Abstract: Optical modulators are provided. A representative optical modulator includes an optical medium that is adapted to propagate optical signals. An array of lattice sites are arranged in the optical medium, with at least some of the lattice sites exhibiting lower refractive indexes than the refractive index of the optical medium. Preferably, a first of the lattice sites incorporates a first optical component that is moveable relative to the optical medium. By moving the first optical component relative to the optical medium, a propagation characteristic of the optical medium can be altered. Optical systems, methods and other optical modulators also are provided.

Abstract: In an optical amplifying section that includes a specific amplifying medium that may be effected by a giant pulse, light subject to amplifying is continuously incoming, while exciting light is continuously supplied. Therefore, in the specific amplifying medium, the giant pulse is not generated, which allows continuous amplified light to be emitted stably from the specific amplifying medium. Meanwhile, of the light outgoing from the optical amplifying section, a light quantity controlling section controls the light quantity of light proceeding a predetermined optical path to a wavelength conversion section, which controls the light quantity of light outgoing from wavelength conversion section as outgoing light of the light source unit. As a consequence, light with high luminance whose wavelength has been converted can be stably emitted.

Abstract: Disclosed are an antiglare film having a high level of anti-scintillation properties, high sharpness of transmitted images, high light transmittance (total light transmittance), and a high level of external light reflection preventive properties, and a process for producing the antiglare film. A resin and non-agglomerative particles having a specific particle diameter are selected so that the difference in refractive index between the resin and the particles is 0.05 to 0.15. The resin and the non-agglomerative particles are brought to a coating composition using, as a solvent, a good solvent for the resin and a poor solvent for the resin. The coating composition is coated onto a substrate film to form a coating which is then dried. In the course of the drying, as the amount of the good solvent in the coating decreases, the poor solvent acts to cause the gelation of the particles and the resin. Thus, good concaves and convexes can be advantageously formed on the surface of the coating.

Abstract: A first multimode interferometer has a first input port to which an optical signal is applied, a first output port, and a second output port. A first optical waveguide is connected to the first output port of the first multimode interferometer. The first optical waveguide has a refractive index changed in response to a trigger signal externally applied. A second optical waveguide is connected to the second output port. A triggering unit supplies, to the first optical waveguide, the trigger signal for changing the refractive index of the first optical waveguide. An optical switch is provided which can increase the processing speed, can reduce the device size, and is free from dependency on the polarization state of an optical signal.

Abstract: Optical systems and methods for optical wavelength conversion are provided. One such optical system includes a waveguide located in a substrate at least partially of a non-linear optical material, the waveguide structured to receive a continuous-wave optical signal, a grating located at least partially in the non-linear optical material section of the waveguide, the grating structured to receive an input optical signal, and an output port optically aligned to receive the continuous wave optical signal propagated through the grating when the input optical signal is incident on the grating. The optical system incorporates a grating with a period “d,” and the waveguide produces a photonic bandgap when a forward propagating state of photonic energy of the continuous wave signal is separated from a backward propagating state of photonic energy of the continuous wave optical signal by a wavenumber (kZ) equal to (2&pgr;/d), at a first photonic energy level in the waveguide.

Abstract: A technique for selectively frequency translating optical channels in an optical network is disclosed. In one exemplary embodiment, the technique is realized as a method for selectively frequency translating optical channels in a system having W optical frequencies. The method comprises selectively directing an optical channel operating at a respective one of the W optical frequencies based at least in part upon the respective optical frequency of the optical channel. The method also comprises shifting the respective optical frequency of the selectively directed optical channel by an amount defined by ±2i&Dgr;f, wherein &Dgr;f is an optical frequency spacing between adjacent optical channels, and i=0, 1, . . . log2W−1.

