Showing papers on "Optical switch published in 1981"

Solid state: Bistable optical devices promise subpicosecond switching: Extensive research in materials and phenomena could lead to their ultimate use in optical communications, despite high power dissipation

Abstract: Describes the principles of bistable optical elements and their probable applications in optical communications and reviews the research into materials and phenomena that is now taking place.

Optical switch attenuator

Abstract: An optical switch having low insertion loss and low crosstalk is provided by two slabs of birefringent material having a polarization rotator as a control element interposed therebetween. By controlling the polarization rotator electrically, a selectable ratio of transmitted-to-displaced output optical power is realized. The optical switch therefore can function as an attenuator to a light beam traversing through it. In the preferred embodiment calcite crystals are used for the slabs, and a liquid crystal cell for the polarization rotator.

Electrostatically deformographic switches

Abstract: This describes a dual electrode electrostatically deflectable deformographic switch. The switch can be driven by co-incident voltages and can be made to retain and store information. The switch can be used either as a display or a memory and has a number of engineering advantages, for it is a direct drive display which does not need either vacuum envelopes or electron beam drives. Furthermore, greater efficiencies can be realized and no refresh is necessary since the switch will operate in a standby condition. Also only two voltage levels above ground, i.e., a write voltage and a standby voltage, are required. The switch will enable copiers to be directly driven by computers. The switch can also be used as an optical waveguide transmit/receive switch or an accelerometer.

Low-cross-talk 2 x 2 optical switch

Abstract: An electro-optical 2 x 2 switch for fiber-optic applications has been developed. Optical cross talk is reduced significantly by inserting two 2 x 1 switches in each optical path. A compact structure is used to contain the four 2 x 1's that are required. We observed -27-dB cross talk and 2.5-dB insertion loss in both switching states. The device is controlled by a 5-V twisted-nematic liquid-crystal cell. Multimode, unpolarized light is switched.

Laser diode switch

Abstract: Optical switches using laser diodes are proposed. Basic switching operation using an AlGaAs CSP laser is demonstrated for the first time. Isolation is better than 71 dB, signal bandwidth is broader than 1.5 GHz, and switching time is shorter than a few nanoseconds.

Pressure-actuated optical switch

Abstract: An optical switching element utilizes a spherical diaphragm mounted for snap-action movement between a concave and convex shape. A light beam is directed through a small aperture to impinge on the diaphragm. The aperture is positioned at a distance from the diaphragm equal to the radius of curvature of the diaphragm to obtain maximum reflection of the light when the diaphragm is in its concave shape. Upon movement of the diaphragm to the convex shape in response to an external stimuli, substantially all of the light is absorbed within the supporting housing with little or no light being reflected through the small aperture. The presence or absence of the light beam thus provides an indication of the external condition which may be a temperature value, pressure value or the like. The switch may also be utilized as a mechanical limit switch or a plurality of such optical switches may be fabricated to form a keyboard for entry of data into a computing system.

Rotary type optical switch

Abstract: Disclosed is an optical switch of the rotary-type in which a pair of opposing optical transmission path mounting members are disposed on the same axis. A plurality of junction faces of optical transmission paths disposed on the respective opposing plane portions of the mounting members along phantom circles which are opposite to each other and concentric with the pair of mounting members respectively with respect to the axis so that the junction faces on the respective plane portions are capable of being correspondingly opposite to each other. When the pair of the mounting members are relatively rotated about the axis, the facing mates of the opposing junction faces of the optical transmission paths are changed over to switch the optical transmission paths. In the case where an optical path relay member is interposed between the pair of the optical transmission path mounting members, the optical transmission paths can be switched by only the rotation of the optical path relay member.

Thermo-optic effect in LiNbO3, for light deflection and switching

Abstract: Light deflection and switching in LiNbO3 via thermo-optic effect based on the temperature dependence of the refractive index are demonstrated. The switching speed of 1 ms order has been confirmed in the thermo-optically induced waveguide switch.

