Abstract: An automatic gain control system for a fiber optic gyroscope control loop includes an adjustable gain applied to the gyro output signal. A pilot signal is injected into the fiber optic gyroscope control loop. A compensation loop receives signals output from the control loop and also receives pilot signals. The compensation loop processes the pilot signal to produce a compensation signal that is combined with signals output from the control loop to provide a compensated fiber optic gyroscope output signal. An automatic gain control loop is connected between the compensation loop and the adjustable gain applied to the fiber optic gyroscope output signal. The automatic gain control loop includes a gain error demodulator that multiplies the compensated fiber optic gyroscope output signal and the compensation signal together to produce a gain error signal used to control the adjustable gain in order to stabilize the gain of the gyro control loop.

Abstract: A fiber optic gyroscope signal process dither system permits application of a low amplitude dither signal for many sampling periods without increasing the noise in the sampled outputs due to residual dither signals. A dither loop and an accumulator are added to a closed loop fiber optic gyroscope rotation sensing system. The dither loop has a delay and a gain that are adjusted to match the gain and delay of the fiber gyro loop. A zero mean dither of amplitude sufficient to break up the deadband is injected into to gyro and the dither loop. The dither loop filters the dither signal in the same manner as the gyro loop to provide a signal that is input to a differencing circuit to remove the dither signal from the gyro output.

Abstract: A fiber optic gyroscope signal process dither system permits application of a low amplitude dither signal for many sampling periods without increasing the noise in the sampled outputs due to residual dither signals. A dither loop and an accumulator are added to a closed loop fiber optic gyroscope rotation sensing system. The dither loop has a delay and a gain that are adjusted to match the gain and delay of the fiber gyro loop. A zero mean dither of amplitude sufficient to break up the deadband is injected into to gyro and the dither loop. The dither loop filters the dither signal in the same manner as the gyro loop to provide a signal that is input to a differencing circuit to remove the dither signal from the gyro output.

Abstract: The present invention relates generally to an integrated optics encryption device. The preferred embodiment of the invention is an integrated optics encryption device comprising a coherent light source connected to a multi-functional integrated optics chip (MIOC). The MIOC comprises two divergent paths with mirrored ends. The MIOC also has an encrypted message output. One path is connected to a message signal input that can alter the refractive index of the path. The other path is connected to a key signal input that can alter the refractive index of the other path.

Abstract: An apparatus in one example comprises one or more light sources, one or more long period Bragg gratings that are optically coupled with the one or more light sources, and one or more amplification fibers that are optically coupled with the one or more long period Bragg gratings. The one or more light sources send one or more pump optical signals to one or more of the one or more long period Bragg gratings. The one or more of the one or more long period Bragg gratings transmit the one or more pump optical signals to one or more of the one or more amplification fibers. The one or more of the one or more amplification fibers absorb one or more of the one or more pump optical signals and emit one or more output signals. The one or more of the one or more long period Bragg gratings attenuate one or more of the one or more output signals.

Abstract: An apparatus in one example comprises one or more light sources, one or more long period Bragg gratings that are optically coupled with the one or more light sources, and one or more amplification fibers that are optically coupled with the one or more long period Bragg gratings. The one or more light sources send one or more pump optical signals to one or more of the one or more long period Bragg gratings. The one or more of the one or more long period Bragg gratings transmit the one or more pump optical signals to one or more of the one or more amplification fibers. The one or more of the one or more amplification fibers absorb one or more of the one or more pump optical signals and emit one or more output signals. The one or more of the one or more long period Bragg gratings attenuate one or more of the one or more output signals.

Abstract: A system and method for optically generating random numbers in a chaotic manner using an optical random number generator. The optical random number generator includes an optical interferometer having a chaotic output which is dependent upon temperature fluctuations in its surrounding micro-environment. The interferometer receives light from a light source, splits the received light between a pair of temperature-sensitive optical paths, and interferes the split light traveling on the pair of optical paths to generate an output signal. The power of the interferometer output signal is measured and compared with a threshold value in order to generate a random number based on the measured interferometer output power. Chaotic behavior in the interferometer output power is achieved by making the interferometer phase shift extremely sensitive to temperature fluctuations, where small changes in the temperature of the interferometer microenvironment will alter the output power of the interferometer.

Abstract: A system and method for optically generating random numbers in a chaotic manner using an optical random number generator. The optical random number generator includes an optical interferometer having a chaotic output which is dependent upon temperature fluctuations in its surrounding micro-environment. The interferometer receives light from a light source, splits the received light between a pair of temperature-sensitive optical paths, and interferes the split light traveling on the pair of optical paths to generate an output signal. The power of the interferometer output signal is measured and compared with a threshold value in order to generate a random number based on the measured interferometer output power. Chaotic behavior in the interferometer output power is achieved by making the interferometer phase shift extremely sensitive to temperature fluctuations, where small changes in the temperature of the interferometer microenvironment will alter the output power of the interferometer.

Abstract: Attenuation of an optical signal at the end of an optical fiber is achieved by positioning a high absorption region at the end of the fiber. A first embodiment teaches highly doped cylinders within a tapered end of the fiber. The highly doped cylinders adjacent the light transmitting core serves to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped cylinders are in proximity to the core due to the tapering. The cylinders, which are preferably heavily doped with a rare earth such as erbium, absorb the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface.

Abstract: Attenuation of an optical signal at the end of an optical fiber is achieved by positioning a high absorption region at the end of the fiber. A first embodiment teaches highly doped wedges within a tapered end of the fiber. The highly doped wedges adjacent the light transmitting core serve to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped wedges are in proximity to the core due to the tapering. The wedges, which are preferably heavily doped with a rare earth such as erbium, absorbs the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface.

