We report critical coupling of electromagnetic waves to plasmonic cavity arrays fabricated on Moiré surfaces. Dark field plasmon microscopy imaging and polarization dependent spectroscopic reflection measurements reveal the critical coupling conditions of the cavities. The critical coupling conditions depend on the superperiod of the Moiré surface, which also defines the coupling between the cavities. Complete transfer of the incident power can be achieved for traveling wave plasmonic resonators, which have a relatively short superperiod. When the superperiod of the resonators increases, the coupled resonators become isolated standing wave resonators in which complete transfer of the incident power is not possible. Analytical and finite difference time domain calculations support the experimental observations.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: April 29, 2011
Revised Manuscript: June 13, 2011
Manuscript Accepted: June 21, 2011
Published: July 19, 2011
Sinan Balci, Coskun Kocabas, and Atilla Aydinli, "Critical coupling in plasmonic resonator arrays," Opt. Lett. 36, 2770-2772 (2011)