METHOD AND DEVICE FOR TUNABLE OPTICAL FILTERING USING VERNIER EFFECT

摘要

An optical device (200) for processing a WDM optical signal comprising a plurality of channels lying on a grid of optical frequencies equally spaced by a frequency spacing and occupying a WDM optical bandwidth, the optical device comprises: a first optical filter (450) comprising a first optical path (430) apt to receive the WDM optical signal; a first resonator (452) optically coupled adjacently with the first optical path and having a first free spectral range (FSR) which is less than or equal to the WDM optical bandwidth and exceeds the half of the WDM optical bandwidth by more than the frequency spacing; a second resonator (454) optically coupled adjacently with the first resonator and having a second FSR which is less than or equal to two thirds of the first FSR and is greater than or equal to 0.55 times the first FSR; and a second optical path (456) optically coupled with the second resonator; and a second optical filter (460) comprising a third optical path (440) optically connected to the first optical path (430); a third resonator (462) optically coupled adjacently to the third optical path and having a third FSR which differs, in absolute value, from the first FSR by more than a quarter of said frequency spacing; and a fourth optical path (466) optically coupled with the third resonator. A method for tuning a channel to be filtered is also disclosed.