Optical communication network measurement method

摘要

The method involves feeding a test beam (PL1) of predetermined wavelength (lambda m) from e.g. a laser diode (HT1) into an optical wavelength section (HR) in the forward direction. The backscatter (RL1) is returned to the feed point via an optical path (LW1) which is transparent only for the measurement wavelength in the blocking direction (SRH). Preferably, the return path includes two circulators (ZH1, ZR1), an isolator (IR1) and an amplifier (AR1). The branch optical waveguide (LW1) includes a wavelength-selective filter (FI1) which transmits the test wavelength but blocks the backscattered component of useful signal (RSH).