Abstract: An optical modulator having a voltage-optical output characteristic in which optical output varies periodically with respect to a voltage value of an electrical drive signal is driven by a modulator driving voltage signal, which has an amplitude of 2·V&pgr; between two light-emission culminations or two light extinction culminations of the voltage-optical output characteristic. A low-frequency superimposing unit superimposes a prescribed low-frequency signal on the modulator driving voltage signal, and an operating-point controller controls the operating point of the optical modulator by detecting operating-point drift of the optical modulator based upon the low-frequency signal component contained in an optical signal output from the optical modulator and controlling the bias voltage of the optical modulator in dependence upon the drift of the operating point of the optical modulator.

Abstract: In an optical transmitter which modulates a continuous-wave optical carrier with an electrical data pulse, the carrier is modulated with a clock signal having ½n (where n is an integer equal to or greater than unity) of the frequency of a fundamental sinusoidal component of the data pulse so that the modulated carrier contains at least a center frequency spectral component. On the modulated optical carrier a filtering operation is performed so that the filtered carrier contains a carrier frequency component and first sideband components. Before or after the clock modulation is performed, the data pulse is used to perform data modulation on the optical carrier.

Abstract: A hologram that can obtain high diffraction efficiency when reconstructed and is superior in productivity is provided. An arbitrary object image and a recording surface in which representative points are disposed with predetermined pitches are defined by use of a computer. At the position of each individual representative point, a complex amplitude for the wave front of object light emitted from the object image is calculated, and a complex amplitude distribution is calculated on the recording surface. This complex amplitude distribution is expressed by a three-dimensional cell having a groove in the surface thereof. Four kinds of groove depths are defined in accordance with the phase &thgr;, and seven kinds of groove widths are defined in accordance with the amplitude A.

Abstract: The invention relates to a modulation controlling circuit for supplying a modulating signal to an external modulator that outputs a modulated optical signal, while setting a proper operating point in the external modulator. The external modulator that operates in cooperation with the modulation controlling circuit of the invention enables high-quality modulation at a wide bit rate range. Therefore, in an optical transmission system or a measuring instrument to which the invention is applied, the characteristics and the performance are improved and the operation is made stable without loss of advantages of the external modulator.

Abstract: The present invention discloses an electronically frequency tunable and phase modulatable quasi-optic grid oscillator. The oscillator includes a reference signal input port whereby a small external reference signal is introduced that entrains the frequency and phase of the oscillator signal to it. Amplitude modulation techniques are introduced to further enhance the utility of the oscillator as a modulator.

Abstract: An external analog modulation system is described, comprising an electro-optical modulator with a double output and a driving circuit.

Abstract: The present invention relates to an optical transmitter and particularly to an optical transmitter including an external optical modulator such as Mach-Zehnder type optical modulator which modulates the light from a light source to output an optical signal with a drive voltage signal generated depending on an input signal According to the present invention is achieved by providing an optical modulator, which add weighting to operating point control signal in accordance with optical output level of the modulator.

Abstract: An apparatus for performing high speed scanning of an optical delay and its application for performing optical interferometry, ranging, and imaging, including cross sectional imaging using optical coherence tomography, is disclosed. The apparatus achieves optical delay scanning by using diffractive optical elements in conjunction with imaging optics. In one embodiment a diffraction grating disperses an optical beam into different spectral frequency or wavelength components which are collimated by a lens. A mirror is placed one focal length away from the lens and the alteration of the grating groove density, the grating input angle, the grating output angle, and/or the mirror tilt produce a change in optical group and phase delay. This apparatus permits the optical group and phase delay to be scanned by scanning the angle of the mirror. In other embodiments, this device permits optical delay scanning without the use of moving parts.

Abstract: A spatial frequency converting device in which the amount of conversion of spatial frequency characteristics is variable. An optical system using the spatial frequency converting device is a variable-focus optical system in which the depth of field can be enlarged by fixed signal processing. A pupil modulation element provided in a fixed-focus optical system includes a plurality of elements. At least one of the elements is rotated about an optical axis. In the variable-focus optical system, a movable lens placed on the object side of a pupil modulation element is moved along an optical axis.

