Passive phase modulator for optical fiber gyroscope

Abstract

The invention discloses a passive phase modulator for an optical fiber gyroscope. The passive phase modulator for the optical fiber gyroscope comprises two polarization maintaining optical fiber collimators, two Faraday optical rotation devices with opposite rotation directions and a quarter-wave plate; at one end of the phase modulator, polarized light is input in a manner of forming an included angle of 45 degrees with a principal axis of the wave plate, and the polarized direction of the polarized light rotates to be the same with the direction of a fast axis of the wave plate through the polarization maintaining optical fiber collimators and the two Faraday optical rotation devices, then the polarized light enters the other Faraday optical rotation device through the wave plate, and the polarized direction of the polarized light rotates back to be consistent with the incident direction, and finally, the polarized light leaves the phase modulator through the other polarization maintaining optical fiber collimator. In the process, the polarized light diffuses through the fast axis of the wave plate. Similarly, because the optical rotation processes are opposite, the polarized light passing through the phase modulator from the other end diffuses through the slow axis so as to generate a stationary phase difference. In an interference-type optical fiber gyroscope, the passive phase modulator replaces a traditional piezoelectric phase modulator or an integrated optical block modulator, can improve the accuracy and the reliability, and can reduce the cost.

Description

technical field [0001] The invention relates to an optical phase shifting device, in particular to a passive phase modulator for an optical fiber gyroscope. Background technique [0002] In the past few decades, gyroscopes or rotational speed sensors have achieved enviable achievements in practical applications, and most of their fiber optic loops use active biasing, that is, piezoelectric phase modulators (PZT) or integrated optical blocks (Y waveguide devices). Although the active-biased fiber optic Sagnac interferometric gyroscope is practically successful, researchers have never stopped trying to use passive biasing in the fiber-optic gyroscope interferometric optical path. This is because the passive bias device has its attractive aspects, including simple and solid structure, low noise, easy tuning (most do not need to be tuned, but run by the system itself), high sensitivity, long-term stable operation, and low cost. [0003] An early attempt at passively biasing a f...

AI Technical Summary

Problems solved by technology

The main defect of the sensor structure thus constituted is that the single-mode optical fiber does not have the function of maintaining the polarization state of light, so the optical fiber interference sensor comprising a 3×3 single-mode optical fiber coupler cannot be stable, so that it cannot be practical

Since Faraday rotation optical devices are difficult to achieve extremely high precision, this method of phase bias technology will bring large phase noise of the Sagnac interference circuit

Images