Showing papers on "Optical modulator published in 2003"

Laser projection display system

Abstract: A display apparatus, includes a laser light source for emitting a light beam; a beam expander for expanding the light beam; a spatial light modulator; beam shaping optics for shaping the expanded laser beam to provide uniform illumination of the spatial light modulator, the beam shaping optics including a fly's eye integrator having an array of lenslets; and a moving diffuser located in the laser beam between the laser light source and the spatial light modulator.

Rapid depth scanning optical imaging device

Abstract: An optical imaging device includes a reference scanning unit offering a high signal-to-noise ratio and capable of scanning an object rapidly. An interference optical system can be realized inexpensively. In the optical imaging device, low coherent light passed through an optical coupler and another optical coupler, irradiated from an optical scanner probe, reflected from an observed point in a living tissue, returned to the optical coupler, propagated over a fourth SM optical fiber, and routed to another optical coupler shall be referred to as sample light. Light passed through an optical length variation optical system via the optical coupler and routed to the optical coupler shall be referred to as reference light. At this time, a difference between a delay time undergone by the sample light and a delay time undergone by the reference light is proportional to a difference between an optical length for the sample light and an optical length for the reference light. When the optical length difference falls within a coherence length, the sample light and reference light interfere with each other. An interfering signal is acquired into a computer through detectors, a differential amplifier, a demodulator, and an A/D converter.

Optical intensity modulators for digital and analog applications

Abstract: This tutorial describes the basic principles and performance analysis of optical intensity modulators using electrooptic and electroabsorption effects, for use in analog and digital communication systems. These include lithium niobate modulators, semiconductor electroabsorption modulators, semiconductor Mach-Zehnder modulators, and polymer modulators.

Generation of nondiffracting Bessel beams by use of a spatial light modulator

Abstract: A laser beam with phase singularities is an interesting object to study in optics and may have important applications in guiding atoms and molecules. We explore the characteristics of a singularity in a nondiffracting Bessel beam experimentally by use of a programmable spatial light modulator with 64-level phase holograms. The diffraction efficiency with 64-level phase holograms is greatly improved in comparison with that obtained with a binary grating. The experiments show that the size and deflection angle of the beam can be controlled in real time. The observations are in agreement with scalar diffraction theory.

Projection type display device

Abstract: PROBLEM TO BE SOLVED: To solve the problem that the number of parts is made large and an entire projection type display device is not made small in size, light in weight and inexpensive because surface light sources emitting respective color light beams R, G and B and spatial optical modulators corresponding to the respective light sources are required in order to perform color display on the projection type display device SOLUTION: A light emitting diode emitting ultraviolet light is used for the light source, and a visible light reflection film having characteristic that the ultraviolet light is transmitted and visible light is reflected is formed on the surface of a color wheel on the light source side, and phosphor layers respectively emitting the visible light corresponding to the color light beams R, G and B by the radiation of the ultraviolet light are formed on the back surface side of the color wheel COPYRIGHT: (C)2005,JPO&NCIPI

120-GHz wireless link using photonic techniques for generation, modulation, and emission of millimeter-wave signals

Abstract: We present a wireless link system that uses millimeter-wave (MMW) photonic techniques. The photonic transmitter in the wireless link consists of an optical 120-GHz MMW generator, an optical modulator, and a high-power photonic MMW emitter. A uni-traveling carrier photodiode (UTC-PD) was used as the photonic emitter in order to eliminate electronic MMW amplifiers. We evaluated the dependence of UTC-PD output power on its transit-time limited bandwidth and its CR-time constant limited bandwidth, and employed a UTC-PD with the highest output power for the photonic emitter. As for the MMW generation, we developed a 120-GHz optical MMW generator that generates a pulse train and one that generates a sinusoidal signal. The UTC-PD output power generated by a narrow pulse train was higher than that generated by sinusoidal signals under the same average optical power condition, which contributes to reducing the photocurrent of the photonic emitter. We have experimentally demonstrated that the photonic transmitter can transmit data at up to 3.0 Gb/s. The wireless link using the photonic transmitter can be applied to optical gigabit Ethernet signals.

