Nanosecond mode-locked erbium doped fiber laser based on zinc oxide thin film saturable absorber

In this paper, we report a nanosecond mode locked erbium doped fiber laser (EDFL) using zinc oxide (ZnO) nanoparticles as a saturable absorber (SA) for the first time. Due to its excellent optical properties, in particular a high nonlinear optical response and fast recovery time, ZnO nanoparticles can be used as a saturable absorber device for pulsed laser generation. For easy integration into the laser cavity, the ZnO nanoparticles were imbedded into a polymer film using a seeding solution technique. 400 ns mode locked pulse train was successfully obtained at a relatively low threshold pump power of 45.4 mW. The output laser operates at the fundamental frequency of 1 MHz with a center wavelength of 1558.34 nm. The highest pulse energy and peak power achieved by the laser are estimated at 11.6 nJ and 27.3 mW respectively at the maximum available pump power of 142 mW. The results show that the SA derived from ZnO nanoparticles is capable of producing nanosecond mode locked EDFL for possible applications that require high pulse energy and medium output power.