Abstract: A narrow passband, reflective optical filter at a wavelength L, has a container filled with a pressurized gas, the pressurized gas having a ground state transition corresponding to the wavelength L and transparent to all other wavelengths. The container has at least one optically transparent major planar surface serving as the face thereof, whereby incoming broadband light is absorbed by the gas, except at its resonance wavelength L, which is specularly reflected. The optically transparent face of the container optionally has a broadband anti-reflective coating to improve its out-of-band rejection of unwanted wavelengths of the light signal.

Abstract: A method for coupling light from one or more light-emitting devices into corresponding optical fibers includes placing the light-emitting devices on the top surface of a substrate and forming, by photolithographical means, on the top surface of said substrate V-grooves for holding fibers in precise relationship with said light-emitting devices. Additionally, alignment pedestals or posts are formed on said substrate in predetermined relationship to the light emitting devices and alignment V-grooves are photolithographically formed on the top surface of said substrate parallel to said fiber V-grooves. The substrate is cleaved into two sections and said sections are assembled in orthogonal relationship with the section containing the light-emitting devices and alignment posts section being secured to the section containing the fiber and alignment V-grooves so that said posts fit into said alignment V-grooves, thereby aligning the fiber V-grooves with the light-emitting devices.

Abstract: A fiber optical Y-junction device includes a l.times.N optical fiber coupler connected to N fiber optic amplifier module structures constructed from a doped optical fiber. When the optical Y-junction structure contains a fiber optic amplifier, the fiber optical Y-junction device is operable as either a modulator or lossless power divider. A nonblocking optical switch is constructed by coupling M.times.l optical fiber couplers to the outputs of the fiber optic amplifier module structures utilizing the fiber optical Y-junction.

Abstract: A semiconductor optical amplifier includes an active region having facets at opposite ends thereof which define an optical cavity having maximum optical gain at a gain peak wavelength .lambda..sub.pk. An antireflection coating on each of the facets has a wavelength .lambda..sub.min of minimum reflectivity that is separated in wavelength from the gain peak wavelength, preferably by about 5 to 30 nanometers. The optical amplifier is operated at a bias current greater than a stimulated emission threshold bias current of the device. The input optical signal has a wavelength at or near the wavelength .lambda..sub.min of minimum reflectivity of the antireflection coatings. The optical amplifier has an electrical bandwidth on the order of 1 to 10 GHz.

Abstract: A method for coating finely divided material with titania is disclosed. The method involves the fluidization of the finely divided material in an inert carrier gas containing vaporized titanium isopropoxide. The isothermal fluidized bed is kept at a temperature equal to or below approximately 300.degree. C. The vaporized titanium isopropoxide reacts to form a coating of titania on the surfaces of the particles within the fluidized bed. The greatest coating efficiency occurs when the fluidized bed is kept at approximately 300.degree. C. for approximately the first 10 minutes of the reaction and thereafter at approximated 250.degree. C. The titania coating process is particularly useful for electroluminescent phosphors such as copper doped zinc sulfide phosphor. The titania coated electroluminescent phosphors are relatively insensitive to moisture. Lamps made from the coated electroluminescent phosphor are also relatively insensitive to moisture.

Abstract: A second-order predistortion circuit for linearizing a nonlinear device having a transfer function of the form F=C.sub.1 I.sub.1 -C.sub.2 (I.sub.1).sup.2, where I.sub.1 is a current applied to an input of the nonlinear device, and C.sub.1 and C.sub.2 are constants. The nonlinear device is typically a laser diode. The predistortion circuit includes a field effect transistor biased for square law operation. An input voltage is applied between the gate and source electrodes of the field effect transistor. An amplifier is connected between the drain electrode of the field effect transistor and the input of the nonlinear device. The gain of the amplifier is selected to minimize second-order distortion in the output of the nonlinear device as a function of the input voltage to the field effect transistor.

