Showing papers on "Optical modulator published in 2002"

Broadband Modulation of Light by Using an Electro-Optic Polymer

Abstract: A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available An appropriate choice of polymers is shown to effectively eliminate the factors contributing to an optical modulator's decay in the high-frequency response The resulting device modulates light with a bandwidth of 150 to 200 GHz and produces detectable modulation signal at 16 THz These rates are faster than anticipated bandwidth requirements for the foreseeable future

Optics arrangements including light source arrangements for an active matrix liquid crystal image generator

Abstract: A system for producing modulated light is disclosed. The system comprises a spatial light modulator including a light modulating medium switchable between different states so as to act on light in ways which form overall patterns of modulated light. The system also includes an arrangement for switching the modulating medium between the different states in a controlled way and an illumination arrangement for producing a source of light. The system further includes an optics arrangement for directing light from the source of light into the spatial light modulator and for directing light from the spatial light modulator through a predetermined source imaging area. The optics arrangement cooperates with the illumination arrangement and the spatial light modulator so as to produce a real image of the source of light within the source imaging area such that an individual is able to view a virtual image of the overall patterns of modulated light from the source imaging area. A variety of novel optics arrangements are disclosed including specific combinations of different light sources, diffusing plates, polarizers, beam splitters, analyzers, lenses, mirrors, and holographic optical elements which allow the overall optical arrangement to be miniaturized to the same degree and in coordination with the spatial light modulator. The different light sources include using a plurality of light sources, such as LEDs, to form an array of light sources, each of the light sources providing light to a corresponding portion of the spatial light modulator.

MEMS-actuated color light modulator and methods

Abstract: A light modulator has one or more gratings and one or more MEMS actuators operable to move the gratings for selectively modulating light from an input light source. Certain embodiments have a plurality of blazed gratings arranged parallel to a plane and movable linearly parallel to the plane by MEMS actuators. Each of the gratings is individually blazed for light of a selected color such as red, green or blue. Associated with the gratings may be portions providing black and/or white outputs. An aperture spaced apart from the plane allows color(s) selected from an input white-light source to be directed to an output. An array of MEMS-actuated modulation devices provides a color spatial light modulator. Other embodiments have a grating adapted to be tilted by a MEMS actuator, either continuously through a range of angles or to a selected angle of a set of predetermined discrete angles, to direct selected wavelengths diffracted by the grating toward collection optics for a modulated light output. Methods specially adapted for making and using such light modulators are disclosed.

Mri-compatible medical device with passive generation of optical sensing signals

Abstract: An optical sense signal generator for medical device's having a photonic catheter containing optical conductors conducting light energy in two directions between electronics at a catheter proximal end and electrical stimulation and sensing components at a catheter distal end. An optical unit receives light delivered from the catheter proximal end and transmits a first portion of the light while diverting a second portion of the light. The transmitted light is fed to an opto-electrical converter for conversion into electrical stimulation signals. The diverted light is directed to one or more optical modulators that modulate the diverted light output under an applied electrical signal. An electrical circuit generates electrical sense signals corresponding to one or more sensed physiological conditions and provides the signals to the optical modulator(s). This results in modulation of the diverted light output into optical sense signals that are transmitted to the catheter proximal end.

Fully dynamic multiple-beam optical tweezers

Abstract: We demonstrate a technique for obtaining fully dynamic multiple-beam optical tweezers using the generalized phase contrast (GPC) method and a phase-only spatial light modulator (SLM). The GPC method facilitates the direct transformation of an input phase pattern to an array of high-intensity beams, which can function as efficient multiple optical traps. This straightforward process enables an adjustable number of traps and realtime control of the position, size, shape and intensity of each individual tweezer-beam in arbitrary arrays by encoding the appropriate phase pattern on the SLM. Experimental results show trapping and dynamic manipulation of multiple micro-spheres in a liquid solution.

Phosphor Free High-Luminous-Efficiency White Light-Emitting Diodes Composed of InGaN Multi-Quantum Well : Optics and Quantum Electronics

Abstract: We fabricated two types of high-efficiency white light-emitting diodes (LEDs) composed of an InGaN multi-quantum well (MQW), which emit light of two or three different colors without phosphors. The Type-1 white LED emits light of two colors (blue and yellow) from the MQW active layer, while the Type-2 LED emits light of three colors (blue, green and red). When the Type-1 white LED was operated at a forward current of 20 mA at room temperature, the color temperature (Tcp), average color rendering (Ra) and luminous efficiency were 7600 K, 42.7 and 11.04 lm/W, respectively. When the Type-2 white LED was operated at a forward current of 20 mA at room temperature, Tcp, Ra and luminous efficiency were 5060 K, 80.2 and 7.94 lm/W, respectively.

