Abstract: A light control element comprising a light control layer containing an electron donating organic compound and an electron accepting organic compound and means for applying an external electric field having an intensity less than a value which is required to cause phase transition in the light control layer to the layer, wherein charge transfer excitons are produced in application of the external electric field.

Abstract: The present invention teaches an ultraviolet active wristband. The ultraviolet active wristband is made of the same materials as any wristband already in the market. However, the present wristband has the intriguing propriety of changing color reversibly from clear to any visible color (violet, blue, red, orange, yellow . . . ) when exposed to an ultraviolet source. The wavelength interval of the ultraviolet source is ?250 nm-400 nm!. Therefore, it is also sensitive to the spectrum of ultraviolet sunlight that is ?290 nm-400 nm!. The active chemical is a photochromic substance such as spiropyrans, spiroxazines.

Abstract: The present invention is directed toward realizing a measurement method that enables finding the intensity waveform of optical short-pulse as well as the change in chirp frequency over time at a high resolution. Such a method involves irradiating an optical short-pulse that is to be measured at a delay time .tau. upon a first photoconductor that enters a conductive state when irradiated by light and upon a second photoconductor that enters a conductive state only when irradiated by light while the first photoconductor is in a conductive state. In this way, the autocorrelation waveform of optical short-pulse that is to be measured is found; the result F(.omega.) of a Fourier transform of the autocorrelation waveform of optical short-pulse to be measured is found; and this result is divided by the result of a Fourier transform of the cross-correlated waveform h.sub.12 (.tau.) of the impulse response waveform h.sub.1 (t) of the first photoconductor and the impulse response waveform h.sub.

Abstract: An optical element and a method capable of electromagnetically inducing transparency in a solid. The optical element includes a solid having a number N of sites characterized by at least three energy levels including a first level higher than a second and a third lower than the second, and an excitation device configured to irradiate the solid with a first light having a wavelength corresponding to the energy difference between the first and the second level, and a second light having a wavelength corresponding to the energy difference between the first and the third level. The solid satisfies .sigma..sub.23 .ltoreq..sigma..sub.12 and .sigma..sub.23 .ltoreq..sigma..sub.13 where .sigma..sub.12, .sigma..sub.13 and .sigma..sub.23 are respectively the standard deviations of the energy differences between the first and second level, between the first and third level, and between the second and third level.

Abstract: An optical computer includes a plurality of functional elements (thin-film elements) each adapted for causing an external signal to act on a two-dimensional-information incident light so as to perform information processing, and light sources for transferring the two-dimensional-information incident light between the functional elements. Each of the functional elements includes nanoparticles comprising molecules of an organic compound and associates/aggregates of these molecules. This structure makes it possible to input light beams from a plurality of functional elements to a single functional element and to output light beams from this single functional element to the plurality of functional elements.

Abstract: Spatially localized radiation, preferably ultraviolet visible radiation, representing information is impinged onto a spatially localized area of a heterostructure comprising a ternary Group III-V Nitride semiconductor material. It has been found that the spatially localized optical radiation reversibly changes the properties of the heterostructure comprising ternary Group III-V Nitride semiconductor material in the spatially localized area, to thereby provide an optical memory. The stored information can be read from the memory by impinging blanket radiation, preferably ultraviolet radiation of the same frequency which was used to write the information, onto the heterostructure comprising ternary Group III-V Nitride semiconductor material including onto the spatially localized area thereof.

Abstract: This monostatic LIDAR system is a pulsed-radiation LIDAR system comprising, for the separation of the laser emitter beam from the laser echo backscattered by the photodetector of the receiver, an optical separator that deflects an incident light beam in different directions, depending on whether it transmits or reflects this beam, the coefficient of transmission or the coefficient of reflection of this optical separator varying as a function of the energy density of said incident light beam. Advantageously, this optical separator is constituted by a layer of vanadium dioxide VO.sub.2 deposited on a transparent plate. An optical separator of this kind is used to obtain a total transmission/reception output greater than that of an optical separator with semi-reflective plate while, at the same time, preserving the advantages that an optical separator of this kind brings about in the optical architecture of a LIDAR, these advantages being simplicity, easy setting, compactness and low-level parasitic reflections.

