A multi-layer detachable single-axis fiber optic sensing device is provided. The device includes a first circuit board, a light source module, an optical carrier, a beam guiding module, a modulation module, a fiber coil, a second circuit board, a detection module, a third circuit board, a transceiver module, a fourth circuit board, a power supply module, a fifth circuit board, and a computing module. The first circuit board, the optical carrier, the second circuit board, the third circuit board, the fourth circuit board, and the fifth circuit board may be arranged in any order, and any two adjacent ones can be detachably assembled together.

A method comprises providing an RFOG that includes a resonator in communication with a light source emitting a first signal at a first power level in a CW direction, and a light source emitting a second signal at a second power level in a CCW direction; adding a common intensity modulation to the first signal, to produce an intensity modulated CW signal; adding the same common intensity modulation to the second signal, to produce an intensity modulated CCW signal; introducing the intensity modulated CW signal into the resonator; introducing the intensity modulated CCW signal into the resonator; detecting modulated rate signals that are output from the resonator at a common intensity modulation frequency; and adjusting a power level ratio between the first and second power levels, to determine a modified power level ratio value where a Kerr effect bias instability due to an asymmetrical loss distribution is reduced or eliminated.

One example includes an optical system. The system includes a laser configured to generate an optical beam and an optical modulation system comprising a plurality of optical modulators arranged in a cascaded sequence. Each of the optical modulators can be configured to provide successive modulation of the optical beam in the cascaded sequence to provide a modulated optical beam. The system further includes an optical assembly configured to receive the modulated optical beam and to implement the modulated optical beam for an optical functional application.

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

A loop pigtail compensation method for a fiber-optic gyroscope, and a fiber length compensator. The fiber length compensator is fixed on a loop pigtail of the fiber-optic gyroscope, and the fiber length compensator includes a peripheral fiber loop and an expansion-and-contraction shaft core capable of realizing deformation of expanding and contracting; and upon detecting that there is a drift in an output of the fiber-optic gyroscope, a length of the peripheral fiber loop of the fiber length compensator is changed by adjusting a coefficient of linear expansion of the expansion-and-contraction shaft core of the fiber length compensator, so that the compensation for the loop pigtail of the fiber-optic gyroscope is realized, and the problem of low accuracy of online adjustment of the pigtail of the fiber-optic gyroscope is solved.