Q-switched and mode-locked pulse generation with samarium oxide film saturable absorber

Q-switched and mode-locked pulses were obtained by utilizing a Samarium oxide (Sm₂O₃) film as saturable absorber (SA) in Erbium-doped fiber laser (EDFL) cavity. The Sm₂O₃ SA film has a modulation depth and saturation intensity of 30% and 90 MW/cm², respectively. The proposed Q-switched EDFL operated stably at 1558.4 nm. The repetition rate was tunable in a range from 75.8 kHz to 99.5 kHz with the raise of pumping power from 81.0 mW to 131.9 mW. At the maximum pumping power of 131.9 mW, the highest pulse energy of 143.9 nJ and the lowest pulse width of 2.12 µs were attained. A stable soliton mode-locked laser was observed at a central wavelength of 1561.6 nm when an additional 100 m long single mode fiber was incorporated into the cavity. The mode-locking operation was maintained at pump power range within 91.2 mW to 142.0 mW with repetition rate of 1.88 MHz and pulse width of 3.40 ps. At 142.0 mW, the maximum pulse energy of 12.00 nJ and peak power of 3.53 kW were obtained. These show that the proposed Sm₂O₃ SA is viable for application in the construction of practical Q-switched and mode-locked pulses operating in the 1.5 micron range.