Abstract: A semiconductor optical waveguide device comprises a stripe-shaped semiconductor optical waveguide, part of the semiconductor optical waveguide being an active layer producing gain by electric current injection, and part of the semiconductor optical waveguide being an intra-band resonant absorption layer in which an intra-band absorption resonant wavelength is arranged within the gain band of the active layer, and means for injecting electric current into the active layer.

Abstract: The modification is accomplished on the basis of the solution known as spectral inversion (or optical phase conjugation). The device (1) comprises a medium, such as typically a dispersion shifted optical fiber (4), into which the signal to be modified is injected together with a pump signal at such a level as to induce modulation instability in the fiber (4). At the output of fiber (4) a spectrally inverted optical signal is available, which signal is translated in wavelength and is obtained with high conversion efficiency. Preferably, in order to avoid stimulated Brillouin scattering, the pump signal is subjected to spectrum broadening, for instance by means of a modulator (5).

Abstract: An optical modulation device comprises an optical modulator in which the operating point is varied according to a bias voltage. A phase deviation of an operating point from a selected optimal operating point is detected by a phase comparator based on an output light of the optical modulator. The bias voltage is generated within a predetermined voltage range by a DC amplifier so as to reduce the phase deviation. A reset circuit resets the bias voltage at the ground voltage associated with the selected optimal operating point when the optical modulator is powered up and passes the bias voltage to the optical modulator at all other times.

Abstract: Incident radiation is focussed by a lens into a non-linear optical material whose index of refraction increases with increased radiation intensity. For normal radiation, the radiation freely passes through the nonlinear optical and an optically-switchable material to an other lens. This other lens directs the radiation onto a photodetector. High-intensity radiation, however, is self-trapped in the nonlinear material to form a columnar beam which falls on the optically-switchable material, causes this material to switch, and is reflected thereby.

Abstract: Systems and methods for optically controlled phase shifters are described.

Abstract: An optical modulator includes pump and signal lasers optically aligned with an optical modulator element having a nonlinear refractive index. In operation, a pulsed optical pump beam is focused inside the modulator element for obtaining oscillatory sagittal and tangential mode radii thereof. A signal beam is propagated through the focus in the modulator element at a crossing angle with the spatially modulated pump beam for phase modulation thereof. Material nonlinearity due to electronic polarization or molecular orientation provides ultrafast rise times with correspondingly high modulation bandwidth.

Abstract: The present invention relates to a three-component optical photorefractive article having improved diffraction efficiency. The article comprises (i) nonphotoconductive polymer, (ii) benzimidazoline, and (iii) a sensitizer.

Abstract: A phase conjugate light generation apparatus for various optical systems, wherein pump light and input signal light are supplied to a non-linear optical medium to generate output signal light and phase conjugate light within the non-linear optical medium. The output signal light and the phase conjugate light are extracted by a signal light/phase conjugate light extraction unit and outputted from respective output ports.

Abstract: A hologram recording device, which comprises a recording layer of a polymer composition a photoconductive element, a second-order super-polarization element and an electron or hole capturing material and having a non-centro symmetric structure is disclosed. Transparent electrode layers are provided on each side of the recording layer. The hologram recording device is capable of space light modulation and real time hologram recording. Also disclosed is a method of manufacturing the hologram recording device and a method of hologram recording using the device. The hologram recording material is of a polymer composition a photoconductive element, a second-order super-polarization element and an electron or hole capturing element. The polymer composition has a non-centro symmetric structure. The hologram recording device according to the invention comprises a recording layer of a polymer composition including a photoconductive element and a second-order super-polarization element.