Abstract: There is disclosed a reshaping device for optical short pulses to effectively perform reshaping of and eliminate noise from an optical short pulse of a pulse width of pico second order less than a carrier life time. Input optical short pulses are applied to a saturable absorption element, while an assist light of a wavelength longer than that of the input optical signal pulses is also applied to the saturable absorption element to accelerate, by stimulated emission, recombination of excited electrons and holes produced in the saturable absorption element in response to the input optical signal pulses, so that the input optical signal pulses reshaped are derived from the saturable absorption element.

Abstract: A full optical type optical element performs an information processing on an input signal light beam through use of only light beams including the signal light beam and an auxiliary light beam for assisting operation. The optical element includes aggregates which are dispersed within the optical element as optical functional aggregates, and which are composed of a single kind or multiple kinds of compounds including a single species of atoms or molecules. Thus, a full optical type optical element having a high resolution can be obtained through use of a thin-film element which contains nanoparticles comprising molecules of an organic compound and associates/aggregates of these molecules.

Abstract: All-optical devices, e.g., optical switches and modulators, and logic gates such as optical AND and OR gates, that include photochromic materials having first and second stable states, such as bacteriorhodopsin, organic fulgides, azo and fluorescent dyes, phycobiliproteins, rhodopsins, and their analogs, irradiated in a four-wave mixing geometry, are described. These devices can be used in a wide variety of systems, such as, e.g., optical signal processors and optical computers.

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: An optical switch in a one-dimensional multilayer dielectric stack having a photonic band gap, composed of at least two groups of layers of dielectric material whose operating wavelength is near the edge of said photonic band gap. At least one layer of each of the groups is composed of a nonlinear c.sub.3 dielectric material, which creates an intensity-dependent shift in the location of the band gap and produces a dynamical change in the transmissive and reflective properties of the multilayer dielectric stack in response to changes in the intensity of light or the transmittance of electromagnetic radiation passing through the multilayer dielectric stack. The width of the photonic band gap is determined by the differences between the refractive indices of the nonlinear dielectric material and that of the other layers of dielectric material in the multilayer dielectric stack.

Abstract: A process for intramolecularly condensing a polyamic acid composition containing an NLO compound to form a polyimide host matrix composition containing as a guest the NLO compound, which process includes the step of uniformly heating the polyamic acid composition, in the absence of a solvent or diluent, to a temperature at which the intramolecular condensation will occur without thermal degradation of the NLO compound, so that the temperature differential within the polyamic acid is below that which will produce localized thermal degradation temperatures, until the intramolecular condensation of the polyamic acid composition to the polyimide host matrix composition is substantially complete. Polyimide host matrix compositions containing guest NLO compounds prepared by the inventive process are also disclosed, wherein the NLO compounds have external field-induced molecular alignments.

Abstract: An optical amplification system directs a diffraction-limited signal beam through a series of crossings, at substantially less than 90.degree. crossing angles, with a number of non-diffraction-limited pump beams in a photorefractive medium. The pump beams are e-polarized while the signal beam travels down the crystal medium's c-axis and is polarized in the same plane as the pump beam polarization, resulting in an energy transfer from the pumps to the signal beam while leaving the signal beam diffraction-limited. The photorefractive medium is preferably a series of BaTiO.sub.3 :Rh crystals that are aligned parallel to the angled edge of a wedged-shape prism through which the pump beams are transmitted, with the crystals cut so that their C-axes are parallel to the signal beam.

Abstract: Logic operations are carried out on binary optical signals using a non-linear optical amplifier having a front port and a rear port respectively receiving a front wave and a modulated rear wave. The output wave via the rear port is separated from the rear wave by exploiting the fact that they have opposite propagation directions. Applications include optical data switching and transmission.

Abstract: Generally and in one form of the invention this is a periodic surface filter comprising at least one element at a surface of the filter and electronic controls to change the optical characteristics of the element. Other methods and devices are disclosed.

