High accuracy polarized fiber optic gyroscopes require sensor coils comprised of relatively expensive polarization maintaining fiber. While this fiber insures minimal polarization cross coupling and thus increased sensitivity, the long required fiber lengths result in sensor coils that are quite expensive. Reduced cost single mode fiber based coils are attractive, but exhibit poor polarization selectivity due to cross coupling that manifests as signal fading and reduced detected signal amplitude. Moreover, random birefringences induced at fiber crossover points impart a nonreciprocity that tends to exacerbate this problem. A crossover-free winding scheme employing a single mode fiber wound in an Archimedean spiral can potentially improve the performance of single mode fiber coils by eliminating these random birefringences, thereby improving coil sensitivity. As well, the bending induced birefringence of these coils can serve to improve polarization maintenance. Geometric and polarimetric analyses of spirally wound coils describing the effects on overall Sagnac area, bending induced birefringence, and polarization mode coupling are examined here. The spatially varying induced birefringence, beat length, and associated mode coupling are modeled and it is found that elimination of the cross coupling due to random crossovers renders the spiral geometry potentially useful for high accuracy inertial guidance systems.

Date Published: 24 August 2006
PDF: 12 pages
Proc. SPIE 6314, Photorefractive Fiber and Crystal Devices: Materials, Optical Properties, and Applications XII, 63140E (24 August 2006); doi: 10.1117/12.683458

Published in SPIE Proceedings Vol. 6314:
Photorefractive Fiber and Crystal Devices: Materials, Optical Properties, and Applications XII
Francis T. S. Yu; Ruyan Guo; Shizhuo S. Yin, Editor(s)