Abstract: Interleavers and deinterleavers for filtering optical signals are described. The interleaver separates subsets of channels. The deinterleavers mix subsets of channels. Interleavers and deinterleavers can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: An interleaver and a deinterleaver for filtering optical signals are described. The interleaver separates subsets of channels. The deinterleavers mix subsets of channels. Interleavers and deinterleavers can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: A structure for the phase modulation of light (32) incident upon said structure comprises a mirror (40), a deformable and transparent dielectric (36) disposed on the mirror (40), at least two electrodes (41; 42; 41a, 41b, 42; 50, 50′) having one or several fixed potentials and being adapted to have one or more control voltages applied thereto for generating an electric field (58) in at least a partial region of said dielectric (36), thereby changing the optical path length of the light passing through said dielectric (36) with respect to a state of the dielectric (36) in which the electric field is not applied thereto. An arrangement of a plurality of such phase-modulating structures applied on a CMOS active matrix constitutes a very large scale integrated spatial light modulator.

Abstract: The present invention provides several apparatus, methods, and computer program products for phase shifts in an optical signal generated by an optical device. The present invention includes a optical phase modulator for altering the phase of the optical signals output by an optical device. The present invention also includes a detector assembly that receives an interference signal generated by an optical interference of a power signal and a reference signal. The detector assembly generates a lockin signal representing the optical phase difference between the power signal and the reference signal. Connected to both the detector assembly and the optical phase detector is a processor. The processor receives the lockin signal from the detector assembly and compares the lockin signal to at least one predetermined set point value. The predetermined set point value represents either a desired maximum lockin signal value or a range of acceptable lockin values.

Abstract: In an optical communication system, efficient use of a Mach-Zehnder modulator requires accurate knowledge of the AC halfwave voltage at the desired modulation frequency. At high modulation frequencies this can be difficult to measure directly. A method of accurately measuring the AC halfwave voltage of a Mach-Zehnder modulator is described. The Mach-Zehnder modulator is biased at the peak of the transfer function curve and a sinusoidal signal of known amplitude and the desired frequency of measurement is applied. The optical power is measured with and without the sinusoidal signal. The ratio of the two optical powers is used in the Mach-Zehnder transfer equation to calculate the AC halfwave voltage.

Abstract: A demodulation system used in connection with an analog optical link that provides a wide dynamic range and SNR potential for large RF signal bandwidths. An optical carrier signal modulated with an RF signal is applied to an optical splitter in the demodulation system that splits the signal into first and second carrier signals. One of the carrier signals is applied to a coarse demodulator that provides either PM or FM demodulation to generate a demodulated signal representative of the signal that includes the RF signal and the additive inverse of an error signal. The output from the coarse demodulator is inverted, and integrated in the FM case, and then applied to a phase modulator along with the second optical carrier signal from the optical splitter.

Abstract: A delay element and method for delaying an RF/microwave signal. The delay element uses a laser and an RF modulator to modulate a laser beam using an applied RF/microwave input signal. Collimating optics collimate the modulated laser beam and couple the beam to a delay element that controllably delays the modulated laser beam and hence the RF/microwave signal. The delay element has fixed retroreflectors, moveable retroreflectors disposed on a moveable armature or permanent magnet, and a coil disposed on a spring and coupled to the moveable armature. The beam is reflected multiple times between the fixed and multiple moveable retroreflectors. A dash pot may be used to suppress mechanical oscillation of the permanent magnet and moveable retroreflectors. A delay control current source supplies current to the coil to control movement of the moveable retroreflectors and thus the path length and delay experienced by the modulated laser beam.

Abstract: An interleaver and a deinterleaver for filtering optical signals are described. The interleaver separates subsets of channels. The deinterleavers mix subsets of channels. Interleavers and deinterleavers can be used to increase the bandwidth of an optical network. The interleavers and deinterleavers can be used to interface components designed for a first channel spacing to components designed for a second channel spacing.

Abstract: An optical pickup includes: a light source, an object lens, and an aberration correction unit for correcting aberration by giving a phase difference to a light beam. The aberration correction unit corrects astigmatism caused by an optical system of the optical pickup.

Abstract: An optical arrangement comprising a plurality of cells arranged in a two-dimensional array on, into, or partly into an optical medium, each said cell having a pattern structure comprising a number of grooves which are parallel to each other and which form a grating. The grating of each cells forms at least two sections which are displaced in relation to each other by a predetermined distance in a direction which is essentially perpendicular to the longitudinal direction of the grooves. The grooves of two or more adjacent cells are unaligned with one another for controlling the phase or amplitude of one or more incident optical waves when the cells receive the incident optical waves.

