Abstract: A liquid crystal panel (441) has an optical modulator body (500), an accommodating portion (511) for accommodating the optical modulator body (500), a holding frame (510) for pressing and holding the optical modulator body (500) against the accommodating portion (511), and a frame member (512C) made of heat-conductive material and interposed between the optical modulator body (500) and a fixing plate (512), the frame member (512C) being provided on an outer periphery of a first substrate (501A) of a pair of substrates (501A, 501B) disposed on the side of the fixing plate (512), the fixing plate (512) and the frame member (512C) being integrally formed.

Abstract: Disclosed is a projector apparatus including a color separation optical system which separates illumination light into a plurality of color light components, a plurality of image forming panels illuminated with the plurality of color light components, respectively, a color synthesis optical system which synthesizes the light components from the plurality of image forming panels illuminated, a projecting optical system which projects light from the color synthesis optical system, and transparent substrates each arranged on at least one of incident and exit surface sides of the plurality of image forming panels, each of the transparent substrates holding a polarizer, wherein a surface area of at least one of the plurality of transparent substrates is larger than those of the remaining transparent substrates.

Abstract: A liquid crystal panel (441) has an optical modulator body (500), an accommodating portion (511) for accommodating the optical modulator body (500), a holding frame (510) for pressing and holding the optical modulator body (500) against the accommodating portion (511), and a frame member (512C) made of heat-conductive material and interposed between the optical modulator body (500) and a fixing plate (512), the frame member (512C) being provided on an outer periphery of a first substrate (501A) of a pair of substrates (501A, 501B) disposed on the side of the fixing plate (512), the fixing plate (512) and the frame member (512C) being integrally formed.

Abstract: Optical infinite impulse response (IIR) filters are efficient polarization mode dispersion (PMD) compensators, requiring fewer stages than finite impulse response (FIR) filters. IIR filter architectures incorporating allpass filters allow the phase and magnitude compensation to be addressed separately. An IIR filter PMD compensator comprising a polarization beam splitter, allpass filters, polarization rotation devices, a 2×2 filter, and a polarization beam combiner optically coupled is described.

Abstract: A semiconductor optical device includes a substrate, an optical waveguide layer on the substrate and having well and barrier layers. The semiconductor optical device also includes an optical absorbing layer on the substrate and adjacent to the optical waveguide layer so that incident light having an incident wavelength &lgr;LD is guided into the optical absorbing layer. Each of the well layers has a wavelength &lgr;g corresponding to the band gap of the well layers and that is larger than the incident wavelength &lgr;LD. Also, the band gap energy between base levels of a conduction band and a valence band of the optical waveguide layer is larger than the energy of the incident light having the incident wavelength &lgr;LD.

Abstract: A tunable liquid crystal switch is disclosed. An electronic controller provides an electronic drive scheme for achieving low intra-channel crosstalk of less than −40 dB using only electronic compensation. A cross-talk less than −50 dB is provided by combining coarse temperature turning and electronic compensation. This is acheived by designing the thickness of the liquid crystal device to cause a minimum to occur at a wavelength longer than a longest operating wavelength and at a temperature greater than a maximum operating temperature. This ensures that the liquid crystal device is tunable over all operating wavelengths and temperatures using electronic compensation.

Abstract: In a polarization compensator for converting a polarization state of a lightwave, and a wavelength division multiplexing apparatus using same, a controller of the polarization compensator controls a rotator to orient a polarization plane of an input lightwave to a polarization plane of a reference polarizer. Also, the controller receives an output lightwave from the polarization compensator, of the above-mentioned present invention, which inputs the input lightwave through the rotator and a first ¼ wave plate, through a second ¼ wave plate and a polarizer having the polarization plane set in the reference direction, and the input lightwave is compensated to a linear polarization having the polarization plane of the reference direction based on a received polarization signal.

Abstract: An electroabsorption semiconductor optical modulator includes a light absorption layer for generating a modulated light beam by absorbing an incident light beam. A well layer in the light absorption layer, accumulates charge carriers generated by the light absorption layer. The charge carriers are guided and released from the well layer upon receipt of an incident excitation light beam having a wavelength corresponding to the bandgap energy of the well layer. The incident light beam is modulated by changes in absorption coefficient in response to an externally applied voltage. The modulator responds to a high-intensity incident light beam at high frequency, free from deterioration of extinction characteristics, and has good transmission characteristics.

