Showing papers on "Optical switch published in 1974"

Polarization converter and circuit elements for use in optical waveguides

Abstract: Wave propagation in thin film optical waveguides using gyrotropic or anisotropic material in either the substrate or adjacent top layer with respect to the thin film waveguide is analyzed and a mode converter capable of converting TE to TM or TM to TE polarization is disclosed. Several mode converters constructed in accordance with the present invention are set forth. Also disclosed are other optical circuit elements constructed from such mode converters including a gyrator, isolator, an optical switch, and a non-destructive optical readout for magnetic memories.

Magneto‐optics and motion of the magnetization in a film‐waveguide optical switch

Abstract: We discuss magnetic properties of iron‐garnet films and the use of these films as film‐waveguide optical switches. Our experimental study involves the observation of magnetic domains, measurements of Faraday rotation constants, coercive forces and anisotropy fields, and a detailed investigation of the switching process between 0 and 300 MHz. Our theoretical study includes magneto‐optics in film waveguides, and analysis of the serpentine circuit, and an extensive calculation of the motion of the magnetization. For low driving fields, the process of optical switching is the formation of periodic domains and the subsequent motion of domain walls. For higher driving fields, the process is rotation of the magnetization in unison. The switching field required for 100% modulation is several times the anisotropy field in the film, which can be as small as 0.1 Oe.

Integrated optical signal processing system

Abstract: An electrooptic thin film wave guide structure is used to deflect an incident optical beam such as a laser beam. This structure is made of an electrooptic thin film material of high resistivity which can be obtained by either epitaxial growth on a conducting substrate or by mechanical thinning of a bulk wafer. A single electrode or multiple electrodes are fabricated on the thin film material. By applying a voltage to the electrode or electrodes, a refractive index change is produced in the thin film material and the incident laser beam is deflected within the plane of the thin film material. By forming a plurality of electrodes on the thin film material and applying properly programmed voltage wave forms to the electrodes, the refractive index profile in the plane of the thin film material may be varied to produce a high speed optical switching function. This optical switch can be used as a multiplexing terminal to steer a single or multiple beams in either time, space or frequency domains.

Terminal and repeater stations for telecommunication system using optical fibers

Abstract: In the telecommunication system using optical fibers, each terminal or repeater station comprises negative feedback via an optical channel, the output electroluminescent diode being coupled to the input photodiode by an optical fiber.

Optical switch and modulator

Abstract: First and second optical waveguides are disposed along a coextensive parallel length sufficient in relation to the distance of propagation of optical energy for light transfer from one guide to the other. Thus, light propagating along one guide of the parallel waveguide arrangement will emerge from the other optical waveguide. Electrodes are disposed contiguous to the waveguides for generating electric fields of opposite sense upon the application of an electrical potential. Antisymmetric changes are thus induced in the refractive indices of the optical waveguides causing the light energy to be coupled back into the originally energized waveguide and modulating the intensity of the outputs of both waveguides.

Liquid crystal optical switch coupler

Abstract: An optical switch to divert a portion of optical energy from a multimode transmission line. Two rod-like dielectric materials positioned adjacent each other sandwich a liquid crystal material between the two. Input and output fiber bundles are connected to each of the rods. By use of optically transparent electrodes the index of refraction of the liquid crystal is controlled to pass one polarization of light when the crystal index of refraction is the same as the two rod-like dielectric materials and no light transfers when the index of refraction is lower.

Liquid crystal switch for optical waveguide

Abstract: This disclosure is directed to an electrical means for input and output coupling of light in optical waveguides.

The GaAs P-N-P-N laser diode

Abstract: The general structure of double-heterojunction diode lasers is shown to be consistent with the required geometry of the Shockley diode or p-n-p-n switch. When the two devices are combined in a single structure, there results an extremely simple source of high optical power (>0.5-W) pulses of very short duration (<10 ns) without the need for a complex external driver. In principle, pulse triggering and repetition rate are easily controlled, suggesting that the device has potential application in pulse-coded optical communication systems.

Optical switching system

Abstract: In an optical switching system having a transmitter and a receiver optically coupled together via a fiber optic light guide, the transmitter utilizes a piezoelectric device which provides an electrical signal to a light emitting device when a mechanical strain is imparted to the piezoelectric device The light emitted by the light source is provided at the receiver via the fiber optic guide The receiver generates a signal in response to the light received thereat via the fiber optic guide This generated signal is used to control the power flowing to a load via a switching device so that, for example, one generated signal is used to turn on the switching device and the next succeeding generated signal is used to turn off the switching device

Wide‐angle electro‐optic switch

Abstract: A new electric‐field‐actuated optical switch capable of wide‐angle deflection is described. The switch element makes use of the high angular selectivity of thick Bragg gratings and can be fabricated both in bulk and in thin‐film configurations. Experimental verification of the switch action in a bulk configuration is presentd. Modulation of 35% was observed in this first observation of the effect.

Switching system to short-circuit a load with minimum residual voltage

Abstract: A controlled main switch, typically a semiconductor switch, is connected in parallel to the load. In accordance with the invention, an auxiliary switch, typically also a semiconductor switch such as a switching transistor is directly connected across the terminals of the load, and with an impedance, for example a resistance, diode, or Zener diode to the main switch, and controlled to switch in synchronism with the main switch, so that the residual voltage across the load due to inherent voltage drop across the terminals of the switch becomes a minimum. Integrated technology may be used, combining preamplifiers and distribution networks in one monolithic chip.

Acoustic activated switch

Abstract: An acoustic switch including two tuned transducers, a bistable switch coupled to one of the transducers and a monostable switch coupled to the other transducer is responsive to acoustic signals in a predetermined frequency range to control the two functions of an auxiliary device coupled to the switch. In one embodiment, the auxiliary device is a television receiver and the functions controlled are the electrical power to the receiver and the channel selection.

Isolation circuit for arc reduction in a dc circuit

Abstract: An isolation circuit for a direct-current circuit including a load, power supply and switch for opening and closing the D.C. circuit. The isolation circuit comprises a triode-type switch device, such as a transistor in which the collector and emitter are connected in series with the power supply and the load, while the base is connected through a resistive gating circuit to the switch.

Integrated monolithic switch for high voltage applications

Abstract: An integrated monolithic switch is fabricated in an epitaxial layer united to a semiconductor substrate. The switch includes a Darlington amplifier, a power output switch, a bilateral device, typically a diffused diode, and an epitaxial resistor, the combination being connected between a set of high voltage lines. The epitaxial layer has an appropriate thickness and resistivity to accommodate all active and passive elements. For a first input signal, the switch is connected to one high voltage line. For a second input signal, the switch is connected to the other high voltage line. The switch is adapted to sink current. The diode structure, when forward biased by the sinking current, forms a parasitic path to direct the sinking current to the substrate even though the high voltage lines are up. The Darlington is connected to the switch output to lower output voltage during the sinking condition. A set of switches of the same conductivity type may be employed to drive a cross point in a gas panel display.

Theory, fabrication and performance of some integrated optical devices

Abstract: Recent progress in the fabrication of low attenuation optical fibers raises the attractive possibility of optical communications via these waveguides. Integration of different optical functions on one substrate in the form of optical circuits will form ideal terminals for such a communication network. We shall discuss the theory, fabrication and performance of a few "building stones" of such optical circuits. Optical directional couplers capable of coupling light from one channel to another will be described and their use as switches will be discussed. Distributed feedback for integrated lasers will be analyzed. Laser action in a GaAs waveguide, in which distributed feedback was supplied by corrugations fabricated on the surface, will be described. Longitudinal and transverse mode control of such a laser will also be discussed. We shall conclude with an analysis of nonlinear interactions in thin films, pointing out new methods for phase matching and ways to implement them.

Electronic control circuit for the drive motor of a magnetic sound device

Abstract: An electronic control circuit is provided for a magnetic sound device of the type having a sound recording medium transport, a direct current drive motor for the transport, a main control switch, andd a circuit interconnecting the motor to a direct current power supply through the main control switch in accordance with a first polarity and an audio circuit. The present circuit comprises an auxiliary control switch interposed between the motor and main switch and a switch circuit including first and second transistor switches connected between the main control switch and motor for reversing the polarity of the interconnection between the power supply and motor. A capacitor is interconnected between the motor and the transistor switches for activating the transistor switches during the charge-up time of the capacitor when the auxiliary switch is open. The present circuit further shorts out the audio circuit for a brief time period after the auxiliary switch is opened or closed.

Fully Electronic Space-Division Telephone Exchanges Using Semiconductor Crosspoints and Optical Switching

Abstract: The state of the art in fully electronic space-division telephone exchanges shows that neither can semiconductor crosspoints directly replace reed relay contacts in Public exchanges, nor can hitherto semiconductor switching networks compete with reed relay switching networks. Though semiconductor crosspoints fulfill all transmission requirements, they are too expensive. Investigations on this field by the authors led to the following results. 1) A semiconductor crosspoint with high breakdown voltage and low on-resistance has been developed. This crosspoint can be connected to a subscriber's line and thus directly replace a reed relay in a public exchange at only slightly higher cost. 2) These crosspoints with high voltage capability can be combined with low cost, low breakdown voltage MOS semiconductor arrays in large-scale integration (LSI) techniques which are isolated from the subscriber lines by transformers to form a fully electronic switching network. 3) A crosspoint free of on-attenuation which can be monolithically integrated to crosspoint arrays has been developed; 4) A thick-film hybrid crosspoint for switching of commercial high-resolution video signals has been developed. The state of the art of optical switching systems shows that switching networks using a laser beam enable the transmission of wideband video signals with comparatively high crosstalk attenuation.

Method and system to protect electronic switching components

Abstract: To protect electronic switching elements against short circuits in loads connected in series therewith, particularly switching transistors and the like, a momentary test pulse is generated upon connection of the load to a live circuit. The test pulse is connected to the switch in a direction to close the switch, and the voltage appearing at the switch is then tested, the switch being blocked immediately if the voltage appearing thereat is not within a permissible voltage range resulting in normal current flow through the switch, the switch permitting to remain conductive, or closed, if the sensed voltage at the connected switch terminal is within design values.

Electronic switching circuit with zero voltage switching

Abstract: Disclosed is an electronic switch circuit including a switching thyristor with two switch terminals that are connected to a controlled circuit. A trigger circuit is coupled to the gate terminal of the thyristor to selectively supply trigger signals and the trigger circuit receives its power from a power supply which is connected to switch terminals and draws its energy from the controlled circuit. An energy storage capacitor in the power supply provides trigger energy when the voltage across the switch terminals is approximately zero, such as at A.C. crossovers. The thyristor exhibits zero voltage switching.

Signal comparison circuits

Abstract: Circuits for indicating the order in which two concurrent signals arrive and the period during which both signals are present. These circuits include two signal powered switches, such as transistors, each receptive of a different signal. When the first arriving signal is present it closes its switch and the closed switch keeps the other switch open. Circuits controlled by the respective switches produce output indications, each during the period a switch is both open and receiving the second arriving one of the signals.