Showing papers on "Optical switch published in 1980"

Optical residue arithmetic computer having programmable computation module

Abstract: An optical computer based on the residue number system employs a plurality of computational modules which may be programmed using electronic pulses to perform addition, subtraction, multiplication and division operations. Each module comprises an array of optical switches in the form of directional wave guide couplers interconnected by optical transmission paths to form a series of maps corresponding to a given modulus. The optical switches are arranged in rows and groups of rows may be selectively activated to adapt the module to perform various arithmetic operations. One residue is input to the module in the form of light pulses and is spatially arranged to automatically select the proper map to perform a desired function. The optical switches in each row thereof are electrically interconnected to a bi-stable electrical switch that simultaneously switches all of the logical switches in that row in accordance with a programming input pulse delivered to one of the bi-stable switches. The light output from the last row of optical switches correspond to the function of two residues whose function has been computed and is delivered in spatially oriented form. The inputs of the electrical switches associated with one module may be connected with the light output of another module so as to permit various functions, such as polynomials, to be computed using chain processing techniques. Arrangements for encoding, decoding, and scaling are also disclosed.

Electrically controlled optical switch for multimode fiber applications

Abstract: An electrically controlled optical switch based on polarization principles is described. It uses a liquid crystal twist cell that rotates polarization by 90°, and it operates on an ac voltage that switches between 0.8 and 2.5 V rms. The switch has a loss of ~0.4 dB, neglecting reflections, in an unpolarized incoherent beam and a cross-talk ratio of ~−20 dB. It operates in collimated light, but it can be applied to multimode fibers using collimating lenses, which are expected to add <0.8 dB to the loss.

Optical switch for a very large number of channels

Abstract: An optical switching system comprising two optical fiber arrays 4 and 5 facing one another. In the space between these two arrays, a propagation mode converter 6 or 7, deflector 9 or 11, a deflector control device 13 or 14 and control logic 15 or 16 controlled by a processor 19 are placed for each fiber.

Total switching of unpolarized fiber light with a four-port electro-optic liquid-crystal device

Abstract: A liquid-crystal switch capable of switching nearly 100% of unpolarized light from one multimode fiber to another had been conceived and demonstrated experimentally. The switch uses a double interaction with a single layer of nematic liquid crystal in which the liquid alignment is initially in plane at 90° to the light propagation. This four-fiber optical reversing switch has a simple structure, a low insertion loss, and a low operating voltage. It should find a wide range of applications in fiber-optic communication systems.

Dual array fiber liquid crystal optical switches

Abstract: The invention pertains to improved electrooptical devices for switching pluralities of unpolarized or polarized optical signals between input and output multimode single strand fiber optical guides and more particularly relates to novel electrooptical switch elements employing electric field-effect liquid crystal compositions adaptable for the construction of large scale, integrated multiple switch arrays.

Fiber-optic rotation sensor technology

Abstract: A concept for an all-waveguide fiber-optic rotation sensor is discussed, and the results of preliminary tests of key elements are described. A single channel waveguide coupler design provides the functions of an optical switch, a 3-dB beam splitter, a phase retarder, and a signal modulator, all of which may be formed on the same chip and interconnected by channel single-mode waveguides. Preliminary test results for the waveguide coupler and for a rotation sensor without the coupler are presented. Signal processing, polarization control, and interconnection of the waveguide components are discussed.

Isolated DC voltage monitoring system

Abstract: Apparatus for electrically isolating a DC voltage source while the voltagef the source is being measured or otherwise monitored. An electronic switch is provided for selectively coupling the apparatus to the source, and a first optical device coupled to the switch receives a control signal which directs switch operation. The first optical device electrically isolates the switch from electrical equipment which generates the control signal. A device for generating an internal voltage data signal is also coupled to the switch, the frequency of such signal varying according to the voltage of the source. A second optical device receives the internal data signal, and couples an external data signal to voltage monitoring equipment, the external data signal having a frequency which varies according to the frequency of the internal data signal, the second optical device electrically isolating the switch from the voltage monitoring equipment.

Semiconductor Devices for Optical Communications

Abstract: (1980). Semiconductor Devices for Optical Communications. Optica Acta: International Journal of Optics: Vol. 27, No. 10, pp. 1398-1399.

Ferrofluid optical switches

Abstract: A controllable magnetic field influences the position or shape or density distribution of a ferrofluid so that the ferrofluid causes or prevents the coupling of light between optical paths either by physically causing movement of a waveguide (e.g., optical fiber) or by itself physically moving into or out of a coupling region between optical paths.

