Spectral Engineering Via Complex Patterns of Circular Nano-Object Miniarrays: II. Concave Patterns Tunable by Integrated Lithography Realized by Circularly Polarized Light

Abstract

The use of circularly polarized beams in interferometric illumination of colloid sphere monolayers enables the direct fabrication of rectangular patterns composed of circular nanohole miniarrays in metal films. This paper presents a study on the spectral and near-field effects of complex rectangular patterns consisted of a central nanoring and slightly rotated satellite nanocrescents in azimuthal orientations, which promote coupling between localized and propagating plasmons. To inspect the localized modes separately, we investigate the spectral responses and near-field phenomena of hexagonal patterns composed of uniform nanorings and nanocrescents, which can be fabricated by a single, homogeneous, circularly polarized beam incident perpendicularly and obliquely, respectively. To understand the interaction of localized and propagating modes, we analyze artificial rectangular patterns composed of a singlet nanoring, a singlet horizontal nanocrescent, and a quadrumer of four slightly rotated nanocrescents. The results demonstrate that on the rectangular pattern of a singlet horizontal nanocrescent the interacting C2 and C1 localized resonances in the C orientation ($$0^{\circ }$$ 0 ∘ azimuthal angle) and the U localized resonance coupled with propagating surface plasmon polaritons (SPPs) in the U orientation ($$90^{\circ }$$ 90 ∘ azimuthal angle) manifest themselves in similar split spectra. Moreover, split spectra appear due to the coupling of the azimuthal orientation independent localized resonance on the nanorings and the SPPs propagating on their rectangular pattern in the U orientation. The spectral response of the complex miniarray pattern can be precisely tuned by varying the geometrical parameters of the moderately interacting nanoholes and the pattern period. In appropriate configurations, the fluorescence of the dipolar emitters is enhanced, which has potential applications in bio-object detection.

Optimalizált nanoplazmonika

“…A kolloidgömb monorétegek interferáló nyalábokkal történő kivilágításával megvalósítható integrált litográfiával létrehozható komplementer konkáv és konvex nano-objektumokból felépülő struktúrák spektrális és közeltérbeli hatásait vizsgáltuk. Olyan komplex struktúrákat tanulmányoztunk, amelyek a 100 nm átmérőjű arany kolloidgömbök 60° azimutális orientációban elhelyezett monorétegének 400 nm-es cirkulárisan polarizált fénnyel történő kivilágításával hozhatók létre, két 12.83° szögben beeső interferáló nyalábbal (5. ábra) [5,6].…”

Spectral engineering via complex patterns of circular nano-object miniarrays: I. convex patterns tunable by integrated lithography realized by circularly polarized light

“…3b, c and Fig. 4-8/b) [49][50][51]. Localised plasmon resonances on the nanorings and nanocrecents are distinguished by using r and c in the abbreviations.…”

“…In our present study the size parameters of the inspected ring-and crescentshaped nano-objects, the ε opening angle and the ω orientation of the nanocrescents, as well as the pattern periods are equal to those of the complementary concave patterns described in our corresponding papers, in order to ensure comparability [50,51]. Namely, uniform nanorings with 10 nm and 46 nm (50 nm) inner and outer diameters were inserted into the hexagonal pattern (artificial rectangular pattern of singlet nanorings and both rectangular patterns of analogue miniarrays).…”

“…The interferometric illumination of colloid-sphere monolayers (IICSM) enables the direct structuring of positive resists, whereas the masks can be transferred into convex patterns by a lift-off procedure. The spectral and near-field properties of complex concave patterns consisting of rounded nanohole miniarrays is described in Part II of this paper, where it is detailed, that the rounded nano-objects originate from circularly polarized light, whereas the pattern periodicity is determined by the interference pattern periodicity [50]. In order to uncover the localized modes supported by the building blocks, the spectral and near-field effects of hexagonal patterns composed of uniform nanorings and nanocrescents that can be fabricated by colloid sphere lithography followed by a lift-off procedure, was also studied.…”

Metamaterial properties of Babinet complementary complex structures

“…In our previous studies, illumination by linearly polarized light was realized to compare the transmittance and reflectance of complementary convex and concave complex pattern configurations that can be fabricated by integrated colloid-sphere and interference lithography [44][45][46] . We demonstrated that in the case of linearly polarized light illumination, the convex transmittance subtracted from unity (reflectance) and the concave inverted rectified reflectance (rectified transmittance) extracted from the polarization unspecific power-outflow read-out, are complementary [44][45][46] . In our present study, the polarization specifically read-out transmittance signals of Babinet complementary single and multilayers illuminated by linearly and circularly polarized light are determined via Jones matrix elements to demonstrate metamaterial capabilities [47][48][49] .…”