We have demonstrated, for the first time to our knowledge, a coupled tandem optical parametric oscillator (OPO) configuration in which a second ZnGeP2 OPO is placed within the resonator of the first, KTiOPO4, OPO. A significant enhancement in the overall cascaded efficiency of this OPO compared with standard two-stage OPO's was observed. With a multimode Nd:YAG laser, an overall optical-to-optical efficiency (from 1.06 µm to the mid IR) of 5.2% was obtained from operating only ∼1.4 times above oscillation threshold. The measured overall slope efficiency was attractively high at 35%. With a single set of mirrors we obtained a broad wavelength-tuning range from 2.7 to 8 µm.
© 1998 Optical Society of America
P. B. Phua, K. S. Lai, R. F. Wu, and T. C. Chong, "Coupled tandem optical parametric oscillator (OPO): an OPO within an OPO," Opt. Lett. 23, 1262-1264 (1998)