Disclosed is a method for producing an optical fiber coil including the following steps: a. symmetrical winding of an optical fiber around a shaft, the winding forming a pattern including a same number N of layers of each half of the optical fiber, one layer including a set of turns of optical fiber and spaces between adjacent turns, the winding forming a sectored arrangement including a regular stacking area including at least one continuous sealing surface between two layers of adjacent turns, and an overlap area where portions of optical fiber linking different turns cross each other; b. infiltration of a glue through an external surface of the overlap area in such a way that the glue infiltrates into the spaces located between adjacent turns in the regular stacking area.

Interferometric measurement device includes a light source emitting a source signal and optical coupling elements receiving the source signal, directing part of the latter towards a measurement pathway including a Sagnac ring interferometer, of frequency f.sub.p, producing a power output signal P.sub.OUT polarized according to a first polarization direction, tapping off another part of the source signal towards a compensation pathway producing a return power compensation signal P.sub.RET, and directing the output and compensation signals towards detection elements. The compensation pathway includes polarization rotation elements producing the compensation signal according to a second cross-direction of polarization, and optical looping elements redirecting part of the compensation signal towards the measurement pathway; the detection elements include a single detector connected to the coupling elements for receiving the output signal and the compensation signal; the device further includes power equilibration elements equalizing the output power and/or return power are routed towards the detector.

Many optical gyroscopes are based on an optical Sagnac interferometer configuration including various interferometric fiber-optic gyroscopes (IFOG) to measure magnitude and direction of rotation. IFOGs require active phase modulation in their fiber coil to decipher direction of rotation. This patent document discloses a new type of IFOGs that utilizes a passive topological (also known as geometric) phase shift to sense magnitude and direction of rotation without requiring active phase modulation.

Method and apparatus are disclosed for use of a fiber-optic sensor loop for use within a wellbore; with a plurality of light sources optically coupled to the fiber-optic sensor loop; at least one electromagnetically sensitized region within the fiber-optic sensor loop; and a plurality of detectors optically coupled to the fiber-optic sensor loop; and using the sensing system to detect changes in a magnetic field within the wellbore.

An acousto-optic waveguide device comprises a substrate comprising a first material having a first refractive index and a first acoustic velocity; a cladding layer over the substrate, the cladding layer comprising a second material having a second refractive index that is distinct from the first refractive index, the second material having a second acoustic velocity that is distinct from the first acoustic velocity; and an optical core surrounded by the cladding layer, the optical core comprising a third material having a third refractive index that is higher that the first refractive index and the second refractive index, the third material having a third acoustic velocity that is distinct from the first acoustic velocity and the second acoustic velocity. The cladding layer that surrounds the optical core has a thickness configured to substantially confine acoustic waves to the cladding layer when an optical signal propagates through the optical core.

An acousto-optic waveguide comprises a cladding region comprising a first material having a first refractive index and a first acoustic velocity, and a pair of optical waveguide layers embedded in and extending through the cladding region. The optical waveguide layers are separated from one another by a gap region comprising the first material. The optical waveguide layers each comprise a second material having a second refractive index that is higher than the first refractive index and a second acoustic velocity that is higher than the first acoustic velocity. The optical waveguide layers substantially confine acoustic waves that are generated during optical signal propagation through the acousto-optic waveguide. The acoustic waves are substantially confined to the area around the optical waveguide layers and the gap region along the direction of the optical signal propagation.

The low magnetic sensitivity PM-PCF based on mechanical buffer is obtained by adding buffer structures in the cladding layer of the photonic crystal fiber. In the center of the fiber, the core region contains at least 3 layers of air-holes, enclosed by the cladding layer. The buffer structures are placed in the cladding layer. These buffer structures are formed by replacing silica of any shape by air, and are symmetrically located in X-axis and Y-axis directions to achieve mechanical isotropy. The buffer structures improve the fiber's performance in fiber coiling and stress conditions. Therefore, the fiber optic gyroscope using the PM-PCF can do without a magnetic shield, thus greatly reducing the weight of the fiber optic gyroscope and extending the scope of its application. Compared with the conventional commercial PCF, the PM-PCF provides the fiber optic gyroscope with lower temperature sensitivity and improved accuracy.

Various examples of a closed-loop optical gyroscope are disclosed. The closed-loop optical gyroscope includes a broadband light source configured to generate broadband optical signal(s). The broadband optical signal(s) propagate in an optical resonator and are coupled in and out of the optical resonator by optical couplers. A phase modulator applies phase modulation to the optical signal(s) based on a sawtooth modulation signal. The optical signal(s) repropagate in the optical resonator in a different direction. The optical signal(s) are then received and analyzed to determine parameter(s) of the phase modulator. One or more processors configure the phase modulator based on the determined parameter(s).

A gyroscope comprises first and second light sources that emit first and second beams with broadband spectrums, and a waveguide arrangement that communicates with the light sources. A resonator communicates with the waveguide arrangement to receive the beams. A first circulator is coupled to the waveguide arrangement between the first light source and the resonator. A second circulator is coupled to the waveguide arrangement between the second light source and the resonator. A first rate detector communicates with the resonator through the first circulator, and a second rate detector communicates with the resonator through the second circulator. The rate detectors produce rate measurements based on a detected resonance frequency shift of the beams in the resonator caused by rotation of the gyroscope. Outputs of the rate detectors are used to calculate a rotation rate that is corrected for errors due to a time varying pathlength change in the resonator.

A spherical multi-axis optical fiber sensing device is formed by a three-axis optical interference sensor composed of a multi-level opto-mechanical integrated unit kit. The opto-mechanical integrated unit kit is composed of three fiber rings, which are respectively a large fiber ring, a medium fiber ring and a small fiber ring. The multi-level opto-mechanical integrated unit kit is combined with the use of the mechanism component technology that can be freely rotated and positioned to achieve the functional purpose of establishing a three-axis orthogonal optical fiber sensing unit in a single sphere volume.