Optical notch filter manufacture

摘要

An optical notch filter is created in a bared length (21) of single mode fibre (20) by using a microburner (24) and longitudinal stretching of the fibre to form a set of equispaced sharply localised non-adiabatic biconical tapers (30) at a pitch corresponding to the beat length between the core-guided HE11 mode and the cladding-guided HE12 mode, the latter being stripped downstream of the tapers by a plastics protective coating surrounding the fibre. <IMAGE>