Abstract: In one aspect of the present invention a capacitor is placed in series with the ballast and the lamp. The capacitor lowers the impedance during lamp starting and is shorted out when final arc conditions of the lamp are reached. Method and device for improvement of lumen maintenance of high intensity discharge lamps through minimizing the wall blackening during lamp starting is disclosed. Reducing the electrode material sputtering during the thermionic arc phase of the lamp starting process was achieved by decreasing the cathode fall voltage. The cathode fall voltage in these lamps was decreased by increasing the current flowing through during the starting phase. The increase of starting current was achieved by increasing the open circuit voltage or by decreasing ballast impedance.

Abstract: A phosphor having a continuous protective bi-layer coating of alumina surrounding silica surrounding the phosphor particles is disclosed. The method of making a bi-layer coating on phosphor particles is also disclosed. The first layer surrounding the phosphor is silica. The second layer surrounding the phosphor is alumina. The bi-layer phosphor is useful in fluorescent lamps providing improved maintenance and brightness. The bi-layer phosphor can also be used in high color rendition lamps employing blends of phosphors.

Abstract: An electrodeless lamp may be formed with a capsule having a radiant energy transmissive material defining an approximately cylindrical enclosed volume having an external length less than 20.0 millimeters, and an outer diameter less than 8.0 millimeters. The enclosed volume is filled with a lamp fill excitable by a high frequency electromagnetic field to produce radiant energy. The small size capsule produces a particularly efficient, orientation tolerant arc discharge. The arc is then highly stable as to position, yielding a good optical source to design for. The temperature gradient is small, thereby yielding little thermal stress on the capsule. An electrodeless HID headlamp system may be formed with the efficient capsule from a radio frequency source operating from the power supply of a typical automobile. The headlamp system includes a high frequency power source, a transmission line, a coupler, an excitable lamp fill captured in a lamp capsule, a reflector and a lens.

Abstract: A junction field effect transistor having an array of electrically floating gate elements located between the control gate and the drain in the path of current flow from the source to the drain. As the drain voltage increases the depletion zone of the control gate expands until it reaches the nearest floating gate. The maximum electric field at the control gate is clamped while the nearest floating gate increases in potential and its depletion zone expands toward the next floating gate, and so on. In this way the applied voltage is spread over the array of floating gates clamping the maximum electric field at a value that is less than the avalanche breakdown field. Then, the avalanche breakdown voltage of the device is increased.

Abstract: A ceramic-metal article including a ceramic rod, a metal rod, and a braze joining the ceramic and metal rods at a braze area of a coaxial bore in the metal rod. The bore gradually decreases in diameter, having an inward seat area sized for close sliding fit about the ceramic, a larger brazing area near the joint end, and a void area intermediate the braze and seat areas. The ceramic is seated without brazing in the bore seat area. The side wall between the brazing area and the metal outer surface is about 0.030-0.080 inch. The braze includes an inner braze layer, an outer braze layer, and an interlayer about 0.030-0.090 inch thick. A shoulder between the brazing and void areas supports the interlayer during bonding while preventing bonding between the void area and the ceramic member, leaving a void space between the void area and the ceramic member. A venting orifice extends generally radially through the metal member from the outer surface to the void space.

Abstract: In the fabrication of a junction field effect transistor, specifically a static induction transistor, an epitaxial layer of high resistivity N-type silicon is grown on a substrate of low resistivity N-type silicon. A plurality of elongated parallel grooves separated by interposed ridges are formed by reactive ion etching. A layer of silicon oxide is grown on all exposed surfaces including the side walls and bottoms of the grooves. Fluorine is ion implanted into the silicon oxide. The grooves are filled with deposited silicon oxide or polycrystalline silicon, and material is removed to form a flat planar surface with the silicon at the surfaces of the ridges exposed. P-type doping material is ion implanted into alternate (gate) ridges. The wafer is heated to diffuse the P-type doping material and form gate regions. Heating also activates the implanted fluorine ions which react with unbonded silicon atoms at the silicon oxide-silicon interface thus quenching vacant bond sites.

Abstract: Apparatus for optical transmission of first and second digital channels. Each digital channel has first and second signal levels. The appparatus has a tunable laser for emitting an optical output at optical frequencies corresponding to current levels. Current responsive to the signal levels of the two channels provides current levels to cause the laser to emit a first optical frequency when the first channel has a second signal level and the second channel has a second signal level, a second optical frequency when the first channel has a first signal level and the second channel has a second signal level, a third optical frequency when the first channel has a first signal level and the second channel has a first signal level, and a fourth optical frequency when the first channel has a second signal level and the second channel has a first signal level. An optical transmission medium is coupled to the output of the laser. A tunable optical filter is coupled to the optical transmission medium.