Systems engineering for long-haul optical-fiber transmission

Abstract: Optical-fiber transmission systems application to long-haul optical trunk lines is studied. Development on optical transmission systems is found to be most advanced for short-haul interoffice systems, with many countries in the world already having systems in commercial use. This is largely due to the amount of demand that exists in this field, and that insufficient laser diode reliability does not permit constructing a long-haul optical circuit. However, from an economical viewpoint, optical transmission systems introduction into long-haul trunk lines is quite attractive. This paper reports the results of a survey on some economic and reliability aspects of the system, together with the technology state of the art. Attainable repeater spacings are estimated after detailed consideration of optical-fiber loss and dispersion. Some experimental results are also shown to clarify the transmission characteristics for high-speed signals and long repeater spacing systems. Based on the survey, future developmental targets are discussed.

Voltage controlled non-saturating semiconductor switch and voltage converter circuit employing same

Abstract: A voltage controlled semiconductor power switch including a bipolar transistor efficiently driven by a field effect transistor coupled between collector and base electrodes for providing a non-saturated conduction of the transistor and rapid switching speeds. The switch is employed in voltage converter circuits which require minimum dead time in the application of drive pulses, and have an efficient circuit operation and reduced circuit complexity.

Monitoring system of an optical power in an optical repeater

Abstract: The operation of a laser in an optical repeater in an optical transmission system using an optical fiber cable is telemonitored at a terminal station by changing the mark ratio of the test signal which is transmitted from the terminal station to the circuit. Each of the repeaters has an optical-electrical conversion element for the conversion of the input optical energy to electrical energy, an amplifier for amplifying the electrical output of said conversion element, a laser for converting the electrical output of the amplifier to an optical output power, a device for controlling the optical output power of the laser, a switch for providing the signal return path between the upward circuit and the downward circuit, and a monitoring circuit having a reference voltage generator for providing a reference lever which is lower than the normal signal level when the signal has the mark ratio of 1/2, and a comparator for comparing the laser output with the reference level, and a device for turning OFF the switch when the monitoring circuit provides the output signal indicating that the laser output is equal to the reference level. The terminal station designates the particular repeater and closes the switch of the designated repeater, then, transmits the test signal having the controlled mark ratio. That test signal returns to the terminal station reflected by that closed switch. By adjusting the mark ratio of the test signal, the monitoring circuit of the repeater provides the output when the laser output equals to the reference level, and has the switch turned OFF. Thus, the terminal station recognizes the degree of the degration of the laser from the mark ratio when the circuit is broken.

Nonblocking 8×8 optical matrix switch for fibre-optic communication

Abstract: A compact nonblocking 8×8 optical switch composed of 64 pentagonal prisms is described. The switch dimensions are 60×120×120 mm. Insertion loss was from 1.7 to 4.0 dB, and switching repeatability was 1 dB.

A Broad-Band Optoelectronic Microwave Switch

Abstract: A broad-band optoelectronic switch based on an avalanche photodiode is described. The microwave signal is supplied to the switch as intensity modulation on an optical carrier wave. Switching is achieved by reverse biasing the APD for the on-state and forward biasing for the off-state. Isolation of better than 80 dB is reported over a signal frequency range of 10 MHz to 1 GHz. In the same switch, isolation greater than 60 dB is observed up to 3 GHz. A turn-on time of 400 ns was observed without special techniques for discharging the junction, the turn-off time is much shorter.

Optical LiNbO 3 3-branched waveguide and its application to a 4-port optical switch

Abstract: An optical multimode 3-branched waveguide in Ti-diffused Z-cut LiNbO3 is discussed experimentally and theoretically. The guided light was selectively fed into three branches with the extinction ratio of nearly 10 dB at an applied voltage of V0 = ±25 V. As an example of the applications, we propose a 4-port optical switch which consists of 3-branched waveguides and bent waveguides. The bent waveguide with a 0.5-mm radius of curvature was fabricated in Nb2O5/Ti:LiNbO3.

Broadband high speed optoelectronic semiconductor switch

Abstract: The optoelectronic switch includes a photosensitive GaAs FET onto which an optical signal may be directed. The optical signal is derived from an RF modulated light source. A voltage circuit is connected to the FET to switch the FET "on" or "off" by placing a positive or zero voltage respectively on the drain. An isolation of over 70 dB is obtained in this FET switch.

