POLARIZATION-MAINTAINING FIBER USING A NOVEL GLASS SYSTEM

A new glass dopant system, A1P04 is used to form the stress-producing regions of a polarisation-maintaining optical fibre. The advantages of this glass system are that it can match match the refractive index of silica and does not have a fundamental absorption peak near the optical frequencies of interest, allowing it to be placed in close proximity to the fibre core to optimise birefringence. This material was used for the cladding of a preform, which was then flattened to yield an elliptical fibre upon drawing. This fibre demonstrated an extinction ratio at 1.3 μm of 42.5dB for a 10m length and 22dB for 500m for h = 1.3 × 10-5m-1. The beat length at λ = 0.488 μ was about 9 mm, corresponding to a modal birefringence of 5.3 × 10-5. © 1990, The Institution of Electrical Engineers. All rights reserved.