Gte Laboratories Incorporated

William H McNeill

Paul O Haugsjaa

Robert J Regan

Joseph Martin Lech

Joseph M Proud

Alfred E Feuersanger

Yung J Chen

Jerry Martin Kramer

Leslie A Riseberg

Richard A Bessett

William F Nelson

Yung-Jui Chen

Gary M Carter

An optical device used as an optical switch or bistable device, with surface plasmons, is comprised of a semiconductor base material forming a non-linear dielectric layer along with a metal layer, with an interface between the metal and semiconductor layers including a submicron grating. The device is optically excited from a light source of given intensity. In accordance with the invention, dispersion relation of surface plasmons may be changed by varying the intensity of an input laser so as to provide bistable or hysteresis effect switching. The concepts of the invention may be implemented in either an unadorned device as set forth, or may be fabricated in an optical waveguide.

Optical device with surface plasmons

An electrooptic device for controlling the intensity of a monochromatic light beam comprises a first transparent element such as a triangular prism or hemicylindrical prism having a planar surface. A thin layer of a material such as a metal is in contact with the planar surface of the transparent element and a semiconductor material is adjacent to the metal layer. A voltage source provides a potential difference between the metal layer and the semiconductor material to alter the charge density in the semiconductor material to affect the degree of coupling between the light beam entering the device and surface plasmon waves generated within the device to correspondingly control the intensity of the light beam exiting the device.

High frequency light modulation device

An electrooptic device for controlling the intensity of a monochromatic light beam comprises a transparent element having opposed planar surfaces operable to reflect a collimated light beam alternately from the two surfaces. A plurality of semiconductor structures contact one surface of the device at regions where the collimated light beam reflects from that surface. Each semiconductor structure includes a thin layer of a material such as a metal in contact with the planar surface of the transparent element and a semiconductor material adjacent to the metal layer. A voltage source provides a potential between the metal layer and the semiconductor material of each structure to separately alter the charge density in the semiconductor material of each structure to affect the degree of coupling between the light beam entering the device and surface plasmon waves generated within each structure. The device is operable as a signal mixer or an optical logic switching device.

High frequency light modulator

A light source including two high intensity discharge devices, such as metal vapor discharge tubes, electrically coupled in parallel to provide fast restart and immediate illumination after a momentary power interruption. Upon application of power, one of the discharge devices starts and operates while the other discharge device remains below its maximum starting temperature and in readiness for immediate restart. The discharge devices can be enclosed by a common outer envelope. The discharge devices can alternatively be high pressure electrodeless lamps coupled in parallel to provide fast restart.

High pressure discharge lamps with fast restart

An electromagnetic discharge apparatus has a power coupling fixture which couples power to both ends of an electrodeless discharge vessel and produces a substantially uniform arc. Power can be coupled to the fixture from two high frequency power sources or can be coupled from a single high frequency power source by using a power divider. If power is coupled to the electrodeless discharge vessel from a single source, power transfer to the vessel is optimized when the electrical length of the circuit is an integral number of wavelengths. In an alternative embodiment, a second coupler is utilized in a conventional electrodeless light source to shape the electric fields and produce a more uniform arc.

Electromagnetic discharge apparatus with double-ended power coupling

An electrodeless lamp apparatus includes an electrodeless, light-transmitting, envelope for housing a rare-earth compound fill, and a termination fixture, electrodelessly coupled to the envelope, adapted to create an electrical condition for exciting the fill.

Electrodeless light source having rare earth molecular continua

A light source includes an electrodeless lamp having a generally cylindrically shaped envelope made of a light transmitting substance. A volatile fill material, enclosed within the envelope, emits light upon breakdown and excitation. A termination fixture has an outer conductor disposed around its inner conductor, both conductors having a first end which couples power to the lamp and a second end coupled to an alternating current power source. A first end of conductive means is coupled to the first end of the inner conductor, a second end of the conductive means being open-circuited. The conductive means has an electrical length whereby axial electric field maxima and minima occur thereon. The envelope is oriented centrally and axially within the conductive means so that an axial, non-toroidal arc occurs within the envelope, but does not attach to its interior walls, thereby enhancing the life of the lamp. The conductive means can be formed in a helical or spiral configuration. The spiral configuration can take various forms, such as constant or continuously varying. A small spherical conductor can be affixed to the second end of a helical conductive means to inhibit electrical breakdown from an otherwise sharp end. A power source operates at a frequency having a wavelength .lambda..sub.o. The discharge is contained in an envelope (having an internal length substantially n halves of an axial wavelength .lambda..sub.z) centrally located within the spiral conductive means. Axial electric field minima occur distances 2n.lambda..sub.z /4 from the open circuited end of the conductive means (i.e., at the ends of the envelope) and an axial non-toroidal arc occurs within the envelope but does not attach to its interior wall. If the outer conductor circumferentially surrounds the spiral conductive means and the envelope therewithin to form a cylinder having a radius b, and the spiral conductive means includes a coil having a radius a and a constant pitch p then ##EQU1## With certain designs, a plurality of arcs can occur within the envelope. An electrodeless lamp having a generally cylindrically shaped envelope with an internal length n.lambda./2 (wherein n is a positive integer) can be excited by providing an electric field consisting of a voltage standing wave with points of axial electric field minima separated from each other by a distance .lambda./2, and orienting the lamp with respect to the field so that the opposed ends of the lamp are aligned with different points of the axial electric field minima, so that an axial, non-toroidal arc occurs within the envelope but does not attach to its interior wall.

