Generation of spatially incoherent short pulses in laser-pumped neodymium stoichiometric crystals and powders

TLDR

The emission originates from collective effects. Mirrorless quasi‑monochromatic laser sources using stoichiometric neodymium compounds pumped by nanosecond laser pulses were developed. High‑intensity pumping produced subnanosecond, 0.15‑nm narrow‑band pulses that are spatially incoherent, showing that strongly quenched, poor optical materials can generate incoherent short pulses.

Abstract

We have developed mirrorless quasi-monochromatic laser sources made of stoichiometric neodymium compounds (Nd0.75:La0.25P4O15 and NdCl3· 6H2O) pumped by nanosecond laser pulses. We find that short subnanosecond and narrow-bandwidth (0.15-nm) pulses are generated in both compounds when they are pumped at high intensities. This emission is spatially incoherent as shown by a speckle statistics analysis. Its origin is discussed in terms of collective effects. This shows that poor optical materials with strongly quenched emission may be useful for generating incoherent short pulses.