Applications of spatial light modulators in atom optics

Abstract: We discuss the application of spatial light modulators (SLMs) to the field of atom optics. We show that SLMs may be used to generate a wide variety of optical potentials that are useful for the guiding and dipole trapping of atoms. This functionality is demonstrated by the production of a number of different light potentials using a single SLM device. These include Mach-Zender interferometer patterns and the generation of a bottle-beam. We also discuss the current limitations in SLM technology with regard to the generation of both static and dynamically deformed potentials and their use in atom optics.

Wavelength channel data rewrite using saturated SOA modulator for WDM networks with centralized light sources

Abstract: This paper describes a method for realizing the efficient utilization of wavelength resources in wavelength-division multiplexing networks with centralized light sources. Using a deeply saturated semiconductor optical amplifier (SOA) modulator located in a remote node (RN), we erase the data on a downstream signal with a low extinction ratio and modulate it with new data to generate an upstream signal. Thus, we use only one wavelength for bidirectional transmission between a center node and an RN, without placing lasers at the RN. In this paper, we analyze the data suppression characteristic of the SOA using a large signal model. We also estimate the bit error rate degradation in the presence of an unsuppressed downstream bit pattern in an upstream signal. We then report experimental results that confirm the basic characteristics of the wavelength channel data rewriter, which we constructed using a linear amplifier and an SOA. Finally, we provide the results of a data transmission experiment that we undertook using the data rewriter.

Low-power-consumption short-length and high-modulation-depth silicon electrooptic modulator

Abstract: We propose and analyze a novel compact electrooptic modulator on a silicon-on-insulator (SOI) rib waveguide. The device confines both optical field and charge carriers in a micron-size region. The optical field is confined by using a planar Fabry-Perot microcavity with deep Si/SiO/sub 2/ Bragg reflectors. Carriers are laterally confined in the cavity region by employing deep-etched trenches. The refractive index of the cavity is varied by using the free-carrier dispersion effect produced by a p-i-n diode. The device has been designed and analyzed using electrical and optical simulations. Our calculations predict, for a 20-/spl mu/m-long device, a modulation depth of around 80% and a transmittance of 86% at an operating wavelength of 1.55 /spl mu/m by using an electrical power under dc conditions on the order of 25 /spl mu/W.

Optical carrier supply module using flattened optical multicarrier generation based on sinusoidal amplitude and phase hybrid modulation

Abstract: This paper presents an optical carrier supply module (OCSM) that functions as a common multicarrier light source, a wavelength bank, for superdense wavelength-division multiplexing (SD-WDM) networks that utilize a large number of wavelengths with narrow channel spacing. A novel sideband generator based on a sinusoidal amplitude-phase hybrid modulation scheme is the key technique. The sideband generator generates nine flattened optical sidebands within 3 dB from one seed light source, and the input from wavelength-division multiplexing (WDM) seed carriers expands the number of generated sidebands. Scalability against the number of wavelengths is achieved by increasing the number of seed carriers used. The SD-WDM system employing OCSM reduces the number of laser diodes (LDs) and attendant wavelength monitoring/stabilization circuits. Multiple distributions to SD-WDM networks by splitting the OCSM output can promote this effect. We designed OCSM and experimentally investigated its performance pertaining to the electrical signal-to-noise ratio (SNR) of the OCSM output. The experimental results show the wavelength scalability to 1000 channels. We also developed an OCSM prototype that generated 12.5-GHz-spaced 256-channel WDM carriers. All the generated carriers exhibit the electrical SNR of more than 31.5 dB at 2.5 Gb/s and the power flatness of within 3 dB. The distribution over 100 SD-WDM networks is experimentally confirmed.

