L-band femtosecond fiber laser with Cu₂Te-PVA thin film

Abstract

For the first time, this research proposed a copper telluride (Cu2Te)-polyvinyl alcohol thin film as a saturable absorber (SA) in an erbium-doped fiber laser (EDFL) operating in the long-wavelength band (L-band). The nonlinear optical absorption measurement of Cu2Te thin film revealed a saturation intensity of 3.26 kW cm−2 and a modulation depth of 2.7%. Furthermore, the mode-locked pulse was successfully generated by integrating a Cu2Te thin film into the L-band cavity at a threshold pump power of 135.61 mW with a center wavelength and pulse duration of 1565.48 nm and 770 fs, respectively. When observing the output mode-locked pulse, the pump power for the EDFL ranged from 135.61 mW to 201.28 mW, with the fundamental mode having a repetition rate 10.28 MHz. Furthermore, the magnitude of the signal-to-noise ratio was approximately 61.3 dB, indicating that the laser was stable with no significant fluctuations during the stability test. Overall, the findings showed that Cu2Te thin film has an excellent output and a promising candidate for an SA, implying that it could have a lot of potentials in pulsed laser application.