Showing papers on "Optical switch published in 1978"

Theory of a lossless nonlinear Fabry-Perot interferometer

Abstract: A Fabry-Perot interferometer filled with a medium whose refractive index depends upon intensity has a multiple-valued transmission-vs-intensity characteristic. When the incident light is circularly polarized, and the nonlinearity is only cubic in the fields, Maxwell's equations may be solved exactly for the plane-parallel resonator field in terms of elliptic functions. An accurate approximate analysis is given for more general cases, including resonators with spherical mirrors and finite beams, where self-focusing is important. The theory is developed to yield design information for operation as an optical switch, "transistor," and power limiter.

Interferometer apparatus using electro-optic material with feedback

Abstract: A nonlinear interferometer apparatus is disclosed wherein a Fabry-Perot cavity is substantially filled with an electro-optic material having terminals to which a potential can be applied. A single frequency, single mode, linearly polarized source of optical radiation is coupled into the cavity and a beam splitter at the output of the cavity deflects a portion of the optical energy coming from the cavity. This deflected portion of output optical energy is incident on a photodetector whose output is amplified and connected to the terminals of the electro-optic material. The resulting device exhibits differential gain, and can function as an optical switch, limiter or optical memory element. With sufficient amplification of the detector output, an optical quantizer is provided. By properly adjusting the cavity length and providing a substantially constant optical signal to the input end of the cavity, an amplified replica of an amplitude modulated optical signal applied to the photodetector appears at the output end of the cavity.

Optical channel waveguide switch and coupler using total internal reflection

Abstract: Light beam switching and coupling in a four-port channel waveguide-horn structure has been accomplished using electrooptic modulation of the critical angle of a refractive index interface in a Y -cut LiNbO 3 substrate. The resulting double-pole double-throw switch/coupler is potentially capable of simultaneously providing a combination of desirable characteristics.

Polarization-independent optical switches/modulators

Abstract: Optical channel waveguide switches/modulators having polarization-independent operation are disclosed. Electrodes are disposed in proximity to the waveguide channels to provide an electric field that is primarily horizontally directed in at least one channel and an electric field that is primarily vertically directed in at least one channel. Since the different electric-field orientations electrooptically induce different changes in the index of refraction for waves of different polarization in the guides, this permits improved electrooptic control over both TM-like and TE-like modes. Embodiments of both modal interference switches/modulators and branching waveguide switches/modulators are disclosed.

Optically controlled two channel integrated-optical switch

Abstract: An integrated optical bistable device based on a waveguide directional coupler switch is demonstrated. The device has four optical ports, and the power incident on the two input ports exists from two distinct output ports so that all-optical data processing or remote optical switching can be performed. On/off ratios as high as 12 dB have been observed. A switching time of \sim300 \mu s and switching energy of ∼3 pJ have been achieved.

Integrated bistable optical devices

Abstract: We describe several versions of an integrated bistable optical device fabricated with Ti in‐diffused waveguides in LiNbO3. The ends of the LiNbO3 crystal are cleaved to form a Fabry‐Perot resonator. These devices can be operated with as little as 1 pJ of optical switching energy.

Generation of picosecond pulses of variable duration at 10.6 μm

Abstract: Ultrashort transients of variable duration have been generated at 10.6 μm by operating a fast optical switch with picosecond pulses from a mode‐locked Nd : glass laser. The switch, which takes advantage of the large free‐carrier contribution to the infrared optical susceptibility in Ge, has been used to generate megawattt picosecond pulses at 10.6 μm by synchronous operation of a TEA CO2 laser with the 1.06 μm source.

Fiber-optic circuit element

Abstract: A fiber-optic circuit element is provided of the type for coupling signal ght from a first optical fiber to at least one second optical fiber wherein at least one of the optical fibers has a free end which is controllably movable to be in or out of alignment with the other fibers. Movement of the free end of the fiber is achieved by an expansion layer applied to the fiber and acting as a heatable bimetallic element. Heating of the expansion layer can be achieved by absorption of electromagnetic radiation, including an independent source of control light and/or a portion of the signal light itself. Electrical heating mechanisms can also be used. This circuit element can be advantageously used without limit in optical switches, astable multivibrators, bistable multivibrators, optical resonators, and environmental temperature and pressure detectors.

