Abstract: A white light interferometric fiber-optic gyroscope based on a rhombic optical path difference bias structure includes a laser, a rhombic optical path difference bias structure, a fiber coil and a photodetector. The white light interferometric fiber-optic gyroscope adopts an all-fiber structure to simplify the complexity of a gyroscope system and reduce the overall cost. A white light interferometric demodulation algorithm is used to realize linear output of rotation rate signals.

Abstract: A ring laser gyroscope comprises an optical block that defines an optical closed loop pathway; at least one mirror structure mounted on the optical block and in communication with the closed loop pathway; at least one volume Bragg grating mounted on the optical block and in communication with the closed loop pathway; and a pump laser in communication with the volume Bragg grating, the laser operative to emit a light beam at a selected incident angle such that the beam passes through the volume Bragg grating and overlaps with the closed loop pathway. The volume Bragg grating is operative as a gain medium to increase an optical power of the beam, and a pair of counter-propagating beams is produced within the closed loop pathway from the beam. The mirror structure and the volume Bragg grating are positioned and angled to reflect the counter-propagating beams around the closed loop pathway.

Abstract: An optical gyroscope includes, in part, an optical switch, a pair of optical rings and a pair of photodetectors. The optical switch supplies a laser beam. The first optical ring delivers a first portion of the beam in a clockwise direction during the first half of a period, and a first portion of the beam in a counter clockwise direction during the second half of the period. The second optical ring delivers a second portion of the beam in a counter clockwise direction during the first half of the period, and a second portion of the beam in a clockwise direction during the second half of the period. The first photodetector receives the beams delivered by the first and second optical rings during the first half of the period. The second photodetector receives the beams delivered by the first and second optical rings during the second half of the period.

Abstract: For secure wireless communications the sender device uses a rail encoder that outputs dual rail-encoded states of light in a time slot. The states of light dual rail-encode information according to a phase and/or intensity difference between the dual rails, and the rail-encoded states of light may further be converted to a polarization-encoded state. This may be implemented using at least two polarizing beam-splitters with at least one quarter-wave plate disposed therebetween; and/or with integrated waveguides that convert three optical inputs to two optical outputs that are input to a polarization rotator-combiner. The encoder may randomly define the polarization-encoded state such as by randomly selecting from a finite number of at least N=3 possible polarization rotations. The recipient device may use 2N parallel channels to decode the dual rail-encoded states of light, each channel comprising a detector configured to detect one of N possible polarization states.

Abstract: This invention describes a gyroscope using a fiber coil which is coupled using integrated on-chip 3×3 and 2×2 couplers in coplanar as well as non-coplanar (NCP) configuration along with photodetectors, light sources, and processing electronics using Si, SOI, and InGaAs-on-Si, and other substrates. In one embodiment, a high sensitivity gyroscope using a combination of 2×2 and 3×3 waveguide couplers is described. The signals from three photodetectors can be used to generate feedback signals to produce high sensitivity. Still in another embodiment, usage of multiple quantum well (MQW) waveguides is illustrated. MQW waveguides can be tuned to achieve phase modulation/correction in couplers.

Abstract: The present invention provides a simple means of demodulating optical signals, e.g. wideband M-ary orthogonal. The demodulator comprises an optical processor and a comparison module. The optical processor transforms M input optical signals into 2 log2(M) intermediary optical signals and the comparison module determines the logical representation of the input data based on log2(M) binary comparisons of the optical power of the intermediary signals. Example embodiments may be reconfigurable to receive optical signals using M-FSK, M-PPM, M-PolSK, and hybrid M-ary orthogonal modulation formats. Example embodiments also offer small size, weight and power consumption for both free-space and fiber optic environments as well as improved receiver sensitivity and reduced electron bandwidth requirements.

Abstract: Optical methods, devices, and systems for noninvasively detecting transient surface displacements in a neuron are disclosed. Methods, devices, and systems provided may employ a phase-sensitive optical low coherence reflectometer. In addition, surface displacements due to action potential propagation in neural tissues may be detected in some embodiments using back-reflected light. According to some embodiments, exogenous chemicals or reflect ion coatings are not required. Transient neural surface displacement of less then 1 nm in amplitude and 1 ms in duration may be detected and may be generally coincident with action potential arrival to the optical measurement site. The systems and methods may be used for noninvasive detection of various neuropathies such as retinal neuropathies. They may also be useful in detecting the effects of various pharmacological agents.

Abstract: An optical imaging apparatus based on optical frequency domain measurement (OFDM) collects scatter data at multiple locations within or on the DUT as a function of time. A light source launches light into a device under test (DUT) which scatters light at one or more locations along the DUT. A light detector detects a portion of light scattered at each of multiple locations along the DUT. Data is determined using OFDM data processing that corresponds to an amount of light collected at each of the multiple locations along the DUT as a function of time. The data is stored for each of the multiple locations along the DUT. User information is provided that indicates an amount of light scattered at each of the multiple locations along the DUT based on the stored time domain data. The OFDM processing permits fine time resolution (e.g., 0.1 picoseconds) that allows small optical delay distances (e.g., 30 microns) to be resolved and allows for accurate detection of small amounts of scatter (e.g.