Abstract: An optical phase characteristic measuring apparatus includes a harmonic generator for generating a harmonic wave from a fundamental wave of output light from a light source; a beam splitter for splitting a fundamental-wave component of the output light and a harmonic component; a sample disposed in one of optical paths along which light beams from the beam splitter propagate; a unit that is composed of a signal generator and a mirror and is adapted to modulate the length of one of the optical paths; an optical mixer for mixing the light beams containing the fundamental-wave component and the harmonic component; an optical separator for separating light output from the optical mixer into a fundamental-wave component and a harmonic component; a first optical detector for detecting a fundamental-wave component of an output from the optical separator; a second optical detector for detecting a harmonic component of the output from the optical separator; and a phase detector for detecting the phase difference betwe

Abstract: An apparatus for enhancing the extinction ratio in an optical NRZ-to-RZ converting system, and an optical modulation system, are disclosed. The extinction ratio is improved by using an optical fiber loop mirror together with optical amplifiers. The apparatus for enhancing the extinction ratio includes a variable coupling means for receiving external signals to split them to respective terminals of a loop mirror. A variable optical delaying means delays the phases of the signals after their dispersion by the variable coupling means. An optical amplifying means positioned asymmetrically smaller than a bit time of an RZ signal pattern inputted slightly departed from the center of the loop mirror amplifies the optical intensity, and varies the refractive index so as to cause a phase delay. A polarization adjusting means adjusts the polarization of the optical signals, and an optical band pass filtering means removes noises from signals outputted from the loop mirror.

Abstract: A dual stage optical modulator is disclosed that uses optical predistortion to achieve a high degree of linearity and also provides signals having substantially no residual phase modulation, or chirp. The modulator allows fiber optic transmission over fibers having a zero dispersion wavelength that is significantly different from the operating wavelength of the source laser without a chirp-induced dispersion penalty. In one embodiment of the modulator, an input Y-junction splits an optical input signal into a first interferometer, also referred to as a phase/intensity modulator, having first and second interferometer arms and an electrode structure for modulating the split signal. The electrode structure includes a pair of ground electrodes and a modulating electrode for receiving a first RF modulating voltage and associated DC bias.

Abstract: An interferometer having semiconductor optical amplifiers in one or both arms of the interferometer converts information from a first wavelength to another predetermined wavelength. The original data signal (at the first wavelength) is coupled into the interferometer in such a way that it is confined to propagate, either co-directionally or contra-directionally, in only one arm of the interferometer together with the lightwave signal at the predetermined wavelength. This arm includes the semiconductor optical amplifier. In this way, the original data signal is utilized effectively to maximize the interference effect, which is required for wavelength conversion, while minimizing the problems associated with simultaneously saturating amplifiers in the interferometer structure.

Abstract: Generally speaking, in accordance with the invention, an optical transmission modulation apparatus is provided for modulating light transmitted through the apparatus. The apparatus comprises a metal film having a periodic array of subwavelength-diameter holes provided therein, and a supporting layer. At least a portion of the supporting layer has a selectively variable refractive index, the selectively variable refractive index portion being substantially adjacent to the metal film such that the metal film and the supporting layer form a perforated metal film unit. Selective variation of the refractive index of the selectively variable refractive index portion modulates the intensity of the light transmitted through the perforated metal film unit without substantially changing the direction of the light. Flat panel displays, spatial light modulators and tunable optical filters based on the optical transmission control apparatus are also provided.

Abstract: For the generation of amplified, phase-coherent light pulses, a sequence of phase-coherent, equidistant input light pulses (21) is coupled into a resonator device (1) with at least two resonator mirrors (11, 14), forming a light path (10) with a predetermined resonator length, in such a way that the coupled in input light pulses in the resonator device are linearly superimposed in succession to form at least one circulating light pulse, whereby the circulating light pulse is coupled out of the resonator device as an output light pulse (31) as soon as the circulating light pulse has reached a preset minimum level of energy.

Abstract: An apparatus for measuring displacement information of an object. The apparatus has a light source emitting a light beam, an electro-optical crystal member, a voltage applying system for imparting a predetermined frequency difference between light beams passing through two different areas in the electro-optical crystal member, and a light receiving system for receiving scattered light from the object to which the two light beams emergent from the electro-optical crystal member have been projected. The electro-optical crystal member is disposed so that a light beam from the light source may partly enter the two different areas to form the two light beams to which the predetermined frequency difference is imparted. The displacement information of the object is obtained from the scattered light received by the light receiving system.