Abstract: An optical-path-superposing-and-separating unit superposes optical paths of two inputted signal lights with each other, and then separate them. A non-linear waveguide is arranged in an area where the optical paths are superposed with each other. First and second optical waveguide are connected to the optical path superposing-and-separating unit. The second optical waveguide has a longer optical path than the first optical waveguide. A control light is introduced to the non-linear waveguide. An interference separator distributes the inputted two signal lights depending on a phase difference therebetween. Third and fourth optical waveguides connect the optical-path-superposing-and-separating unit to the interference separator.

Abstract: A multiple-wavelength ultrashort-pulse laser system includes a laser generator producing ultrashort pulses at a fixed wavelength, and at least one and preferably a plurality of wavelength-conversion channels. Preferably, a fiber laser system is used for generating single-wavelength, ultrashort pulses. An optical split switch matrix directs the pulses from the laser generator into at least one of the wavelength conversion channels. An optical combining switch matrix is disposed downstream of the wavelength-conversion channels and combines outputs from separate wavelength-conversion channels into a single output channel. Preferably, waveguides formed in a ferroelectric substrate by titanium indiffusion (TI) and/or proton exchange (PE) form the wavelength-conversion channels and the splitting and combining matrices. Use of the waveguide allows efficient optical parametric generation to occur in the wavelength-conversion channels at pulse energies achievable with a mode-locked laser source.

Abstract: The apparatus for generating at least three visible light beams of different output wavelengths for display purposes comprises a passively mode-locked solid-state thin-disk laser and means for at least partially converting said primary light beam into electromagnetic radiation characterized by said at least three different output wavelengths including an optical parametric oscillator (OPO). The OPO is preferably an optical fiber feedback OPO. An optical fiber feedback OPO comprises a nonlinear optical element and feedback means for feeding back at least a proportion of the radiation emitted by the nonlinear medium to the nonlinear element, wherein the feedback means comprise an optical fiber.

Abstract: A frequency shifting device. The present invention provides a device and method for shifting a frequency of an optical signal comprising the steps of providing a layer of optically refractive material having a moving refractive boundary responsive to an application of an electrical signal. The inventive device includes a layer of optically refractive material having a refractive boundary responsive to an application of an electrical signal and an arrangement for providing an electrical signal to the layer to effect a predetermined frequency shift of an optical signal passing therethrough. In an illustrative embodiment, the device includes an active polymer layer, an optically conductive first cladding disposed beneath the active polymer layer, and a second cladding layer disposed above the active polymer layer, a microstrip line disposed over the second cladding layer and a ground plane beneath the first cladding layer.

Abstract: A first electrode and a second electrode are provided in separation on a main surface of a substrate made of a ferroelectric single crystal. A first voltage is applied between the first electrode and the second electrode, for example, on condition that the first electrode is positive and the second electrode is negative, to generate and grow a first polarization-inverted portion toward the second electrode from the first electrode. Then, the distance between the first electrode and the second electrode is changed, and a second voltage is applied between the first electrode and the second electrode on the same condition, to generate and grow a second polarization-inverted portion, in a different area from that of the polarization-inverted portion, toward the second electrode from the first electrode.

Abstract: A voltage controlled oscillator is provided. The oscillator includes a surface acoustic wave element for forming a feedback circuit for an amplifier, and a phase adjustment circuit including a filter which is interposed in the feedback circuit. The oscillator also has a phase shifter including a hybrid coupler to which an additional control part is attached for changing a phase value within an oscillation loop with a control voltage supplied from an external source. An equal power divider equally distributes output power within the oscillation loop and supplies the output power outside the oscillation loop. A multi-layer board is used for mounting the amplifier, surface acoustic wave element, phase adjustment circuit, phase shifter, and equal power divider in at least two separate layers.

Abstract: A method and apparatus are provided for increasing the energy of chirped laser pulses to an output in the range 0.001 to over 10 millijoules at a repetition rate 0.010 to 100 kHz by using a two stage optical parametric amplifier utilizing a bulk nonlinear crystal wherein the pump and signal beam size can be independently adjusted in each stage.

