Layered gallium telluride for inducing mode-locked pulse laser in thulium/holmium-doped fiber

Abstract

In this work, layered gallium telluride (GaTe) was used as a saturable absorber (SA) to initiate the generation of mode-locked pulses in a Thulium/Holmium-doped fiber (THDF) laser. The GaTe solution has been embedded onto the surface of fabricated D-shaped fiber by using the drop-casting method. This action was taken to allow the strong nonlinear interaction between the GaTe solution and the evanescent field of the wave propagating in the D-shaped fiber. The nonlinear optical absorption for the prepared GaTe/D-shaped based SA exhibits a modulation depth of 31.35%, saturation intensity of 3.35 kW/cm2, and a non-saturable loss of 68.65%. A stable mode-locked pulse laser was observed with a repetition rate of 10.71 MHz at a threshold pump power of 281.0 mW. The soliton pulse generated from the proposed THDFL cavity centered at 1946.24 nm with a spectral bandwidth of 2.92 nm. The mode-locked pulse produced pulse duration of 1.396 ps and a signal-to-noise ratio (SNR) value of 63 dB. Overall, the excellent output performance of the laser-generated in this work has shown the credibility of the GaTe/D-shaped based SA device as another possibility for ultrafast laser application.