Simultaneous temporal characterization of telecommunication optical pulses and modulators by use of spectrograms

Abstract: We demonstrate a simple technique for simultaneous and complete characterization of the optical pulses and temporal modulators commonly used in telecommunication. The electric field of a pulse and the response of a modulator are obtained from the analysis of the two-dimensional spectrogram of the pulse gated by the modulator. The measurement sensitivity is greatly improved compared with the conventional nonlinear optical techniques. Trains of picosecond pulses as weak as 10-17 J are accurately characterized with an electroabsorption modulator as the temporal gate. The time-resolved transmission and phase of the modulator are also presented.

Method and apparatus for dynamic equalization in wavelength division multiplexing

Abstract: An adjustable diffractive light modulator is used to equalize the power level of wavelength multiplexed signals in wavelength division multiplexing applications. An optical channel transmits a multi-wavelength input signal through a wavelength demultiplexer. The input signal comprises a plurality of component signals defined according to a plurality of wavelengths. The de-multiplexer spatially separates the multi-wavelength input signal into its respective plurality of component signals, which are transmitted through a plurality of optical channels onto a plurality of controllable diffractive light modulators. The diffractive light modulators are advantageously comprised of grating light valves. Component signals are reflected off their respective diffractive light modulators and collected in a plurality of optical channels for re-transmission into a wavelength multiplexer. The reflected signals are combined through a multiplexing process and transmitted as an output beam. Control of the diffractive light modulator is achieved by sensors measuring the power level of signals passing through the plurality of optical channels. The measured power levels of light are converted to digital values which are input into an electronic controller for processing. Control output signals from the controller are used to independently control individual pixels within the diffractive light modulator to equalize the reflected light signals.

Rotational control within optical tweezers by use of a rotating aperture

Abstract: We demonstrate a simplified method of rotational control of objects trapped within optical tweezers that does not require high-order modes, interferometric precision, or computer-controlled optical modulators. Inserting a rectangular aperture into the optical beam results in a focused spot that also has rectangular symmetry. We show that an asymmetric object trapped in the beam has its angular orientation fixed such that rotation of the aperture results in a direct rotation of the particle.

Electro-optic sensors for electric field measurements. II. Choice of the crystals and complete optimization of their orientation

Abstract: We present a simple method to determine both direction of the electric field component to which an electro-optic sensor is sensitive and sensitivity to this component. For this purpose we introduce the concept of an electro-optic sensitivity vector. This work is done for electro-optic sensors working as amplitude modulators, as phase modulators, or as polarization state modulators. The method applies to any anisotropic crystal, regardless of crystallographic group. After defining three kinds of electro-optic sensor geometry that allow longitudinal, transversal or fully vectorial electric field probing, we make a comparative study of several commonly used electro-optic crystals. We derive the optimal orientations of the crystals with respect to the optical probe beam that lead to high-performance electro-optic sensors. We also treat isotropic crystals in the case of polarization state modulators. In contrast to anisotropic crystals that are sensitive to a unique electric field component, we show that isotropic crystals are sensitive to two orthogonal electric field components simultaneously.

Fundamental limitations of optical resonator based high-speed EO modulators

Abstract: Expressions for the modulation bandwidth and drive voltage for optical resonator-based modulators are presented. A comparison with lumped element Mach-Zehnder (MZ) modulators and with traveling wave MZ modulators is presented.

Integrated semiconductor superlattice optical modulator

Abstract: Devices and techniques for integrating a silicon superlattice optical modulator on a silicon substrate with other circuit elements. The superlattice structure is designed to convert the indirect bandgap structure of silicon into a direct bandgap structure to achieve more efficient optical absorption. The modulator can be fabricated based on a structure of a circuit element by using standard fabrication processes for silicon integrated circuits such as metal oxide semiconductor processing.

Method and arrangement for the depth-resolved detection of specimens

Abstract: An arrangement comprises an optical modulator for fast modulation which is provided in an interferometer arm of the interferometer arrangement for heterodyne detection. In one aspect, the modulator is used simultaneously for switching and/or beam attenuation in a laser scanning microscope. A method for operation of the arrangement by using such laser scanning microscope for single-photon and/or multiphoton fluorescence and using the heterodyne detection for referencing the fluorescence to regions deep in the specimen is also disclosed.