Abstract: Lanthanum cerium aluminate phosphor compositions are disclosed wherein the formula for the phosphor can be characterized as follows:La.sub.1-x Ce.sub.x Al.sub.y O.sub.(3/2)(y+1)wherein 0<x<1 and 11.ltoreq.y.ltoreq.13.8.

Abstract: A photonic time-slot interchanger with fiber-loop delay-line memories is provided with multistage, cascade-structured integrated optical switches in the write-in, store and circulate and read-out functions to provide improved signal-to-crosstalk ratios and control tolerances, and to increase significantly the number of time slots supported by the improved interchanger.

Abstract: An optical preamplifier includes a semiconductor optical amplifier monolithically integrated with an optical detector and electrically isolated from the detector by an isolation region. The isolation region consists of a low-loss, preferably transparent, insulating material whose index of refraction is matched to at least the refractive index of the amplifier, leading to reduced facet reflectivity at the amplifier output facet. Alternative device structures may include a waveguiding layer in the isolation region, a grating integrated with or following the optical amplifier, and a tuning region positioned between the amplifier and isolation region for filtering spontaneous emission.

Abstract: A fuel cell which converts chemical energy from a fuel/oxidant gas mixture to electricity for power usage or gas-sensing applications is disclosed. The fuel cell has a solid electrolyte wall with electrodes on each side. Each side of the wall is surrounded by a partition which forms a first and second chamber whereon the fuel/oxidant gas mixture is allowed to diffuse. Means are provided to initiate a voltage drop between the electrodes which initiates the chemical reaction. Electricity is collected from the electrodes. In an alternate design the fuel cell has a first and second electrolyte wall with electrodes on each side of the walls. A partition wall separates the first and second walls thereby forming a first chamber with the first wall and the partition wall and a second chamber with the partition wall and the second wall. Gas-flow limiting means exist between the fuel/oxidant gas mixture and the first chamber and the first chamber and the second chamber.

Abstract: Optical communication methods and apparatus are disclosed for transmitting two or more optical signals with different optical carrier frequencies on a single optical fiber with high spectral efficiency. Each optical carrier is typically modulated with multiple modulated subcarriers. In one embodiment, an optical phase modulator provides cancellation of second order intermodulation products in each optical signal, thereby permitting the optical carrier frequencies to be spaced by 2f.sub.max, where f.sub.max is the maximum modulation frequency. In another embodiment, a single sideband optical phase modulator provides cancellation of second order intermodulation products and one signal sideband, thereby permitting the optical carrier frequencies to be spaced by f.sub.max. Quadrature optical phase modulators for simultaneous transmission of two independent baseband digital data signals or two independent subcarrier multiplexed signals are disclosed.

Abstract: Apparatus for optical transmission of first and second digital channels. Each digital channel has first and second signal levels. The apparatus has a tunable laser for emitting an optical output at optical frequencies corresponding to current levels. An input which provides a current responsive to the signal levels of the two channels provides current levels to cause the laser to emit a first optical frequency when the first channel has a first signal level and the second channel has a second signal level, a second optical frequency when the first channel has a first signal level and the second channel has a first signal level, a third optical frequency when the first channel has a second signal level and the second channel has a first signal level, and a fourth optical frequency when the first channel has a second signal level and the second channel has a second signal level. An optical transmission medium is coupled to the output of the laser. A local oscillator provides a LO frequency.

Abstract: Electrical ohmic contacts are made to a matrix of silicon having conductive rods embedded therein without making contact to any of the rods. Those rods which extend to the surface in the selected area of the matrix to be contacted are etched to form holes. The holes are filled with insulating polycrystalline silicon. The region of the selected area is heavily doped, and an ohmic contact member is made thereto. The underlying rods are spaced from the ohmic contact member and the heavily-doped region by intervening polycrystalline silicon.