Multimode integrated optical bistable switch.

Abstract: A multimode integrated optical bistable switch using a LiNbO(3) phase modulator in a noncavity configuration was constructed and tested. Bistability and discriminator operation were observed in this device using a He-Ne laser.

Broadband switching system utilizing optical fiber waveguides

Abstract: The present invention relates to an optical-fiber switch. The switch is used in switching between at least two optical signals which are capable of being modulated with a broadband RF signal including digital signals. The switch is comprised of at least two optical-fiber cables for feeding the at least two optical signals to at least two fixed positions. An optical-fiber output cable is provided having one end which is movable between at least two positions which are directly adjacent said two fixed positions. A drive unit is provided for moving the optical-fiber output cable between the at least two positions, whereby the optical signals are selectively fed to the optical-fiber output cable.

Multiple optical switch

Abstract: A multiposition optical switch is disclosed in which two quarter-period graded refractive index (GRIN) lenses (1 and 2) having first (1.2 and 2.1) and second (1.1 and 2.2) end surfaces are supported in a structure (33 and 34) in an axially aligned fashion with their first surfaces abutting in a substantially parallel relation which permits rotating at least one lens about the common lens axis (3 and 3.1). An input fiber (10) is affixed to the second surface (1.1) of one GRIN lens at a predetermined radial offset to the common lens axis; and a multiplicity of output fibers (11-16) are affixed to the second surface (2.2) of the other lens at the same predetermined radial offset, but at a plurality of angular displacements about the common lens axis. By rotating one lens relative to the other, light from the input fiber is selectively coupled to the output fibers.

Rib waveguide switches with MOS electrooptic control for monolithic integrated optics in GaAs-Al(x)Ga(1-x)As.

Abstract: Low-loss (1.4-cm−1) single-mode rib waveguides in AlxGa1−xAs heterostructures are fabricated by liquid phase epitaxy, double anodization, and photolithographic techniques. Switching of optical channels between adjacent waveguides is accomplished with directional coupler switches controlled with electrodes laid over an isolating dielectric, making a metal-oxide-semiconductor (MOS) configuration. Complete switching is achieved with <20 V applied to a stepped Δβ reversal electrode configuration. A 2 × 4 switching matrix with low-loss lateral offsets of the waveguides is demonstrated. By laying out several optical switching and guiding experiments within a 128-μm stripe, we show that independent optical circuits can be packed with adequate optical isolation using centerline separations ≈10 μm.

Optical switching device

Abstract: An optical switching means including an optical fiber moving means which is moved by an electromagnetic force, a spring body which has a guide hole through which an optical fiber passes and at least one magnetic body. The magnetic body is fixed on one of its ends and one end is arranged so as to be almost parallel with the moving optical fiber. The moving optical fiber is connected with a fixed optical fiber by moving the magnetic body with an electromagnetic force, thereby effecting optical switching with low attenuation and high accuracy.

Optical delay line matched filters

Abstract: Two multimode optical fibers connected mutually at several locations along their lengths can act as an encoding or decoding structure depending on which terminals are used for the input/output of the data. It is shown that two multicoupled lines have one input which acts as the matched filter for another input, thus enabling easy correlation of data in real time. The performance of such a structure was simulated on a digital computer and the results are discussed.

Optical coupler module in a distributed processing system

Abstract: An optically linked distributed data processing system having a plurality of stations and first and second transmission lines associated with each station. The first transmission line carries optical signals to its associated station and the second transmission line carries optical signals from its associated station. An active optical coupler module couples each first transmission line to every second transmission line. The coupler module includes a tapered waveguide for directing the optical signals from each of the first transmission lines to a single optical path, an optical detector for converting the optical signals to electrical signals, an amplifier for amplifying the electrical signals. In one embodiment a single optical source converts the amplified electrical signals back to optical signals, and in a second embodiment a plurality of optical sources, one for each of the second transmission lines, convert the amplified electrical signals back to optical signals.

