Abstract: A fiber optic sensor system for cancelling phase noise while it senses a measurand field is disclosed. The system includes circuitry for developing a light beam that is frequency modulated at a fundamental frequency. First and second unbalanced interferometers, having equal path imbalances, are responsive to the frequency modulated light beam for producing respective first and second optical outputs. Detection circuitry is responsive to the fundamental frequency, the second harmonic of the fundamental frequency, and the first and second optical outputs for producing a plurality of sine and cosine signals containing phase difference and phase noise components. A signal processor is responsive to the plurality of sine and cosine signals for cancelling the phase noise components and only producing output sine and cosine components of the difference in the phase shift between the first and second unbalanced interferometers.

Abstract: A field-emitter-array device includes layers of conductive material and irvening layers of insulating material. The lateral edges of the layers form a field-emitter array including a field emitter edge electrode interposed between a pair of control electrodes. The control electrode edges produce an electric field causing the flow of field emitted electrons to be substantially parallel to the plane of the control and field emitter edge electrodes. The direction of electron flow can be further controlled by additional electrodes in the form of additional conductive layers or external electrodes.

Abstract: A FET device for sensing a magnetic field, the FET device comprising: a semiconductor material having a source at a first position therein and receiving means at a second position therein for receiving charge carriers; bias voltage means for providing a bias voltage between the source and the receiving means to produce a movement of charge carriers between the source and the receiving means; a channel layer disposed within the semiconductor material between the source and the receiving means through which the charge carriers move as a function of the bias voltage and the magnetic field being sensed; a resistive gate disposed between the source and the receiving means and above the channel layer; a first resistive gate contact disposed in a first preselected position with respect to the source; a second resistive gate contact disposed in a second preselected position with respect to the receiving means; a resistive gate voltage means for providing a resistive gate bias voltage between the first and second resi

Abstract: A flashpumped, tunable, two-micron, solid state laser is disclosed in which laser spiking is suppressed. The solid state laser comprises: a laser cavity defined by a first reflective element and an output coupler reflective element to form a reflective path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material doped with preselected activator ions sufficient to produce a pulse of laser emission at a desired laser transition wavelength in a range between about 1.9 microns and about 2.1 microns when the crystal is optically excited to produce the laser emission; a pulsed flashlamp for optically exciting the laser crystal to produce a pulse of laser emission at the desired laser transition wavelength; a tuner disposed in the laser cavity between the laser crystal and one of the reflective elements for tuning the laser emission to the desired laser transition wavelength in the range of wavelengths between about 1.9 microns and about 2.

Abstract: A fiber optic Michelson interferometric sensor system with passive elimination of polarization fading and source feedback isolation is disclosed. In a preferred embodiment, an optical source provides light of a first polarization state to a polarization selective element. Output light from the polarization selective element passes through a length of optical fiber into a Michelson interferometric sensor which utilizes a Faraday rotator/mirror assembly, that is coupled to distal ends of sensing and reference arms of the Michelson interferometer, to provide for the passive elimination of polarization fading. The polarization selective element at the output of the optical source provides isolation of the optical source from the Michelson interferometer sensor.

Abstract: A simple analog phase tracking circuit used with an open-loop fiber gyrose is disclosed that imitates the operation of a true closed-loop gyroscope, by electronically generating a sinusoidal output which nulls the Sagnac phase shift. The nulling or tracking technique is based on the generation of sine and cosine dependent interferometric outputs from an open-loop gyroscope using dynamic phase modulation. Cross-multiplication of the outputs with electronically generated phase shift components and combining these signals obtained from the cross multiplication process produces a component which is dependent on the difference between the Sagnac phase shift and the electronically generated phase. By controlling the electronic phase shift, the output can be nulled. In this way, the phase tracking approach imitates the operation of a true closed-loop gyroscope and uses the simple structure of open-loop gyroscope. The scheme has a wide dynamic range, relatively low drift and short term noise.