Abstract: A method and apparatus for dynamically controlling variation in an attribute of a light beam employing materials with unusually high electrooptical coefficients that are subject to optical damage from the light beam being controlled. The method includes providing a transmission medium composed of a high sensitivity electrooptic material transparent to the light beam and having a nonzero electrooptic coefficient, where the medium is adapted to receive, propagate, and output the light beam. The medium is subjected to an electric field, the strength of which is controlled to determine the amount of variation of the light beam attribute. The field is generated by electrodes appropriately enclosing the medium and inducing a voltage across the electrodes. The medium is illuminated by a suppressing light source, the illumination being intense enough to significantly reduce charge distribution inhomogeneity within the medium.

Abstract: An apparatus and method for calibration of each individual driver channel in a multichannel driver circuit for a spatial light modulator used in an image display apparatus. A separate calibration sequence is initiated in which, for each positive and negative half-cycle of the driver circuit, a ramped voltage, applied as the drive circuit voltage (18), is compared against a standard black-video drive voltage. When the ramped voltage equals the standard drive voltage, calibration for this half-cycle is complete and a digital value corresponding to a correction component of the ramped voltage is stored in memory (40). The process is duplicated for each positive and negative half-cycle of the drive voltage signal (18). For gain calibration, a ramped voltage is applied as the drive circuit voltage 18 and compared against a standard white-video signal level.

Abstract: Disclosed is a projector apparatus including a color separation optical system which separates illumination light into a plurality of color light components, a plurality of image forming panels illuminated with the plurality of color light components, respectively, a color synthesis optical system which synthesizes the light components from the plurality of image forming panels illuminated, a projecting optical system which projects light from the color synthesis optical system, and transparent substrates each arranged on at least one of incident and exit surface sides of the plurality of image forming panels, each of the transparent substrates holding a polarizer, wherein a surface area of at least one of the plurality of transparent substrates is larger than those of the remaining transparent substrates.

Abstract: The present invention relates to a modulated light source, in particular for use as part of an opto-electronic communication network. The modulated light source has a laser and an external electro-optic modulator for modulating the intensity of light produced by the laser. A temperature sensor senses the temperature of the laser and the modulator. A control circuit connected to the temperature sensor adjusts the bias on the modulator so that the band edge of the modulator follows the changes in wavelength of the laser as the laser warms up during operation. This avoids the need for a cooling element to keep the temperature of the laser constant.

Abstract: A tunable liquid crystal switch is disclosed. An electronic controller provides an electronic drive scheme for achieving low intra-channel crosstalk of less than −40 dB using only electronic compensation. A cross-talk less than −50 dB is provided by combining coarse temperature tuning and electronic compensation. This is acheived by designing the thickness of the liquid crystal device to cause a minimum to occur at a wavelength longer than a longest operating wavelength and at a temperature greater than a maximum operating temperature. This ensures that the liquid crystal device is tunable over all operating wavelengths and temperatures using electronic compensation.

Abstract: A light receiving module and a light receiving method to reduce polarization dependence, used in evaluation of polarization characteristics of various optical parts. The light receiving module has an optical mechanism including a first light transmission plate and a second light transmission plate between a first lens and a second lens, and a light receiving element of the outside of the optical mechanism. The first light transmission plate is inclined at such an angle as to have the same value as polarization dependence due to the inclination of the light receiving surface of the light receiving element, and subsequently the first light transmission plate is rotated by 90° in relation to the optical axis.

Abstract: An optical modulation device which can facilitate a reduction in size of a device and prevent overheating of the optical modulation device, and a projection display device utilizing the optical modulation device are provided. In the optical modulation device, sapphire glasses are affixed to the light-incident side and the light-emitting side surfaces of liquid crystal panels which respectively modulates light of three colors of red, green, and blue emitted from a light source according to image information. Therefore, heat generated on optical modulation devices can be discharged, so that overheating of the optical modulation devices can be prevented, and a reduction in size can be achieved. In addition, since the sapphire glass is difficult to scratch, it becomes easy-to-handle, thereby facilitating the management of the optical modulation devices.