Thermovision pyrometer for remote measurement of temperature of an object

Abstract: A thermovision pyrometer for measuring the temperature of an object t.v. camera for focusing thermal radiation, an optical switch for alternately passing at least two spectral components of the radiation, a detector for sensing each spectral component and for generating respective video signals proportional to the density of the spectral components. The synchronizing signal of the t.v. camera controls the optical switch. The pyrometer also includes a gating circuit for generating a gating marker signal which control the position of the point of observation. The gating circuit also is controlled by the t.v. synchronizing signal. Further, the pyrometer includes a sampling circuit for sampling and measuring the amplitudes of the video signals from both the t.v. camera and the gating circuit, as well as circuitry for determining the temperature of the object based upon the ratio of the flux densities of the respective spectral components detected at the point of observation. This ratio information is transferred to a computer via an information signal transfer switch which switches the information path between the gating circuit and the raster scanning circuit to drive a character generator which displays on a t.v. monitor temperature information relative to an object under investigation. The result achieved is to minimize temperature measurement error due to nonuniformity in surface emissivity of the object or raster sensitivity of the vidicon tube used in the t.v. camera.

Analyses and experiments on integrated optical multivibrators using electrooptically controlled bistable optical devices

Abstract: Three different types of integrated optical multivibrators, astable, bistable, and monostable ones, based on hybrid bistable optical devices are proposed and analyzed for the first time using a pair of electrooptical switches with suitable electronic feedback loops. Preliminary experiments demonstrating these three regimes of optical multivibrators were performed using a pair of integrated Mach-Zehnder (MZ) type interferometric optical switches made of Ti-indiffused LiNbO 3 waveguides. The experimental results obtained were in good agreement with the theoretical analyses, and thus verified clearly their feasibility and practical capability. The purely integrated version of these optical multivibrators could probably be used as a key element for high density and fast optical logic, for use in optical digital data processing as well as the optical computer of the future.

Polarization-insensitive optical switch apparatus

Abstract: Polarization-insensitive optical switch and dual channel carrier multiplexer includes a polarization beam splitter for receiving an input collimated beam which has arbitrarily polarized components, splitting the beam into the two components. One of the components is rotated by a 1/2 wave plate so as to yield a polarized beam which is polarized in the same direction as the other beam. The two polarized beams are then applied to a polarization sensitive interferometric multimode fiber optic switch and modulator. The output of the interferometric multimode fiber optic switch and modulator contains two beams, both polarized in the same direction. One of the beams is rotated ninety degrees by a 1/2 wave plate, and the two mutually perpendicularly polarized beams are then recombined by a polarization beam splitter operated in reverse to yield an output beam containing mutually perpendicular components.

Switch matrix apparatus for satellite-switched TDMA system or the like

Abstract: A switching matrix enables the impedance to be easily matched at the connecting points of the distributing, the switching and the combining circuits, and of the external circuits. The switching circuit used by the switch matrix, includes PIN diodes, Schottky barrier diodes, field-effect-transistors (FETS), coaxial relays, or mixers. These devices can gain the ON/OFF ratio required for the switching circuit. However, in an M×N switch matrix, the input impedance of the switch circuit is usually dependent on the number of inputs or outputs to be selected, and therefore, there are deviations in the ON/OFF ratio required for the switch operations and a resulting deterioration in the signal-to-noise ratio. The present invention provides a switch matrix which is flexible enough to allow easy changes of the number of input/output terminals, with only a small insertion loss, even with a great number of input/output terminals. The switch matrix has a greater ON/OFF ratio, by cascade-connecting the switch circuits in multiple stages, with a smaller output level of deviation which is caused by the routing differences for signals. The switch matrix has a high switching speed, small size, light weight, and low power consumption.

Sample-and-hold circuit

Abstract: In a sample-and-hold circuit having two voltage amplifiers connected in series via a switch, which is arranged to perform on-off operations in accordance with a control signal, the noninverting input terminal of the second voltage amplifier of output side is grounded so that the switch can be used at an imaginal short point of the second voltage amplifier. As a result, a semiconductor switch having a simple construction may be used as the switch, while a switch drive circuit may also be simple. Furthermore, since great negative feedback effect can be attained during sampling mode, the sample-and-hold circuit is capable of operating with high accuracy. Additional switches may be employed for improving feedthrough characteristics, while means for preventing undesirable oscillation may be provided if necessary.

