The active Q switching and mode locking of an erbium-doped fiber ring laser with an erbium-doped fiber cooled to 4.2 K have been investigated. Curious Q-switched pulses were observed that were caused by mode beats between the longitudinal modes and the saturable absorption effect in the 4.2-K erbium-doped fiber. Stable cw mode locking was observed with a pump power of 250 mW to a room-temperature erbium-doped fiber amplifier, and the pulse width was 9–30 ns, which is broader than the dipole relaxation time T2.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics