Effect of the active-ion concentration on the lasing dynamics of holmium fibre lasers

The lasing dynamics of fibre lasers with a core based on quartz glass doped with holmium ions to concentrations in the range of 10¹⁹-10²⁰ cm^-3 is investigated. It is shown that fibre lasers with a high concentration of active holmium ions generate pulses, but a decrease in the holmium concentration changes the lasing from pulsed to cw regime. At the same time, a decrease in the active-ion concentration and the corresponding increase in the fibre length in the cavity reduce the lasing efficiency.