Titania-carbon nanocomposite as a saturable absorber for generation passively ytterbium-mode locked pulses

Passively pulse dual-wavelength ytterbium-doped fiber laser (YDFL) around 1 μm utilizing titania–carbon nanocomposite (TiO2–C NC) thin film as the optical modulator is experimentally demonstrated. The TiO2–C NC thin-film reveals great nonlinear saturable absorption characteristics with a transmission difference of 24.06% at the lasing emission around the 1 μm region. Stable self-starting mode-locked emission with a pulse of ~8 ns and a repetition rate of 30.7 MHz was achieved at threshold exciting power of about 115 mW. By adapting the polarization controller (PC) together with the pump power, fundamental, third, and sixth harmonic frequencies can be switched to each other. The corresponding pulse durations to the third and sixth harmonic mode-locked were 6.8 and 1.8 ns, respectively. The corresponding maximum output power was 1.8 mW. This work opens up another way to build cost-effective, greatly stable optical modulators, and presents the option to build novel nanocomposite-based photonic devices with TiO2–C NC. •Demonstrating successfully mode-locked ytterbium-doped fiber laser (YDFL) at 1 μm utilizing titania–carbon nanocomposite (TiO2–C NC) thin film as the saturable absorber (SA).•Stable self-starting mode-locked pulses with the repetition rate of 30 MHz and pulse duration of about 8 ns was achieved at threshold pump power of about 115 mW with fundamental, third and sixth harmonic frequencies.•The corresponding maximum average output power was 1.8 mW for pulse energy of 0.2 n J.