All fiber normal dispersion mode locked ytterbium doped double-clad fiber laser using fiber taper with WS2-ZnO saturable absorber

Abstract

Efficient and stable mode-locking operation at 1075 nm is demonstrated in a double-clad ytterbium-doped fiber laser (DC-YDFL) with WS2-ZnO deposited on a fiber taper as a saturable absorber (SA). The WS2-ZnO composite is prepared by a simple and cost-effective heating method and deposited onto the fiber taper before being incorporated into the laser cavity. A high power mode-locked normal dispersion output at 1075 nm with a 3 dB bandwidth, repetition rate, pulse width and pulse energy of 3.7 nm, 10.98 MHz, 459 fs and 139.3 nJ respectively are obtained at a pump power of 3.65 W. Due to the interaction of the WS2-ZnO nanoparticles with the evanescent field of the propagating signal instead of directly, the SA has a higher laser damage threshold, therefore allowing for higher pulse powers to be obtained.