Abstract: A semiconductor optical device having an optical waveguide which represents nonlinear refractive index change due to control light absorption. The waveguide has a bandgap wavelength that increases from its entrance to its exit. In the case of the waveguide divided into first to n-th regions, the bandgap wavelengths .lambda..sub.1, .lambda..sub.2, . . . , .lambda..sub.n-1, .lambda..sub.n of the regions satisfy the relationship .lambda..sub.1 <.lambda..sub.2 < . . . <.lambda..sub.n-1 <.lambda..sub.n. In the case of the waveguide not divided into regions, the bandgap wavelength .lambda. of the waveguide monotonously increases from the entrance to the exit. This device can operate by the control light having a lower energy than the conventional one.

Abstract: Generally, the present invention is an optically controlled optical waveguide circuit comprising a substrate 30, an inorganic waveguide core 34 disposed within one or more cladding layers 36 upon the substrate 30 and an active cladding drop-in component 40 comprising a non-linear optical material adjacent to the waveguide core wherein the phase of an optical signal within the waveguide core may be modulated by controlling the index of refraction of the active cladding region. An embodiment of the present invention uses an inorganic optical waveguide 34 with a drop-in component of non-linear silica 40 as an active cladding to provide a phase modulator for a Mach-Zender interferometer which can be used to implement high speed low loss switching of optical signals.

Abstract: An optical amplifier for amplifying signals of different wavelengths throughout a spectral window modifies the amplification of each signal such that the output levels of the signals are more equal than the input levels thereof when the input levels differ by more than a predetermined amount. In one embodiment this is achieved by providing a dichroic reflector at one end of an amplifying fibre so that standing wave patterns are set up in the amplifying fibre by interference of the forward and reflected signal lights, at the different wavelengths, the signal at each wavelength preferentially decreasing its own gain with increasing signal level.

Abstract: The invention relates to an optical switch (1) which is switchable by means of light. The switch (1) comprises an optical wave-guiding structure (3) having an entrance (5) to which a signal can be applied and an exit (7). The refractive index of the wave-guiding structure (30) is variable by means of light intensity. The switch (1) further comprises a radiation source unit (15) whose radiation can be injected into the wave-guiding structure (3). The radiation source unit (15) comprises a pulsed laser (17) having a repetition time T and a pulse duration p and a medium (19) for transporting the radiation supplied by the laser (17). The radiation source unit (15) is provided with setting means (21 ) for stabilizing the wavelength of the laser (17) at a number n of selected wavelength bands from a number N of possibly selectable wavelength bands within one and the same pulse supplied by the laser (17). Moreover, the medium (19) is dispersive at a wavelength-dependent travel time t.sub.

Abstract: A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2 m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

Abstract: An optical pulse generator for producing a soliton pulse train having a modulator which amplitude and phase modulates an optical frequency output of a continuous optical wave source. The modulator is driven by first and second harmonically related continuous sinusoidal waves from first and second CW voltage sources and the generator includes a pulse compression means for producing at the output of the generator a soliton pulse train.

Abstract: The present invention relates to polymeric materials that exhibit an erasable photorefractive effect which can be fabricated into optical devices such as optical wave guides.

Abstract: An optical switching device is described which comprises a substrate of light absorbent material, a plurality of holes defined through the substrate containing a liquid material having an index of refraction which is highly temperature dependent within a selected temperature range of operation, the liquid-filled holes defining a plurality of waveguides for conducting light through the substrate.

Abstract: The present invention relates to an improved process for producing photorefractive net gain two beam coupling utilizing polymeric materials.

Abstract: Optical energy transfers, via stimulated scattering, to a seed beam from a pump beam that has a non-uniform optical intensity distribution are made with an enhanced spatial uniformity of amplification by spatial mixing of the pump beam within the medium where amplification takes place. In a stimulated Brillouin scattering (SBS) phase conjugate mirror (PCM) having an amplifier and a phase conjugating oscillator, beam mixing elements are provided on opposite sides of the amplifier to mix both the input and return phase conjugated beams within the amplifier, and to restore the beams after they have exited. The preferred mixing mechanism is a plurality of cylindrical lenses that are spaced along the beam path, and/or have unequal focal lengths to produce a series of foci within the amplification medium that are rotated with respect to each other. Amplitude replication as well as high fidelity phase conjugation are enhanced using SBS.