Abstract: When an intensity modulating operation and a phase modulating operation are carried out by employing a 2-electrode MachZehnder type optical modulator preferably a LN-MZ type optical modulator, a drive signal of this 2-electrode LN-MZ type optical modulator is produced from an intensity modulation signal and a phase modulation signal with a low loss and a simple arrangement.

Abstract: In a device with a laser for image presentation in which the laser emits laser light of a defined coherence length L at a given wavelength .lambda. and in which there is arranged in the path of the laser light a first structure with which phase displacements can be carried out for individual photons of the laser light in accordance with a predetermined distribution, it is provided that the average path given by the ratio of the average root mean square of the phase displacement formed by the distribution and the magnitude of the wave vector k=2.pi./.lambda. of the laser is greater than the coherence length L multiplied by a factor of 1/(12).sup.1/2.

Abstract: A deadband error reducer for a fiber optic gyroscope, which is an offset modulation signal that averages the deadband producing error over the range of the feedback modulation signal provided to the phase modulator. Although the offset modulation signal may be introduced at any of several points in the feedback loop, the offset modulation must approximate a critical amplitude at the phase modulator. If the offset modulation is a signal having segments that are linear with time, the critical amplitude of this signal will be 2.pi..

Abstract: Bandwidth reduction methods and apparatus that offset the effects of dispersion on a signal transmitted through an optical fiber. The apparatus and methods employ a generator of modulated optical signals in cascade with a modulator. One of the generator and the modulator may be an optical intensity or amplitude modulator and the other a phase (or frequency) modulator. With the application of specific signals, the cascaded generator and modulator produce an optical signal with reduced energy in one half of the transmission bandwidth. One important benefit in the method is the fact that by exploiting the less obvious spectral characteristics of single sideband signals, a simple modulator design is achieved. All of the designs exploit a method of generating analytic signals via hybrid modulation.

Abstract: An optical modulator suitable for use in, for example, a terminal apparatus in an optical communication system when an optical signal is modulated has a power splitting unit for splitting a power of an incident light into two split lights, a first intensity modulating unit for performing an intensity modulation on one of the split lights split by the power splitting unit and outputting an intensity-modulated optical signal containing a direct current component, an optical phase shifting unit for performing a phase shift on the other of the split lights split by the power splitting unit such that the light has a phase opposite to that of the intensity-modulated optical signal, and a direct current component suppressing unit for making the intensity-modulated optical signal and the light subjected to the phase shift interfere with each other to suppress the direct current component contained in the intensity-modulated optical signal and outputting the intensity-modulated optical signal, thereby obtaining the mo

Abstract: An apparatus includes a driving voltage generator that generates a pulse driving voltage having a rising edge and a decaying edge. An optical modulator produces a first pulse at the rising edge of the pulse driving voltage and a second pulse at the decaying edge of the pulse driving voltage. Therefore, the first and second pulses are both produced from a single driving pulse voltage. The frequency of the first pulse is determined by the slope of the rising edge of the pulse driving voltage and the frequency of the second pulse is determined by the slope of the decaying edge of the pulse driving voltage. The first and second pulses are transmitted through a transmission line. A detection device detects the first and second pulses after being transmitted through the transmission line.

Abstract: In a light phase grating device, by forming the beam with a bottom conductive layer, the beam will not stick to the conductive layer on the substrate. The triboelectric effect will not occur, because the bottom conductive layer of the beam will allow charges to dissipate.

Abstract: A polarization independent optical phase modulator comprises first and second substrates. A reflector is disposed between the first and second substrates and a quarterwave plate is disposed between the reflector and the first substrate. A polarization dependent electrooptic layer is disposed between the quarterwave plate and the first substrate. The quarterwave plate has an optic axis which is aligned at 45 degrees to the polarization whose phase is modulated by the electrooptic layer.

Abstract: An optical modulator for a high power laser transmitter includes a laser source coupled through a phase modulator to a signal modulator. A noise source provides a band limited noise signal to either the laser source or the phase modulator or both. Alternatively, an optical modulator for a high power laser transmitter includes a laser source providing a laser output optical signal and a phase modulator. First and second continuous wave signals at respective first and second frequencies are combined to modulate either the laser source or the phase modulator. The first frequency is different than the second frequency. The laser and phase modulation produces a broadened optical output signal such that the broadened optical output signal is characterized by beat frequencies harmonically related to the first and second frequencies. The modulation bandwidth includes no significant beat frequencies.

