Au coated ZnO/MWCNTs nanocomposites film-induced four-wave-mixing effect for multi-wavelength generation in erbium-doped fiber laser

High optical nonlinearity of nanostructured materials has been attested as a reliable technique for the generation of a multi-wavelength fiber laser. Herein, we experimentally demonstrate a simple and efficient method for generating continuous-wave (CW) multi-wavelength erbium-doped laser (EDFL) using a nonlinear effect of four-wave mixing (FWM) in a highly nonlinear nanocomposite film. A nanocomposite film containing gold nanostars coated zinc-oxide nanorods/multi-walled carbon nanotubes (ZnO-NRs@Au NSs/MWCNTs) embedded in polyvinyl alcohol (PVA) polymer was prepared, characterized, and then incorporated into the laser cavity to induce the FWM effect. Benefiting from the FWM processes, the induced intensity-dependent gain alleviates the intense gain-competition in the EDFL and increases the number of lasing wavelengths. A five-lasing line with a side mode suppression ratio (SMSR) of 36.3 dBm has been observed by appropriately adjusting the pump strength to 300 mW. Repeated measurements verified the high stability of the laser operating at room temperature with less than 3 dBm fluctuations on output power and 0.21 nm lasing wavelength drifts for all wavelengths cases. To the best of the author's knowledge, this is the first demonstration of multi-wavelength fiber laser utilizing ZnO-NRs@Au NSs/MWCNTs nanocomposite. The results reveal the excellent nonlinear optical properties of the prepared nanocomposite and lay a foundation for its application in the generation of a multi-wavelength fiber laser.