Fiber-optic sensors (including but not limited to: angular velocity/angular acceleration sensors, vibration sensors, gravity sensors, temperature sensors, as well as fiber-optic gravity gradiometers, rotational seismometers, six-component seismometers, fiber-optic gyroscopes) and their signal processing (including but not limited to: rotational seismology, high-speed-railway seismology, geodesy, underground navigation, etc.), mechanisms and suppression of noises in fiber-optic interferometers, and noise suppression in geophysical electromagnetic detection.