Abstract

Recent developments in fibre grating writing techniques have lead to the fabrication of gratings whose parameters vary periodically along the optical fibre.^1,2 Such grating superstructures may have significant applications in fibre lasers, as they can be designed to have a reflection spectrum spanning the entire Erbium gain bandwidth². Grating superstructures have earlier been investigated in semiconductor geometries,^3-5 and have also been studied theoretically.^6,7 Much of the previous analysis is applicable to weak gratings superstructures; in contrast we present here a general approach which is suitable for deep grating superstructures as well. Such a general description is pertinent for grating superstructures in optical fibre,¹ where, although the refractive index modulation is small, the variations in the modulation can be large.

© 1995 Optical Society of America