Abstract: The invention relates to a light wave converter assembly, comprising a light guide and a light wave converter, comprising a converter substance, which converts a part of the incident light into light of a longer wavelength, whereby the converted light is guided together with the unconverted light through the light guide to an exit port.

Abstract: An optical wavelength converter converts an optical input signal having a first wavelength into an optical output signal having a second wavelength. The wavelength converter includes a saturable absorber switch having a control beam waveguide and an input waveguide. The converter further includes a first input coupled to the control beam waveguide and adapted to receive the optical input signal, and a second input coupled to the input waveguide and adapted to receive a second optical signal having the second wavelength from an optical source.

Abstract: The present invention provides an optoelectronic device, a method of manufacture thereof and an integrated optoelectronic system incorporating the same. The optoelectronic device may be a tunable laser that includes a capacitor located over one of the first outer surface or the second outer surface. The outer metal layers of the tunable laser can be used to form a first electrode of the laser, after which a dielectric layer and a second electrode are deposited and patterned to form the laser having a capacitor incorporated thereon.

Abstract: A compensated nonlinear optical frequency mixer for compensating the walk-off produced by group velocity mismatch (GVM) between interaction waves. The compensated mixer has a first mixing region in which the interaction waves participate in a non-linear optical mixing process and where walk-off occurs between the interaction waves due to GVM. The compensated mixer is equipped with a frequency selective coupling and time delay structure located after the first mixing region for eliminating the walk-off produced between the interaction waves in the first mixing region by guiding the waves in arms whose lengths differ by a re-synchronization length. A second mixing region is located after the frequency-selective coupling and time delay structure, such that when the waves emerge in phase from the frequency selective coupling and time delay structure they continue to interact efficiently in the second mixing region.

Abstract: A wavelength selective light source is disclosed. The wavelength selective light source comprises a broadband light source producing light having a plurality of wavelengths and a demultiplexer that receives the light and separates at least one of the plurality of wavelengths from said light. Further, a multiplexer is included for coupling the at least one of said plurality of wavelengths into an output waveguide. Finally, a semiconductor optical amplifier is provided that receives the at least one of the plurality of wavelengths from the output waveguide and amplifies the at least one of the plurality of wavelengths.

Abstract: In a wavelength converter using a nonlinear polymeric waveguide, a wavelength variable wavelength converter having a nonlinear polymeric waveguide in which insertion losses are minimized and wavelength conversion efficiencies are improved, and an optical device using the wavelength converter are provided. The wavelength converter for converting the wavelength of inputted light includes a semiconductor substrate, a first electrode formed on the semiconductor substrate, a lower cladding layer formed on the first electrode, a core layer formed on the lower cladding layer and formed of nonlinear polymer by which the wavelength of light is substantially converted by the inputted light, an upper cladding layer formed on the core layer, and a second electrode formed on the upper cladding layer, which tunes center wavelengths of the conversion by adjusting the refractive index of the core layer.

Abstract: A method for producing an optical waveguide part includes the steps of preparing a ferroelectric single crystalline substrate having a polarization-axis substantially parallel to a main surface thereof and having a given ferroelectric domain-inverted pattern, and epitaxially growing a ferroelectric single crystalline film on the ferroelectric single crystalline substrate. The ferroelectric domain-inverted pattern is thereby transcribed from the substrate into the ferroelectric single crystalline film to form a ferroelectric domain-inverted structure therein.

Abstract: A wavelength converter with a monolithically integrated delay loop in a delayed interference configuration that needs only one SOA or other non-linear optical element coupled to the input fiber, a first coupler arranged to split the output of the SOA or other non-linear optical amplifying element into two paths having controllable delay and phase shift characteristics, and at least one output coupler to combine the signals present on the two paths to provide the converter output. One embodiment of the invention has a monolithically integrated delay loop utilizing one or more asymmetric couplers. Another embodiment of the invention has a coupler that does not require an asymmetric splitting ratio, and has either a gain element in one of the paths, an attenuation element in one of the paths, or both.