Abstract: A laser system and method for producing a laser emission at a wavelength of substantially 2.8 microns and having a quantum efficiency of at least unity and a slope efficiency of about 36%. In a preferred embodiment of the invention, the laser system comprises a laser cavity defined by first and second reflective elements with one of the reflective elements operating as an output coupler; a crystal disposed in the laser cavity and having a GSGG host material doped with a preselected percent concentration of erbium, the GSGG host material and preselected percent concentration of erbium being selected so as to provide a quantum efficiency of at least unity by the .sup.4 I.sub.13/2 +.sup.4 I.sub.13/2 .fwdarw..sup.4 I.sub.9/2 +.sup.4 I.sub.15/2 upconversion process and a slope efficiency of about 36% when the crystal is resonantly pumped; and a resonant pump laser for directly pumping the .sup.4 I.sub.

Abstract: A communications system which decreases noise errors and increases informon rate without sacrificing bandwidth is formed by a transmitter and a receiver designed to handle long pulse compression wavforms. An encoder connected to the transmitter converts a voice message into digitized voice words, encodes the digitized voice words into the time shifted code sequences, and phase modulates the long pulse compression waveform, producing a M-ary coded signal at the output of the transmitter. The receiver is connected to a decoder which includes at least one convolver for computing the correlation of received digitally coded words with independently generated time shifted code sequences, and a controller for generating a plurality of data values according to the largest correlation values, and a transducer responsive to the data values.

Abstract: A field emitter structure is disclosed which comprises: a substrate selec from the group consisting of a semi-insulating substrate and an insulating substrate, the substrate having first and second surfaces and at least one hole therethrough; a first conducting layer disposed on the first surface of the substrate and having at least one aperture aligned with an associated at least one hole in the substrate, the at least one aperture of the first conducting layer comprising an extraction electrode; and a second conducting layer disposed on the second surface and projecting into the at least one hole in the substrate and into the at least one associated aperture of the first conducting layer and forming at least one associated apex inside the at least one hole, the at least one associated apex comprising an associated electron field emitter.

Abstract: A photoluminescence sensor for detecting a photoluminescent light from a toluminescent material is disclosed. In a preferred embodiment the photoluminescence sensor comprises: a source of light; a concave mirror having at least one perforation for passing the source light through the at least one perforation; an optical waveguide having proximal and distal ends with the photoluminescent material being disposed at the distal end; an objective for directing the source light into the proximal end of the waveguide; an objective for receiving photoluminescent light and for focusing the photoluminescent light onto the perforated concave mirror; a liquid filter for passing the photoluminescent light reflected from the perforated concave mirror to a detector to detect the photoluminescent light.

Abstract: An improved inline fiber optic sensor array is achieved by packaging a pllity of fiber optic sensor units such that each fiber optic sensor unit incorporates a complete functional sensor and adjacent fiber optic sensor units are separated by a delay element connected in series between each pair of fiber optic sensor units. Delay elements temporally separate measureand signals received from the individual fiber optic sensor units and permit decoupling of signals produced in response to environmental stress on the non-sensor unit portions of the array.

Abstract: An apparatus for generating a relatively high-power, modulated optical beam s disclosed. The apparatus comprises a first element for emitting a relatively low-power laser beam at a preselected wavelength, means for focusing the laser beam into a focused beam, a damage-resistant integrated optic modulator responsive to the focused beam for developing a modulated beam, optical means for shaping the modulated beam into a shaped modulated beam, and semiconductor means having a large active area responsive to the shaped, modulated beam for producing a relatively high-power, output modulated beam. In a first embodiment, the semiconductor means is a semiconductor amplifier which amplifies the modulated beam to produce the high-power, modulated output beam.

Abstract: An antiresonant nonlinear mirror to replace one mirror of a laser for passive modelocking of the laser, the antiresonant nonlinear mirror comprising: a beam splitter for coupling the mirror to a laser cavity; a mirror arrangement for defining an optical ring with the beam splitter in which two light beams produced by the beam splitter in response to a light beam from the laser cavity can counterpropagate around the ring; an intensity dependent anisotropic nonlinear element disposed within the ring; and a polarization sensitive element disposed within the ring for adjusting the birefringence thereof to produce spontaneous modelocking in the coupled laser cavity.

