light that has been converted into parallel light by the plurality of collimating lenses; and an optical fiber (5) having a square waveguide core (SC) which has a square shape, the fiber receiving and synthesizing the laser light condensed by the condensing lens. A longitudinal axis of a condensed beam condensed by the condensing lens is aligned with a diagonal axis of the square waveguide core.

Abstract: In the field of narrow linewidth laser sources and a laser device that comprises a laser source and a waveguide of determined refractive index with which it is coupled, a waveguide is single-mode and includes at least four reflectors in the form of trenches etched into the waveguide and irregularly distributed along the waveguide, the distance separating two neighbouring reflectors being above 1 ?m, and the waveguide and the laser source have respective lengths such that the length of waveguide over which the reflectors are located is greater than the length of the laser source itself.

Abstract: In the method for generating blue laser light with high optical and electrical efficiency, wherein the improvement comprises the step of using a phosphate glass photonic crystal fiber rod as a gain medium.

Abstract: A fiber gain medium provided by a rare-earth doped fiber (10) is contained in a first resonant cavity by end reflectors (12, 18). The reflector (12) is wavelength selective to limit the frequency band of the first resonant cavity. The first resonant cavity also contains a second resonant enhancement cavity (16) with multiple transmission bands lying within the first resonant cavity's frequency band. Multiple standing wave modes of the first resonant cavity lie within both the frequency band of the first resonant cavity and the transmission bands of the second resonant cavity, and it is these standing wave modes that support laser action when the rare-earth doped fiber is suitably pumped by pump lasers (40).

Abstract: The present invention relates to compact, low noise, ultra-short pulse sources based on fiber amplifiers, and various applications thereof. At least one implementation includes an optical amplification system having a fiber laser seed source producing seed pulses at a repetition rate corresponding to the fiber laser cavity round trip time. A nonlinear pulse transformer, comprising a fiber length greater than about 10 m, receives a seed pulse at its input and produces a spectrally broadened output pulse at its output, the output pulse having a spectral bandwidth which is more than 1.5 times a spectral bandwidth of a seed pulse. A fiber power amplifier receives and amplifies spectrally broadened output pulses. A pulse compressor is configured to temporally compress spectrally broadened pulses amplified by said power amplifier. Applications include micro-machining, ophthalmology, molecular desorption or ionization, mass-spectroscopy, and/or laser-based, biological tissue processing.

Abstract: A method for manufacturing a polarizing splitter includes providing a substrate including a top surface; forming a ridged asymmetric Y-shaped waveguide and a base by etching the substrate from the top surface into an inner region, the base includes an upper surface paralleling with the top surface, the ridged asymmetric Y-shaped waveguide projects from the upper surface of the base, and includes an input section configured for transmitting both a transverse electric wave and a transverse magnetic wave, a first branch configured for transmitting the transverse magnetic wave only, and a second branch configured for transmitting the transverse electric wave only, the first and the second branches branch from the input section; and forming a pair of strip-shaped first electrodes on the upper surface of the base, the strip-shaped first electrodes arranged at opposite sides of the input section and parallel with a central axis of the input section.

Abstract: The present invention provides a tunable optical frequency converter based on a phase modulator, which comprises a laser, a first optical isolator and a circulating frequency shift module. Said circulating frequency shift module is composed of an optical coupler, a phase modulator, an optical amplifier, a second optical isolator, a first optical circulator, an optical fiber Bragg grating, a second optical circulator, a tunable filter and a tunable attenuator. Light outputted by said laser is inputted to said circulating frequency shift module to conduct frequency converting repeatedly after passing through the first optical isolator, and then separated by a tunable filter and a second optical circulator, then the frequency converted light is outputted from the port of the circulating frequency shift module.

Abstract: Normal group velocity dispersion mode-locked optical frequency combs are provided on-chip. On-chip coherent frequency comb generation includes pulses showing temporal durations of about 74 fs. Pump detuning and bandpass filtering are provided for stabilizing and shaping the pulses from normal group velocity dispersion microresonators.

Abstract: A frequency comb generator fabricated on a chip with elimination of a disadvantageous reflow process, includes an ultra-high Q disk resonator having a waveguide that is a part of a wedge structure fabricated from a silicon dioxide layer of the chip. The disk resonator allows generation of a frequency comb with a mode spacing as low as 2.6 GHz and up to 220 GHz. A surface-loss-limited behavior of the disk resonator decouples a strong dependence of pumping threshold on repetition rate.

Abstract: A pulsed laser system may include a Raman fiber that is configured to act as multiple wavelength Raman laser. The fiber is configured to receive a pulsed input beam from an input source and convert the input beam to an output beam having narrow band outputs at first and second frequencies v1 and v2.

Abstract: A wavelength conversion element includes a core formed of a ferroelectric crystal having a periodically poled structure in which first and second domains having mutually inverted directions of spontaneous polarization are alternately aligned side by side, and a cladding covering all side surfaces of the core along a light propagation direction and having a uniform refractive index. Boundary surfaces of the first and second domains are arranged in a non-parallel manner with respect to the light propagation direction.

Abstract: A frequency comb generator fabricated on a chip with elimination of a disadvantageous reflow process, includes an ultra-high Q disk resonator having a waveguide that is a part of a wedge structure fabricated from a silicon dioxide layer of the chip. The disk resonator allows generation of a frequency comb with a mode spacing as low as 2.6 GHz and up to 220 GHz. A surface-loss-limited behavior of the disk resonator decouples a strong dependence of pumping threshold on repetition rate.

Abstract: A frequency comb generator fabricated on a chip with elimination of a disadvantageous reflow process, includes an ultra-high Q disk resonator having a waveguide that is a part of a wedge structure fabricated from a silicon dioxide layer of the chip. The disk resonator allows generation of a frequency comb with a mode spacing as low as 2.6 GHz and up to 220 GHz. A surface-loss-limited behavior of the disk resonator decouples a strong dependence of pumping threshold on repetition rate.

Abstract: It is provided a wavelength converting device comprising a periodic domain inversion structure for converting a wavelength of a fundamental wave to generate a harmonic wave. The wavelength conversion device includes a ferroelectric substrate and the periodic domain inversion structure formed in the ferroelectric substrate. A vertical domain inversion boundary of the periodic domain inversion structure is inclined with respect to a normal line of an upper face of the ferroelectric substrate, provided that the ferroelectric substrate is viewed in a cross section parallel with a propagating direction of the fundamental wave and parallel with the normal line of the upper face.

Abstract: A system for conversion or amplification using quasi-phase matched four-wave-mixing includes a first radiation source for providing a pump radiation beam, a second radiation source for providing a signal radiation beam, and a bent structure for receiving the pump radiation beam and the signal radiation beam. The radiation propagation portion of the bent structure is made of a uniform Raman-active or uniform Kerr-nonlinear material and the radiation propagation portion comprises a dimension taking into account the spatial variation of the Raman susceptibility or Kerr susceptibility along the radiation propagation portion as experienced by radiation travelling along the bent structure for obtaining quasi-phase-matched four-wave-mixing in the radiation propagation portion. The dimension thereby is substantially inverse proportional with the linear phase mismatch for four-wave-mixing.