Methods of and apparatus for electrodeless discharge excitation

A tunable frequency pulse generator capable of providing high energy pulses having an in-line construction includes an annularly shaped spark gap and a movable insulator support which includes a conductive sleeve that varies the resonant frequency of the generator. The input voltage is connected to the resonant element through a central aperture provided in the spark gap rings for high efficiency operation.

Tunable radio frequency pulse generators

A solid state microwave power source for providing microwave power to excite an electrodeless lamp is designed so as to provide an acceptable impedance matching characteristic during lamp warm-up when the lamp impedance is high and changing with temperature to provide sufficient power to the lamp during the running state when the lamp impedance is matched to the source. The microwave power source includes a dc power source providing power at variable levels, a microwave oscillator receiving the dc power to produce a microwave signal, and a microwave power amplifier. The oscillator has a transistor in a common base configuration, a microstrip capacitive feedback element to sustain oscillations, and an output impedance matching arrangement formed from microstrip. The microwave signal is amplified in the solid state power amplifier having a power transistor in a common base configuration. An impedance matching section between the amplifier and the input of a termination fixture for the lamp includes a length of transmission line which transforms the input impedance of the fixture to a level at the collector of the power transistor in the amplifier so as to maximize the power delivered to the lamp at reduced power levels while maintaining the collector voltage within a safe limit.

Solid state microwave power source for use in an electrodeless light

A half wavelength resonant cavity having inner and outer coaxial conductors is coupled at one end to a dc power source, and a gas discharge electrodeless lamp is disposed in the region between the conductors at the other end of the cavity. Repetitive bursts of radio frequency oscillations occur within the cavity, the oscillations causing breakdown of the fill material within the lamp to produce light.

DC powered microwave discharge in an electrodeless light source

A starting assist control circuit for an electrodeless light source in which a UV source for assisting in starting an electrodeless lamp is coupled in series with the DC supply for a microwave power source for the lamp so that a reduced DC voltage is supplied to the microwave power source at lamp starting. An electronic circuit is provided which continuously decreases the DC current through the UV source and increases the DC voltage for the microwave power source in relation to the amount of light generated by the electrodeless lamp. More specifically, the emitter and collector of a transistor are coupled across the UV source to provide a shunt path and the potential of the base of the transistor is controlled by a photosensitive resistor which senses the amount of light from the lamp. As the lamp generates increased light, the transistor becomes more conductive, thereby continuously decreasing current to the UV source and increasing voltage to the microwave power source.

Continuous automatic starting assist UV circuit for microwave powered

A starting assist control circuit for an electrodeless light source in which a UV source for assisting in starting an electrodeless lamp is coupled in series with the dc supply for a microwave power source for the lamp so that a reduced dc voltage is supplied to the microwave power source at lamp starting. At staring, a capacitive impedance element is coupled across the inner and outer conductors of the fixture to provide an additional starting assist by creating a condition of resonance in the fixture. A heat responsive bimetallic switch element associated with both the capacitor and the UV source automatically shorts out the UV source and decouples the capacitor after the lamp has started thereby permitting full dc power to the microwave power source during the operating condition of the lamp.

Automatic starting system for solid state powered electrodeless lamps

In a light source excited with power at a high frequency, an electrodeless lamp is located in a termination fixture comprising an inner and outer conductor, the lamp being located at the end of the inner conductor. An internal tuning element is located within the fixture for creating a resonant condition when the lamp is to be started to create a maximum electric field for initiating breakdown and excitation of the fill material within the lamp. The tuner may comprise a variable capacitance coupled in parallel across the conductors at the power input end of the fixture or a variable inductance connected across the conductors at the lamp end of the fixture.

Internal match starter for termination fixture lamps

A light source includes a source of high frequency power, an electrodelsss lamp and a termination fixture for coupling power to the lamp, the fixture having an outer conductor and an inner conductor whose length is adjustable for providing dynamic matching of the impedance of the lamp during the operating mode to the output impedance of the source. Variations in the power level from the source, such as is desirable in providing lamp brightness selectivity, vary both the real and imaginary components of the lamp impedance, and corresponding adjustments of the inner conductor length provide a tuning technique to compensate for these variations.

Adjustable length center conductor for termination fixtures for

An electrodeless lamp is excited by high frequency power in a termination fixture having an inner and an outer conductor, the lamp being located in the high field region at the end of the conductors. A source of ultraviolet radiation is located near the lamp and is activated momentarily when the lamp is to be excited. The radiation assists in initiating breakdown and excitation of the fill material in the lamp.

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Carlisle, MA, United States of America

William H McNeill