Abstract: A microwave repeater with antenna isolation comprises a first receiving anna for receiving an input signal from a distant source; an amplifier section for amplifying and modulating the input signal to produce an output signal; a transmitting antenna coupled to the amplifier section; and an isolation control means including a second receiving antenna for isolating the first receiving antenna from the transmitting antenna. In one preferred embodiment, the second receiving antenna is aligned so as to match the gain and phase from the transmitting antenna to the first receiving antenna. The isolation control means comprises a phase shifter coupled to the second receiving antenna; and a power combiner having inputs coupled to the first receiving antenna and the phase shifter and an output coupled to the amplifier section. The power combiner receives the input signal from the first receiving antenna and a 180.degree. phased shifted signal from the phase shifter.

Abstract: An optical pulse generator for producing mode-locked optical pulses comprises: a beam splitter; first and second optical loops coupled together by the beam splitter so as to define a figure eight optical path in which a light beam propagating toward the beam splitter in one of the first and second optical loops is split by the beam splitter to form two light beams propagating in opposite directions around the other one of the first and second optical loops; a direction dependent loss element disposed in the first optical loop for reducing the intensity of light propagating in a predetermined direction around the first optical loop; a nonlinear element disposed in the second optical loop and having an intensity dependent nonlinear optical transmission characteristic; an optical gain medium disposed in a selected one of the first and second optical loops; coupling apparatus for coupling pump light into the selected one of said first and second optical loops having the gain medium, and for coupling mode-locked o

Abstract: A system and method for subtracting excess noise from a high sensitivity gyroscope system in which a laser diode array is focused into an Nd-doped active fiber. A resultant gyro signal is polarized, detected, and amplified. A noise signal is polarized, delayed, detected, and amplified such that the noise signal is polarized parallel to the gyro signal and delayed by a fiber delay, of a length equal to a length of a gyroscope fiber coil. The excess noise component in the amplified gyro signal is reduced by modulating the amplified noise signal with a portion of the amplified gyro signal and subtracting the amplitude-modulated noise signal from the amplified gyro signal to produce a reduced noise gyro signal.

Abstract: A fiber superfluorescent light source is disclosed which suppresses laser cillations without interfering with the pump light or the super luminescence. In a preferred embodiment of the invention, the fiber superfluorescent light source comprises a laser diode array for providing a pump beam at a wavelength of 0.81 microns, a first fiber doped with neodymium activator ions and being responsive to the pump beam for providing a spontaneous emission at a wavelength of 1.06 microns, and a second fiber optically coupled between the laser diode array and the first fiber for passing the pump beam therethrough to the first fiber to enable the first fiber to spontaneously emit light at the 1.06 micron wavelength and for suppressing backemissions of the 1.06 micron wavelength from the first fiber toward the laser diode array to prevent back reflection from the laser diode array and oscillations in the first fiber.

Abstract: A depolarized fiber optic gyroscope with a detector for detecting a rotat about an axis of rotation and a method therefor is disclosed. The gyroscope includes a depolarized light source for generating the depolarized light; a gyro coil for conducting depolarized light about the axis of rotation, the gyro coil including a coil of a non-polarization preserving fiber having first and second ends; a depolarizer with first and second ports for eliminating birefringence induced scale factor variations caused by the non-polarization preserving fiber, the first port of the depolarizer being coupled to the first end of the gyro coil; and a coupler device for coupling the second end of the gyro coil, the second port of the depolarizer, the detector and the depolarized light source, without utilizing a polarizer.

Abstract: A continuous wave(CW) activator ion doped fiber laser is presented which lases at a normally self-terminating laser transition at a slope efficiency greater than that achieved by a self-terminating fiber laser. Two laser transitions, one corresponding to a self-terminating laser transition and the other to a transition out of the lower level of the self-terminating transition, are simultaneously stimulated in the activator ion doped fiber. Through simultaneous lasing of the two wavelengths corresponding to these transitions, the lower level of the self-terminating transition is sufficiently depopulated so that CW operation is achieved.