Abstract: An apparatus containing an integrated optical circuit that enhances phase stability of the injection-locking process of two slave lasers. The integrated optical circuit helps to reduce phase noise by keeping environmental or mechanical perturbations uniform everywhere on that circuit. Also, the integrated optical circuit provides connections for additional components to be coupled, which can monitor and control the performance characteristics of the integrated optical circuit and the injection-locking process.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: A wavelength converter is disclosed. The converter comprises a broadband light source producing light having a plurality of wavelengths. Further, a semiconductor optical amplifier is provided that receives the light from the light source. The semiconductor optical amplifier amplifies the light under the control of a control signal related to an optical signal of a first wavelength. Next, a demultiplexer receives the output of the semiconductor optical amplifier and extracts from the amplified optical signal at least one of the plurality of wavelengths.

Abstract: An optical-to-optical wavelength converter for converting a plurality of optical bits from a first wavelength in a first wavelength band to a second wavelength in a second wavelength band. The optical-to-optical wavelength converter employs a directional coupler. The directional coupler includes at least one optical element having an index of refraction, which changes in response to optical power substantially in the first wavelength band.

Abstract: A synchronously pumped optical parametric oscillator generates pulses with duration 25 ps and repetition rate of 10 Hz. The bandwidth of the radiation is 1.36 cm−1, close to the Fourier limit. A single pulse from each oscillator is further amplified with an optical parametric amplifier obtaining pulse energies up to 3.7 mJ. This source can be tuned between 410 nm-2000 nm. The system is not a laser but an optical parametric oscillator where amplification is obtained in a parametric process rather than by population inversion. The oscillator is pumped by a pulse train from a Nd: Yag laser. In each roundtrip the bandwidth of the radiation is reduced by a grating-mirror assembly. After a number of roundtrips a close to ideal pulse is obtained. This single pulse is then amplified by an optical parametric amplifier obtaining a single tunable narrow bandwidth pulse with a duration of about 25 ps.

Abstract: A periodic dielectric structure having a three-dimensional photonic bandgap and a method of fabricating same. The structure includes a plurality of stacked first and second two-dimensionally periodic slabs arranged in an alternating sequence. The first two-dimensionally periodic slabs comprising lower dielectric rods surrounded by higher dielectric material. The second two-dimensionally periodic slabs include higher dielectric rods surrounded by lower dielectric material. The rods of the first or second two-dimensionally periodic slabs are laterally offset from the rods of a nearest consecutive two-dimensionally periodic slab of the same type.

Abstract: An ultraviolet laser apparatus has a laser generating single-wavelength light between infrared and visible, a fiber optical amplifier for amplifying the laser light, and a converting portion converting the amplified laser light into single-wavelength ultraviolet light, using a non-linear optical crystal. An exposure apparatus transfers a pattern image of a mask onto a substrate and has light source including a laser apparatus for emitting laser light having a single wavelength, a first fiber optical amplifier for amplifying the laser light, a light dividing device for dividing or branching the amplified laser light into plural lights, and second fiber optical amplifiers for amplifying the plural divided or branched lights, respectively; and a transmission optical system for transmitting the laser light emitted from the light source to the exposure apparatus.

Abstract: A frequency shifting device. The present invention provides a device and method for shifting a frequency of an optical signal comprising the steps of providing a layer of optically refractive material having a moving refractive boundary responsive to an application of an electrical signal. The inventive device includes a layer of optically refractive material having a refractive boundary responsive to an application of an electrical signal and an arrangement for providing an electrical signal to the layer to effect a predetermined frequency shift of an optical signal passing therethrough. In an illustrative embodiment, the device includes an active polymer layer, an optically conductive first cladding disposed beneath the active polymer layer, and a second cladding layer disposed above the active polymer layer, a microstrip line disposed over the second cladding layer and a ground plane beneath the first cladding layer.

