Cs_xWO₃ nanorods with broadband nonlinear response for Q-switched and mode-locked pulse generation

Nano-CsxWO3 with broadband local surface plasmon resonance is the promising candidate for nonlinear pho-tonics applications. In this work, Q-switched and mode-locked pulses were generated from Er-and Tm-doped fiber lasers by using CsxWO3 nanorods (NRs) as saturable absorbers (SAs). The CsxWO3 NRs were synthesized by a water controlled-release solvothermal process. Then they were mixed with sodium carboxymethylcellulose (NaCMC) solution to fabricate a SA film and deposited onto a D-shaped fiber to fabricate a D-shaped fiber SA. These SAs exhibited excellent nonlinear optical properties at 1.5-mu m and 2-mu m. A -1560 nm Q-switched fiber laser with the shortest pulse width of 3.8 mu s, the maximum average power of 10 mW, a pulse energy of 0.35 mu J was obtained by using the filmy CsxWO3 SA. A stable soliton mode-locked fiber laser at -1943 nm was realized based on the D-shape fiber CsxWO3 SA, it had a maximum average output power of -50 mW, a pulse duration of -292 fs, and a repetition rate of 25.5 MHz. Our results show that the CsxWO3 NRs are potential nonlinear materials for broadband ultrafast response and Q-switched/mode-locked pulse generation.