Optical switch with rotating, reflective, concave surface

Abstract: An optical switch is disclosed which relies only on a rotatable, reflective concave surface (3) to couple light between an optical source (1) and a preselected one of a plurality of optical receptors (6). The switch is bidirectional, i.e., the position of the source(s) and receptor(s) can be interchanged. Optical fibers may be used as the source(s) and receptor(s). The source, however, may also be chosen from such devices as lasers, light-emitting diodes or any other optical source known to those skilled in the art. Similarly, avalanche photodiodes or the like may be used as optical receptors. The above switch structure requiring only a reflective element is particularly suitable for switching light signals in telecommunication applications. The elimination of the need for a refractive element, such as a lens, provides a structure in which the output signal is independent of wavelength and index of refraction.

Mirror-type optical branch and switch.

Abstract: An optical branch and switch based on a unique mirror effect were fabricated by varying the amount of Ti diffused in a LiNbO3 waveguide, and their properties were investigated. In this type of optical branch, the branching ratio of the light intensity could be varied by the electric field as well as by the separating angle and the effective indices of the waveguides. The main features of this optical switch are (1) small and simple electrode form and (2) a separating angle large enough to accommodate a number of switches on a single substrate. The ratio of the optical branch light intensity to that of the main waveguide was varied from 0.10 to 12.4 by applying the electric field from 0 V/μm to 8 V/μm.

Total internal reflection integrated-optics switch: a theoretical evaluation.

Abstract: Previously demonstrated planar thin-film optical switch employing the total internal reflection phenomenon is given a full theoretical evaluation for its possible adaptability to an optical channel waveguide system and also to polarization insensitive immultiport fiber-channel switch.

Bragg switch for optical channel waveguides

Abstract: An optical switch based on the deflection of optical beams between two crossed channel waveguides by an electro‐optic grating was designed and tested. The waveguide medium is Ti‐diffused LiNbO3. At 30 V applied voltage, 92% depletion in the original channel and 48% deflection in the deflected channel was obtained.

Moving optical-fiber switch experiment.

Abstract: The switch uses a V-grooved connecting device The mechanism is suitable for a large switch, which is desirable for an optical switching system A moving fiber is inserted into one of the radially arranged V grooves using the elastic bending force as the drive current The insertion condition, which realizes stable connection and high durability, is discussed Switch structure and experimental results are described Insertion loss was 033 dB, and the variation in transmissivity was 3%

Voltage sequencing circuit for sequencing voltages to an electrical device

Abstract: The present invention provides means for sequencing various supply voltages to electronic circuits and devices to thereby protect those circuits and devices from exposure to deleterious voltages. A first transistor switch connects a first voltage source to a first output terminal. A second transistor switch is connected to the control electrode of the first transistor switch. The second transistor switch, when conducting, causes the first transistor switch to conduct. The second transistor switch is turned on by a second voltage source which is connected through a delay circuit to the control electrode of the second transistor switch. The second voltage source also is connected through a diode and capacitor circuit to a second output terminal.

Electro-optical device based on electroplating action

Abstract: Electrically activated optical switches, couplers, and modulators are disclosed which can be incorporated in waveguide networks in optical communications systems. Disclosed devices comprise an electroplating medium in combination with a suitable source of an electric field whose strength can be varied to cause transition of the electroplating medium between plated and unplated states. Changes of reflectivity and refractive index are the bases of switching and coupling applications, respectively.

Electro-optical switch and modulator

Abstract: An electrically controlled light switch, which can also be used as a light modulator in integrated optical circuits is disclosed. The coupling length of a directional coupler is modified by applying a voltage between two electrodes positioned upon two rectilinear parallel waveguides made of an electro-optical material and arranged on a common substrate, thus generating a field distribution crossing the two waveguides in opposite directions and resulting in opposite signed refractive index variations thereof.

