A novel technique for the fabrication of a saturable absorber for fiber lasers: pulsed laser deposition

Abstract

In the present work, for the first time, it is demonstrated that a zinc oxide (ZnO) thin film deposited directly on a fiber ferrule using a pulsed laser deposition (PLD) is a novel technique to prepare a saturable absorber (SA) for doped fiber lasers. The erbium-doped fiber laser based on this SA and erbium-doped fiber as a gain medium yields optical pulses with emission wavelength 1567.86 nm at a 3 dB spectral bandwidth of 1.24 nm at 42 mW. As the pump power is increased, the pulse duration decreases from 23.58 µs to 5.6 µs, and the pulse repetition rates increase from 10.79 kHz to 70.78 kHz. A maximum peak power, pulse energy and average output power of about 9.4 mW, 65.8 nJ, and 4.6 mW, respectively, have been achieved at a maximum pump power of 368 mW. The long-term stability and the damage threshold of the SA are also discussed. These findings suggest that the PLD technique is a promising technique to fabricate a cost-effective and stable SA for the fabrication of passively Q-switched fiber lasers.