Abstract: A nonlinear optical material composed of a polyimide obtained from a diamine and/or a diacid anhydride or dithioacid anhydride substituted by a portion having a nonlinear optical effect or of molecules having a benzocyclobutene structure substituted at the portions having an nonlinear linear optical effect.

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 invention relates to an optical modulator allowing to modulate a coherent light beam (2) by an optical signal (4). According to the invention, it comprises an optical cavity (3) composed of two superposed glass substrates (8, 9), each carrying an interferometric tridimensional lattice, said coherent beam (2) being susceptible to be directed on a first surface of said cavity (3), whereas said optical modulation signal (4) is directed against said first surface or the opposite surface of this cavity, the output signal of this modulator being constituted by said beam after reflection on said optical cavity (3).

Abstract: A rhodopsin family protein is inserted into an etalon type cavity having partially reflecting mirrors as principal components having a reflectivity of 50% to less than 100% for light having a wavelength in the 650-800 nm region and a transmissivity of 30% or more for light having a wavelength in the 400-600 nm region to form a photo-controlled spatial modulator. By utilizing a change in the refractive index by light of the photo-sensitive protein, near infrared light of a stronger intensity can be controlled by weaker visible light, and the information contained in the light signal on a two-dimension plane can be rapidly controlled by a light signal of weaker intensity of another two-dimension plane by using an optical switch of a simple construction.

Abstract: A photorefractive pirouette display device can produce the sonogram of speech sounds by incorporating the short-time Fourier spectrum of speech waves as the input. The device requires a coherent source of optical radiation which can be obtained for a variety of different lasers. A photorefractive circuit is used to display a time-dependent signal, beam. An analog signal is imposed on the beam as temporal modulations on its intensity and/or phase, the pump beam is a plane wave constant amplitude. The signal beam interferes with the pump beam in the photorefractive crystal, the resultant intensity modulation pattern nonuniformly excites the charge carriers in the crystal. The excited charge carrier migrate in the crystal to form a microscope electric field, which produces an index grating in the crystal due to the Pockels effect. The crystal is rotating continually with angular velocity. The pump beam diffracts off of the holographic grating and reconstructs the signal beam.

Abstract: An actively pumped optical filter includes a vapor cell having a population of electrons with the plurality of energy levels which receives light and transmits light according to a pumping mechanism. A magnetic source is provided for applying a magnetic field to the vapor cell. A first pulsed dye laser applies a first beam of light to the vapor cell causing transitions of the electrons from a first energy level to a second energy level. A second pulsed dye laser is used for measuring the transmission through the vapor cell. A third laser applies a beam of light to the first laser and a beam of light to the second laser. The third laser may be an Nd:YAG laser. Polarizers are disposed before and after the vapor cell and a delay path is provided for delaying the second beam of light before the second beam of light is applied to the laser cell. The delay path is tuned by adjusting the length.

Abstract: The present invention relates to an optical transistor which uses photo-excited carriers to modulate the interaction between the plasma oscillation of free carriers and input electromagnetic radiation to change reflectivity by a large margin, thereby realizing high-speed light modulation, light switching and light detection. The device functions like a transistor, but uses a light beam instead of an electric current. The invention also provides implementation schemes for different devices using optical transistors such as a light power modulator, a combined detector, a reflective or transmissive light switch and a spectral scanner.

Abstract: An apparatus for amplifying the optical power ratio includes first and second input electro-absorption modulators coupled together in series that each receive an optical input beam. First and second output electro-absorption modulators are coupled together in series and each generate an optical output beam. A voltage amplifier electrically couples a first node located between the first and second input modulators to a second node located between the first and second output modulators. In operation, the power ratio of the output beams is a function of the power ratio of the input beams.

Abstract: An optical amplifier includes a photodetector such as a photodiode for receiving an optical input signal to be amplified. An electro-absorption modulator is responsive to a photocurrent generated by the photodetector such that the modulator absorbs a portion of an optical beam transmitted therethrough in an amount proportional to an amplified replica of the photocurrent. The remaining portion of the beam transmitted through the modulator forms a signal that is an inverted, amplified replica of the input signal.

