Abstract: Multiple resonator fiber optic gyroscope (RFOG) configurations comprising one or more mode filters inside the resonator are adopted to effectively suppress unwanted high order spatial modes which can be a significant source of gyro bias errors. The resonator comprises at least a loop fiber, either two or more in/out coupling elements, and connectors that link elements into a circulating loop. Directional elements may be used to separate output light from input light in some of the embodiments. In all embodiments, mode filters are placed in the resonator to guarantee that the light reaching the photodetector is filtered by at least one mode filter in the resonator at least once. The mode filters may contain both spatial mode filters (such as single mode fibers or waveguides) and polarization mode filters (such as polarizing elements) so that both spatial and polarization mode filtering can be implemented simultaneously.

Abstract: A device and a method for suppressing 2nd order harmonic distortion in a Resonator Fiber Optic Gyroscope includes driving a laser to generate at least one of a plurality of counter propagating laser beams traveling through a fiber optic resonator according to a modulated signal. The modulated signal can be represented by a polynomial having two terms, and each of the two terms is suitably multiplied by a coefficient and a constant. A modulation amplitude adjuster amplifies the modulation signal by an amplification factor as it is used to drive the laser. When the amplification factor is suitably chosen to represent a square root of a ratio of the constants, the total harmonic distortion in the RFOG is minimized.

Abstract: A method, implementable in a resonator fiber optic gyroscope (RFOG) having a first wave generator configured to produce a first resonance-detection modulating signal at a fundamental resonance frequency, includes generating with at least a second wave generator a second modulating signal at an even harmonic of the first modulating signal. The second signal is amplitude-modulated (AM) at a frequency that is harmonically unrelated to the first signal. The first signal is added to the second signal with a summing element to produce a resonator output bias error signal. An optimum amplitude is determined from the error signal. Subsequently, the amplitude of the first signal is controlled to the optimum amplitude.

Abstract: Systems and methods for performing modulation error correction. An example system applies common phase/frequency modulation to first and second laser beams, a first intensity modulation to the first modulated beam, and a second intensity modulation to the second modulated beam. Signals outputted are demodulated according to the frequency of the common phase/frequency modulation. Then the first of these demodulated signals is demodulated based on the frequency of the intensity modulation of the first beam, and the second of these demodulated signals is demodulated based on the frequency of the intensity modulation of the second beam. Then, rate of rotation is determined based on demodulated signals. Frequencies of the intensity modulations are unequal and not harmonically related, and intensity modulation encodes each light beam with a unique signature.

Abstract: A device and a method for suppressing 2nd order harmonic distortion in a Resonator Fiber Optic Gyroscope includes driving a laser to generate at least one of a plurality of counter propagating laser beams traveling through a fiber optic resonator according to a modulated signal. The modulated signal can be represented by a polynomial having two terms, and each of the two terms is suitably multiplied by a coefficient and a constant. A modulation amplitude adjuster amplifies the modulation signal by an amplification factor as it is used to drive the laser. When the amplification factor is suitably chosen to represent a square root of a ratio of the constants, the total harmonic distortion in the RFOG is minimized.

Abstract: Substantially symmetric RFOG configurations for rotation rate sensing using two input/output coupling components. Configurations are disclosed where optical coupling components handles both input and output lightwaves. Reducing the number of input/output coupling components while maintaining a substantially symmetric configuration for the CW and CCW beam reduces losses, prevents realization of bias errors due to asymmetric light paths in the resonator, and produces better signal to noise performance. In addition, the invention discloses systems integrating multiple functions into compact micro-optic devices that are easier to fabricate and package, leading to compact RFOGs with reduced cost and improved manufacturability.

Abstract: Systems and methods for reducing intensity modulation-induced rotation rate measurement error in a resonator optical gyroscope. The method includes tapping an intensity modulated light beam, directing a portion of the tapped light beam toward a photo detector, outputting from the photo detector a signal proportional to the amplitude variation of the light beam, amplifying the signal, and then providing the signal to the intensity modulator as a control input. Intensity modulation-induced error is reduced by an amount proportional to the gain of the feedback loop.

Abstract: Systems and methods for reducing rotation sensing errors in a resonator fiber optic gyroscope. An example method propagates a primary light wave through a resonator having an optical fiber and a plurality of optical surfaces for directing the light wave exiting a first end of the optical fiber back into an opposite end of the optical fiber. The optical fiber is wound onto a piezo-electric transducer (PZT) tube. A sinusoidal voltage is applied to the PZT tube to modulate a length of a fiber cavity within the optical fiber. The amplitude and frequency of the fiber cavity length modulation is selected to produce a relative phase modulation between the primary light wave and a double-back reflected light wave, such that the rotation sensing errors resulting from double backscatter of light is at a frequency above a frequency band of interest. This allows the associated error to be filtered out of the rotation rate signal.

Abstract: Improved optical alignment precision to a passive optical cavity is provided by including a combination of a weak focusing element and a translation plate in the input coupling optics. Adjustment of positions and angles of these optical elements, preferably after all other input optical elements are fixed in place, advantageously provides for high-precision optical alignment to the cavity, without requiring excessively tight fabrication tolerances. Fabrication tolerances are relaxed by making the optical power of the weak focusing element significantly less than the optical power of a strong focusing element in the input optics. The position and angles of the beam with respect to the cavity can be adjusted, as can the size of the beam at the cavity. Differential adjustment of the beam size in two orthogonal directions (e.g., tangential plane and sagittal plane) at the cavity can also be provided.

Abstract: Apparatus is provided for a fiber optic gyro. The fiber optic gyro includes a ring resonator having first and second counter-propagating directions. The ring resonator includes a coil having an axis and an optical fiber having a hollow core. The ring resonator is configured to produce a first resonance frequency when a first light beam circulates through the hollow core in the first counter-propagating direction and produce a second resonance frequency when a second light beam circulates through the hollow core in the second counter-propagating direction. A difference between the resonance frequencies indicates a rotation rate of the fiber optic gyro about the axis.

Abstract: An optical coupling device for connecting hollow core optical fiber coils in a fiber optic gyro system. An example fiber optic gyro system includes a recirculator or an integrated optics chip, a fiber coil of hollow core optical fiber with first and second ends, and a coupling device that holds an end of the hollow core optical fiber in an enclosed cavity at some predefined distance from the recirculator or integrated optics chip. The coupling device includes a housing for rigidly holding the fiber end in position. The housing includes a cavity that receives the fiber end.

Abstract: A fiber optic gyroscope includes first and second gyroscopes. The first gyroscope includes: a first light source for emitting two lights; a first optical fiber loop which includes a sensor coil structured such that an optical fiber is wound in a multilayer manner, through which the two lights travel in opposite directions, and which constitutes a laser resonant circuit with the first light source; and a first optical detector for detecting an angular velocity based on a beat frequency which is produced by the two lights. The second gyroscope includes: a second light source for emitting light; an optical distributor for dividing the light into two lights; a second optical fiber loop through which the two lights travel in opposite directions and enter both respective ends of the sensor coil; and a second optical detector for detecting an angular velocity based on a phase difference between the two lights.

Abstract: A semiconductor ring laser gyroscope includes: a semiconductor laser for emitting two lights from both end surfaces thereof; an optical fiber ring through which the two light propagate in the respective opposite directions, which, in association with the semiconductor laser, constitutes a laser resonator, and which includes a sensor coil made of an optical fiber wound in a multilayer manner; and an optical detection unit for detecting a rotational angular velocity based on beat frequencies of the two lights, wherein an expression: 2?Fbeat—max<Frlg?10?Fbeat—min is satisfied in which Frlg=C/nL, where ?Fbeat—max and ?Fbeat—min are beat frequencies corresponding respectively to the upper and lower limits of an angular velocity measuring range, Frlg is a ring resonance frequency, C is a light speed, n is a refractive index of the optical fiber, and L is an overall length of the optical fiber.

Abstract: An improved resonator fiber-optic gyro (RFOG). An example RFOG includes a closed-coil resonator where counter-propagating laser beams are done by fiber couplers. Signals are extracted from the ring resonator using other fiber couplers. The fiber couplers may be fiber spliced couplers, free-space fiber-to-fiber coupling elements or comparable coupling devices. A silicon structure may be used to align components of the gyro or just the coupling elements. The resonator includes a hollow-core fiber.

Abstract: Systems and methods for performing modulation error correction. An example system applies common phase/frequency modulation to first and second laser beams, a first intensity modulation to the first modulated beam, and a second intensity modulation to the second modulated beam. Signals outputted are demodulated according to the frequency of the common phase/frequency modulation. Then the first of these demodulated signals is demodulated based on the frequency of the intensity modulation of the first beam, and the second of these demodulated signals is demodulated based on the frequency of the intensity modulation of the second beam. Then, rate of rotation is determined based on demodulated signals. Frequencies of the intensity modulations are unequal and not harmonically related, and intensity modulation encodes each light beam with a unique signature.