Semiconductor device and method of manufacturing the same

Abstract: PROBLEM TO BE SOLVED: To provide a high performance optical integrated semiconductor element and a method of manufacturing the same wherein an optical integrated circuit using semiconductor crystal of Si, GaAs, InP or the like may be manufactured easily, high speed modulation can be realized using a dielectric material waveguide modulator, and the waveguide and light receiving element/light emitting element may be allocated through higher optical coupling efficiency. SOLUTION: The semiconductor device is provided with a first oxide dielectric material substrate, an optical modulator formed on the first oxide dielectric material substrate by growth of a first semiconductor crystal on the oxide dielectric material substrate, a semiconductor laser device including a first active layer to the semiconductor crystal region formed on the first oxide dielectric material substrate, a semiconductor optical detector including a second active layer, an optical modulator drive circuit, and a semiconductor optical detector/semiconductor laser drive circuit. COPYRIGHT: (C)2003,JPO

Reflective microelectrical mechanical structure (mems) optical modulator and optical display system

Abstract: A MEMS optical display system includes an illumination source for providing illumination light, a collimating lens for receiving the illumination light and forming from it collimated illumination light, and a microlens array having an array of lenslets for receiving the illumination light from the collimating lens. The converging microlens array directs the illumination light through an array of pixel apertures in an aperture plate to a microelectrical mechanical reflector array positioned opposite the aperture plate. The microelectrical mechanical reflector array includes an array of microelectrical mechanical actuators that support reflectors in alignment with the array of pixel apertures and selectively orients the reflectors to direct the illumination light back through the pixel apertures (to form part of a display image) or against the aperture plate (to be blocked). The illumination light passing back through the pixel apertures passes through the microlens array and a beamsplitter to a display screen.

Continuous direct-write optical lithography

Abstract: An optical lithography system comprises a light source, a spatial light modulator, imaging optics and means for continuously moving a photosensitive substrate relative to the spatial light modulator. The spatial light modulator comprises at least one array of individually switchable elements. The spatial light modulator is continuously illuminated and an image of the spatial light modulator is continuously projected on the substrate; consequently, the image is constantly moving across the surface of the substrate. While the image is moving across the surface, elements of the spatial light modulator are switched such that a pixel on the surface of the substrate receives, in serial, doses of energy from multiple elements of the spatial light modulator, thus forming a latent image on the substrate surface. The imaging optics is configured to project a blurred image of the spatial light modulator on the substrate, enabling sub-pixel resolution feature edge placement.

Light source unit and wavelength stabilizing control method, exposure apparatus and exposure method, method of making exposure apparatus, and device manufacturing method and device

Abstract: The light source unit includes a single wavelength oscillation light source, a light generating portion which has an optical modulator converting and emitting light from the light source into a pulse light, a light amplifying portion made up of an optical fiber group in which each fiber has a fiber amplifier to amplify the pulse light from the optical modulator, and a light amount controller. The light amount controller performs a step-by-step light amount control by individually turning on/off the light output of each fiber making up the optical fiber group, and a light amount control of controlling at least either of the frequency or the peak power of the emitted pulse light of the optical modulator. Accordingly, in addition to the step-by-step light amount control, fine adjustment of the light amount in between the steps becomes possible due to the control of at least either the frequency or the peak power of the pulse light, and if the set light amount is within a predetermined range, the light amount can be made to coincide with the set light amount.

Electro-optical integrated transmitter chip for arbitrary quadrature modulation of optical signals

Abstract: An optical device includes, a first Mach-Zehnder modulator (105, 106) that produces a first output and a second Mach-Zehnder modulator (205, 206) which produces a second output. A splitter (212 )couples the first and second Mach-Zehnder modulators. A combiner (213) combines the first and second outputs. A phase shifter (107, 207) is coupled to the first and second Mach-Zehnder modulators. The first Mach-Zehnder modulator, second Mach-Zehnder modulator, splitter, combiner and the phase shifter are each formed as part of a single chip made of electro-optical material. Such two similar optical device integrated together with polarization combiner provide a two-polarization performance.

Complex modulation with a twisted-nematic liquid-crystal spatial light modulator: double-pixel approach.

