Q-Switched Fiber Laser with a Hafnium-Bismuth-Erbium Codoped Fiber as Gain Medium and Sb₂Te₃ as Saturable Absorber

We successfully demonstrate Q-switched fiber laser with a 20 cm long Hafnium-Bismuth-Erbium codoped fiber (HBEDF) as an active medium in conjunction with Antimony Telluride (Sb₂Te₃) saturable absorber (SA). The HBEDF has an Erbium ion absorption coefficient of 100 dB/m at 980 nm; thus, the laser setup only requires a very short length of gain medium for lasing in the 1550 nm range. We realize the Sb₂Te₃ SA obtained by embedding the material into Polyvinyl Alcohol (PVA), and a Q-switched pulse train operating at 1560.7 nm is realized, using only a 20 cm long active fiber, when the prepared Sb₂Te₃ thin film is integrated into the laser ring cavity. The repetition rate of the Q-switched pulses is tunable from 47.7 to 74.8 kHz as the pump power is raised from the threshold value equal to 69.9 mW to a value of 105.0 mW. The maximum attainable pulse energy is 31.2 nJ. Our results indicate that the Sb₂Te₃ material is useful as an effective Q-switcher especially for the laser operation in 1.55 μm range.