Abstract: A polarization mode dispersion (PMD) emulator may include one or more modular “cells” that emulate PMD. Each of the cells may include optical delay and phase modulation components. The optical delay and/or the phase modulation components may be adjusted to account for differences in PMD and two or more of the cells may be combined to further adjust the overall PMD of the apparatus. Similarly, a PMD compensator may include one or more modular “cells” that compensate for PMD, with each of the cells including optical delay and phase modulation components. The optical delay and/or the phase modulation components may be adjusted to compensate for various PMD values and two or more of the cells may be combined to further adjust the overall PMD compensation of the apparatus. The PMD compensator apparatus may be used to compensate for PMD in wideband applications, such as wavelength division multiplexed (WDM) systems.

Abstract: A device for erasing overhead modulation of an optical signal, wherein said optical signal is injected into an optical device able to modulate the optical signal (for example a semi-conductor optical amplifier driver by a bias control) and for which one an automatic gain control does not need to detect the residual overhead modulation, is characterised in that said bias control means applies to said amplifier a compensation voltage presenting a modulation out of phase with respect to said overhead modulation, and in that modulation index of said compensation voltage is (substantially) proportional to the modulation index of said optical signal.

Abstract: An optical device comprises a first birefringent crystal having a first length, a second birefringent crystal having a second length, and a dynamic polarization rotator. An optical signal propagating through the first and second birefringent crystals has an effective optical path length based, at least in part, upon the first length of the first birefringent crystal and the second length of the second birefringent crystal. The dynamic polarization rotator adjusts the effective optical path length of the optical signal in response to a control signal.

Abstract: The invention includes an apparatus for processing an input optical beam. The apparatus has at least one variable optical element to dynamically alter the polarization state of an optical beam to form a polarization-altered optical beam, wherein the polarization-altered optical beam includes elliptical polarization. At least one wave plate operates on the polarization-altered optical beam, each wave plate has a selected retardation, order of retardation, and orientation. A polarization analyzer, operating in conjunction with the at least one variable optical element and wave plate, alters the transmitted amplitude of the polarization-altered optical beam as a function of wavelength, and thereby produces an output optical beam with transmitted amplitude adjusted as a function of wavelength.

Abstract: Systems and methods for adjusting the polarization of one or more recording laser beams can correct (in whole or in part) for the changes in the polarization of the recording laser beam(s) caused by changes in the dominant polarization direction within the film substrates used for recording holograms. Using information about the dominant polarization direction of portions of holographic film substrate, a polarization adjusting device can be used to adjust the polarization of the recording laser beam(s) to compensate for the effects that changes in the dominant polarization direction of the holographic film substrate have on the recording laser beam(s) and thus the recorded hologram.

Abstract: An optical signal regenerator includes a mechanism for reconstituting an optical signal carrier wave. The optical signal is thus regenerated on the same wavelength as the incoming carrier wave.

Abstract: A photonic device including an array of lasers providing light to an array of electro-absorption modulators, both on a common substrate. In some embodiments the lasers are in a closely spaced array and lase at different wavelengths, providing with associated electro-absorption modulators a compact wavelength selectable laser.

Abstract: A tunable liquid crystal switch is disclosed. An electronic controller provides an electronic drive scheme for achieving low intra-channel cross-talk of less than −40 dB using only electronic compensation. A cross-talk less than −50 dB is provided by combining coarse temperature tuning and electronic compensation. This is acheived by designing the thickness of the liquid crystal device to cause a minimum to occur at a wavelength longer than a longest operating wavelength and at a temperature greater than a maximum operating temperature. This ensures that the liquid crystal device is tunable over all operating wavelengths and temperatures using electronic compensation.

Abstract: A system that optically performs complex transforms, such as Fourier transforms. The system includes a pixel addressable spatial modulator that, in parallel, adjusts the phase of the light of each pixel. The modulator can be a reflective or transmissive type device. A transform lens, such as a Fourier lens, performs a two dimensional transform of the pixels outputs. This operation is repeated for the characteristic function (real and imaginary) of the function. The transformed outputs of the characteristic functions are sampled by a light detector and processed by a computer using simple fast operations, such as addition, into the final transform.

