The F-PM1550 Polarization Maintaining Fiber offers low attenuation and excellent birefringence for high performance applications. This Corning PANDA PM fiber has a 1550 nm operating wavelength with beat lengths ranging from less than 1. Optimized for use at 1550 nm, these fi ers are used in all PM applications for data and telecom. Coherent has applied its unique manufacturing facility and capabilities to this product area and has establish d leading optical, mechanical and. Coherent Polarization Maintaining Telco fibers are designed for today's most advanced networks. The device guides optical light in one direction and eliminates back.