Abstract: An optical system includes a fiber-optic amplifier having a section of optical waveguide doped with a rare-earth element and a pump-light source for emitting pump light, the fiber-optic amplifier receiving signal light of a first wavelength and outputting at least signal light of a second wavelength. An optical-to-electrical transducer receives the signal light of the second wavelength from the fiber-optic amplifier and produces an electrical output signal. The signal light of the second wavelength is pump light which is unabsorbed in the section of optical waveguide.

Abstract: A method and apparatus for wavelength shifting an intensity-modulated optical signal are provided. The present invention utilizes an intensity-modulated first optical signal at a first wavelength, a second optical signal at a second wavelength and an optical amplifier with a gain which varies with the intensity modulation of the first optical signal. The optical amplifier receives and amplifies the first and second signals such that variations in the intensity modulation of the first optical signal alter the optical amplifier gain, producing an amplified second optical signal with corresponding intensity variations. In accordance with the invention the power level of the second optical signal is adjusted to reduce the amplifier gain recovery time and thereby reduce the rise time of the intensity variations of the amplified second optical signal. Optical wavelength shifting by amplifier gain compression is thereby made possible at bit rates of 10 Gbits/sec or higher.

Abstract: An all-optical inverter device is achieved by employing an optical amplifier having a optical filter positioned in a feedback loop arranged so that an output signal of the optical amplifier having a first characteristic wavelength is inversely related to an input signal to the optical amplifier having a second characteristic wavelength.

Abstract: A process and apparatus for the modulation and amplification of light beams having at least one input light beam (8) supplied to at least one Fabry-Perot resonator having at least one resonance mode, and defined by two mirrors (M1,M2) and produced by stacking layers on a substrate (4). At least one of the layers form an active medium (6) able to amplify the input light beam by stimulated emission, the wavelength thereof being around the resonance of the resonator and the density of free charge carriers in the active medium being varied in such a way as to make the latter sometimes absorbent and sometimes an amplifying with respect to the input beam and thus obtain at least one output light beam (10) whose intensity is modulated and amplified relative to the input beam. Application to optical telecommunications and to optical interconnections.

Abstract: A method and system for compressing and amplifying light pulses using degenerate cross-phase modulation and degenerate four-wave mixing. A probe pulse and a pair of pump pulses are arranged so as to copropogate in condensed matter with the pump pulses having the same frequency as the probe pulse. The first pump pulse overlaps with the front end of the probe pulse while, the second pump pulse overlaps with the tail end of the probe pulse. The probe pulse is linearly polarized. The pump pulses are orthogonally polarized relative to the probe pulse so that they can be filtered out using a polarizer and have a greater intensity than the probe pulse. The propagation constant mismatch between the probe pulse and the pump pulses is equal to about zero.

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: Described here is an all-optical switch having two states, one that absorbs ncident coherent optical radiation and another that amplifies incident coherent optical radiation. The state of switch is changed in response to the passage of an ultra-short coherent optical pulse when the peak field strength of the pulse is in a wide region about the effective dipole moment per unit volume, a characteristic material parameter proportional to the density and the dipole transition moment of the selected active two-level systems which are uniformly distributed with sufficient density so that there is more than one two-level system per cubic transition wavelength causing dipole-dipole interactions to be non-negligible.

Abstract: A configuration or system of lenses for use in an arc welding environment variably filters light so that the dramatic contrasts of light present in the welding area are reduced for better remote viewing. A photochromic lens forms a negative image of the welding area. The negative image of the photochromic lens serves as a variable density optical filter to reduce the brightness of the image incident upon the photochromic lens. A first lens initially gathers and focusses the light upon the photochromic lens. Subsequent lenses further prepare the image for camera reception by eliminating ultraviolet (UV) light, by eliminating light at spectral lines, and/or by enhancing the depth of field of the image.

