FBG Technology: Utilizes Fiber Bragg Grating (FBG) to reflect the 1650nm wavelength while transmitting others. They can be used to monitor live network utilizing OTDR operating at 1650nm. Robust Design: SC/APC. These 1650nm optical reflectors with Fiber Bragg Grating (FBG) technology are designed specifically for OTDR, PON/FTTx, and fiber monitoring system applications that require and/or benefit from a strong back-reflection of the optical test signal. The in-line, attenuator-style housing allows for. The FBG reflector is a standard SC type connector structure, which package a special FBG in the ceramic ferrule.