The drift (/h) for an interferometric fiber optic gyroscope (IFOG) means the variations on the voltage generated versus the zero angular (rotation) rate, while IFOG is not under influence of any angular rate effect. If the drift of an IFOG is predefined, the compensation of the drift can trivially be carried out by a subtraction process. However, with this invention, the necessity of the predefinition of the zero rotation rate voltage of the IFOG which belongs to the primary coil called Gyro Coil herein, is removed because the instantaneous variations on the zero rotation rate voltage of the IFOG can be monitored either periodically or whenever required with help of a secondary coil, called as Monitor Coil, which is able to be switched by a microcontroller controlled-MEMS fiber optic ON/OFF switches. The new configuration of IFOG, to be referred as Dynamical Drift Monitoring-Interferometric Fiber Optic Gyroscope (DDM-IFOG) and the new method presented and implemented in this invention are valid for IFOG having open-loop and closed-loop schemes by engaging the voltage of zeroing the total phase (Feedback Phase plus Sagnac Phase Shift) in the sensing coil instead of directly using the voltage of the demodulation circuit induced by the Sagnac Phase Shift (SPS).

Disclosed is an optical fiber interferometric system including a light source (1), a fiber optic coil (8), a coil splitter (3), a photodetector (2), and a polarization filtering unit. According to an embodiment, the polarization filtering unit includes a first waveguide polarizer (51), at least one second thin-plate polarizer (52) and an optical waveguide section (12), the at least one second polarizer (52) being disposed in the Rayleigh zone between a first waveguide end (21) of the first polarizer (51) and a second waveguide end (22) of the optical waveguide section (12).

The invention relates to an integrated optical coupler (1) comprising a substrate (3), at least two planar waveguides (4), which are arranged on or in the substrate (3) and consist of a material having a virtually isotropic refractive index (anisotropy of the refractive index of less than 10.sup.6), and al least three monomode fibers (8, 9, 10) coupled to the planar waveguides (4). One of the monomode fibers (8) is a polarization-maintaining fiber. A fiber optic system according to the invention comprises an integrated optical coupler (1) according to the invention, a light source (21) that is suitable for generating light beams, and a first pigtail fiber (22), which is connected at one end to the light source (21) and at the other end to the polarization-maintaining fiber (8) of the integrated optical coupler (1).

A directional coupler with reduced phase deviation is provided. The directional coupler includes a first coupler waveguide and second coupler waveguide. At least one of a spaced distance between the first coupler waveguide and the second coupler waveguide and a length of the first coupler waveguide and the second coupler waveguide selected to achieve an acceptable phase deviation and a set coupling ratio. The phase deviation is caused by a difference in loss coefficients between a first optical mode in the first coupler waveguide and a second optical mode in the second coupler waveguide.

An instrument for detecting a position in space may include a proof mass arranged along an input axis, an electromagnetic coil arranged at each end of the proof mass and configured to suspend the proof mass therebetween, wherein the proof mass is configured to rotate along the input axis, and at least one rotation sensor configured to detect the rotational position of the proof mass.

Totally six polarization-maintaining optical fibers having the same beat length are arranged at both ends of a single-mode optical fiber and both ends of a single-mode optical fiber coil, respectively. An angle between a principal axis of polarization in a first polarization-maintaining optical fiber and a plane of polarization of linearly polarized light from a light source is 45 degrees. The optical length of each of the six polarization-maintaining optical fibers is larger than a coherent length of the linearly polarized light from the light source. The total of the optical lengths of the six polarization-maintaining optical fibers into which polarization rotation in the process of passing through the single-mode optical fibers is factored is larger than the coherent length of the linearly polarized light from the light source.

The disclosed structures and methods are directed to a chip for an optical gyroscope and methods of manufacturing the chip for the optical gyroscope. The chip comprises a substrate, a waveguide having a first waveguide cladding layer and a waveguide core; and a ring resonator having a first ring cladding layer and a ring resonator core attached to the first ring cladding layer. A side wall of the ring resonator core forms an obtuse angle with an upper surface of the substrate. The method comprises etching a ring groove and a waveguide groove; placing the optical fiber ring into the ring groove and the optical fiber waveguide into the waveguide groove. The method further comprising splicing two ends of an optical fiber; annealing the ring junction of the optical fiber ring; and attaching the optical fiber waveguide to the waveguide groove and the optical fiber ring into the ring groove.

A system for rotationally biasing a fiber optic gyroscope includes a fiber optic gyroscope assembly comprising a light source that emits an optical signal, an optical coupler in optical communication with the light source, and a fiber optic coil in optical communication with the light source. The fiber optic coil receives the optical signal through the optical coupler and imparts a phase shift proportional to rotation. A rate sensing detector in optical communication with the fiber optic coil receives the optical signal from the fiber optic coil through the optical coupler. A motor coupled to the fiber optic coil applies a periodic rotation to the fiber optic coil to impart a biasing phase modulation to the optical signal. A signal processing unit is coupled to the fiber optic gyroscope assembly and the motor. The signal processing unit converts a measured intensity of the optical signal to rotation rate data.

Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05/Hr or below (e.g. as low as 0.02/Hr), which makes them comparable to fiber optic gyroscopes (FOGs) in terms of performance, at a much lower cost. The low bias stability value in the integrated photonics optical gyroscope corresponds to a low bias estimation error (in the range of 1.5/Hr or even lower) that is crucial for safety-critical applications, such as calculating heading for autonomous vehicles, drones, aircrafts etc. The integrated photonics optical gyroscopes may be co-packaged with mechanical gyroscopes into a hybrid inertial measurement unit (IMU) to provide high-precision angular measurement for one or more axes.

A fiber optic gyroscope sensing coil, with which winding process of optical fiber may be simplified, crosstalk due to winding deficiencies may be reduced, and temperature sensitivity of gyroscope may be reduced. A coil body 13 includes two potted coils 12 having respective windings of optical fiber which are wound in an aligned winding configuration while the same tension is applied to optical fiber and at the same feed speed of optical fiber between the two potted coils and encapsulated within a potting material 16. The potted coils 12 are united together to form the coil body 13 by adhering the potted coils with each other at respective one side faces 12b thereof by using the potting material 16 as adhesive, and the tip ends of respective first fiber end sections 12c of optical fiber 14 of the potted coils 12, which are guided out from respective outermost layers of the windings of the potted coils 12, are connected with each other by fusing to form a continuous length of optical fiber of the coil body 13 wound in one direction.