A miniaturized BOSA with a stabilized light source for fiber-optic gyroscope

A novel design of bi-directional optical sub-assembly (BOSA) for fiber optic gyroscope (FOG) applications to improve the drawbacks of bulky discrete components, and time consuming optical fiber splicing has been proposed. This FOG BOSA integrated a 1550nm super-luminescent light emitting diode (SLED), a photodiode (PD), a 50/50 splitter, a dual-stage optical isolator, a fiber receptacle, and especially, a thermal electric cooler (TEC) in a volume less than 1.5cm in diameter and 2.5cm in height. A three dimensional model was established to simulate the thermal distribution and to optimize the thermal performance of the FOG BOSA. By using the laser welding process, a compact and robust FOG BOSA has been built. For the range beyond the 38°C TEC set point, such as +42 to +72°C, BOSA reached a peak-to-peak wavelength stability of 0.15nm which corresponding to a less than 100ppm peak-to-peak variation.