Fibre-optic comb filter with tunable central wavelength and channel isolation at sub-microsecond speed

Reported is a novel and compact tunable fibre-optic comb filter with the tuning implemented based on two electro-optic phase retarders made of lead magnesium niobate–lead titanate. Both the central wavelength and the channel isolation can be tuned at a sub-microsecond speed. A prototype filter with insertion loss of around −1.3 dB and channel isolation up to 26 dB is achieved.