Method and apparatus for article inspection including speckle reduction

Abstract: A method and apparatus for reducing speckle during inspection of articles used in the manufacture of semiconductor devices, including wafers, masks, photomasks, and reticles. The coherence of a light beam output by a coherent light source, such as a pulsed laser, is reduced by disposing elements in a light path. Examples of such elements include optical fiber bundles; optical light guides; optical gratings; an integrating sphere; and an acousto-optic modulator. These various elements may be combined as desired, such that light beams output by the element combinations have optical path length differences that are greater than a coherence length of the light beam output by the coherent light source.

A radiation conditioning system

Abstract: A holographic imaging system and method includes a radiation source for generating radiation. A data base has a set of elements, each element is indicative of a trajectory of a light ray exiting a point in a recorded scene. A spatial light modulator is receptive of the radiation from the radiation source and the elements of the data base mapped to the spatial light modulator, thereby projecting from the spatial light modulator an optical signal in the nature of a two dimensional bitmap of the recorded scene. A diffractive optical element includes a set of basis fringes receptive of the projected optical signal from the spatial light modulator for diffracting the optical signal in a specified direction. A multiplexer is receptive of the elements of the data base for multiplexing the elements of the data base to the spatial light modulator. A timing device synchronizes multiplexing the elements of the data base to the spatial light modulator and diffracting the optical signal in a specified direction.

Optical modulator, optical modulator manufacturing method, light information processing apparatus including optical modulator, image formation apparatus including optical modulator, and image projection and display apparatus including optical modulator

Abstract: A center beam which is formed out of a thin film constituted to be combined with a light reflection film provided on one surface of the center beam, which has both ends fixed and which is deformed by an electronic force; a substrate electrode which is opposed to the center beam through a gap formed on the other surface of the center beam; an opposed surface which is a surface of the substrate electrode opposed to the center beam modulating the incident light on the light reflection film, the opposed surface restricting deformation of the center beam due to application of a driving voltage to the substrate electrode by abutting on the center beam; and a substrate which has the substrate electrode having the opposed surface, formed in a concave section, and which holds a to-be-held section of the center beam, are provided. As a result, the structure of modulating light by changing the reflection direction of the incident light is simple, response is fast, the wavelength of the incident light to be used is not limited, operation is stable, reliability is high, the number of manufacturing steps is small and cost reduction can be achieved.

Electrostatic drive type mems element and manufacturing method therefor, optical mems element, optical modulator, glv device and laser display

Abstract: PROBLEM TO BE SOLVED: To flatten a beam composing an electrostatic drive type MEMS element or stabilize and uniformalize a beam shape. SOLUTION: The electrostatic drive type MEMS element comprises a substrate side electrode 33, a beam 36 disposed opposite to the substrate side electrode 33, having a drive side electrode 37 and supported on the both ends thereof, and at least two supporting parts 35A, 35B and 35C, 35D are provided on the both ends of the beam 36 respectively. In the supporting parts 35, the height t1 of the inner supporting parts 35B, 35C is set to be lower than the height t2 of the outer supporting parts 35A, 35D. COPYRIGHT: (C)2004,JPO

Optical single sideband transmitter

Abstract: With the normal modulation method, it is difficult to construct a Hilbert transform device because it is complicated. To solve the problem, the present invention generates a single sideband modulated optical pulse train by driving a Mach-Zehnder optical modulator for optical pulse generation with a laser source's sine wave clock signals rendered 90 degrees out of phase from each other. The generated pulse train is entered into an optical modulator, modulated with an NRZ (nonreturn-to-zero) data signal, and filtered by a narrow-band optical filter to obtain one of two sidebands.

An illumination system for one-dimensional spatial light modulators employing multiple light sources

Abstract: The present invention is directed to illuminating a one-dimensional spatial light modulator (70) using an illumination system employing multiple light sources (10). The illumination system comprises a parallel array of light sources which provides a plurality of light outputs to an optical train (200). The optical train effectively combines the light sources into a single light source. The single light source provides a single light output for uniformly illuminating the spatial light modulator. The optical train includes a first optical train for receiving the light outputs from each light source, magnifying each light output, and overlaying each of the light outputs to form a single real magnified image. A mode conversion lens receives the single real magnified image, converts a mode profile of the single real magnified image into a top hat mode profile, and outputs a diverging light beam with a top hat mode profile. A second optical train shapes the light beam into an appropriate spatial geometry in such a manner that the light beam effectively illuminates the entire spatial light modulator, and directs the light beam onto the spatial modulator.