Abstract: A method and apparatus for imaging an object that is part of, embedded in or viewed through a scattering medium is provided. A first broadband beam generator, such as a broadband pulse laser, provides a first broadband beam. A second broadband beam generator, such as a Raman Stokes generator disposed to receive the first broadband beam, generates a second broadband beam capable of correlation with the first broadband beam. A coherent anti-Stokes Raman scattering material is disposed to receive the second broadband beam after dispersion in the scattering medium. A variable delay path also illuminates the coherent anti-Stokes Raman scattering material with the first broadband beam. The coherent anti-Stokes Raman scattering material produces an anti-Stokes beam which contains an extracted image of an object in the scattering medium, which image is recorded on a photodetector.

Abstract: A single-polarization fiber optical amplifier and corresponding method is provided capable of amplifying an optical input signal by a fiber optic amplifier constructed of fiber which may be non-polarization-maintaining. The single-polarization fiber optical amplifier provides a direction-selective coupler which receives an optical input at a first port and outputs an optical output at a second port. A fiber optic amplifier is operatively connected to the direction-selective coupler at a bidirectional port for amplifying the optical input. A retro-reflecting orthogonal polarization converter is operatively connected to the fiber optic amplifier, reflecting the amplified optical input from the fiber optic amplifier in a return direction through the fiber optic amplifier and in an orthogonal polarization to the amplified optical input. The direction-selective coupler outputs the reflected amplified orthogonal optical input at the second port as the optical output of the direction-selective coupler.

Abstract: A pulse discharge laser is provided having a pair of electrodes disposed within a laser chamber pressurized with a high-pressure gas. A preionizer generator intermittently produces preionization energy to preionize the high pressure gas in the laser chamber. A pulse forming network intermittently supplies a ramping voltage to the pair of electrodes. When the high pressure gas in the laser chamber is not properly preionized by the preionization energy a damaging arc may occur and lasing will not occur by discharge of the ramping voltage on the electrodes. A passive electrode arc protector is provided connected across the pair of laser electrodes to discharge the ramping voltage across the electrodes when the high pressure gas is not properly preionized to protect the laser electrodes from a damaging arc between them.

Abstract: An apparatus comprised of a depolarized light source for fiber optic sensors is disclosed. In a preferred embodiment, the depolarized light source of the apparatus comprises: a first laser for generating a first beam at a first frequency, the first beam having a linear polarization state; a second laser for generating a second beam at a second frequency, the second beam having a linear polarization state; a means for rotating the polarization state of the second beam so that the first and second beams have orthogonal linear polarization states with respect to each other; and a means for combining the first beam with the polarization-rotated second beam to obtain a composite beam which is depolarized.

Abstract: In a preferred embodiment, a Tm.sup.3+ :YAG laser crystal and a Ho.sup.3+ :YAG laser crystal are placed within a reflective path of a laser cavity for intracavity pumping the Ho.sup.3+ :YAG laser crystal. The Tm.sup.3+ :YAG laser crystal emits a substantially 2.0 .mu.m laser emission after being resonantly end-pumped by a pump beam at a wavelength of about 785 nm and the substantially 2.0 .mu.m laser emission is used to pump the Ho.sup.3+ :YAG laser crystal. The intracavity-pumped Ho.sup.3+ :YAG laser crystal emits an output laser emission at substantially 2.1 .mu.m. The slope efficiency of the Ho.sup.3+ :YAG laser crystal output power is about 40% of the pump power absorbed by the Tm.sup.3+ :YAG laser crystal.

Abstract: The directly pumped holmium (Ho) quasi-two level laser of the invention comprises a directly pumped holmium laser having a host material doped with an amount of holmium ions sufficient to produce an output laser emission at a wavelength of about 2.1 .mu.m when the holmium laser is pumped by a pump beam at a wavelength of about 2 .mu.m and a pumping laser for producing the pump beam. In an exemplary embodiment, the pumping laser comprises a Cr,Tm:YAG laser pumped by a flashlamp.

Abstract: An apparatus for the time-gated optical examination of objects that are p of, embedded in or viewed through dense scattering materials is disclosed.

