Two-mode fibre spatial-mode converter using periodic core deformation

Efficient conversion between the LP/sub 01/ and LP/sub 11/ modes in a two-mode fibre is achieved by periodically ablating the fibre surface with a CO/sub 2/ laser and then annealing the fibre with an electric arc. The resulting periodic core deformation produces 99% mode conversion over a 37 nm bandwidth around 1540 nm and 0.38 dB insertion loss.