Optical modulator and plane display element

Abstract: PROBLEM TO BE SOLVED: To provide an optical modulator and a plane display element in which a movable part is simply composed, a low voltage driving and a high speed response are possible. SOLUTION: In the optical modulator 21 which performs an optical modulation with an optical interference caused between the movable part 25 and a substrate part 23 by a dislocating action of the movable part 25 by an electrostatic force and an elastic returning action of the movable part 25, the movable part 25 is composed of a movable mirror layer 37 and a movable transparent electrode 39. The movable mirror layer 37 of the optical modulator 21 can be composed of a dielectric multilayer film, and in this case, a TiO 2 layer and a SiO 2 layer are used as the dielectric multilayer. Further, the optical modulator 21 may be composed in a way that the movable mirror layer 37 which is the dielectric multilayer functions as a transparent electrode. In this case, the dielectric multilayer may be composed of an indium tin oxide (ITO) layer and the SiO 2 layer. COPYRIGHT: (C)2004,JPO&NCIPI

Analysis and improvement of Mach-Zehnder modulator linearity performance for chirped and tunable optical carriers

Abstract: Photonic systems that use a variable or chirped optical wavelength and a single Mach-Zehnder modulator have been analyzed to determine the relation between optical bandwidth and spur free dynamic range. A novel wavelength insensitive biasing technique is proposed which significantly reduces the second-order distortion and increases the optical bandwidth.

Optical modulator array and method of manufacturing same

Abstract: PROBLEM TO BE SOLVED: To provide an optical modulator array in which the decrease in film and a residual stress of a movable transparent electrode due to a removing process of a sacrificial layer for making a gap are suppressed and the moving operation of the movable part is stably performed, and to provide a method of manufacturing the optical modulator array. SOLUTION: The optical modulator array is composed by providing a transparent substrate 1, a substrate having a transparent electrode 2, and a movable part 8 which is furnished on the substrate with a gap 5, and composed of a flexible thin film having a transparent electrode 7 on the surface opposite to the substrate and a protective film 40 having a translucency and covering the transparent electrode 7, and arranging the optical modulators, which emit light emitted from a light source from the movable part 8 to the outside by moving the movable part 8 to the side of the substrate with an electrostatic force generated by applying a voltage between both transparent electrodes 2 and 7, in a two-dimensional matrix. COPYRIGHT: (C)2004,JPO&NCIPI

All-optical Mach–Zehnder modulator using a photochromic dye-doped polymer

Abstract: An all-optical Mach–Zehnder modulator is demonstrated which is composed of a polymer waveguide doped with a photochromic dye in the core and a thick light blocking metal layer on it. The metal layer was opened on one arm of the Mach–Zehnder modulator, so that only one arm of the modulator could be irradiated by modulation light, thus allowing a differential phase shift. The optical modulator exhibited an extinction ratio of about −12 dB at a wavelength of 1.55 μm. A simple kinetic model developed to delineate the refractive index change in the dye-doped polymer film was applied to predict the evolution of the modulation characteristics.

Wireless relay system

Abstract: PROBLEM TO BE SOLVED: To provide a wireless relay system that is applied to a wireless communication system adopting a single carrier so as to reduce the cost resulting from non-electric source. SOLUTION: In this wireless relay system, a main relay section 2A of a relay facility 2 is installed in a substantial communication area wherein a mobile station 1A is located, a forward relay section 2B is installed at a place apart from the main relay section 2A and around which a communication area is separately to be set, a direct modulation laser diode 2A3 converts a high frequency signal CU received by an antenna 2A5 of the main relay section 2A into a laser beam signal, which is transmitted to the forward relay section 2B through an optical fiber cable 5, a photodiode 2B2 converts the laser beam signal into an electric signal, and a transmission antenna 2B4 transmits the signal as a radio wave, which a mobile station 1B can receive. An external optical modulator 2B1 converts a high frequency signal CD transmitted from the mobile station 1B and received by a reception antenna 2B3 of the forward relay section 2B into a modulated laser beam signal, which is transmitted to the main relay section 2A through an optical fiber cable 4, a photodiode 2A2 converts the modulated laser beam signal into an electric signal a transmission reception antenna 2A5 transmits as a radio wave, which the mobile station 1A can receive. COPYRIGHT: (C)2004,JPO