Abstract: A wavelength converter is disclosed. The converter comprises a broadband light source producing light having a plurality of wavelengths. Further, a semiconductor optical amplifier is provided that receives the light from the light source. The semiconductor optical amplifier amplifies the light under the control of a control signal related to an optical signal of a first wavelength. Next, a demultiplexer receives the output of the semiconductor optical amplifier and extracts from the amplified optical signal at least one of the plurality of wavelengths.

Abstract: A wavelength converter is provided. The wavelength converter includes a substrate; first and second semiconductor optical amplifiers (SOAs) provided in parallel on the substrate, each of the SOAs including a first portion which passes light at one end, and a second portion which passes light at the opposite end; a first waveguide connected to the second portions of the first and second SOAs; a second waveguide connected to the first portion of the first SOA; and a third waveguide connected to the first portions of the first and second SOAs. The first through third waveguides are arranged on one side of the substrate in the vicinity of the first portions of the first and second SOAs. The first waveguide is connected to the second portions of the first and second SOAs through a unit for changing an optical progressing path.

Abstract: An optical wavelength converter, particularly useful in a wavelength-division multiplexing communication system, including a semiconductor junction in one arm of a Mach-Zehnder interferometer through which a data signal at a first wavelength and a probe signal at a second wavelength counter propagate. The junction is reversed biased into avalanche to selectively absorb the data signal and thereby phase modulate the probe signal according to the data impressed on the data signal. The phase modulated probe signal is beat against an unmodulated probe signal, thereby converting the wavelength of the optical carrier. A tunable laser may produce a probe signal of selectable wavelength. The data signal may first be converted by cross-gain modulation to a third wavelength out of band from the other signals before it is interacts with the probe signal.

Abstract: An optical-path-superposing-and-separating unit superposes optical paths of two inputted signal lights with each other, and then separate them. A non-linear waveguide is arranged in an area where the optical paths are superposed with each other. First and second optical waveguide are connected to the optical path superposing-and-separating unit. The second optical waveguide has a longer optical path than the first optical waveguide. A control light is introduced to the non-linear waveguide. An interference separator distributes the inputted two signal lights depending on a phase difference therebetween. Third and fourth optical waveguides connect the optical-path-superposing-and-separating unit to the interference separator.

Abstract: A multi quantum well layer has a lamination of first and second quantum well layers each sandwiched between barrier layers and defining a quantum well. The band gap of the second quantum well layer is larger than the band gap of the first quantum well layer. Current is flowed through the multi quantum well layer from a pair of electrodes. A first optical system input inputting a signal light wave to the multi quantum well layer via an input plane of the multi quantum well layer. A second optical system propagates an output light wave output from an output plane of the multi quantum well layer. A wavelength converting device is provided which can suppress the conversion efficiency from being lowered at a large detuning angular and obtain a relatively high conversion efficiency even at a negative detuning angular frequency.

Abstract: A method for fabricating periodically poled structures. The method produces an electric field within a ferroelectric substrate by applying a voltage waveform to an electrode structure disposed on a surface of the substrate. The waveform raises the electric field magnitude to a level substantially greater than that required to reverse domains within the substrate. Domain reversal continues through to completion at which time the poling field is turned off or substantially reduced to induce spontaneous backswitch poling. The forward poling field is then reapplied to stop the backswitch poling. The ability to selectively enable and terminate backswitching allows for the formation of domain patterns with small feature sizes and high uniformity through large volumes of material.

Abstract: An optical converter 1 has a light source 2 producing light of one wavelength and an optical fibre 4 in which light from the source 2 is converted by Raman scattering from the one wavelength to another wavelength. The light of the another wavelength is output from the fibre 4. The fibre 4 is doped with deuterium which has a relatively long Stoke's shift such that the minimum number of shifts are involved in the conversion from the one wavelength to the another wavelength. The doping is achieved by saturating the fibre 4 with deuterium which is fixed by exposure to UV light.