Abstract: I modify the double-phase holographic code to implement complex modulation with a transmission twisted-nematic liquid-crystal display. This device is employed in the mostly phase configuration, for which the phase modulation is coupled with a nonconstant amplitude modulation. The modified double-phase code implements arbitrary complex modulation employing the constrained complex modulation of the display.

Encoding amplitude and phase information onto a binary phase-only spatial light modulator.

Abstract: We report what to our knowledge is a new technique for encoding both amplitude and phase information onto a single binary-valued spatial light modulator. In our approach, we spatially modulate the diffraction efficiency of the filter. Light that is not diffracted into the first order is sent into the zero order, effectively allowing amplitude modulation of either the first-order or zero-order diffracted light. This technique has applications in both optical pattern recognition and image processing. Experimental results are included.

Measurement of chirp parameters and halfwave voltages of Mach-Zehnder-type optical modulators by using a small signal operation

Abstract: A method is described for measuring the chirp parameters and the halfwave voltages of Mach-Zehnder-type optical modulators. These parameters can be obtained from the optical spectrum components by using a small signal operation, while the conventional method needs large voltages. We demonstrated the measurement of the frequency responses up to 40 GHz.

Control of an optical modulator for desired biasing of data and pulse modulators

Abstract: In an optical transmitter, continuous wave light from a laser passes through a data modulator (DM) for non-return-to-zero (NRZ) encoding of a data stream and through a pulse modulator to add return-to-zero encoding to the modulated optical signal. A modulator controller monitors the output optical signal power, optimizes the bias setting for the DM and the PM, and optimizes the phase relationship between the pulse and data components of the modulated optical signal. For each optimization, a low amplitude and low frequency dither signal is injected at appropriate points in the modulator. A single photo detector and electrical receiver are used in a multiplexed fashion to monitor the optical output signal and derive separate feedback signals. Remaining control circuitry forces a null in a respective residual dither component in the optical output signal to maintain the desired bias level or phase alignment.

Optical transmission system

Abstract: An optical transmission system comprises a light source to output an optical carrier having a predetermined wavelength, a photoelectric converter, an optical transmission line, an optical circulator to apply an output light from the light source to one end of the optical transmission line and to apply a light through the same end of the optical transmission line to the photoelectric converter, and an optical modulator disposed on the other end of the optical transmission line to return a portion of the light from the optical transmission line as a reference light to the optical transmission line without modulation and to modulate another portion of the light from the optical transmission line with a transmission signal to return it to the optical transmission line as a modulated light.

Method for optical carrier suppression and quadrature control

Abstract: A suppressed carrier optical communications signal is generated by driving (biasing) an optical modulator capable of complex modulation of an optical carrier signal to a bias point near a zero-crossing point of the modulator's E-field response. A complex input signal is then used to drive excursions of the E-field response to impress the input signal onto the optical carrier. The resulting lightwave emerging from the complex modulator exhibits an optical spectrum characterized by a pair of sidebands and a strongly suppressed carrier. Bias control of the complex modulator is implemented on the basis of the optical power detected at the output of the complex modulator. This enables the optical modulator to be treated as a “black box”, in that calculation of the bias signals does not relay on knowledge of the precise performance characteristics of the modulator.

Method of modulation and electron modulator for optical communication and data transmission

Abstract: The present invention provides a method for modulating light by a driven particle beam is disclosed. An optical beam is being sent to metal-dielectric structure so that the optical field partially transforms into a delayed electromagnetic wave, in a preferred embodiment into the surface evanescent mode, and the beam of charged particles, such as electrons, is also sent to said structure the way that the particle's kinetic energy partially transforms into energy of the delayed electromagnetic wave having the same phase-frequency characteristics as transformed field of optical beam; at that, transformation of the optical beam and excitation of wave by particle beam commonly take place at the same small space region, which is localized by said metal-dielectric structure. Delayed electromagnetic wave, which is generated by particle beam, is summarized with the optical field, which is transformed on said structure. Therefore, the particle beam influences on intensity of optical beam observed after passing the region of localized transformation. The controlled changing of parameters of particle beam in interaction region leads to adequate changing of intensity of the optical beam passed through said region and this way the predetermined modulation realizes.

