Tunable Er 3+ -doped fibre ring laser usingfibre gratingincorporated by optical circulator or fibre coupler

Efficient narrow linewidth Er3+-doped fibre ring lasers using a single fibre Bragg grating incorporated by a fibre optical circulator or a fibre coupler are investigated. Tunability of the fibre lasers is obtained by compressing the fibre grating in a specially designed unit. Tunabilities of 18 and 12 nm are achieved for fibre ring lasers with an optical circulator and fibre coupler, respectively.