Abstract: The invention relates to a transverse electro-optic modulator for modulating a light beam having a mean wavelength &lgr;. The transverse electro-optic modulator includes at least one birefringent single-crystal modulator element of a predefined length, and controlled by means of an electronic amplifier. The transverse electro-optic modulator further includes a compensator element is made of the same birefringent single-crystal material. The invention is characterized in that for any thickness and a defined length, the thickness of the at least one modulator element is less than both the height and the width of the compensator element.

Abstract: An optical modulation device which can facilitate a reduction in size of a device and prevent overheating of the optical modulation device, and a projection display device utilizing the optical modulation device are provided. In the optical modulation device, sapphire glasses are affixed to the light-incident side and the light-emitting side surfaces of liquid crystal panels which respectively modulates light of three colors of red, green, and blue emitted from a light source according to image information. Therefore, heat generated on optical modulation devices can be discharged, so that overheating of the optical modulation devices can be prevented, and a reduction in size can be achieved. In addition, since the sapphire glass is difficult to scratch, it becomes easy-to-handle, thereby facilitating the management of the optical modulation devices.

Abstract: A device for erasing overhead modulation of an optical signal, wherein said optical signal is injected into an optical device able to modulate the optical signal (for example a semi-conductor optical amplifier driver by a bias control) and for which one an automatic gain control does not need to detect the residual overhead modulation, is characterised in that said bias control means applies to said amplifier a compensation voltage presenting a modulation out of phase with respect to said overhead modulation, and in that modulation index of said compensation voltage is (substantially) proportional to the modulation index of said optical signal.

Abstract: The invention is an instrument for sensing the state of polarization (SOP), and for transforming the SOP of a beam of light from an incident continuously-varying arbitrary SOP to a desired exit SOP, using a polarization compensator under feedback control. A polarization sensor uses two or three samples of a beam to sense the Poincare sphere latitude and longitude error in SOP. A polarization controller adjusts the SOP of light, which is then sensed by the polarization sensor, which develops signals to drive the polarization compensator using feedback methods. Unlike prior-art systems, the feedback seeks a mid-point rather than an extremum in the sensed signals, so there is no sign ambiguity in the feedback control. Further, the sensor signals indicate orthogonal displacements in SOP that correspond to specific elements in the polarization controller, so there is no ambiguity as to which element needs adjustment in order to correct a given error in SOP.

Abstract: An optical modulation device which can facilitate a reduction in size of a device and prevent overheating of the optical modulation device, and a projection display device utilizing the optical modulation device are provided. In the optical modulation device, sapphire glasses are affixed to the light-incident side and the light-emitting side surfaces of liquid crystal panels which respectively modulates light of three colors of red, green, and blue emitted from a light source according to image information. Therefore, heat generated on optical modulation devices can be discharged, so that overheating of the optical modulation devices can be prevented, and a reduction in size can be achieved. In addition, since the sapphire glass is difficult to scratch, it becomes easy-to-handle, thereby facilitating the management of the optical modulation devices.

Abstract: A device and a method is proposed for writing on imaging material (3) with a radiation source (1) producing an electromagnetic radiation having a wavelength suitable for recording image information on the imaging material (3). The radiation produced by the radiation source (1) can be modulated with a waveguide which is integrated in a substrate material (49) and operates as a modulator (2). A modulation signal containing the image information can be received at an input (9) of the modulator (2). According to the invention, a compensator (6, 12) compensates a modulation error which occurs during modulation of the radiation.

Abstract: Dual Pockels cell containing: a bar (112) in electro-birefractive material having a first (122) and a second (124) end, a first and a second ring electrode (126, 128) deposited at the ends of the bar, and a third electrode (127) formed on the bar between the first and second electrodes. Application to the fabrication of modulators or electro-optical switches.

Abstract: A spatial light modulator with an anti-reflective coating (ARC) 100 integrated into its structure. The manufacturing of the device is altered to include deposition of an ARC 100, and any necessary patterning and etching to allow the elements of the array to operate properly. The ARC could reside in several places of the element structure including over the addressing circuitry 26, over a middle layer 32 or on the underside of the reflective structure 10. Micromechanical spatial light modulators, as well as non-moving modulators, such as reflective and transmissive LCD modulators can use the invention.

