Abstract

In the last few years optical fibre photosensitivity has been noticed to be anisotropic; that is the photoinduced index change is birefringent.[1] The photoinduced anisotropy of germanium doped silica fibres has allowed the fabrication of polarisation converting gratings analogous to mechanically produced periodic birefringent fibre structures made in the past.[2-8] Such gratings are known as polarisation couplers or rocking filters when they couple forward-travelling fibre modes and as Bragg exchange gratings when backward travelling light is produced.

© 1995 Optical Society of America