Design and analysis of efficient and tunable plasmonic lasers with directional radiation

Abstract

In this work, we propose room-temperature plasmonic crystal based nanolaser with low divergence emission. Usually, performance of nanolasers based on plasmonic crystal nanocavity is a ected by a couple of issues: coupling of lasing emission to both re ection and transmission side of the device and multiple di racted orders of lasing emission. In our proposed nanolaser design, we have overcome these bottlenecks to substantially increase the emission intensity and e ciency. Our proposed structure consists of periodic apertures in thin metallic lm. In this design, feedback action necessary for lasing action is provided by localized hole resonance of the nanohole array. To improve the lasing intensity and e ciency, a one dimensional photonic crystal is incorporated on top of the metallic nanohole array. Under optical pumping, this photonic crystal structure excites optical Tamm states in the locality of the metal hole array. Field enhancement due to Tamm state results in pronounced ampli cation of extraordinary transmission leading to substantially increased lasing emission in near-IR wavelength. Moreover, the photonic bandgap of the crystal selectively guides laser emission towards the transmission side of the device. Due to sub-wavelength lattice period of the nanohole array, lasing emission is con ned only to the zeroth order of di racted mode. Resonant emission through each of the holes in periodic array interfere constructively to produce narrow-beam emission with low divergence in the direction normal to the nanolaser surface. Besides, emission peak wavelength of this nanolaser can be tuned in real-time by changing the angle of incidence. Moreover, the laser emission wavelength can be engineered over a broad range of wavelength by changing thicknesses of the photonic crystal layers.