INSERTION AND EXTRACTION OF A THIRD CHANNEL OR BAND ON A FIBRE OPTICS CARRYING TWO CHANNELS OR OPTICAL BANDS THROUGH ONE SINGLE MACH-ZEHNDER INTERFEROMETER

摘要

The present invention finds its application in an on-line control system of an optic fibre transmission network, supporting or destined to support optic signals in a second (μ1) and/or third (μ2) window and including the transmission by means of said fiber of a control signal having a band or wavelength (μ3) out of said second and third window. The system employs a single Mach-Zehnder interferometer as insertion and extraction device of said third service optic channel or optic band (μ3), consisting of: a first and a second directional coupler having a first L1 and a second L2 coupling length, respectively; a phase shifting stage suitable to introduce an optic path ΔL difference. Parameters L1, L2 and Δ are dimensioned in such a way to satisfy some pre-set relations.