The Modulation Effect of Local Density of Optical states of Plasmonic Nanoantennas on their Photoluminescence

Fan-Cheng Lin Chemistry, National Tsing Hua University, Hsinchu, Taiwan Wei-Liang Chen Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Yu-Yang Lee Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Feng-Chieh Li Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Yu-Ming Chang Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan Jer-Shing Huang Chemistry, National Tsing Hua University, Hsinchu, Taiwan National Tsing Hua University, Frontier Research Center on Fundamental and Applied Sciences of Matters, Hsinchu, Taiwan

Upon resonant excitation, gold plasmonic nanoantennas can generate strongly depolarized two-photon photoluminescence (TPPL), which serves as ideal local broadband visible source for the spectroscopic investigation of nanoantenna eigenmodes [1, 2]. In this work, TPPL emission spectra of three arrays of single-crystalline gold nanoantennas are comprehensively investigated with careful comparison with dark-field scattering spectra and numerically simulated spectra. We demonstrate the modulation of the TPPL spectrum due to the transverse bonding mode, the higher-order bonding modes and the dark anti-bonding modes [2]. Numerical simulations are performed in order to confirm the resonance phenomenon. Our work provides direct experimental evidence on the nanoantenna-mediated near-to-far-field energy coupling and gains insight into the emission spectrum of the TPPL from gold nanoantennas.

Fig. 1: SEM images of the single-crystalline gold nanoantennas (left) and the TPPL spectra showing the modulation effects of the non-fundamental longitudinal modes (middle) and the fundamental transverse mode (right).

[1] Wissert, M. D.; Ilin, K. S.; Siegel, M.; Lemmer, U.; Eisler, H.-J. Coupled Nanoantenna Plasmon Resonance Spectra from Two-Photon Laser Excitation. Nano Lett. 10, 4161-4165 (2010).

[2] Huang, J.-S.; Kern, J.; Geisler, P.; Weinmann, P.; Kamp, M.; Forchel, A.; Biagioni, P.; Hecht, B. Mode Imaging and Selection in Strongly Coupled Nanoantennas. Nano Lett. 10, 2105-2110 (2010).

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