Abstract: A wavelength conversion element includes a substrate made of LiTaO.sub.3 of non-linear medium, a three-dimensional waveguide formed in the substrate and a second harmonic generation portion for defining a change in refractive index in the waveguide with a period .LAMBDA. and generating a second harmonic of a fundamental wave introduced into the wave guide, where .LAMBDA.=2m.pi./{.beta.(2.omega.)-2.beta.(.omega.)}, m is a natural number, .omega. is a frequency of fundamental harmonic, .beta.(.omega.) is a propagation constant of the fundamental wave, and .beta.(2.omega.) is a propagation constant of second harmonic.

Abstract: An optical logic element is disclosed which performs an XOR operation through utilization of the high-speed property of light. On each branched waveguide of a Mach-Zehnder interference type optical waveguide there is provided a phase modulating element whose refractive index undergoes a change when it is irradiated by light. The interference type optical waveguide is adapted to provide different optical output levels when the refractive index changes of the phase modulating elements are both zero or a predetermined value and when they differ from each other. Thus, the optical logic element is capable of performing the XOR or XNOR operation at an ultrahigh speed.

Abstract: The optical apparatus includes first and second deflection members, a mask, a pumping light source, and a controller. The first and second deflection members are formed of nonlinear optical material whose refractive index is changed upon light radiation. The mask is arranged on an optical path extending from a front side of the first deflection member to a rear side of a second deflection member. The mask has a predetermined transmission pattern. The pumping light source radiates first and second beams on predetermined regions of the first and second deflection members. This changes the refractive indices of the predetermined regions to bend the optical path. The controller variably controls the intensity of the first and second beams.

Abstract: The invention relates to a photorefractive device made of single crystal of which the chemical composition substantially is Ba.sub.1-x Sr.sub.x TiO.sub.3 (0.01<x<0.1 BST) The method for manufacturing said device comprises: growing BST single crystal by Czochralski technique; annealing said crystal in oxidizing atmosphere; machining said crystal into cuboid with polished surfaces; poling said cuboid mechanically and electrically into single-domain state. Said device may ba a piece of said single-domain crystal, or an optoelectronic assembly including at least one of said crystal as the core part. Performances of said device are similar to the one made of BaTiO.sub.3. A reflectivity as high as 52% has been reached using said device as a self-pumped phase conjugator. Compared to BaTiO.sub.

Abstract: All-optical modulation occurs in crystalline organic semiconductor waveguides (10a) grown by the ultrahigh vacuum process of organic molecular-beam deposition onto substrates (10b). Two light beams with wavelengths of 1.06 and 0.514 .mu.m from a first source (12) and a second source (34), respectively, may be used as the guided and the pump light sources, respectively. A resonant non-linear coefficient at room temperature of 5.4.times.10.sup.-5 cm.sup.2 /W at 1.06 .mu.occurs at a pump intensity of 1.0 W/cm.sup.2. This large non-linear effect is attributed to free electron-hole pairs produced by the dissociation of excitons generated by the short wavelength beam. A carrier lifetime of (17.+-.1) us, which determines the modulator switching time, is in good agreement with theoretical predictions. This appears to be the first observation of free-carrier-induced index modulation in crystalline organic waveguides.

Abstract: The present invention relates to a high performance nonlinear optical device by utilizing an optical medium of large second order nonlinear optical effects, which has acceptable processability and stability. The second-order nonlinear optical device of the present invention comprises an optical element of a monoclinic crystal of 4-hydroxy-3-methoxy-4'-nitrostilbene represented by the formula (I): ##STR1## said crystal belonging to space group P2.sub.1, point group #4, said optical element having at least one substantially optically smooth surface.

