Actively modelocked, quadruple-wavelength fibre laser with pump-controlled wavelength switching

An actively modelocked quadruple-wavelength erbium-doped fibre laser with two wavelengths in each of the C- and L-bands (with wavelength spacings of 3.5 nm and 0.4 nm, respectively) is reported. The pulse durations are 50–55 ps with corresponding time-bandwidth products of 0.48–0.63. By simple adjustment of the pump power, the laser can be switched to emit at any combination of the 4 wavelengths, without changing the repetition rate of the output pulses.