Possibility of using an optical fiber Brillouin ring laser for internal sensing

The feasibility of using an optical fiber Brillouin ring laser as an inertial rotation sensing device is examined. Following a brief review of possible inertial sensing devices combining the advantages of active laser gyros and optical fibers, the optical fiber Brillouin ring laser is presented as a device based on stimulated light scattering from acoustic phonons in which the light beams derive their gain from distinct media thereby eliminating lock-in error and facilitating low-input-rate measurements. Results of analyses of the output of an experimental Brillouin ring laser system are presented which indicate that the device behaves as a traveling wave amplifier with linewidth reduction occurring as a consequence of frequency-dependent gain, with little cavity feedback influence. It is noted, however, that when the optical fiber was rotated at a rate expected to produce a beat frequency in the 10-100-kHz range, no beat frequency with which to determine the amount of rotation in an inertial device was observed, most likely due to an insufficient Q factor.