Low Threshold Q-Switched Er-Doped Fibre Laser (EDFL) Using SnS2 as a Saturable Absorber (SA)
A.A.A. Jafry, M.B.H. Mahyuddin, A.H.A. Rosol, M.F.M. Rusdi, S. LI, S.W. Harun and N. Kasim
The SnS2 possessing bandgap of 2 to 2.4 eV is compatible with the visible and ultraviolet (UV) emission spectrum; however, the imperfect crystal structure of SnS2-polyvinyl alcohol (PVA) has an adjustable sub-bandgap which was suitable for near-infrared (NIR) to mid-infrared (MIR) pulse generation. We, therefore, developed an in-house and employed SnS2-PVA as the saturable absorber (SA) inside an Er-doped fibre laser (EDFL) cavity to initiate Q-switching at 1557 nm, a pulse width as short as 7.05 μs which corresponded to a repetition rate of 69.44 kHz. The EDFL cavity initiated stable Q-switched pulses within pump power of 21 to 49 mW. At a maximum attainable pump power of 49 mW the laser cavity consumed a maximum output power of 5.28 mW which corresponds to a pulse energy of 76.04 nJ. The Q-switched EDFL was stable, exhibiting a signal-to-noise ratio (SNR) of 68.4 dB and a pump efficiency of 13.37%. Our Q-switched EDFL cavity was optimized as we captured stable Q-switching within a 1.55 μm region and, consequently, provided opportunities for laser commercialization in the area of micromachining and laser cutting.
Keywords: Er-doped fibre laser (EDFL), laser cavity, tin disulphide (SnS2), polyvinyl alcohol (PVA), Q-switching, saturable absorber (SA)