Static power switching system for induction heating

Abstract: A static power switching system utilizes a parallel LC resonant circuit which is energized from a unilateral electrical power source through a switch circuit beginning at the point of minimum voltage across the switch circuit. Current drive to the resonant circuit at the point of minimum voltage across the switching element is obtained by controlled switching of a power transistor switch circuit using a switch control circuit that detects the minimum point of a voltage swing across the switch circuit and generates a switch control signal pulse. The switch control signal pulse is adjustable in duration depending upon load requirements and is applied as base drive to the power transistor. Power take off is by coupling to the inductor of the resonant circuit through its magnetic field. The switching system is particularly adapted for use in induction heating apparatus.

Electronic sensor on/off switch

Abstract: Electronic sensor on/off switch for a load connected to an a-c supply network, including a controlled semiconductor switch connected in a series circuit with the load, a sensor for switching the load on and off, a control circuit connected from the sensor to the switch, the switch being addressable by the control circuit in a conducting state with the load switched on by a signal holding the switch in the conducting state at the zero crossing of a current passing through the load, and in a non-conducting state with the load disconnected by signal switching the switch into the conducting state for switching on the load at the zero crossing of an output a-c voltage at the switch, a power supply circuit connected to the control circuit, a current transformer having a primary and a secondary winding and being operable in saturation, the current transformer being connected in series with the switch, the control circuit including a first rectifier being coupled to the secondary winding and having an output producing a supply voltage with the switch in the conducting state relative to a reference potential equal to a reference potential point of the output a-c voltage, and a branch of the series circuit including the primary winding, the switch, a storage capacitor chargeable by the output a-c voltage and a second rectifier producing the supply voltage in the non-conducting state.

Large-Scale and Low-Loss Optical Switch Matrix for Optical Switching Systems

Abstract: A new mechanical optical switch matrix and optical switching network structure are proposed for a wideband switching system, in which optical signals are exchanged without optoelectric conversion. The principle used for the switch matrix is suitable for low-loss and large-scale structure as it has no optical mode conversion. The experimental switch matrix is 10x10 scale and has insertion loss of 0.95 dB. The switching network has a four-stage structure with 8192 subscriber terminals. The transmission loss calculation and traffic analysis are discussed to show the possibility of local connection without a repeater.

Computation module for addition and multiplication in residue arithmetic

Abstract: A computation module useful as part of a optical numerical computer based on the residue number system includes an M×N array of double input, double output electrically actuated optical switches. Optical pathways interconnect each of the outputs of the switches of a row of the array and certain inputs of the switches in the subsequent adjacent row. Each row of the array has an associated bi-stable electrical switch which is interconnected to all of the light switches in that row and causes such light switches to assume a common state dependent upon the state of the electrical switch. The module computes either the sum or product of two modulo M residues, depending upon its interconnection pattern. One of the residues is introduced as a light input to one of the electrical optical switches in the first row of the array. The other residue is operative to condition one of the bi-stable electrical switches to assume a different state than all of the other electrical switches. The output from the module is in the form of a light signal from one of the electro-optical switches in the last row of the array.

Polarization transmission characteristics of optical fibers with elliptical cross section

Abstract: In the transmission via optical fibers connected to laser diodes, optical switches, optical filters, etc., or in high-sensitivity high-selectivity optical heterodyne detection system, polarization characteristics become important in addition to transmission loss and dispersion. The polarization transmission characteristics of optical fibers with elliptic cross-section are calculated by characteristic matrix method for large values of ellipticity. For two orthogonal polarization modes (oHE11 and eHE11 modes) the transmission velocity, group velocity and their difference (elliptic double refraction) are obtained. The group delay difference among modes is very small but elliptic double refraction greatly affects the polarization characteristics.

Optical bistability using a directional coupler and a detector monolithically integrated in GaAs

Abstract: An electro‐optic directional coupler has been integrated on the same GaAs chip with a proton‐implanted detector located in one of the output rib waveguide channels. The association of this monolithic device with an external electrical amplifier has allowed optical bistable operation to be demonstrated at 1.06 μm. With an amplifier gain equal to unity, the bistable device switches in about 1 μs, the optical switching energy being less than 1 nJ.

