NARROWBAND FILTER METHOD AND APPARATUS

摘要

The present invention relates to a narrow-band filter method and apparatus. The apparatus includes input and output optical fibres (21, 22), a walk-off plate (23) which spatially separates the orthogonal polarization components of the input light, a birefringent plate (27) which separates at least one of the orthogonal polarization components into further sub components having different trajectoires, a quarter-waveplate (28) and a Gires-Tournois resonator (GT) (29). The method includes the steps of projecting substantially orthogonal polarization beams onto the surface of the GT resonator (29) for applying a wavelength dependent phase delay to said beams and utilising a relative resonant wavelength shift in the phase delay response of the GT resonator (29) to produce a corresponding spatial separation in a predetermined wavelength range of said input optical signal. The method can further include the step of projecting substantially orthogonal polarization beams onto the surface of the GT resonator (29) at slightly different angles of incidence.