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.