40 GHz pulse generation using a widely tunable all-polarisation preserving erbium fibre ring laser

Optical pulses of less than 6 ps duration have been generated at repetition rates up to 40 GHz using an all-polarisation preserving actively modelocked erbium doped fibre ring laser. The wavelength tuning range was 43 nm at this repetition rate and extended over 52 nm (1518-1570 nm) at 20 GHz. Minimisation of the overall ring dispersion offered wavelength tunability at nearly constant repetition rate throughout the whole tuning range.