Nanosecond pulse fibre laser based on nonlinear polarisation rotation effect

Abstract

A nanosecond pulse erbium‐doped fibre laser (EDFL) is demonstrated based on nonlinear polarisation rotation effect using a highly concentrated EDF in a ring cavity. The EDFL generates a stable multi‐wavelength comb with a constant spacing of 0.22 nm in the 1533.6 nm wavelength region at a pump power of 87.6 mW. A stable mode‐locked operation also commences with a constant repetition rate of 77 MHz with pulse width that varies from 5.3 to 6.8 ns as the pump power is increased from 87.6 to 168.9 mW. With careful adjustment of the polarisation controller, a stable square pulse is obtainable at a pump power of 128.3 mW with a pulse width of 6.5 ns and an average output power of 5.0 mW, which translates to the pulse energy of 35 pJ. The square pulse is generated based on the nonlinear polarisation switching effect inside the laser cavity.

Q‐switching and mode‐locking pulse generation with graphene oxide paper‐based saturable absorber

“…Pulse fibre lasers have great potential applications in many fields including spectroscopy, biomedical diagnoses, fibre communication and others [1, 2]. Up‐to‐date, most of the pulse fibre lasers have been realised using passive techniques, where saturable absorbers (SAs) are a key component.…”