Method and apparatus for integrating an optical transmit module

Abstract: An optical transmit module. In one aspect of the present invention, an optical beam is generated with a gain medium disposed in a semiconductor substrate. A tunable Bragg grating also disposed in the semiconductor substrate may be optically coupled to the gain medium to tune an output wavelength of the optical beam. The semiconductor substrate further includes an optical modulator optically coupled to receive the optical beam. The optical modulator is coupled to modulate the optical beam in response to a modulation signal.

Electrooptic polymer modulators with an inverted-rib waveguide structure

Abstract: Polymeric APC-CPW electrooptic modulators incorporating an inverted-rib waveguide structure were fabricated and tested for the first time. The inverted structure greatly simplifies fabrication procedures, and additionally improves propagation loss performance. Mach-Zehnder electrooptic modulators fabricated using this structure exhibited 6 dB of fiber-to-fiber insertion loss for 2.3-cm length and 6 V of driving voltage for a one-arm micro-strip electrode of 1.5-cm interaction length, at a wavelength of 1.55 /spl mu/m.

Design, fabrication, and testing of an integrated Si-based light modulator

Abstract: We have fabricated and characterized a novel Si-based light modulator working at the standard communication wavelength of 1.5 /spl mu/m. It consists of a three-terminal bipolar mode field effect transistor integrated with a silicon rib waveguide on epitaxial Si wafers. The modulator optical channel is embodied within its vertical electrical channel. Light modulation is achieved moving a plasma of carriers inside and outside the optical channel by properly biasing the control electrode. The carriers produce an increase of the Si absorption coefficient. The devices have been fabricated using clean-room processing. Detailed electrical characterization and device simulations confirm that strong conductivity modulation and plasma formation in the channel are achieved. The plasma distribution in the device under different bias conditions has been directly derived from emission microscopy analyses. The device performances in terms of modulation depth will be presented.

Dynamic range enhancement of image display apparatus

Abstract: Image display apparatus comprising projector means, optical means for splitting incident light, a first modulator for modulating red light, a second modulator for modulating green light, a third modulator for modulating blue light, optical means for recombining the combined modulated red light, green light and blue light, and control means for controlling the operation of the first, second, third and fourth modulators such that the dynamic range of the image display apparatus is enhanced.

Method and apparatus for synchronizing a pulse carver and a data modulator for optical telecommunication

Abstract: Method and apparatus for synchronizing two different types of modulators in an optical transmission system includes a first modulator generating an optical pulse train, a second modulator encoding data onto the optical pulse train, an optical filter resolving upper and lower modulation sidebands of the optical data and an analyzer measuring the optical power of modulation sidebands and converting the received optical power of the sidebands into a control signal for synchronizing the two modulators. A wedged etalon is the filter element selecting the USB and LSB from the optical data spectrum. The analyzer contains photo-detectors measuring the optical power of the filtered USB and LSB and an electronic differential amplifier producing a control signal based upon photo-detector output. The phase shifter, in response to said control signal, adapts the temporal delay of the first modulator to reduce differences between the power levels of said upper and lower sidebands.

Multifunctional optical device having a spatial light modulator with an array of micromirrors

Abstract: A reconfigurable multifunctional optical device has an optical arrangement for receiving an optical signal, each having optical bands or channels, and a spatial light modulator for reflecting the at least one optical signal provided thereon. The optical arrangement features a free optics configuration with a light dispersion element for spreading each optical signal into one or more respective optical bands or channels for performing separate optical functions on each optical signal. The spatial light modulator includes a micro-mirror device with an array of micro-mirrors, and the respective optical bands or channels reflect off respective micro-mirrors. The free optics configuration includes a common set of optical components for performing each separate optical function on each optical signal. The separate optical functions reflect off separate non-overlapping areas on the spatial light modulator. The separate optical functions include optical switching, conditioning or monitoring functions.