Intracavity second-harmonic and sum-frequency generation with a laser-diode-pumped multitransition-oscillation LiNdP4O12 laser

Efficient simultaneous intracavity second-harmonic and sum-frequency generation that is free from irregular large amplitude fluctuations (the so-called green problem) is achieved with a laser-diode-pumped LiNdP(4) O(12) (LNP) laser with a type II phase-matching KTiOPO(4) crystal. Observed frequency-mixing operations result from the simultaneous single-frequency oscillations on different transitions that arise from the wide fluorescence linewidth in a stoichiometric LNP laser that possesses inherently high Nd concentrations. Sum-frequency generation has been shown to arise from the interaction of oscillating longitudinal modes that belong to different transitions. A promising application to coherent terahertz-wave radiation by use of photomixers is proposed.