Abstract: An optical display system includes a source of white uncollimated light, a color separator for separating the white light into spectral components, a reflective ferroelectric light valve for spatially modulating the spectral components, and a polarizing beam splitter for directing vertically polarized light towards a display lens. The system further includes a corrective film disposed in an optical path between the white light source and the light valve. The film, which may be made of a ferroelectric material or other birefringent material, ensures that retardance of the light valve is approximately 180 degrees or some other desired angle over a spectrum of interest. In this manner, the light valve is achromatized by the film.

Abstract: A method, a system and a computer program product configured to determine a differential group delay of two sequential optical beams based on a frequency dependence of a length of an optical path traveled by the two sequential optical beams in a dispersion compensation grating. The determined differential group delay provides a measure of polarization mode dispersion in the dispersion compensation grating.

Abstract: A method of, and an apparatus for, operating an optical modulator employ an optical attenuation versus voltage response which is cyclic and which includes an input to which the application of a bias voltage moves the modulator's response along the voltage axis to maintain the modulator's response at a desired voltage position. The apparatus comprises a bias voltage generator for generating a bias voltage which comprises the sum of a first and a second voltage component. The first component is fixed during normal operation and is selected to correspond to the expected bias voltage required for maintaining the modulator's response at a desired voltage position. The apparatus further comprises circuitry for detecting the position of the modulator's response and adjusting the second voltage component to maintain the response at the desired voltage position.

Abstract: The specification describes a Mach-Zehnder electro-optic modulator device in which the ridge containing the waveguides in the interactive electro-optic regions have re-entrant sidewalls. This shifts the peak in the RF field profile to below the surface of the ridge and closer to the peak of the optical field, thereby producing a device with reduced drive voltage.

Abstract: A tunable semiconductor laser comprises a gain section having an MQW active region, a uniform pitch grating DFB region, and first waveguide. A composite reflector, including a second MQW region and a second waveguide, forms a cavity resonator with the DFB region. A tuning voltage applied to the composite reflector induces refractive index changes, thereby allowing the center wavelength to be altered.

Abstract: A liquid crystal display device comprises a reflective type liquid crystal panel with pixels which are arranged in two-dimentionally and which modulate irradiated light utilizing polymer dispersed liquid crystal capable of exhibiting two conditions including scattering and unscattering. The device is provided with an optical member having a multiple-interference effect at a predetermined angle with respect to the surface of the reflective type liquid crystal panel.

Abstract: A pilot signal is generated and injected into the input (108) of a signal modulator (104). The harmonic signal of a pilot signal produced at the output (110) and due to the non-linear transfer function of the signal modulator (104) is coherently sampled in the time domain to produce a plurality of digital samples defining a digital sample signal. The digital sample signal is cross-correlated with a reference signal having a phase based on the pilot signal to produce a cross-correlation signal. The bias voltage at which the signal modulator (104) is biased is adjusted to minimize the difference between the phase of the correlation signal and an optimum phase value corresponding to a linear mode of operation of the signal modulator 104.

Abstract: An electro-optic modulator and a method for its use, in which an optical carrier is effectively suppressed for transmission of a radio-frequency (rf) modulating signal over an optical communication link, to provide improved demodulator performance. A carrier component is recovered from the modulator, amplified, and reused, to minimize the effect of optical carrier losses. In one embodiment of the invention, a modulator (10) with complementary output ports (20 and 22) generates a carrier-suppressed output (FIG. 2B) containing rf sidebands from one port (20) and a strong carrier component (FIG. 2C) from the other output port (22). The carrier component is filtered in a residual sideband filter (14), amplified in an optical amplifying medium (12) and returned to the modulator (10) as its carrier input. In a second embodiment of the invention, a modulator (30) with a single output port produces rf sidebands and a suppressed carrier component (FIG.

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: A walk-off device is used to split an incoming beam into two parallel outgoing beams having orthogonal polarization. A polarization flipper is positioned to change the polarization of one of the two beams exiting from the walk-off device so that the two beams are parallel and have essentially identical polarizations. A nonreciprocal device receives the two beams, and the resulting apparatus is a polarization independent nonreciprocal device. Conversely, a polarization flipper flips the polarization of one of the two parallel beams of like polarizations into orthogonal polarizations and subsequently a walk-off device combines or superimposes these two beams to form an unpolarized single beam.