Abstract: An optical beam amplification and delivery system and method employs a central station with a laser oscillator, a laser amplifier and a phase conjugate mirror (PCM). Low power, near diffraction limited laser beams are delivered to each of a plurality of local stations through single-mode polarization preserving fibers. From the local stations the low power beams are transmitted back to the central station through high power multi-mode optical fibers. At the central station the received beams are amplified, phase conjugated and transmitted back through the amplifier and multi-mode fibers to their respective local stations. Distortions imposed upon the beams by the multi-mode fibers during transmission back to the central station, and by the amplifier, are compensated during the return path, providing high power yet near diffraction limited beam quality at the local stations.

Abstract: A nonlinear all-optical switching device including a waveguide of an organic conjugated material which forms a nonlinear optical medium. The nonlinear material has an index of refraction which is a function of the local intensity of light. Light beams passing through the waveguide intersect and interact causing diffraction into secondary beams. The intensity of the diffracted beams is a function of the intensity and frequency of the intersecting light beams. The nonlinear material can respond extremely fast and provide a bandwidth exceeding 500 GHz.

Abstract: An optical switching device employs a rare earth bis-phthalocyanine having good third-order nonlinear susceptibilities. In a preferred optical switch, the rare earth bis-phthalocyanine is employed as a nonlinear optical material body that fills the space between two partially reflecting mirrors. When light incident on the switch is below a given intensity level, light passes through the switch and the switch is in an open state. When light is above a given intensity level, light is trapped in the nonlinear optical material and the switch is in a closed state.

Abstract: A nonlinear optical device for controlling a signal light by a control light comprises a waveguide region consisting of an optical nonlinear semiconductor material, and an electrostatic field generator, which is a DC supply for example. Carriers (electrons and holes) generated by excitation of electrons due to a control light having a predetermined wavelength supplied to the waveguide region are swept away from the waveguide region by an electrostatic field, so that the change of nonlinear refractive index of the waveguide region can follow the change of the control light to increase the operation speed of the nonlinear optical device.

Abstract: An erbium-doped fiber optical amplifier, characterized in that said fiber has a mode radius which is not greater than 2.7 .mu.m at a wavelength of 1.55 .mu.m, and in that it has at least one pump wavelength situated in the following regions of the spectrum: 0.98 .mu.m.+-.0.4 .mu.m and 1.48 .mu.m.+-.0.4 .mu.m; the region of the spectrum of at least one signal to be amplified being 1.5 .mu.m to 1.6 .mu.m.

Abstract: An optical waveguide apparatus comprising a substrate made of material the refractive index of which is changed by an electric effect, and an optical waveguide which is formed on a portion of the substrate and allows passage of guided light. In the apparatus, the optical waveguide includes an optical path changing section for periodically producing an electromotive force under the control of one of control light and guided light.

Abstract: An apparatus and method for switching unpolarized light are provided. The apparatus includes GaInAs/GaAs optical switching devices which can be fabricated using conventional processes on a single wafer in matrix arrangement to provide an n.times.m cross bar switch. Switching is accomplished by shifting the band gap of the GaInAs material of a device using electrical or optical power to heat the material. Each switching device may comprise two-polarity (n/p) or single polarity (n or p) semiconductor materials.

Abstract: A light activated switching device is disclosed in which the receipt of a light signal is used to switch a light beam between two output ports. The input light beam is reflected from an interface between two regions having different indices of refraction when the light signal is present. The reflected light beam then exits through the first output port. In the absence of the light signal, the two regions have the same index of refraction, and the light beam passes through both regions and exits through the second output port.

Abstract: A variable interval electromagnetic pulse train generator having a semiconductor substrate on which is mounted on one surface thereof a plurality of spaced apart electrodes and on another surface thereof an electrode base plate. A voltage source is connected to each of the plurality of spaced apart electrodes while the space between electrodes have optical pulses directed thereon. By controlling the voltage applied to the electrodes and the optical pulses directed between electrodes the pulse train generator is capable of emitting a series of variable, spaced apart electromagnetic pulses.