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<sub>4</sub> O<sub>12</sub> (LNP) laser with a type II phase-matching KTiOPO<sub>4</sub> 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.
© 1999 Optical Society of America
Kenju Otsuka, Ryoji Kawai, and Yusuke Asakawa, "Intracavity second-harmonic and sum-frequency generation with a laser-diode-pumped multitransition-oscillation LiNdP4O12 laser," Opt. Lett. 24, 1611-1613 (1999)