Coupled tandem optical parametric oscillator (OPO): an OPO within an OPO Phua, P. B. ; Lai, K. S. ; Wu, R. F. ; Chong, T. C. Abstract Publication: Optics Letters Pub Date: August 1998 DOI: 10.1364/OL.23.001262 Bibcode: 1998OptL...23.1262P