Surface plasmon lasing observed in metal hole arrays

Philips Research Laboratories, Professor Holstlaan 4, 5656 AA Eindhoven, Netherlands(Received 26 February 2013; published 13 May 2013)Surface plasmons in metal hole arrays have been studied extensively in the context of extraordinaryoptical transmission, butso far these arrays have not been studied as resonators for surface plasmon lasingat optical frequencies. We experimentally study a metal hole array with a semiconductor (InGaAs) gainlayer placed in close (20 nm) proximity of the metal hole array. As a function of increasing pump power,we observe an intense and spectrally narrow peak, with a clear threshold. This laser emission is donutshaped and radially polarized. Three experimental observations support that the system shows surfaceplasmon lasing. First, the full wavelength dispersion of the observed resonances can be understood byusing a single surface plasmon mode of the system. Second, the polarization of these resonances is asexpected for surface plasmons. Third, the magnitude of the avoided crossing, which results from modecoupling at the holes, has a similar magnitude as found in simulations using surface plasmons.