Abstract: The optical interconnection apparatus includes one or more terminator blocks which hold a plurality of jacketed optical fibers and a flexible matrix which encloses the jacketed optical fibers and partially surrounds the terminator blocks so as to anchor the terminator blocks within the matrix. Each terminator block comprises a jacket holder and a jacket clamp. The jacket holder has a surface with a plurality of grooves for receiving a plurality of jacketed optical fibers. The jacket clamp clamps a plurality of jacketed optical fibers in the plurality of grooves of a jacket holder. The terminator blocks are used with a mold having one or more guide structures for use in guiding each of the terminator blocks into the mold, a terminator block having one or more guide followers which engage and follow the guide structures of the mold when the terminator block is inserted into the mold.

Abstract: Attenuation of an optical signal at the end of an optical fiber is achieved by positioning a high absorption region at the end of the fiber. A first embodiment teaches a highly doped annulus within a tapered end of the fiber. The highly doped annulus about the light transmitting core serves to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped annulus is in proximity to the core due to the tapering. The annulus, which is preferably heavily doped with a rare earth such as erbium, absorbs the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface.

Abstract: A fiber optic sensing coil formed in a polarization-maintaining optical fiber has two optical fiber leads extending therefrom. A multifunction integrated optics chip linearly polarizes optical signals input to the sensing coil. Fiber optic leads formed of polarization-maintaining optical fiber extend from the multifunction integrated optics chip. The fiber optic multifunction integrated optics chip leads are arranged such that the linear polarization of optical signals output from the multifunction integrated optics chip is directed along one of the principal axes of birefringence of each of the fiber optic multifunction integrated optics chip leads. Splices are formed between corresponding the first sensing coil leads and the multifunction integrated optics chip leads. The sensing coil leads and the multifunction integrated optics chip leads are arranged such that their corresponding principal axes of birefringence are at angles of approximately 45.degree. relative to one another.

Abstract: A method for modulating a fiber optic gyroscope achieves a reduction in output noise beyond that possible through increased peak power with conventional phase modulation. A periodic modulation waveform is applied to an electro-optic modulator, such as an MIOC, to induce a periodic phase shift .phi..sub.M (t) where the form of the periodic phase shift is chosen such that the gyro random walk is below that associated with maximum output signal modulation.

Abstract: Apparatus for suppressing the bias errors induced by the Faraday effect in the output of a sensor coil exposed to a magnetic field. Arrangements are formed at two leads of the sensor coil for compensating the bias shifts. One of such arrangements comprises at least one loop of optical fiber for compensating the effect induced by the magnetic field component oriented transverse to the axis of the sensor coil while the other comprises at least one loop oriented at a predetermined pitch angle for compensating the effect induced by a magnetic field component along the axis. In each case, a predetermined degree of twist of a preselected fiber twist mode is imposed upon the compensator loop for creating a counteracting, corrective Faraday effect. Cross-coupling does not occur between the two compensators as their twist rate perodicities are unequal.

Abstract: A fiber optic gyroscope is formed of two distinct sections, one having optical paths of low-birefringence fiber and the other having paths formed of polarization-maintaining (PM) fiber. The two sections are joined at a low-birefringence-PM fiber splice. The PM section includes at least one MIOC and an associated rotation sensing coil of PM fiber while the low-birefringence section includes the optical source, and associated couplers and detectors. The arrangement minimizes polarization fading and polarization non-reciprocity (PNR) bias error while allowing maximum use of lower cost and, in many cases, more durable, components to minimize overall system cost without loss of performance.

Abstract: An inexpensive fiber optic gyro using a fiber optic sensing coil that is fed from two single-mode light carriers such as an optical waveguide or optical fibre. The light carriers obtain their energy, through a mode splitter, from a double-mode light carrier. The double-mode carrier is, in turn, energized by an at least partially coherent light source through a single-mode light carrier. The light source is preferably a laser. Detectors are attached to light carriers which tap different predetermined positions along the double-mode waveguide to produce substantially sinusoidal signal functions of sensed rotation.

Abstract: Single and multiple axis fiber optic gyroscope systems employ orthogonal sequences to minimize the effects of both intra and inter-axis crosstalk. Sequences for driving electro-optic modulators are derived by examination of underlying primary and secondary demodulation sequences. Such underlying sequences are examined for orthogonality in accordance with a number of selection rules. When the selection rules are satisfied, the corresponding modulation sequences for driving the gyro(s) are identified and applied. By selecting the modulation waveforms in accordance with orthogonality criteria, one is assured of mean-zero bias errors within a predetermined number of loop transit times.

Abstract: Methods are disclosed for providing a rugged attachment of an optical fiber to an integrated optics chip. A first plate is attached to a first surface of the chip, the thickness of the chip is reduced to a value less than the diameter of the fiber but of sufficient optical thickness so that the evanescent field of a guided mode is negligible outside the chip, a second plate is attached to a second major surface of the reduced-thickness chip, the fiber is coaxially jacketed with a material suitable for attachment to the first and second plates, the fiber is positioned with respect to a waveguide on the chip, and the jacket of the fiber at its end face is symmetrically attached to both the first and second plates at a plurality of locations. Alternatively, a single plate can be attached to the first surface of the chip without reducing the thickness of the chip and either a jacket on the fiber or the curved periphery of the fiber itself can be attached symmetrically to both the plate and the substrate.

Abstract: An integrated optics chip which is the central module for an interferometric gyro. The invention configuration performs bias reduction, noise reduction, and improves scale factor linearity and repeatability. The chip is fabricated in an electro-optic material using conventional waveguide fabrication techniques, for example, titanium infusion into LiNbO.sub.3. Light propagating into the chip from a source is split equally between two legs which are coupled to optical fibers. Similarly light propagating in the legs may be coupled together and the combined signal coupled into an optical fiber.