C + L band ultra-widely tunable SOA hybrid fiber laser based on acousto-optic add-drop filter induced by polarization conversion

Scientific and industrial applications have put forward new requirements for the wavelength tuning range of continuous-wave lasers. Herein, the constructed filter based on the acoustically-induced polarization conversion in single-mode fiber (SMF) covers the wavelength from 1464.2–1640.8 nm, and the tuning range is about ∼176.6 nm. The lasing wavelength is managed by the acousto-optical interaction in the SMF. Moreover, the gain spectrum of semiconductor optical amplifier (SOA) is flat and wide, which can achieve a wide range of laser tuning. Hence, we propose and demonstrate an ultra-widely tuning range ring cavity C + L tunable SOA hybrid fiber laser. Eventually, the tuning channel of the fiber laser is from 1527.3–1613 nm with the tuning range of about ∼85.7 nm, and its tuning range is determined by the gain bandwidth of SOA. The measured output power and center wavelength variations of the proposed fiber laser over a long-term observation are less than 0.11 mW and 0.44 nm, respectively. This work opens up a new way to expand the tuning range of other types of lasers.