Patent ID: 9124362
Filing Date: 2015-09-01
Classification: H04B

Abstract:
1. Optical amplification stage for OTDR monitoring, the optical amplification stage comprising a first and a second optical signal path having respectively first and second direction of propagation of a respective first and second optical signal, the first and second direction of propagation being mutually opposite, a first and a second optical amplifier located along the first and second optical signal path respectively and having an optical amplification band, each of the first and second optical signal being a WDM signal occupying a WDM band comprised within the optical amplification band, a first optical coupler placed along the first optical signal path downstream the first optical amplifier with respect to the first direction of propagation, a second optical coupler placed along the second optical signal path downstream the second optical amplifier with respect to the second direction of propagation and an optical by-pass path optically connecting the first and the second optical coupler, each coupler having the optical amplification stage further comprising a first and a second optical reflector optically connected to the second by-pass port of respectively the first and second optical coupler, and an optical filter placed along the optical by-pass path and having an attenuation greater than or equal to 25 dB over the entire WDM band, wherein the first and second reflector and the optical filter are structured so that the sum, in dB, of the attenuation of the optical filter at a first and second OTDR wavelengths, comprised within the amplification band and outside the WDM band, and of the optical power ratio of the optical radiation incident to each optical reflector to the radiation reflected thereby at the first and second OTDR wavelengths, is less than or equal to 20 dB.