Generating electronic carrier signals in the optical domain

摘要

A dual wavelength optical fibre distributed feedback (DFB) laser (10) comprises a pump laser (12) coupled to an Erbium-Ytterbium fibre (18) in which a first grating device (20) (two co-located single phase-shift fibre Bragg gratings (FBGs)) is provided. The device (20) gives the laser two potential lasing modes in each of two orthogonal polarisation states. A polarisation mode coupling FBG 30 (fabricated in high-birefringence fibre 28) selects two orthogonally polarized modes for the laser (10) to operate at. In a photonic data carrying signal source (50) the laser (10) is coupled to a polarisation dependent optical modulator (56) operable to apply an amplitude modulation, at a data signal frequency, to one polarisation mode of the laser output. In an optical waveguide based electronic signal transmission system (70) the modulated and un-modulated polarisation modes output from the source (50) are transmitted across a fibre transmission line (72) to a polarising optical fibre (78) in which the two modes heterodyne to generate an electronic carrier signal in the optical domain. <IMAGE>