Abstract: Passively biased fiber-optic Sagnac interferometric sensor architecture, for gyroscope and current sensor in particular, is disclosed. One embodiment uses a 3×3 coupler entirely made of circular polarization maintaining fiber that serves as a beam splitter and meanwhile a passive bias. An alternative is to use a 3×3 hybrid coupler consisting of two linear polarization maintaining fibers and one conventional single-mode fiber, with the former two connected in a common interferometric sensor circuitry, and with the latter one cut short at both ends to form matched terminations. Still another alternative is an integral unit of Faraday rotator, whose central part is a fiber-optic magneto-optic 45° rotator, with a “zero to fast” fiber-optic quarter wave plate attached to one side, and a “fast to zero” fiber-optic quarter wave plate to the other. Advantages of passive bias are simplicity in construction, no need of manual adjustment and operational stability.

Abstract: Systems and methods for performing vibration error suppression in a fiber optic gyro sensor. An example system includes a light source, a sensing loop assembly, a photo detector, and a processing component. The light source generates a light signal that is then modulated by the sensing loop assembly and applied to a fiber optic coil in the assembly. The photo detector receives a modulated light signal that is an output of the sensing loop assembly (coil) and generates an analog signal. The processing component converts the generated analog signal into a modulated digital signal, determines an average of the modulated digital signal, determines an intensity modulation amplitude based on the determined average of the modulated digital signal, and re-scales the modulated digital phase signal based on the determined intensity modulation amplitude.

Abstract: This invention discloses to a type of fiber gas lasers and fiber ring laser gyroscopes based on these fiber gas lasers. The fiber gas lasers comprise of excitation gases, optical resonator and excitation source, etc. The optical resonator is made by connecting two selected arms of a single mode fiber coupler to the two ends of hollow-core fiber to form a ring resonator. The hollow-core of the fiber is filled with excitation gases to act as gain medium. The fiber laser is simple to construct, lower cost, and has adjustable size and good amplification performance. The fiber ring laser gyroscopes based on this novel type of gas lasers can be applied on robotics, automobile navigation, etc.

Abstract: An optical return loss detecting device is provided for measuring the optical return loss (ORL) of a device under test (DUT). The detecting device comprises a light source, an optical isolator connected to the light source for preventing reflected light by the DUT entering the light source, a first optical coupler connected to the isolator, a second optical coupler connected to the first coupler and the DUT respectively, and a module communicating with the second coupler for performing test and calculation functions thereof.

Abstract: A fiber optic ring interferometer, such as an interferometric fiber optic gyro (IFOG), with a sensing loop doubler. The IFOG device includes a light source, a circulator in optical communication with the light source and a photo diode, an integrated optical chip (IOC) capable of splitting light emitted from the circulator into two paths each of which is capable of being modulated, the IOC further being capable of combining light from each of the two paths when light travels in a direction towards the circulator, a fiber coil, and a polarization maintaining (PM) combiner/splitter disposed in between the IOC and the fiber coil. The PM combiner/splitter operates to send light through the fiber coil a first time in a first polarization state and to subsequently send the same light a second time through the fiber coil in a second orthogonal polarization state, whereby light travels twice the distance compared to a single loop IFOG device and, as such, effectively doubles the LD product.

Abstract: A method of interrogating an optical coupler interconnected to a two beam interferometer, so as to determine an idealized output value, said optical coupler having at least three bidirectional external input/output ports, said method comprising the steps of: for each of said external input/output ports: inserting an optical signal into the port; measuring a corresponding output at each of said ports; forming summations of those corresponding outputs which, in an ideal coupler, would have equal intensities; and determining said idealized output value of said coupler from said summations.

Abstract: A phase and intensity modulated IFOG has a light source responsive to an intensity modulation signal for providing an intensity modulated light signal. A Sagnac interferometer has a fiber optic coil. The coil receives and circulates a clockwise and counter-clockwise beams. The Sagnac interferometer is responsive to an intensity modulated light signal at a first input port, and to a phase modulation signal at a phase modulation input terminal for outputting a non-reciprocal interference signal. A PSD detector system responds to the non-reciprocal interference signal and provides a demodulated bias signal. An intensity signal generator has an output that provides the intensity modulation signal. A phase signal generator provides the phase modulation signal to the phase modulation input terminal. The intensity signal generator and the phase signal generator have a common frequency.

Abstract: A rotational rate comparator for a fiber optic gyroscope has a 3.times.3 coupler and an evaluating computer to calculate the rotational rate from photodiode signals generated by the fiber optic gyroscope. An electrical circuit is provided that is independent of the evaluating computer, and embodies an algorithm for producing at least one signal that depends on the rotational rate as a function of the photodiode signals. When the rotational rate dependent signal exceeds at least one presettable limiting value the comparator supplies an output signal.