Abstract: An optical coupling device for connecting hollow core optical fiber coils in a fiber optic gyro system. An example fiber optic gyro system includes a recirculator or an integrated optics chip, a fiber coil of hollow core optical fiber with first and second ends, and a coupling device that holds an end of the hollow core optical fiber in an enclosed cavity at some predefined distance from the recirculator or integrated optics chip. The coupling device includes a housing for rigidly holding the fiber end in position. The housing includes a cavity that receives the fiber end.

Abstract: An optical waveguide gyroscope includes at least one optical coupler configured to receive a first optical signal at a first port, to transmit a second optical signal to a second port, and to transmit a third optical signal to a third port. The optical waveguide gyroscope further includes a plurality of resonant waveguides optically coupled to the second port and the third port. The resonant waveguides are generally adjacent to one another and optically coupled to one another. At least a portion of the second optical signal propagates from the second port to the third port by propagating through the plurality of resonant waveguides, and at least a portion of the third optical signal propagates from the third port to the second port by propagating through the plurality of resonant waveguides.

Abstract: An integrated optical circuit includes a first waveguide portion of a first material. The first waveguide portion includes an input-port section terminating in a junction section from which first and second branch sections are formed. Second and third waveguide portions are respectively coupled to the first and second branch sections. The second and third waveguide portions are diffused with a second material different from the first material. First and second modulators are respectively coupled to the second and third waveguide portions. Each of the modulators provides respective modulating voltages generating respective electric fields. The second and third waveguide portions are coupled to the first and second branch sections at respective locations where the electric fields are substantially zero.

Abstract: A laser gyro of the present invention includes laser light excitation means (a semiconductor laser device 100) that excites first and second laser lights propagating in the opposite directions to each other in a circular ring-shaped path (an optical path 40), coupling means (optical waveguides 41 and 42) for superimposing the first and the second laser lights, and a photodetector for observing an interference signal generated by the superimposed first and second laser lights.

Abstract: Methods and apparatus are provided for a low cost optical gyro using thin film waveguides to direct light beams among the components of the gyro. The gyro includes a substrate having an insulator layer, a silicon waveguide formed on the insulator layer, and a resonator coupled to the silicon waveguide and configured to circulate a portion of a first light beam in a first counter-propagating direction and circulate a portion of a second light beam in a second counter-propagating direction. The first silicon waveguide propagates the first and second light beams therethrough. Each of the first and second light beams has a resonance frequency when circulating in the resonator.

Abstract: Methods and apparatus are provided for attenuating rotation rate errors in a resonator gyro. The gyro includes a ring resonator having a hollow core optical fiber coil and optical elements that are selected and/or oriented to reduce stray light that may be present in input light beams introduced to the ring resonator. The resonator has a predetermined mode. One of the optical elements partially transmits a portion of the input light beam to a first end of the fiber coil while partially transmitting a portion of the input light beam to a filter. Light having the predetermined mode is accepted into the first end of the fiber coil, and the filter accepts light of the input light beam having a corresponding mode. Transmission components of the circulating light beams indicates resonance peaks of the counter-propagating directions of the ring resonator.

Abstract: An apparatus for detecting rotation and a method for constructing the apparatus are provided. The apparatus comprises an optical fiber having a hollow passageway therethrough, a laser medium within the hollow passageway and interconnecting the first and second portions of the hollow passageway, and first and second electrodes contacting the laser medium such that when a voltage is applied across the first and second electrodes, the laser medium is excited such that the laser medium emits laser light through the hollow passageway.

Abstract: Methods and apparatus are provided for determining the rotational rate of an optical gyro. An optical gyro comprises at least one substrate, a multi-frequency light source (MFLS) mounted on the substrate, and a resonator coupled to the MFLS. The MFLS is configured to produce a first light beam having a first frequency and a second light beam having a second frequency and phase locked with the first light beam. The resonator comprises an optical fiber coil having a hollow core. The resonator is configured to circulate a portion of each of the first and second light beams through the hollow core. The portion of the first light beam propagates in a first counter-propagating direction, and the portion of the second light beam propagates in a second counter-propagating direction. A measured difference between the first and second frequencies indicates a frequency shift proportional to the rotation rate of the optical gyro.

