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Plasmonic Nanolasers |
In recent years, nanolasers based on plasmonic crystal nanocavity structures have attracted significant interest. However, the performance of such lasers is affected significantly by the coupling of the lasing emission to both reflection and transmission sides of the device and to multiple spatial modes in the far field due to higher-order diffraction from plasmonic crystals as well. We proposed a nanolaser design that overcomes the performance degradation of plasmonic crystal based nanolasers and increases the emission intensity significantly. In the proposed nanolaser structure, a nanometer thick gain medium has a one-dimensional photonic crystal on one side and a metal nanohole array on the other side. An incident pump pulse through the one-dimensional photonic crystal excites optical Tamm-states at the metal-gain medium interface that are amplified by the stimulated emission of the gain medium. We find that the intensity of the extraordinary optical transmission through the metal nanohole array increases significantly due to the excitation of optical Tamm-states with wavevector perpendicular to the nanohole array surface. We also find that the subwavelength periodicity in the nanohole array confines the lasing emission to the zero-th order mode only, and hence, makes the far field pattern highly directional. Moreover, the laser emission wavelength can be tuned over a broad range by changing the thicknesses of the photonic crystal layers, gain medium, and in real-time, by changing the angle of incidence of the pump pulse.
In the figures below we show (a) three-dimensional schematic illustration of the proposed nanolaser structure where The 1-D PC is formed by alternating layers of TiO2 and MgF2 and (b) cross-sectional view of a unit cell of the proposed nanolaser structure.
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Publication:
Z. Ahmed and M. A. Talukder, "An efficient and directional optical Tamm state assisted plasmonic nanolaser with broad tuning range," Journal of Physics Communications 2, 045016 (2018). [ PDF ]
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