Abstract: An apparatus and method that permit the transmission of secure communications. The invention uses quantum mechanical effects to establish nonlocal correlations between a pair of photons. This is analogous to an automatic encryption code that exists at only one location and is immediately destroyed after either of the photons is detected. This latter feature also provides a means for detecting any unauthorized tap on the transmission line.

Abstract: An optical logic operation apparatus includes an optical induction refractive index crystal having first and second planes parallel to each other and a device for inputting a coherent probe light from the first plane of the crystal. At least one of the first light output from the first plane of the crystal and the second light output from the second plane of the crystal is taken out so that one of the first and second lights is amplified by the two-wave coupling of the probe light reflected by the second plane and the probe light inputted from the first plane and the other light is attenuated likewise by the two-wave coupling. The inputted image is projected onto the crystal by use of light incoherent to the probe light. With the incidence of the incoherent light, a gain distribution corresponding to the inputted image is generated in the crystal so as to modulate the first and second lights spatially.

Abstract: A photorefractive device is provided for converting an image-bearing incoherent input beam to a high contrast coherent output beam the intensity of which varies as the square of the input intensity pattern. The device uses an incoherent image beam to write a holographic grating directly in a photorefractive medium. In one embodiment, a parallel, laterally displaced, telecentric system of lenses is used to split a quasi-monochromatic, incoherent image-bearing beam into two equal components. The two components are superimposed at the surface of the photorefractive medium to produce the hologram. In a second embodiment, the incoherent input beam is directed through a physically translating external grating to write the hologram in the photorefractive medium. The moving grating improves the diffraction efficiency of the hologram under the influence of an applied electric field and stabilizes the temporal response characteristics for signal processing.

Abstract: A spatial light modulation device includes a spatial light modulation tube and converts a one-dimensional photoelectron image into a two-dimensional electron image, rotating the two-dimensional electron image, subjecting the rotated two-dimensional electron image and a previously stored electron image to addition or subtraction, and stores the electron image thus processed.

Abstract: A light-modulated photoconductor, exhibiting a variable permittivity, provides the basis for various instrumentation devices and methods. In one embodiment, the light-modulated photocondcutor is used as a dielectric between conductive plates to provide a light-modulated capacitor (photocapacitor). One of the conductive plates may be transparent to facilitate application of the modulating light to the photoconductor. The light-modulated capacitor may be used for numerous applications, such as instrumentation used to, e.g., measure the work function of surfaces during processing or as a non-contact voltmeter. In another embodiment, the light-modulated photoconductor is used as a mirror or lens wherein the index of refraction is optically modulated. Such light modulated lens or mirror assembly may be used as a beam steering device, e.g., a solid state infra-red (IR) beam steering device.

Abstract: A transient optical element is created by providing a body of a third order non-linear material and then passing a pulse of light through the body of non-linear material. The pulse of light has a cross-sectional area corresponding to the cross-sectional area of the transient optical element to be created and power sufficient to induce an index of refraction change over the portion of the body of non-linear material through which it passes. The portion of the body of non-linear material having the induced index of refraction change constitutes the transient optical element with the duration of the transient optical element depending on the response time of the non-linear material and the duration of pulse of light. Typical optical elements that can be so created include prisms, lenses, gratings, mirrors, beamsplitters and wave guides. By forming a plurality of optical elements within the third order non-linear material rather than simply a single optical element, a transient optical circuit can be created.

Abstract: An optically switchable device (1) has a heterostructure (2) defining a first potential well (3) separated by a barrier layer (4) from a second potential well (5) which provides an electron energy level (e.sub.5) which is lower in electron energy than the lowest electron energy level (e.sub.3) of the first potential well (3). The barrier layer (4) provides an intermediate electron energy level (e.sub.4) and is sufficiently thick to inhibit tunnelling of holes from the first (3) to the second (5) potential well. The barrier layer (4) thus confines holes of electron-hole pairs generated in the first potential well (3) by an incident optical beam to the first potential well (3) while facilitating transfer of the electrons from the first potential well (3) to the second potential well (5) via the intermediate electron energy level (e.sub.4) provided by the barrier layer (4).