Abstract: A DC bias controller for an optical modulator includes an optical modulator, a demultiplexer, and a controller. The optical modulator intensity-modulates input DC light by a digital main signal superposed with a DC voltage to convert the DC light to an optical signal. The demultiplexer demultiplexes the optical signal from the optical modulator into output signal light and monitor signal light. The controller detects a change in modulation characteristics of the optical modulator on the basis of the monitor signal light from the demultiplexer to control a value of the DC voltage superposed on the digital main signal.

Abstract: A cavity thickness compensated etalon filter. A tuning medium is placed in a Fabry-Perot etalon cavity. The index of refraction of the tuning medium varies as a function of voltage applied across the medium. The etalon is formed of two generally flat substrates disposed substantially parallel to one another. Each substrate has a layer of conductive material within the cavity adjacent the substrate. Each substrate also has a layer of reflective material within the cavity adjacent the substrate. At least one layer of reflective material is only partially reflective so as to enable light to pass into and out of the cavity. Liquid crystal material may be used as a tuning medium in the cavity. In the case of liquid crystal material, the etalon also comprises an alignment layer disposed within the cavity adjacent each substrate to pre-order the liquid crystal material.

Abstract: An improved electro-optic modulator having reduced amplitude of acoustic resonances is provided. Acoustic energy is efficiently removed from the electro-optic crystal and channeled into electrode and side dielectric bars where it is dissipated by materials acoustically matched to the electro-optic crystal, that is, materials that have acoustic impedances within .+-.15% of that of the electro-optic material.

Abstract: Chromatic and polarization dispersion and transmitter frequency chirp are the dominant data rate limiting factors for high-speed, long distance communication systems. To overcome such limitations, a chromatic and polarization dispersion and frequency chirp compensator is utilized. The applicants provide a compensator by combining a wavelength to polarization transformer with a polarization to delay converter having a dispersion characteristic of substantially equivalent in magnitude, and opposite in sign, to the desired amount of dispersion and frequency chirp to be compensated. Optical gain may be incorporated in any of the elements of the compensator which makes the present invention a lightwave amplifier as well as a dispersion compensator. The present invention is also applicable as an optical pulse time compressor that compresses a relatively long width optical pulse to a short width pulse.

Abstract: An optical element consists of an LN or LT crystal doped with MgO or ZnO. A +z surface and a -z surface of the crystal are connected to each other by means of a metal jig and an indium sheet. The +z surface and the -z surface may also be connected to each other by means of an electrically conductive wire material. The optical element may be a bulk crystal, an optical waveguide type electro-optical modulator, or a bifurcated interference type optical modulator. In this way, an optical damage resistant property of the optical element is improved.

Abstract: A raster output scanning system is disclosed which utilizes a single light source, an electro-optical device and a beam-splitter to generate two partially overlapping light beams in order to scan one scan line in which the width of the scan line can be adjusted electronically. The two partially overlapping light beams in effect generate a resulting light beam. By changing the polarization factor of the electro-optical device, the intensities of the two light beams can be modified which in turn will change the width of the resulting light beam and as a result the spot size changes. By changing the spot size, the width of the scan line can be adjusted. Also, by changing the polarization factor, the position of the resulting light beam can be changed.

Abstract: A multilayer stack of alternating low index and high index of refraction low loss dielectric mirror layers are formed on top of a metallic mirror surface, the thicknesses of the mirror layers being chosen to satisfy the Bragg condition at a selected incident angle of polarized light. The dielectric layer adjacent the metallic reflective mirror substrate can have a thickness which produces circularly polarized light exiting the apparatus. An electro-optical layer of EO material can be substituted for the dielectric layer adjacent the metallic mirror and a controlled elliptically polarized output can be produced by altering the electric field applied across the EO layer. This device can be used as a very high power high speed EO modulator.

Abstract: A raster output scanning system is disclosed which utilizes a single light source, an electro-optical device and a beam-splitter to generate two light beams in order to simultaneously scan two adjacent scan lines. Two different trains of pixel information are used to control the intensity of the laser light source and the degree of the polarization of the electro-optical device in order to modulate the two light beams with two separate trains of pixel information without using a modulating device. Each of the two light beams exiting the beam-splitter is modulated in accordance with one of the two trains of pixel information.