METHOD AND ARRANGEMENT OF A MODULATOR FOR MULTISTAGED SHIFT-KEYED POLARISED OPTICAL SIGNALS

摘要

The invention relates to a modulator for modulating an optical signal (OS1) with four-stage or eight-stage polarisation shift keying. Said modulator is provided with Mach-Zehnder interferometers (MZ12, MZ221, MZ222) which are controlled in such a way that the first derivations of the distances between the vectors of the stoke parameters (S1, S2, S3) disappear after the modulation voltages (U12, U221, U222), whereby said vectors are produced in the different modulation states. Feedover is thus avoided.