A high speed optoelectronic matrix switch using heterojunction switching photodiodes

Abstract: Heterojunction switching photodiodes (InGaAs/InP) were used to construct a 3 × 3 optoelectronic matrix switch. Biconical taper type optical power splitters were used to distribute the signals to the matrix switch crosspoints. Isolation and crosstalk losses were better than 63 dB over a frequency range of 10 Hz-400 MHz and 400 Mbit/s NRZ digital signals were switched with switching times shorter than 30 ns.

Photo‐optical switching devices by amorphous As2S3 waveguides

Abstract: A novel optical device based on a ’’dynamical refractive‐index change’’ in an amorphous As2S3 film is constructed. In this device coupling of a red light beam into the thin‐film waveguide with a prism coupler is controlled by illuminating blue light. A switching time of about 10 s and an on/off ratio as high as 6/1 have been achieved. Further, this device can be operated as a photo‐optical switch having a storage function by changing the intensity of the light beams.

Measuring device for wetness of steam

Abstract: PURPOSE: To measure the local wetness of wet steam which flows in a passage continuously and instantaneously, by detecting the quantities of beams of light transmitted and scattered by drops of water in the wet steam which flows in the internal space in a detection part CONSTITUTION: Light source 3, 3', and 3" are powered up successively through a power source switch 25 to turn on, and the light from a light source guided to an optical fiber 6 through an optical switch 23 becomes light 5 incident to a flow of wet steam in a measurement space A The light 13 scattered by drops of water in the measurement space A is guided to a photodetector 16 through an optical fiber 15 and is extracted as a scattered-light signal IS Part of the incident light 5 is attenuated by the drops of water in the measurement space A, but the remainder reaches a prism 9, and is guided to through an optical fiber 11 to a photodetector 12, which generates a transmitted-light signal IT Then, a signal arithmetic processor 27 analyzes the signals IS and IT fetched by wavelengths to find a distribution of grain size, thus calculating the wetness of steam COPYRIGHT: (C)1982,JPO&Japio

A coplanar CMOS power switch

Abstract: A 300 V power switch in a high-voltage CMOS technology compatible with a low-voltage MOS/bipolar technology is presented. This circuit can switch positive and negative 150 V pulses with rise and fall times of 100 ns for a 200 pF capacitive load. The switch has a low-voltage input control (/spl plusmn/15 V). Using earth-symmetrical non-overlapping high-voltage pulses as dynamic supply voltages, it is possible to reduce the power dissipation during the switching time considerably in comparison with the power dissipation of power switches, which use static (i.e., constant) supply voltages under the same conditions.

Polarization-insensitive integrated-optical switches: A new approach

Abstract: Coupled waveguide structures with sections of alternating phase mismatch are proposed as a method to vary the coupling coefficient between the two coupled waveguides by an electrical adjustment. We consider the design of polarization-insensitive microoptical switches/ modulators based on this principle.

Complementary optical bistable switching and triode operation using LiNbO 3 directional coupler

Abstract: Optical bistable switching and optical triode operation have been carried out using an optical directional coupler switch fabricated by Ti diffusion into LiNbO 3 at the 1.15 μm wavelength. The on/off ratio in conventional bistable switching was 10 dB and that in complementary bistable switching was 13 dB. Amplification gain in triode operation controlled by laser diode was 4.8 dB. Complementary operation was found to reduce feedback gain and to improve the on/off ratio in optical bistable switching.

Remote control switch device

Abstract: A remote control switch device having a main switch connected between a power supply and a load circuit, a control circuit having auxiliary contacts interlocking with the main switch, a first diode connected in series with the auxiliary contact, a second diode connected in a direction opposite the first diode coupled across the series circuit, an electromagnetic coil connected in series with the second diode for opening or closing the main switch, an isolating transformer connected to the power supply, and an operation indicating circuit having a push-button switch connected to the secondary side of the transformer and remotely connected to the control circuit. The remote control switch device employs as the main switch a keep relay which is mechanically retained at the open or closed position and controlled by the electromagnetic coil through simple signal communication lines.

