Emission from a YAG:Nd laser with a four-wave thermal mirror in a ring resonator

Hard excitation of a YAG:Nd laser emitting nanosecond pulses was investigated experimentally. Such excitation was achieved in the presence of an external signal in a ring resonator with a self-pumped four-wave mirror based on a thermal nonlinearity of ethyl alcohol. The threshold energy of the external signal needed for lasing was ~ 10 mJ and the maximum energy reflection coefficient reached ~ 30%.