Abstract: A light modulator for both intensity and phase modulating coherent light on a pixel-by-pixel basis includes a modulating material responsive to an electric potential for modulating the intensity of coherent light passing through the modulating material, and electrodes for applying an electric potential across the modulating material on a pixel-by-pixel basis. The coherent light associated with a first set of pixels has a different optical path length through the modulating material than does the coherent light associated with a second set of pixels. The modulating material is a liquid crystal material. The electrodes include a set of first reflective pixel electrodes embedded in the liquid crystal material, the first reflective pixel electrodes having a first thickness, and a set of second reflective pixel electrodes embedded in the liquid crystal material, the second reflective pixel electrodes having a second thickness.

Abstract: A passive acousto-optic modulator for the modulation of a light beam as a function of a variation in air pressure comprising a beam splitter arranged relative to the beam so as to produce a signal beam and reference beam, the beam splitter ideally comprising a flat interface located between two optically transparent mediums such as the end of an optic fiber located within air, the interface being arranged relative to the light modulator such that when the light beam travels through the interface, some of the light beam is able to pass through the interface to form the signal beam, the rest of the light beam being reflected back off the interface to form the reflected reference beam; a light modulator which modulates the signal beam, the light modulator comprising an approximately flat optically reflective surface capable of movement, the reflective surface being located in a position which, at rest is a predetermined distance from the beam splitter and is approximately parallel to and facing the beam splitter

Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device.

Abstract: The instant invention relates to a method and a device for optical phase modulation by means of semiconductor amplifiers. In this case an optical semiconductor amplifier comprises optical waveguides 10, which rise over its length and change in its lateral extension, so that light supplied at the optical inlet 11 undergoes an amplification on its way to the optical outlet 12.

Abstract: An optical modulator for a high power laser transmitter includes a laser source coupled through a phase modulator to a signal modulator. A noise source provides a band limited noise signal to either the laser source or the phase modulator or both. Alternatively, an optical modulator for a high power laser transmitter includes a laser source providing a laser output optical signal and a phase modulator. First and second continuous wave signals at respective first and second frequencies are combined to modulate either the laser source or the phase modulator. The first frequency is different than the second frequency. The laser and phase modulation produces a broadened optical output signal such that the broadened optical output signal is characterized by beat frequencies harmonically related to the first and second frequencies. The modulation bandwidth includes no significant beat frequencies.

Abstract: Apparatus for generation of broadband vestigial sideband (VSB) signals primarily for transmission over optical fibers in which the carrier frequency is in the infrared portion of the electromagnetic spectrum. The modulating signal is normally a broadband digital signal. The apparatus includes an optical fiber, an optical signal source coupled to a modulator with first and second modulation signals modulating the carrier optical signal, plus a method of adding carrier optical signal to the modulator output optical signal and coupling to an output optical fiber. The modulation signals are selected such that an output optical signal transmitted along the optical fiber from the modulator has a vestigial single sideband. Part of the carrier optical signal is transmitted with the output optical signal through the use of a bypass loop or through an appropriate combination of the first and second modulation signals.

Abstract: In a spatial light modulator of the present invention, a photoconductive layer formed of photoconductive material receives write light having a spatial distribution in its intensity and changes resistivity of the photoconductive material dependently on the spatial distribution in the intensity of the received write light. A liquid crystal layer formed of liquid crystal molecules of nematic phase receives read light and presents birefringence with respect to the received read light. An electric voltage is applied through the photoconductive layer and the liquid crystal layer to thereby produce an electric field in the liquid crystal layer. The photoconductive layer changes the electric field produced in the liquid crystal layer in accordance with the resistivity of the photoconductive material so as to electrically control the birefringence of the liquid crystal molecules.

Abstract: A photostrictive device controller and a photostrictive device control method, which can produce a fast response without causing a sharp temperature rise when driving the photostrictive device. The photostrictive device controller comprises: a light source 2 for applying light to the photostrictive device 1 that, upon receiving light, produces a photostrictive effect; an illumination optics 3 for introducing light from the light source 2 onto the photostrictive device 1; and a control device 4 for controlling the energy density of light applied to the photostrictive device 1. The control device 4 of the controller controls the illumination optics device 3 to lower, at a point close to where the photostrictive effect of the photostrictive device 1 is saturated, the energy density of the irradiated light to a level at which the elongation caused by heat can be ignored.