Abstract: Apparatus for selectively limiting the response of an auxiliary liquid crystal light valve which is used in a dual liquid crystal light valve laser optics system for correcting inherent liquid crystal light valve distortion by isolating an atmospheric reference beam from the main laser beam in the auxiliary correction system. Two types of isolation are provided: dual bandwith and dual polarization. In the former, the response bandwidth of the auxiliary liquid crystal light valve is shifted to prevent overlap with the bandwidth of an atmospheric reference wavefront. In the dual polarization form of isolation, provision is made for rotating the polarization of only one of the two interacting beams.

Abstract: An optical modulation source provides a pulsed optical signal 44 by coupling a pulsed optical pump signal 13 polarized along one axis of a polarization preserving fiber 24 having a wavelength .lambda.p and a continuous-wave (CW) probe signal 54 polarized partially along the pump polarization axis having the desired output wavelength .lambda.s provided by a laser 52, into one end 22 of a polarization preserving fiber 24. The pump signal is decoupled at the output end 26 of the fiber 24 and used to drive the laser 52 which provides the CW probe signal 54. The pulsed pump signal 13, when present, changes the polarization of the probe signal 54 by the optical Kerr effect. The probe signal is decoupled at the output end 26 of the fiber 24 and passed through an analyzer 38 yielding an output probe signal 44 which exists only when the pump signal is present (or alternatively, when absent), thereby providing a probe signal 44 having a wavelength .lambda.s of the probe signal and a pulse rate (1/T) of the pump signal.

Abstract: An optical mixer is provided for up/down-converting a first intensity-modulated optical signal (S1), the mixer comprising an optical amplifier (20) and gain-modulating means (23) for modulating the gain of the optical amplifier. The gain-modulating means (23) comprises means for generating a second intensity-modulated optical signal (S2) and launching it into the optical amplifier (20) at an intensity to cause the amplifier to operate at least partially within its saturated gain region. This causes the gain of the amplifier to be modulated at the frequency of modulation of the second optical signal (S2).

Abstract: An all-optical swtich apparatus having an optical gate which is unitarily composed of a nonlinear etalon and a pair of GRIN lenses, or a nonlinear etalon and a GRIN lens, and having collimating GRIN lenses, each of which guides a signal beam and a control beam to the optical gate. The resonance wavelength of the etalon can be regulated by adjusting the incident positions of signal beam and/or control beam to the optical gate by moving the collimating GRIN lenses. This decreases the required thickness accuracy of the etalon by one or more orders of magnitude than in the conventional technique.

Abstract: A photo-driven switching apparatus in which a light beam is switched or modulated by using only light beam(s), comprising (a) a dielectric substrate having "photovoltaic effect"; (b) one or more couples of electrodes formed in or on at least portions of the surface(s) of the substrate so as to polarize the portion(s) positioned between the couple(s) of the electrodes thereby, (c) one or more photo-driving or photo-receiving elements provided at least in the polarized portion(s) of the surface of the dielectric substrate, having a polarization direction arranged at one certain direction, and having photovoltaic effect so as to generate photovoltage; (d) a dielectric rotation element comprising a light beam switching passage or modulator having a couple of polarizers, the polarization direction of each of which is perpendicularly crossed or parallel to each other, positioned on the surface of incoming of a light beam to be modulated, and at the surface of outgoing of the light beam, and a couple of electrodes f

Abstract: A multiple-faced optical device comprising a light-responsive element having multiple faces, at least two of the faces constituting input faces for receipt of non-collinear light signals and at least one of the faces other than the input faces constituting an output face from which light signals transmitted through the light-responsive element are emitted. The light-responsive element is further configured to have optically-induced non-linear susceptibility to light signals transversely propagated through the light-responsive element such that at least one portion of the light-responsive element switches between two stable optical states in dependence on the total intensity of the light signals within the light-responsive element. The above-described optical device can be configured to perform various operations, such as AND/OR and INVERT/PASS logic operations, data line branching, signal time delay, and memory storage.