Showing papers on "Optical switch published in 1972"

Studies of the Use of Gyrotropic and Anisotropic Materials for Mode Conversion in Thin‐Film Optical‐Waveguide Applications

Abstract: Wave propagation in thin‐film optical waveguides using gyrotropic or anisotropic material as substrate is studied. At the film‐substrate boundary, the relation between the incident and reflected fields can be expressed in terms of a scattering matrix with matrix elements representing the TE‐to‐TE and TM‐to‐TM reflection coefficients and the TE‐to‐TM and TM‐to‐TE conversion factors. The property of the scattering matrix is examined, and the condition for continuous and complete mode conversion is derived. Various schemes to achieve complete mode conversion are proposed and the performance characteristics, including the physical dimension and the tolerances in the incident angle and film thickness, for several mode‐converting structures are computed and compared. Once the practicability of complete mode conversion is established, it is possible to study the feasibility of practical devices. Various schemes for the realization of such devices as the gyrator, the isolator, the optical switch, and the nondestr...

An Optical Communication System Using Envelope Modulation

Abstract: A wide-band optical communication system that modulates the envelope of the carrier of a high-speed optical pulse having no relation to the PCM signals, was developed. This optical pulse is supplied from a He-Ne gas laser oscillator that is controlled to generate a single transversal mode. The transmission bit rate of this optical communication system is 123 Mbits/s, and this system has a transmission capacity of three monochrome video signals, three program signals, and one channel of 48-kHz high-speed facsimile signal or one National Television System Commission (NTSC) color TV signal and one program signal. When this optical communication system is used to propagate through the atmosphere for a distance of 2-3 km, reliability is expected to be 99 percent.

Electro-optical waveguide arrangements

Abstract: An optical switching element is described which has at least two optical paths. The paths are formed by blocks of electro-optical material which, when subjected to an electrical field, suffers a change in refractive index. The material is sensitive to the polarity of the electric field and, by appropriately orientating the material forming the two paths, a common electric field applied across both paths will produce a change in refractive index in opposite senses in the two paths. This enables light transfer between the two paths to be controlled. Also described are logic elements formed by coupling two or more such switching elements.

Electro-optic thin-film diffraction loss modulator

Abstract: An optical switch useful in thin-film electro-optic light guides relies on an induced stationary diffraction grating. The grating is produced by an interdigital electrode structure which is deposited on the electro-optic guide. The application of a voltage to the electrode pattern produces a spatial modulation of the refractive index of the guide which acts as a diffraction grating to light traveling in the guide. This grating causes light in the guide to be diffracted out of the guide, thereby stopping transmission. Removal of the voltage eliminates the grating and restores transmission.

Switch for thin-film optics

Abstract: An optical switch for thin-film light guides utilizes electrically induced changes in the index of refraction of the switch material to produce the switching effect. Electrodes located along the length of the switch material and separated from it by an insulating layer induce an electric field in a region of the switch material when a voltage difference is applied to them. This causes the index of refraction to increase in that region to such an extent that a light guide is formed in the switch material, allowing transmission through the switch. Removal of the voltage destroys the guide, thereby stopping transmission.

Solid state crosspoint switch

Abstract: A solid state crosspoint switch particularly suited for use in a telephone switching matrix utilizes two switching transistors and two compensating transistors in a balanced bridge configuration to substantially eliminate crosstalk while the switch is effectively open (all four transistors cut off to provide a high impedance for blocking the passage of audio signals therethrough). Audio signals are enabled to pass through the crosspoint switch via a low impedance path by driving the two switching transistors into saturation from a gated control circuit responsive to appropriate control signals.

Electronic switch module with ceramic case

Abstract: A compact electronic switch module for controlling an electric motor, with the switch module including a sectional switch case mounting various of the switch circuit components thereon, with at least one section of the switch case comprising ceramic material providing a support for components of the switch circuit. The ceramic section facilitates the manufacture and assembly of the switch circuitry which includes solid state switching means, and provides a heat sink for the switching means, as well as facilitating soldering operations on the switch circuitry.

