High-Precision Inertial Measurement Unit with Closed-Loop Fiber Optic Gyros operated by 1550nm 3-Fiber SLED Transceiver

We have developed a new generation of inertial measurement units (IMUs) that are based on 3-axis closed-loop fiber optic gyroscopes (FOGs) operated by a highly integrated SLED transceiver optical module, thereby eliminating several discrete optical components like depolarizers, fiber couplers or fiber-pigtailed photodiodes. Removing many fiber components lowers system costs but also reduces the number of splices of polarization-maintaining (PM) fibers, which dramatically simplifies the IMU's manufacturing processes and improves the system performance. The optical transceiver module is realized as a Butterfly (BTF) module having three PM output fibers with an integrated 1550nm superluminescent diode (SLED), a 1:3 beam divider, a 3-channel optical circulator and three integrated receiver photodiodes.