Abstract: Method and apparatus using four wave mixing (FWM) for wavelength conversion. An optical waveguide doped with a rare earth element is pumped so that an input optical signal is amplified as the input optical signal travels through the optical waveguide. The optical waveguide is provided with at least one light which, together with the input optical signal, causes four wave mixing (FWM) to occur in the optical waveguide. The FWM causes a converted optical signal to be produced in the optical waveguide and having a wavelength different from the input optical signal. If the input optical signal is modulated by a transmission signal, then the converted optical signal will also be modulated by the transmission signal. The optical waveguide can be, for example, an erbium doped optical fiber operating as an erbium doped fiber amplifier (EDFA). Therefore, an EDFA can be used for both amplification and wavelength conversion.

Abstract: An optical waveguide of the present invention includes: a nonlinear optical crystal; a first ion exchange region provided in the vicinity of a portion of a surface of the nonlinear optical crystal; and a second ion exchange region provided in the surface of the nonlinear optical crystal. The second ion exchange region covers a greater area of the surface than an area covered by the first ion exchange region. The second ion exchange region includes a region having an extent of 0.02 &mgr;m to 0.2 &mgr;m along a depth direction in which an ion exchange ratio varies along the depth direction.

Abstract: A film made of a single crystal of potassium lithium niobate is formed on a substrate made of a single crystal of potassium lithium niobate-potassium lithium tantalate solid solution. In this film formation, a temperature of the substrate is maintained in a range of 700° C.-850° C. and the film is formed by a metalorganic chemical vapor deposition method. By utilizing the film structure mentioned above, it is possible to generate a second harmonic wave in the optical waveguide with high efficiency.

Abstract: The process for the manufacture of the rib waveguide (4) is based on the process steps (a) ion implantation of high-energy light ions into a crystal, (b) the application of a mask to the surface (11.1) of this crystal, which defines strips, and (c), the etching of a rib (41) onto the surface (11.1) of this crystal. The process step (a) (ion implantation) causes the formation of a layer (14) with a reduced refraction index at a depth of some micrometers below the surface of the crystal (11.1). By this refraction index barrier (14), the light in the direction vertical to the surface of the crystal is restricted. The lateral guidance of the light is effected by the lateral limits (43.1) and (43.2) of the rib (41). The process is in particular suitable for the manufacture of waveguides in non-linear optical crystals, e.g., ferro-electric oxides (KNbO3, LiNbO3, etc.) and borates (LBO, BBO, etc.).

Abstract: A process shifts wavelengths of optical pulses. The process includes transmitting an incoming optical pulse through a nonlinear optical material, splitting the transmitted pulse into a plurality of mutually coherent optical pulses, and recombining the mutually coherent pulses with temporal delays. The recombined pulses produce a temporal interference pattern. The pattern has a peak whose wavelength is shifted with respect to the wavelength of the incoming optical pulse.

Abstract: A polarization mode dispersion compensating device is formed by a polarization mode dispersion equalizer, a polarization component splitting unit for splitting a part of the polarization mode dispersion compensated optical signal into the TE polarization component and the TM polarization component, an optical XOR circuit for carrying out an optical XOR operation on the TE polarization component and the TM polarization component, and a control system for controlling the polarization mode dispersion equalizer such that the logical operation result outputted by the optical XOR circuit becomes “0”.

Abstract: This invention relates to optical devices such as a fiber-optic frequency shifter and an optical interferometer. This invention also relates to a method of generating optical interference signals to obtain reliable sensor signals independent of polarization fluctuations of the optical waves in the fiber. Fiber-optic interferometers have many advantages such as high sensitivity and convenient way of using even in poor surrounding environments. These interferometer, however, exhibit polarization dependent signal degradation since the polarization of a light wave passing through an optical fiber irregularly changes depending on the birefringence of the fiber. This invention is characterized in that the frequencies of two orthogonal eigen polarizations of a light wave are shifted to different frequency values at one optical path of the interferometer. They produce two beat interference signals after interfering with the light wave passed through the other optical paht of the interferometer.

