L-band short cavity fiber lasers based on home-made highly Er3+-doped silica fiber

L-band(1565-1625 nm) single-frequency and high-repetition-rate mode-locked Er3+-doped fiber lasers based on short cavities show promising application prospects in fields such as optical communications, remote sensing and bioimaging due to their excellent temporal and spectral characteristics. However, the L-band lies at the edge of emission spectrum of Er3+-doped f iber and presents low gain compared to C-band, making the realization of high-performance L-band short cavity lasers challenging. To address this, this paper systematically investigates L-band short cavity lasers using a home-made, highly Er3+-doped silica fiber. Firstly, a distributed Bragg reflector (DBR) single-frequency laser cavity was constructed using a 3 cm segment of this fiber, achieving single-frequency laser output at 1590 nm with an output power of 10.5 mWand a linewidth of 6.06 kHz. Subsequently, a semiconductor saturable absorber mirror (SESAM) high-repetition-rate passively mode-locked laser cavity was successfully demonstrated based on an 8.4 cm segment of the same gain fiber, yielding stable mode-locked output with a repetition rate of 1.24 GHz, a center wavelength of 1584 nm, and a pulse width of 566 fs. These results confirm that the feasibility and performance potential of the home-made highly Er3+-doped silica fiber for L-band short cavity lasers. These laser systems show strong potential to be developed into compact, high-performance sources suitable for precision detection and high-speed communication applications.