Erratum: Bistable optical switch using a yittrium‐iron‐garnet crystal with phase matching films

Abstract: A magneto‐optical switch using a yttrium‐iron‐garnet crystal plate with phase matching films requiring a drive voltage of only 5V is demonstrated at 1.3 μm wavelength. Using a semihard magnetic material, we developed a bistable magneto‐optical switch which drives with a switching speed of 20 μs. An extinction ratio of 24 dB was obtained.

Electronic analog switching device

Abstract: An electronic analog switching device comprises a differential operational amplifier (1) with a feedback circuit between its output (2) and its inverting (-) input such that its (low impedance) output voltage follows the input signal voltage applied to its non-inverting (+) input. The output voltage is sampled by a first switch (5) and the samples are passed to the device output (4) where, for example, they may be stored on a capacitor (7). The feedback circuit has two paths, one via a feedback impedance (9) and the other via the first switch (5) and a second switch (8) operated synchronously with the first switch by control means (6). The "on" impedance of the first switch (5) is greatly reduced by including it in the feedback circuit, and the further inclusion of the second switch (8) and the impedance (9) substantially eliminates unwanted transient voltages that would otherwise occur under some circumstances when the first switch operates.

Circuit arrangement including an opto-isolator device for checking the state of an electric switch

Abstract: An opto-isolator device comprises a light emitting diode (23) and a light responsive transistor (25) which is electrically switched when the diode emits light onto the transistor, and an electric switch (11) which connects an electric load (20) to a source of alternating current (13). The device also includes a rectifier circuit (17, 21, 22, 23, 27, 30 and 32) which continuously checks the state of switch (11) such that if the switch is open the output of the device is a half wave rectified signal and such that if the switch is closed the device output is a full wave rectified signal.

Semiconductor devices for optical communication

Abstract: “This book brings together authoritative material dealiug with the semiconductor components used in optical communication and the associated circuitry needed to build practical systems.” To this end the Editor did a commendable job of selecting a compatible set of authors and topics. Not only are the treatments at a fairly consistent level, but also the continuity of text is maintained. The text is aimed at highlighting those properties of semiconductor devices which affect the performance of the optical-fiber communication systems. The level of treatment appeals to the experienced technical personnel. Extensive badcground knowledge is assumed, but relevant basic principles are given to refresh the reader’s memory. The theories of operation and fabrication are only.briefly discussed for the GaAlAs material system. The characteristics section covers important aspects such as spectral width, linearity, and degradation. A discussion on other material systems for light sources and coherence effects could possibly make the second chapter more complete. One section gives a delightful dissertation of semiconductor photodetectors covering a lot of ground succinctly in a mere 20 pages. Receiver design is the most comprehensive chapter. It leads the reader through basic noise considerations to low noise front end amplifier design and delineates practical requirements. This is also the most weighty chapter. Basic circuit design aspects of transmitter are difficult to handle comprehensively. The treatment here is successful. It concentrates mainly on digital but also touches on analog designs. Apart from some basic design considerations, the essential requirements for an LED and a laser transmitter in a practical design are distinguished. The t3e1 coupler discussion is short and a little redundant. While it contains useful material it is too brief to be maximally effective. Chapters 7 and 8 treat two special topics: the modulation characteristics and the influence of junction heating. The topics include transient effect, high fiequency limit, emission spectrum, and coupled lasers. These are a pair of useful chapters for those wishing to extract the most out of a laser. An illustrative optical communication system is not really needed to complete this book. It probably is intended to illustrate how the semiconductor devices play their roles. This illustrative effect was not achieved. All in all, it was a most welcome addition to the books about optical communication. Besides the informative text, it also has an extensive list of references.