Abstract: A continuous wave modelocked laser is provided which generates output pul having a duration in the picosecond range at a repetition rate in the MHz to GHz ranges. The laser includes a laser cavity defined by spaced, opposed reflective member forming a reflective path therebetween; a host laser crystal disposed in the cavity; an acousto-optic modulator disposed between the host laser crystal and one reflective member for modulating the output of the host laser crystal; and a birefringent filter, disposed in the laser cavity between the host laser crystal and the one reflective member, for tuning the laser emission to any one of a plurality of wavelengths within a range between 1.86 .mu.m and 2.14 .mu.m. A pump source pumps the host laser crystal at a wavelength of substantially 785 nm. A collimating plano-convex lens is disposed so that the planar face thereof faces the laser crystal.

Abstract: A method and apparatus for imaging an object that is part of, embedded in, or viewed through a scattering medium is provided. A broadband stochastic beam generator, such as a broadband laser, generates a broadband stochastic beam and a narrowband beam generator generates a narrowband beam. A non-linear mixing crystal receives the broadband stochastic beam and the narrowband beam and provides a signal light beam conjugate correlated with the broadband stochastic beam to the scattering medium. A multiple-wave mixing cell is disposed to receive the signal light beam from the scattering medium. An adjustable delay path also illuminates the multiple-wave mixing cell with the broadband stochastic beam. A supplemental beam generator is also provided for also additionally illuminating the multiple-wave mixing cell with a supplemental beam having characteristics sufficient to satisfy phase matching with the material of the multiple-wave mixing cell.

Abstract: An optical system for end-pumping the gain medium of a three-level or a self-terminating solid state laser with the optical output from a wide aperture laser diode bar is disclosed. In a preferred embodiment, the optical system includes: a laser diode bar for emitting from an elongated emissive area thereof a bright light having a lateral divergence and a transverse divergence; and an optical assembly disposed between the laser diode bar and the three-level solid state laser for collecting and focusing the bright light into a relatively small high-intensity spot to end-pump the gain medium of the three-level or self-terminating solid state laser.

Abstract: A field-emitter-array device includes a substrate supporting thin-film las of conductive material and intervening thin-film layers of insulative material. The lateral edges of the thin-film layers form a field emitter array including a field-emitter edge electrode interposed between a pair of control electrodes. The control electrode edges produce a symmetric 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 thin-film conductive layers or external electrodes.

Abstract: A color center laser is provided with a crystal disposed within a longitudinally pumped cavity. Optics are provided to transversely excite the crystal. Both a circular lens and a cylindrical lens focus an auxiliary beam into the crystal of the color center laser to produce (F.sub.2.sup.+).sub.A color centers for lasing. The cylindrical lens is used to focus the auxiliary beam to a narrow focal line. The circular lens is used to adjust the length of the focal line. By adjusting the length of the focal line, an entirety of the pump beam is used for excitation. The lenses thus collimate and focus the focal line to a length within an active volume in the crystal of the color center laser essentially equal to a length of the crystal.

Abstract: A three-axis fiber optic vector magnetometer is provided for measuring both he direction and magnitude of a DC or low frequency magnetic field. The magnetometer includes an optical interferometer system including a sensing fiber arm disposed with three respective sensing portions perpendicular to one another and attached to a uni-directional sensor material. The interferometer system also includes a reference fiber arm and a laser light source for generating and introducing a laser light into both of the arms. Respective biasing devices generate a reference AC magnetic bias and a respective reference frequency in the three sensing portions. A detecting device detects a reference light signal from the reference fiber arm and the magnetically altered sensing light signal from the sensing fiber arm and forms an interferometer output signal.

Abstract: A field emitter array memory device having two or more collector electrod an extraction electrode, at least one deflector electrode, and at least one electron field emitter is disclosed. The field emitter array memory circuit has bias voltages for collector electrodes, for the at least one deflector electrode and for the extraction electrode. In a preferred embodiment of the invention, first and second input signal voltages selectively applied to first and second deflector electrodes selectively switch the flow of electrons emitted from an electron field emitter from a first collector electrode to a second collector electrode and vice versa. A latched memory output is also included. Electron flow from the electron field emitter to one of the first and second collector electrodes is maintained until a signal voltage is applied to a deflector electrode to cause the electron flow to deflect from one collector electrode to the other collector electrode.