Abstract: Methods and apparatus are provided for attenuating polarization errors in ring resonators of fiber optic gyros. A ring resonator is provided having first and second resonance frequencies and comprising an optical fiber coil having a hollow core and first and second ends, a light beam generator coupled to the optical fiber coil and configured to generate first and second counter-propagating beams in the hollow core, and a light recirculator coupled to the first and second ends of the optical fiber coil and configured to direct a first light beam exiting the first end of the optical fiber coil into the second end of the optical fiber coil. The first light beam is based on one of the first and second counter-propagating beams. The light recirculator comprises a first polarizing unit configured to reflect a first polarized component of the first light beam and further configured to extract a second polarized component of the first light beam.

Abstract: Apparatus is provided for a fiber optic gyro. The fiber optic gyro includes a ring resonator having first and second counter-propagating directions. The ring resonator includes a coil having an axis and an optical fiber having a hollow core. The ring resonator is configured to produce a first resonance frequency when a first light beam circulates through the hollow core in the first counter-propagating direction and produce a second resonance frequency when a second light beam circulates through the hollow core in the second counter-propagating direction. A difference between the resonance frequencies indicates a rotation rate of the fiber optic gyro about the axis.

Abstract: A method and device are presented for use in determining a rate of rotation of an object. The device comprises a light guide comprising an arrangement of a plurality of coupled optical resonators arranged along a curvilinear optical path. This allows for determining a change in at least one of the light phase and frequency affected by the light propagation through the curvilinear path during the device rotation, said change being indicative of the rotation rate of the light guide.

Abstract: Methods and apparatus are provided for stabilizing laser light sources of a resonator gyro. A resonator gyro comprises a first light source configured to produce a first input light, a second light source configured to produce a second input light, a resonator coupled to the first and second light sources, a resonance detection circuit coupled to the resonator, and a controller coupled to the resonance detection circuit and the first and second light sources. The resonance detection circuit detects a resonance frequency for each of the counter-propagating directions of the resonator. The controller tunes the first input light to a clockwise resonance frequency, and tunes the second input light to a counter-clockwise resonance frequency. A difference between the resonance frequencies is proportional to a rotational rate of the resonator gyro.

Abstract: Methods and apparatus are provided for attenuating rotation rate errors in a resonator gyro. The gyro includes a ring resonator having a hollow core optical fiber coil and optical elements that are selected and/or oriented to reduce stray light that may be present in input light beams introduced to the ring resonator. The resonator has a predetermined mode. One of the optical elements partially transmits a portion of the input light beam to a first end of the fiber coil while partially transmitting a portion of the input light beam to a filter. Light having the predetermined mode is accepted into the first end of the fiber coil, and the filter accepts light of the input light beam having a corresponding mode. Transmission components of the circulating light beams indicates resonance peaks of the counter-propagating directions of the ring resonator.

Abstract: Methods and apparatus are provided for sensing a rotation rate of a ring resonator in a transmission mode. A ring resonator for circulating light beams in counter-propagating directions comprises an optical fiber coil having a hollow core and first and second ends. A first optical element is configured to receive an input light beam and direct a portion of the input light beam in a counter-propagating direction of the ring resonator. A second optical element is configured to direct with the first optical element a majority of a circulating light beam in the counter-propagating direction of the ring resonator and derive a transmission mode component of the circulating light beam at one of the ends. The portion of the input light beam enters one of the first and second ends. The circulating light beam is based on the input light beam. The transmission mode component indicates a resonance peak of the counter-propagating direction of the ring resonator.

Abstract: A system for estimating a parameter selected from the group consisting of a current, a magnetic field, or combinations thereof comprises a resonant frequency tunable magneto-optical loop resonator, wherein the loop resonator comprises a magneto-optical sensing element coupled to an optical waveguide, and wherein the loop resonator is configured for receiving an originating optical signal from a broadband light source and providing a modulated signal indicative of the estimated parameter.

Abstract: An optical resonant modulator includes an optical ring resonator and an optical loop that is coupled to the optical ring resonator by two couplers. The optical ring resonator can have a hybrid design in which the ring resonator is formed on an electro-optically passive material and the optical loop is formed on an electro-optically active material. An amplification section can be inserted between the electro-optically passive and the electro-optically active sections. In analog applications, an optical resonator includes a Mach Zehnder interferometer section having an input and an output, with a feedback path coupling the output to the input. Applications of the optical modulator of the invention, and a method for modulating an optical signal also are disclosed.

Abstract: In an embodiment of a ring laser gyroscope, a hollow bandgap fiber is filled with a gas or material that will generate laser beams within the fiber upon being excited by an energy source. A detector coupled to the fiber detects a standing wave pattern within the fiber, wherein changes in the detected standing wave pattern indicates a corresponding change in the orientation of the fiber.