530V Integrated gated diode switch for telecommunications

Abstract: The objective of this work is to develop a new solid state crosspoint switch for telecommunications circuits. The switch is fully integrated into 580V monolithic circuits with appropriate control circuitry. Integrated arrays, packaged in hermetic chip carriers, perform the high level line circuit switching functions previously realized with arrays of electro-mechanical crosspoints. The Gated Diode Switch (GDS) is a dielectrically isolated lateral P+πPN+diode with a diffused gate on the planar surface and an MOS gate (consisting of the isolation oxide and polycrystalline substrate) on the lower boundary. With the center gate structure it achieves 530V bilateral blocking, very low crosstalk, insensitivity to transients and full current break capability. Two switches, each 0.15mm2, can be connected in antiparallel to realize a bidirectional current capability of 120mA DC and 500mA surge. Electron and hole injection produces conductivity modulation in the π-type tub to realize an incremental on resistance of 18 ohms and a forward voltage of 1.7V at 30mA. The paper describes the properties of the GDS when it is maintaining the off state, turning on and breaking current. The paper also establishes the requirements this switch places on its integrated control circuit. Integrated arrays containing four pairs of bilateral crosspoint switches have been developed for the subscriber line interface circuits of a large digital electronic switching system, #5 ESS.

Optical fiber multiple access communication device

Abstract: PURPOSE:To make the level of an optical signal, which arrives at an optical receiver, constant, by permitting data stations, which use a looped trunk line optical fiber as a common transmission line, to communicate with one another through an optical repeating device. CONSTITUTION:Optical signals with wavelength lambda1 transmitted from data stations 13-17 are coupled with a trunk line optical fiber 1 by T-shaped optical couplers 12a-12e, and transmitted in both the ways of the optical fiber. The optical signals propagating through the fiber 1 are received by an optical repeating device 18 theough the T-shaped optical couplers 12a-12e. The received optical signals are repeated and amplified by the device 18 to be converted into light signals with wavelength lambda2, which are sent out. Those optical signals are distributed to the stations 13-17 through the coupler 11, fiber 1, and couplers 12a- 12e respectively. If the breaking of the fiber 1 occurs, a trunk line controller 9 detects that and operates its optical switch from an open-circuit state to a closed-circuit state, so that both ends of the fiber are connected by the optical transmission line of the optical switch.

Remotely controlled integrated directional coupler switch

Abstract: In this paper experimental results concerning the remote control of a bistable directional coupler switch are reported. It is shown that the output light from the coupler can be switched from one channel to the other via switching information contained in the incident light itself. The principle of operation of the device is demonstrated using a coupler fabricated in an LiNbO 3 substrate. A switching time of the order of 100 μs has been obtained, limited only by the electronic feedback loop used in the experiment.

A new bidirectional solid-state switch for telephone loop plant applications

Abstract: A new high-power bidirectional solid-state switch is described which uses a buried gate layer to pinch the electron hole plasma of a lateral p-i-n diode against the top oxide of a planar structure to produce bilateral blocking. Models of the switch have so far demonstrated blocking voltages up to 500 V, current break capability at currents up to 5 A and "on" state resistance of 1-4 Ω. Millisecond simulated lightning induced surges of up to 17 A have been passed through the switches without damage. The switch is designed for application primarily in telephone loops, where it can be used to control ringing signals, provide test access and perform signaling functions. Circuits are shown demonstrating how the switch may be used as an electrically coupled switch, an optically coupled relay for switching ac or dc, a transient immune crowbar voltage clamp and a short duration line interrupt switch for loop testing.

Prospects Of Monolithic Optical Integration

Abstract: The fundamental principles of basic semiconductor optical waveguide components are reviewed Fabrication of these components require similar material and processing technologies as those used for advanced injection lasers Compatibility of material and processing permits integration of optical and electronic components to form circuits of potentially high complexity The monolithic integration of optical lasers and amplifiers with other waveguide components requires a high degree of control of composition and thick-ness of layer growth and advanced processing technologies which are reviewed briefly Present material and process technologies make monolithic integration particularly attractive for controlling and improving the performance of, injection lasers, for permitting novel high speed modulation schemes, and for a number of switching applications The integrated optic circuit design must allow for relatively large fabrication tolerances for the individual components without causing significant performance degradation or potential reliability problems The feasibility of integration is demonstrated with a few examples such as optical switches, optical isolators and electrooptically tunable injection lasers© (1981) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only