Comparison of directionally outcoupled photoluminescences from luminous layers on Si and Al nanocylinder arrays

Abstract

An array of nanocylinders can modulate photoluminescence (PL) of emitters via simultaneous excitation of local resonances and light diffractions. Regarding the local resonance, localized surface plasmon polaritons (LSPP) of metals has been commonly applied, while the Mie resonance of dielectrics can also be a candidate. Since these two resonances are excited in different classes of materials, experimental comparisons between their enhancement efficiencies are rarely made. In this study, we fabricated periodic arrays of Si and Al nanocylinders with the identical design and compared their PL outcoupling abilities. We deposited ultraviolet (UV)-absorbing and highly luminous dielectric films on the arrays and observed enhanced PLs from the films on the nanocylinder arrays upon a UV laser excitation. The optical transmission with varied incident angles revealed that the dispersion of the hybrid mode of diffraction with the Mie resonance in the Si nanocylinder array was sharper than that of the diffraction-LSPP hybrid in the Al nanocylinder array. The PL enhancement by the Si nanocylinder array was more selective both spectrally and spatially than that by the Al nanocylinders, which could be attributed to the difference between the mode profiles. Our findings experimentally verified the advantage of choosing Si as a constituent of the cylinder array to provide highly directional light sources.