Abstract: Methods and systems are disclosed that dynamically shift the wavelength of an electromagnetic (EM) beam by interacting the beam with a polariton wave having a selected polariton wave frequency.

Abstract: A tunable fiber optic parametric oscillator includes a nonlinear optical loop mirror or fiber Sagnac interferometer NFSI with a dispersion shifted fiber portion. The oscillator is synchronously pumped to amplify a signal wave, while reflecting the depleted pump pulse back towards the pump. The amplified signal wave and simultaneously generated idler waves are directed to a spectral filter. The spectral filter may be a diffraction grating, a Faraday mirror or other optical filter that is tunable to change the signal wavelength that is reflected back to the NFSI. The fiber optic parametric oscillator is tunable over substantially the entire gain bandwidth and is insensitive to the polarization of the pump pulses. The fiber optic parametric oscillator may be used as a tunable source of short pulses for high speed optical communication systems. The fiber optic parametric oscillator may also be used for synchronization and clock recovery.

Abstract: A wavelength converter which has simple configuration and can be easily controlled and operated with stability, and used for a long-distance mass optical communication, comprises a waveguide for causing a change of a nonlinear refractive index. The converter includes a delay interference circuit having two optical paths and of different optical path lengths. A CW light source is input into the waveguide. A coherent length determined by a spectral line width of CW light output from the CW light source is longer than an optical path difference between the two optical paths in the delay interference circuit.

Abstract: A laser beam as fundamental waves which is emitted from a distribution Bragg reflection (DBR) semiconductor laser is incident on an optical waveguide of a light wavelength conversion device in which domain-inverted regions and the optical waveguide are formed in an LiTaO3 substrate. The wavelength of the incident laser beam is then converted so as to obtain higher harmonic waves such as blue light. In the conversion, a drive current to be applied to a DBR portion of the DBR semiconductor laser is changed so as to change an oscillating wavelength of the DBR semiconductor laser, thereby matching the oscillating wavelength with a phase-matched wavelength of the light wavelength conversion device. Thus, the generation of the harmonic waves to be output is stably controlled.

Abstract: An optical waveguide device is provided that can reduce external interference noise. The optical waveguide device includes a substrate, an optical waveguide formed on the substrate, a periodic polarization inversion region formed on the optical waveguide, and an optical thin film formed in a portion of the optical waveguide. The optical waveguide (refractive index: N2) and the optical thin film (refractive index: N1) differ in refractive index dispersion, and the magnitude relationship between the refractive indexes is reversed depending on wavelength. The relationship N1>N2 is established for light having a shorter wavelength, while the relationship N2>N1 is established for light having a longer wavelength.

Abstract: A method of and apparatus for creating a second order non-linearity profile along a waveguide. The method comprises: thermally poling a waveguide structure to generate a second order non-linearity; placing a mask adjacent to the waveguide structure; and exposing the waveguide structure with UV light through the mask to selectively erase the second order non-linearity along the waveguide structure. The mask may be an amplitude mask or phase mask. In a preferred embodiment an amplitude mask is used in combination with an incoherent UV light source to produce selective erasure of a thermally poled second order non-linearity. Apparatus for carrying out this method and devices based on waveguide structures fabricated using the method are also described.

Abstract: A wavelength converter implements high speed, high efficiency, low noise wavelength conversion without performing high voltage poling of a crystal, and enables switching and modulation of converted light in response to an electric field. A KLTN crystal, includes a deposited-gold electrode within its incidence plane, and is connected to a DC power supply via a copper wire. The crystal material is composed of KTa1-xNbxO3 and/or K1-yLiyTa1-xNbxO3. A polarizer controls the polarization of the fundamental wave in the direction parallel to the electric field, and launches it into the electrode of the KLTN crystal. The KLTN crystal, rotating on an axis in the direction of the electric field, launches only part of the generated SHG light with the same polarization direction as that of the incident light into a photo multiplier tube through a polarizer.