Bidirectional mode-locked thulium-doped fiber laser

Abstract

We report a bidirectional mode-locked thulium-doped fiber laser. Mode-locking is enabled by the combination of semiconductor saturable absorption and nonlinear polarization rotation. Two stable mode-locked picosecond pulse trains in opposite directions are generated with a fundamental repetition rate of ∼16.57 MHz. Output wavelengths are tunable over 35 nm.