Coplanar integrated optical waveguide electro-optical modulator

Abstract: A coplanar integrated optical waveguide electro-optical modulator comprises a substrate ( 1 ) of an electro-optic material, at least two optical waveguides ( 41, 42 ) integrated in the substrate in correspondence of a surface ( 71 ) thereof, and an electrode system ( 80, 90, 100; 80, 90, 900; 12 - 15; 120, 130, 140, 150, 160, 170 ) arranged on the surface for applying a modulating electric field to the waveguides suitable for causing a modulation of a refractive index of the two waveguides in a device modulation region ( 50 ) The waveguides are formed, for at least a section thereof ( 411, 421 ) in the device modulation region, in respective substrate regions ( 61, 62 ) which have electro-optic coefficients of opposite sign along an axis transversal to the waveguide sections, so that a modulating electric field of same direction and orientation in the waveguide sections causes refractive index modulations of opposite sign in the waveguide sections Chirp-free coplanar waveguide modulators and single-drive double coplanar strip modulators can thus be obtained

Active semiconductor microdisk devices

Abstract: The design of active semiconductor microdisk switches, modulators, or wavelength routers enabled by modulating the transfer characteristics of a resonant cavity is investigated. A simple theoretical model based on coupled-mode theory is used to elucidate design trends and constraints in the cases where electroabsorption, gain, and free carrier injection are employed to modulate the resonator characteristic.

Injection-seeding of a multi-tone photonic oscillator

Abstract: A multi-tone photonic oscillator comprises a laser; an optical modulator coupled to the laser; and a delay line and a photodetector coupled to the optical modulator for generating a delayed electrical signal representation of the output of the optical modulator; wherein the optical modulator being responsible for the delayed electrical signal for generating multiple tones where the frequency intervals of the tones is a function of the amount of delay imposed by the delay line

Optical modulator array and plane display

Abstract: PROBLEM TO BE SOLVED: To provide an optical modulator array in which a residual stress and strain at the connected part of a support and a movable part are relaxed and the flatness of the movable part is excellent, and to provide a plane display including the optical modulator array. SOLUTION: The optical modulator array and the plane display provided with the optical modulator array are composed of optical modulators 120 which are arranged in a two-dimensional matrix. Each of the optical modulator is provided with: a substrate 100 having a transparent substrate 101 and a transparent electrode 102; a pair of supports 106 which are a predetermined space away from each other and erected on the substrate 100 and formed of a material having an elasticity lower than that of a movable part 111; and the movable part 111 which is composed of a flexible thin film having a transparent electrode 110 on the opposite face from the substrate 100 and mounted on the supports 106. The optical modulator causes light emitted from a light source to pass through the substrate 100 and the movable part 111 and emits the light outward by moving the movable part 111 toward the substrate 100 with an electrostatic force generated by applying a voltage between both transparent electrodes. COPYRIGHT: (C)2004,JPO&NCIPI

Compensation of nonlinear self-phase modulation with phase modulators

Abstract: The compensation of the nonlinear self-phase modulation of a 10 Gbit/s RZ data stream with phase modulators has been experimentally demonstrated. The electrical waveform that drives the phase modulators is synthesised from the recovered 10 GHz clock and its 20 GHz harmonic. The method is broadband, polarisation insensitive and allows nearly arbitrary control of the magnitude and sign of the nonlinear phase compensation.

40-Gb/s X-cut LiNbO/sub 3/ optical modulator with two-step back-slot structure

Abstract: We propose a newly designed X-cut lithium niobate (LiNbO/sub 3/) optical modulator. It has a two-step back-slot structure to satisfy the velocity-matching condition without the buffer layer of silicon dioxide (SiO/sub 2/). Accordingly, this modulator can achieve low drive voltage and low optical insertion loss. In addition, the dc-drift phenomena due to the buffer layer can be suppressed. This structure is fabricated with micromachining technology using excimer laser ablation. The optical 3-dB bandwidth of the fabricated modulator reaches 30 GHz, and the drive voltage is less than 3 V at 1 kHz. From the measurement of the optical eye diagram at 43.5-Gb/s, clear eye openings were obtained. This modulator is sufficient for 40-Gb/s optical transmission systems.