Passive Q-switched generation of all-fiber heavily erbium-doped laser

摘要

Features of the all-fiber heavily erbium-doped laser operation in passive Q-switched regime with a repetition rate of pulses up to 700 kHz and pulse duration 70 ns without the use of an additional nonlinear optical elements have been investigated. The generation dynamics of the heavily erbium-doped fiber laser assembled according to the classical Fabry-Perot scheme with two mirrors under continuous direct core pumping at the 976 nm and 1490 nm wavelength was studied. Passive Q-switching in heavily erbium-doped lasers is realized due to effect, which is opposite to the saturable absorption. The absorption grows with the field intensity instead of being saturated. The reason for the appearance of pulses is the existence of ion pairs at high erbium concentrations. This creates an effective absorption dependent on levels' populations of ion pairs.