Two-lead electrical control apparatus

Abstract: Two-lead electrical control apparatus including a pair of gate controlled switches that form a control switch and a triggering switch, the control switch being connected across a power source and through a load by means of a pair of run leads. A voltage divider circuit is connected with the gate of the triggering switch and includes sensing means responsive to a pre-selected condition to impose a recurring triggering signal on the triggering switch to render such triggering switch conductive to supply a triggering signal to the control switch to thereby trigger the control switch and provide full source voltage across the load.

An isolated transient-free solid-state A.C. power switch.

Abstract: An inexpensive electronic a.c. power switch has been developed for use in environments where switching transients cannot be tolerated. Transient suppression is achieved by using a zero-crossing voltage detector to gate a thyristor into conduction whenever the line voltage is zero. Optical coupling is used electrically to isolate the input-trigger circuit from the thyristor-gating circuit. An additional feature of this circuit is that highly inductive loads can also be switched without generating any transients.

Bistable optical switch utilizing lead phosphate or lead strontium phosphate crystals

Abstract: Lead phosphate and certain mixed phosphates of lead and strontium are pure ferroelastic materials which can be switched from one strain state to another by mechanical stress. The crystals are transparent to visible radiation and the strain states are biaxially birefringent, the optic axes of adjacent domains separated by a domain wall lying in different spatial directions. Accordingly, if a suitable polarizer and analyzer is employed to extinguish light passing through one strain state, the strain state to which it can be switched will transmit light. Thus is there provided mechanically actuated optical switch. The optical properties of the domain wall likewise differ from either adjacent domain and in conjunction with spatial filtering (and/or optionally polarization filtering) can be used to provide mechanically actuated line scanners.

Self scanned charge coupled optical imaging array

Abstract: A 20 × 20 self scanned optical imaging array was designed and fabricated on a 102 × 102 mils chip using the silicon gate technology. The array consists of 400 optical sensing charge coupled units accessed by two novel 20 bit shift registers. The shift registers are charge coupled devices and employ a new technique to give a serial to parallel output for every bit. The basic optical unit consists of a silicon gate integrating electrode, two x and y transfer silicon gate electrodes and a p+diffusion which acts as a common output for the entire line. The organization and design considerations of the array will be described. Experimental results on the basic optical unit which include noise equivalent power, photosensitivity as a function of integration time and spectral response will be given.

Optical switch for transient plasma diagnostics.

Abstract: A photometric technique is described which facilitates the determination of the electron number density profile of a plasma generated by transient microwave pulses.

Chopper duty maximization circuit

Abstract: The duty cycle of a power controlled switch connected in series with a battery and a direct current motor is regulated to control the motor power. Conduction by the power controlled switch is initiated by gate signals from a trigger source, and a shut-off circuit including a shut-off controlled switch and a shut-off capacitor controllably terminates each conduction interval by reverse biasing the power controlled switch. A recharge controlled switch recharges the shut-off capacitor between successive commutations of the power controlled switch. The trigger source provides gate signals for the shut-off controlled switch and the recharge controlled switch as well as the power controlled switch. To maximize the duty cycle of the power controlled switch, and simultaneously obviate overlaps in the conductive states of the shut-off controlled switch and the recharge controlled switch, a control circuit is provided to monitor the shut-off controlled switch and disable the trigger source when the shut-off controlled switch is conductive. The control circuit includes a transistor connected across the anodecathode terminals of the shut-off controlled switch. This transistor cycles on and off in response to the conductive state of the shut-off controlled switch, and it is effective to enable or disable an AND gate in the trigger circuitry to control the application of trigger signals to the recharge controlled switch.

Frequency-Changer Circuit with a Single Ideal Switch

Abstract: The interaction of frequency-selectivity with a periodically-operated switch, as in a simple frequency-changer circuit, is a complex matter which is generally very difficult to visualize. An attempt is made in this note to give a treatment of a very straightforward, physical character, using the simplifying assumptions of an ideal switch and ideal tuned circuits. The conditions for transfer of power from one frequency to another, and especially for the transfer to take place without loss, are derived.