Method of delaying an optical signal and optical routing device

摘要

An optical delay line (4) comprises a wavelength-tuneable laser (6) and a span of optical fibre (8) connected with said laser (6), said fibre (8) having a predetermined amount of chromatic dispersion. The proposed optical delay line (4) further comprises a phase response unit providing a periodic group delay, e.g. a Gires-Tournois (GT) interferometer (7) functioning as a Gires-Tournois Dispersion Compensation Module (GT-DCM), which is connected with said fibre span (8) and adapted to compensate at least part of the chromatic dispersion introduced by the optical fibre (8) without cancelling a group delay introduced by the optical fibre (8) i.e. the intra channel group delay remains constant but differs for each channel. In this way, an optical delay line with increased dynamic range can be devised, which does not suffer from signal distortion due to accumulated chromatic dispersion of the delay line.