High power passively mode-locked laser with Sb2Te3 deposited tapered fiber in Er/Yb doped fiber laser

Abstract

Antimony telluride (Sb2Te3), one of the materials from the topological insulator (TI) family, was studied as a saturable absorber (SA) for producing high-power ultrafast lasers in the C-band region. In order to achieve a mode-locked operation, a tapered fiber with a tapered waist of 6 μm was coated with Sb2Te3 to provide the interaction of the evanescent field with the material. Non-linear optical properties of the constructed SA include a 4.05 % modulation depth and a saturation intensity of 0.35 MW/cm2. Mode-locked pulses were generated when the SA was placed inside the cavity. The mode-locked pulses were solitonic, having a center wavelength of 1561.5 nm and a pulse duration of 1.8 ps at a pump power of 461 mW. The fundamental frequency measured was 18 MHz within pump power ranging from 461 mW to 657 mW. The maximum average output power, pulse energy, and peak power obtained from the generated mode-locked pulses were 269 mW, 14.9 nJ, and 8.3 kW, respectively. The measured signal to noise (SNR) of 55 dB indicates the excellent stability of the mode-locked pulses. This is the first demonstration of mode-locked pulses utilizing Sb2Te3 coated tapered fiber as an SA in a double-clad erbium-ytterbium doped fiber (DC-EYDF) laser cavity that we are aware of.