Lasing in phosphate glasses with high neodymium ion concentrations under pumping with light-emitting diodes

Phosphate glasses containing over $10^{21}$ cm${}^{-3}$ neodymium particles were pumped with $Al-Ga-As$ lightemitting diodes at room temperature. Pulse-periodic lasing was obtained at $1,06\mu m$. A row of light-emitting diodes subjected to rectangular current pulses of $400\mu s$ duration and a repetition frequency up to 10 Hz. The threshold current was 4 A and the power density of the pump radiation reaching the active elements was 20 W/cm${}^2$.