Abstract: A switchable lens includes first and second optically transparent substrates, a first electrically conductive, optically transparent contact film positioned on a surface of the first optically transparent substrate, a second electrically conductive, optically transparent contact film positioned on a surface of the second optically transparent substrate, and phase modulating material sandwiched between the first and second electrically conductive, optically transparent contact films. The phase modulating material has a lens function stored therein which is temporarily erasable by a potential applied between the first and second electrically conductive, optically transparent contact films, the phase modulating material thereby being capable of modulating light passing therethrough.

Abstract: A light modulation device includes a lithium niobate light modulator, an amplifier, and a bias control circuit. The lithium niobate light modulator modulates light from a light source in accordance with an input electrical signal, and outputs the modulated light. The lithium niobate light modulator includes a terminal for terminating the electrical signal. The amplifier amplifies the electrical signal to a level where it can drive the lithium niobate light modulator, and outputs the amplified signal to the lithium niobate light modulator. The amplifier includes an amplifying element at an output stage. A bias voltage of the amplifying element is set by externally supplied DC voltages. The bias control circuit supplies the DC voltages to the amplifying element, and a DC operating voltage to the terminating terminal of the lithium niobate light modulator to set a modulation operating point of the lithium niobate light modulator.

Abstract: An optical transmission system comprises an optical transmitter for transmitting an optical signal, comprising an optical modulator for modulating a intensity of the optical signal in accordance with a binary digital NRZ (nonreturn-to-zero) electric signal and outputting a transmission optical signal, and means for supplying the electric signal and thereby driving the optical modulator, the means including means for adjusting a waveform of the electric signal supplied to the optical modulator so that a timing with which the optical signal outputted from the optical modulator transits from a high level to a low level is later than a timing with which the optical signal transits from the low level to the high level, an optical fiber with wavelength dispersion for propagating the signal light transmitted from the optical transmitter, and an optical receiver for receiving the optical signal propagated along the optical fiber and reconstituting an electric signal from the optical signal.

Abstract: In a photostrictive device whose light-irradiated surface is irradiated with a beam of light with a specified wavelength to produce a photostrictive effect, the light-irradiated surface is formed with a surface roughness Ra related to the wavelength of light. This increases the light absorption of the photostrictive device, thereby improving the responsiveness.

Abstract: The fiber optic true time delay modulator generates a continuously variable true time-delay (i.e., phase shift) by utilizing the dispersion characteristic of a single mode optical fiber. The signal to be variably delayed modulates a continuous wave optical signal from a tunable laser source which is applied to a dispersive optical fiber wherein the phase shift occurs. The optical intensity output of the dispersive optical fiber is converted back into electrical energy by a photodetector for use in radio frequency, microwave and millimeter wave electronic devices. The invention can be used to generate multiple synchronized output signals by using a multiple wavelength laser or by combining outputs from several independently tuned lasers. Also. frequency and phase shifting is inherently provided by modulating the time delay.

Abstract: This invention provides analog phase modulators comprising smetic liquid crystal cells wherein the layers are specifically not aligned perpendicular to the cell walls. The layers are either tilted with respect to the substrate or are in a chevron structure. Application of an analog electric field perpendicular to the cell walls bends the molecules in an analog fashion in a plane not parallel to the cell walls and thereby provides analog phase modulation of incident light. Analog phase modulation can not be directly provided by the surface-stabilized smectic liquid crystal cells known in the art, nor can analog tilting of SmC* liquid crystals be achieved. This invention further provides Fabry-Perot devices containing these analog phase modulators within the resonance cavity. The filter of this invention is optimally suited for wavelength-division multiplexing in photonic networks. It has high throughput, large tuning range, high resolution, and high modulation speed.

Abstract: An interferometric switch for spatially switching either linearly polarized or unpolarized externally derived beams of substantially coherent light includes an optical input unit for dividing an externally derived light beam into a constituent beam pair. An optical phase modulating device includes a nematic liquid crystal pixel for selectively shifting the relative phase of the constituent beam pair. An output unit cooperates to combine respective components of the constituent beam pair along coincident collinear paths so as to form a respective output light beam directed along a selected one of first and second output axes, according to the relative phase imparted by the phase-modulating device. The phase modulating device may comprise a cascading arrangement of pixel stages which can respectively provide a selected incremental phase-shift to each constituent beam passing therethrough.