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: An integrated optic gyroscope is disclosed which is based on a photonic integrated circuit (PIC) having a bidirectional laser source, a pair of optical waveguide phase modulators and a pair of waveguide photodetectors. The PIC can be connected to a passive ring resonator formed either as a coil of optical fiber or as a coiled optical waveguide. The lasing output from each end of the bidirectional laser source is phase modulated and directed around the passive ring resonator in two counterpropagating directions, with a portion of the lasing output then being detected to determine a rotation rate for the integrated optical gyroscope. The coiled optical waveguide can be formed on a silicon, glass or quartz substrate with a silicon nitride core and a silica cladding, while the PIC includes a plurality of III–V compound semiconductor layers including one or more quantum well layers which are disordered in the phase modulators and to form passive optical waveguides.

Abstract: A monolithically integrated semiconductor laser rotation sensor/gyroscope that includes at least two isolated, nonsynchronized semiconductor lasers; at least one being unidirectional and at least a further one being either a straight-line laser or a second unidirectional ring laser configured to propagate lasing light waves in the direction opposite to the first unidirectional ring laser; semiconductor directional waveguide couplers; a semiconductor Y-junction mixing region; and a semiconductor photodetector. Evanescently outcoupled signals are routed to a photodetector for detection of the Sagnac shifted frequencies to discern a beat frequency resulting from rotation of the chip structure. The straight-line semiconductor laser serves as frequency reference insensitive to rotation. Directing, filtering, and radiating unwanted reflections or backscattered light to highly absorbing regions is carried out with waveguide coupler designs and nonreciprocal couplers and filters.

Abstract: A semiconductor ring laser gyro comprising two or more ring lasers, the ring lasers being optically independent of each other, is characterized in that a change in beat frequency with respect to a change in angular velocity of a first ring laser is opposite to that of a second ring laser, and angular velocity of rotation of the gyro is detected by a signal representing a difference between a first beat frequency generated by the first ring laser and a second beat frequency generated by the second ring laser.

Abstract: A gyro comprising a laser device for generating laser beams to be propagated circuitally in opposite directions, wherein an electric signal is taken out from the laser device, the oscillation frequencies of the laser beams being different from each other when the laser device is held stationary.

Abstract: A ring laser of the present invention includes multiple ring resonators with different optical path lengths, wherein at least part of the multiple ring resonators is optically coupled, and a propagating direction of laser light propagating in the ring resonators is not reversed by the coupling.

Abstract: An angular velocity detecting apparatus comprises a ring laser including a tapered light waveguide of an asymmetrical shape in at least a portion of a light waveguide so that the oscillation threshold values of laser beams propagating round in opposite directions of rotation may differ from each other, an optical gyro having a terminal for detecting any change in at least one of an electric current, a voltage and impedance in the ring laser, a measuring device for measuring the information of the cycle of the change in at least one of the electric current, the voltage and the impedance outputted from the terminal of the gyro, a clock generation device for generating a predetermined clock for sampling, and a calculation circuit for inputting the result of the measurement by the measuring device at a predetermined sampling cycle, and calculating information regarding an angular velocity on the basis of the result of the measurement.

Abstract: There is provided a method of generating no error in the output of a resonator fiber optic gyro even when the polarization dependency loss is present in a ring resonator of the resonator fiber optic gyro. The relationship between &Dgr;L and &Dgr;&bgr; is set to satisfy the formula &Dgr;&bgr;&Dgr;L=&pgr;+2n&pgr; [radian] (n: integer), or &Dgr;&bgr;&Dgr;L is close to the value obtained from the formula, where &Dgr;L is defined as the difference between the lengths L1 and L2 of two portions of a waveguide divided by a coupler and a polarization-rotating point in the ring resonator, and &Dgr;&bgr; is defined as the difference in propagation constant of two axes of polarization having the waveguide. &Dgr;L is set so that the error induced by the polarization fluctuation is minimized.

Abstract: A ring laser gyro wherein a first and a second laser beam propagate with propagating directions different with each other comprises electrode areas on an optical waveguide configuring the ring laser and controls an current injected or a voltage applied to the electrode areas, wherein the oscillating frequencies of the first and second laser beams are different from each other, thereby causing an increase and a decrease in the beat frequency enabling to detect the direction and the speed of a rotation at the same time. With regards to a method for detecting a rotation, the anode of the laser gyro is connected to an operational amplifier. Since the signal outputted from the operational amplifier has a frequency corresponding to the angular speed, it is converted into the voltage by a frequency-voltage conversion circuit so as to detect a rotation. This same method can be used for other types of gyros such as a semiconductor laser gyro, a gas lager gyro and the like.

