1.3/1.4 $\boldsymbol{\upmu}\textbf{m}$ bismuth-doped mode-locked fiber laser with a tunable-wavelength range exceeding 100 nm

m all-fiber tunable-wavelength Bi-doped mode-locked fiber laser with a tuning range exceeding 100 nm, achieved using a Lyot filter. The laser can be tuned over two separate wavelength bands (1321.32-1369.05 nm and 1419.45-1471.98 nm). Moreover, the pulse dynamics and evolution processes are directly visualized in real-time using the Time-Stretch Dispersive Fourier Transform (TS-DFT) technique, revealing distinct pulse formation times across the tuning range. This work significantly advances Bi-doped fiber laser technology by combining ultra-broad tunability, all-fiber integration, and real-time pulse evolution insight, thereby offering a promising light source platform for future wavelength-division multiplexed (WDM) optical networks and multispectral biomedical imaging systems.