System for measuring an optical loss in a single mode optical fiber

Abstract: An optical loss in a single mode optical device is measured by utilizing multi-mode equipment. The present system comprises of an optical source (1), a sample (30) to be tested, a reference optical attenuator (31) for replacing the optical loss in the sample (30), a first optical switch (40) provided between the optical source (1) and the sample (30) through a single mode optical fiber, a second optical switch (41) provided between the sample (30) and the light receiver (2) through the multi-mode optical fiber, said reference optical attenuator (31) being provided between the first optical switch (40) and the second optical switch (41) so that the optical path is switched either to the sample (30) or to the reference attenuator (31), the optical fiber between the sample (30) and the second optical switch (41) and the optical fiber connected to the input and the output of the reference attenuator (31) being a multi-mode optical fiber.

All-optical parallel logic operation using fiber laser plate for digital image processing

Abstract: A fiber laser plate exhibits sharp transition and high contrast. We describe the first demonstration of all‐optical parallel logic operations such as A/D conversion and the AND and OR operations important for digital optical computers using the device as an optical switch array.

Electrically controlled electro-optical switch and integrated optical circuit incorporating such a switch

Abstract: An electro-optical switch for switching optical radiation between two wave guides having a coupling zone with two pairs of electrodes (E 11 , E 12 , E 21 , E 22 ) respectively associated with two guides (1, 2) and positioned so as to cover a variable fraction of the width of the guides. As a result, the electro-optical effects produced and, therefore, the propagation velocities in the two guides are made variable as a function of the electrical connection mode of the electrodes. Two switching states are obtained with a considerable tolerance for the length of the guides (2L) and the control voltage.

Single-mode optical fibre switch

Abstract: A 1 × 4 single-mode optical fibre switch is described which has an insertion loss of less than 0.5 dB with repeatability of ±0.01 dB and crosstalk less than −70 dB.

Self-quenching circuit

Abstract: A switch, when closed, provides a low impedance conduction path for power being applied to a load and for the operating potential for a control circuit. The control circuit includes timing circuitry which produces a timing signal, a given time after the switch is closed. The timing signal is then used to turn-off the switch causing power to be removed from the load and the control circuit.

Fiber optic crossbar switch for automatically patching optical signals

Abstract: A system for automatically optically switching fiber optic data signals between a plurality of input optical fibers (10, 11, 12, 13) and selective ones of a plurality of output fibers (56, 56a, 56b, 56c). The system includes optical detectors (14, 16, 18, 20) which are connected to each of the input fibers (10, 11, 12, 13) for converting the optic data signals appearing at the respective input fibers to an RF signal. A plurality of RF to optical signal converters (38, 40, 42, 44a, etc.) are arranged in rows and columns. The output of each of the optical detectors (14, 16, 18 and 20) are each applied to a respective row of optical signal converters (38, 40, 42, 44, etc.) for being converted back to an optical signal when the particular optical signal converter is selectively activated by a DC voltage. These optical signals are then applied via optical fibers (62) to optical detectors (58) which convert the optical signal back to an RF signal which is used for driving the ILDs ( 60). The ILDs (60), in turn, convert the RF signals back to optical signals without any mechanical switching either of the optical signals or the RF signals. The output fibers are connected to the output of the driving ILDs (60).

Electro-optical switching matrix

Abstract: The matrix is used for switching optical signals between input and output single strand optic fibre light guides (10,11, 12, 17, 36, 53). The matrix is simple, relatively inexpensive, and easily constructed, and may be made in larger sizes than devices using solid crystalline materials. Switching is effected by the selective application of voltages to layers of nematic liquid crystal (21,39,41...) between parallel-sided prisms (16, 30,51 ...), causing either transmission or total internal reflectors of the light signal. Light absorbers (75A, 78A, 102A, ...) may be provided at end faces of the prisms not coupled to light guides. The light from the light guides is collimated, and polarizers (P13, P14, P15, ...) may be provided. Inactive regions between the prisms may be filled with material of similar refraction index, or may be provided with mirrors (not shown in Figure 8).

Circuit for use in the detection of the condition of an isolated switch contact

Abstract: A tire pressure monitoring system includes a tuned circuit with a pressure sensitive switch which is closed when the tire pressure is normal, connected across it, the tuned circuit and switch being mounted on the vehicle wheel. Mounted on a part of the vehicle is a detector circuit including an oscillator which includes an inductor which is at least intermittently coupled to the inductor of the tuned circuit. When the switch is closed the oscillator runs normally and its output is detected to indicate that all is well. When switch is open, however, the oscillator output is suppressed whenever the inductors are coupled together. The circuit can also be used in other applications where it is required to detect the state of an isolated switch.