Abstract: A low pressure, low energy measuring device for indirectly and non-invasiy measuring the pressure of a gaseous medium in a sealed system, such as gas discharge lamp, is disclosed. The measuring device and method measures the luminance of an externally-induced, high-frequency glow discharge of a gas in the lamp by non-invasive means. Comparison of the measured luminance with calibrated luminance vs. pressure data provides the pressure for the gas. In one embodiment, the components of the measuring device form a stand-alone unit useful for testing multiple sealed systems. In another embodiment, certain components of the device are integrated into the lamp's discharge system to facilitate measurement in the field. A separate peripheral unit is required with this latter embodiment.

Abstract: A tunable solid state laser for producing a laser emission at any desired w or high laser gain transition in a predetermined range of wavelengths is disclosed. The tunable solid state laser comprises: a laser cavity defined by a first reflective element and an output coupler reflective element to form a reflective path therebetween; a laser crystal disposed in the laser cavity; means for optically exciting the laser crystal to produce a laser emission in the predetermined range of wavelengths; a tunable element disposed in the laser cavity between the laser crystal and one of the reflective elements for tuning the laser emission to any desired laser transition in the predetermined range of wavelengths; and a plurality of optical plates oriented at Brewster's angle in the reflective path in the laser cavity for suppressing oscillation of undesired wavelengths within the laser cavity, the optical plates being transparent to the laser emission over the predetermined range of wavelengths.

Abstract: A system and method for minimizing polarization-induced phase noise in an interferometric fiber sensor is disclosed.

Abstract: A room temperature solid state laser for producing a laser emission at a wavelength of substantially 2.09 microns is disclosed. In a preferred embodiment, the laser includes: a laser cavity defined by first and second reflective elements opposing each other on a common axis to form a path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material capable of accepting Cr.sup.3+ sensitizer ions, Tm.sup.3+ sensitizer ions and Ho.sup.3+ activator ions; an amount of Cr.sup.3+ sensitizer ions between about 0.3% and about 2% dispersed within the host material; an amount of Tm.sup.3+ sensitzer ions between about 3% and about 12% dispersed within the host material; and an amount of Ho.sup.3+ activator ions between about 0.1% and about 0.7% dispersed within the host material; and flashlamp and means for exciting the laser crystal to produce a laser emission at substantially 2.09 microns with a slope efficiency of at least 4%, and preferably of at least 5%.

Abstract: A laser system and method for producing a laser emission at a wavelength of ubstantially 2.8 microns is disclosed. In a preferred embodiment of the invention, the laser system comprises a crystal having a host material doped with erbium; a laser cavity defined by first and second reflective elements at opposing ends of the crystal to form a reflective path therebetween; and resonant pumping means for directly pumping the .sup.4 I.sub.11/2 upper laser state of the erbium with a pump beam at a preselected wavelength to cause the erbium-doped crystal to produce a laser emission corresponding to the .sup.4 I.sub.11/2 .fwdarw..sup.4 I.sub.13/2 laser transition having a wavelength of substantially 2.8 microns, a portion of the laser emission at substantially 2.8 microns being outputted from one of the first and second reflective elements.

Abstract: A microwave switch is provided for controlling the transmission of microw energy in a microstrip transmission line structure. The microwave switch comprises an electrically conducting ground plane in contact with one side of an undoped semiconductor material having on its other side a superlattice of gallium arsenide consisting of a periodic sequence of p- and n-doped gallium arsenide layers. P- and n-type regions are formed integral with and electrically connected to the superlattice, and first and second microstrip transmission lines are electrically connected to respective ones of the n- and p-type regions.

Abstract: A room temperature laser system for producing a CW Laser emission at substantially 2.7 microns is disclosed. In a preferred embodiment, the laser system comprises a laser diode source for producing a CW pump beam at a preselected wavelength; and a fiber laser doped with erbium activator ions to produce an output CW laser emission at a wavelength in the range of 2.71-2.78 microns when the fiber laser is pumped by the CW pump beam.