Abstract: The invention is a compact optical gyroscope based on the Sagnac effect that combines a micro-ring cavity laser comprising a magneto-optical material and a magnetic field to circumvent the lock-in phenomenon at low rates of rotation. The invention also embodies novel processes for breaking lock-in using a transverse Faraday effect.

Abstract: A gyro comprises a first laser adapted to generate a first laser beam propagating in a single direction as a main mode of operation, and a second laser adapted to generate a second laser beam propagating in a single direction as a main mode of operation. The gyro may have a beat signal detection means and a photodetector for receiving the first and second laser beams. The first laser beam and the second laser beam have different respective oscillation frequencies and interfere with each other.

Abstract: A monolithically integrated semiconductor laser rotation sensor/gyroscope that includes at least two isolated, nonsynchronized semiconductor lasers; at least one being unidirectional and at least a further one being either a straight-line laser or a second unidirectional ring laser configured to propagate lasing light waves in the direction opposite to the first unidirectional ring laser; semiconductor directional waveguide couplers; a semiconductor Y-junction mixing region; and a semiconductor photodetector. Evanescently outcoupled signals are routed to a photodetector for detection of the Sagnac shifted frequencies to discern a beat frequency resulting from rotation of the chip structure. The straight-line semiconductor laser serves as frequency reference insensitive to rotation. Directing, filtering, and radiating unwanted reflections or backscattered light to highly absorbing regions is carried out with waveguide coupler designs and nonreciprocal couplers and filters.

Abstract: An optical gyro reduces the coupling loss produced when a laser beam is incident upon a photodetector and the noise generated by the laser beam returning to the laser from an external point of reflection. The gyro includes a ring resonator type semiconductor laser for having laser beams transmitted circularly in opposite directions relative to each other. The angle &agr; formed by the surface of the active layer of the semiconductor laser and the lateral surface of each of the low refractive index layers sandwiching the active layer and showing a refractive index lower than the active layer satisfies the requirement of 75°<a<105° over the entire periphery of the low refractive index layer. The gyro detects a beat signal generated in the semiconductor laser.

Abstract: A gyro comprising a laser device for generating laser beams to be propagated circuitally in opposite directions, wherein an electric signal is taken out from the laser device, the oscillation frequencies of the laser beams being different from each other when the laser device is held stationary.

Abstract: A gyro and an operating method is capable of reducing coupling losses which arise when laser beams enter a photodetector and noise which develops due to light entering into a laser from external reflection points. The gyro includes a ring resonator type laser in which laser beams circularly counter propagate, and detects a change in a current or an impedance based on a beat which is generated by the interference of the laser beams counter propagating each other within the laser.

Abstract: A device for acquiring mechanical variables, namely, angles of rotation, speeds, angular velocities or angular accelerations, comprises at least one fiberglass ring having an elliptical cross section, at least one coupler and decoupler associated with the fiberglass ring, a laser connected to the coupler, and a measuring location connected with the decoupler. The fiberglass ring forms at least two propagation paths wherein the oscillations from the laser rotate in opposite directions. The decoupler decouples the oscillations which are superposed at the measuring location where an evaluation signal is detected.

Abstract: There is provided a method of generating no error in the output of a resonator fiber optic gyro even when the polarization dependency loss is present in a ring resonator of the resonator fiber optic gyro. The relationship between &Dgr;L and &Dgr;&bgr; is set to satisfy the formula &Dgr;&bgr;&Dgr;L=&pgr;+2n&pgr; [radian] (n: integer), or &Dgr;&bgr;&Dgr;L is close to the value obtained from the formula, where &Dgr;L is defined as the difference between the lengths L1 and L2 of two portions of a waveguide divided by a coupler and a polarization-rotating point in the ring resonator, and &Dgr;&bgr; is defined as the difference in propagation constant of two axes of polarization having the waveguide. &Dgr;L is set so that the error induced by the polarization fluctuation is minimized.

Abstract: A gyro and an operating method therefor, capable of reducing coupling losses which arise when laser beams enter a photodetector, and noise which develops due to light entering into a laser from external reflection points. A gyro according to the present invention comprises a ring resonator type laser in which laser beams circularly counter propagate, and it detects a change in a current or an impedance based on a beat which is generated by the interference of the laser beams counter propagating each other within the laser.