Optical waveguide switch (3 × 3) for an optical switching system

Abstract: A new optical switch element is proposed for a switching system which exchanges optical signals in optical transmission lines without optoelectric conversion. It consists of three parallel equidistant straight singlemode waveguides fabricated of an electrooptic material with electrodes deposited on them. The element, whose interaction length is pi/(2)((1/2))k (k is the coupling coefficient of neighboring guides), serves as a 3 x 3 optical switch by control of the differences in propagation constants between those waveguides. Control conditions to realize all the six connecting states of a 3 x 3 switch are discussed with the solution of the coupling equation for those guides.

System and Circuit Considerations for Integrated Industrial Fiber Optic Data Links

Abstract: This paper describes system and circuit considerations for transmit/receive integrated circuits meeting the requirements of industrial fiber optic data links. The integrated circuits are: TTL compatible, operate with arbitrary data format over the range from d.c. to a maximum NRZ data rate of 15 Mbits/s with a 10-9error rate at a minimum receiver detector current of 125 nA, have >55 dB electrical dynamic range and an automatic link monitor, operate from a single +5 V supply and are temperature and voltage compensated. These circuits utilize an internal pulse bipolar line coding to accommodate an arbitrary input signal format or, by switching a control input, an ON-OFF modulation for zero average TTL input signals operating above 2 Mbit/s data rate.

Spectral dependence of microwave power transmission in laser-controlled solid-state microstrip switches

Abstract: Laser-controlled solid-state microstrip switches using a gap and a shunt structure in tandem offer the advantage of employing optical sources over a wide spectrum range. The spectral response of such an optoelectronic switch is mainly determined by the spectral dependence of power transmission through the illuminated semiconductor gap region. The physical and electronic processes within the excited semiconductor region are analysed quantitatively with special regard to the required high-speed laser pulse excitation. The corresponding effects on the microwave power transmission of the switch are studied successfully by using a simple π equivalent circuit. This equivalent circuit consists of several gap and shunt conductances that depend on the incident optical energy and on the optical wavelength of the controlling laser pulses. The optical bandwidth of the device is discussed with special regard to the long-wavelength cutoff, which, in this case, is determined by the specific functioning of the switch rather than by the decrease in photosensitivity. The analytical results are specified for a high-resistivity silicon substrate used in the corresponding experiments. Theoretical and experimental results were found to agree fairly well.

Two-terminal optical sensor

Abstract: A two-terminal optical sensor circuit comprising a light-emitting diode, phototransistor, amplifier, and current source electrically and optically coupled so as to approximate an ideal switch in one quadrant of its V-I characteristic. A remote object is detected when it moves into the optical path between the light source and sensor.

Alignment system using two photocells directed at each other

Abstract: A passive optical switching apparatus for use with a sales display device, or with a secret security device or with a safety device. The apparatus includes two photo resistor systems which are positioned so that their optical axes and field of view intersect. Also included is the complementary electronic circuitry. If a light change occurs within the region defining the intersection a switching signal is created to trigger the device to which it is attached.

Optical switching device using leaky surface wave

Abstract: The decay constants of leaky surface waves in an indiffused LiNbO 3 Y -cut plane propagation can be controlled by electro-optic effect. According to our calculation, we can obtain about 20 dB/ cm optical switching devices for applied electric field of 3 V/μm. Our experiments show that optical switching of 14 dB/cm can be obtained for 300 V/150 μm.

Electro-optical switching apparatus

Abstract: An electro-optical switching apparatus which comprises at least an input photo-emitter circuit which lights up a switching matrix comprising a plurality of switching elements selected with two pluralities of crossed connections. Under the control of switching signals one of these elements turns on and allows the light to pass through. An image of this switching matrix is formed by a lens onto a matrix of photo-receiver circuits and the light transmitted through the turned on switching element induces in one of said photo-receiver circuits a transmitted switched signal.