Fig. 1. Structural diagram and optical simulation results of perfect spherical silver shell array. (a) Structural diagram of perfect spherical silver shell array; (b) simulated absorption, reflection and transmission spectra of complete spherical silver shell array; (c) electric intensity distributions at k-E_in plane for TM₃, TE₁ and TM₂ cavity plasmon modes

Fig. 2. Structural diagram and optical simulation results of perfect ellipsoidal silver shell array. (a) Schematic diagram of perfect ellipsoidal silver shell array; (b) simulated absorption spectra for different ellipticities (d₁/d₂); (c) absorption of TM₃, TE₁ and TM₂ cavity plasmon modes varying with d₁/d₂; (d) electric intensity distributions for TE₁ cavity plasmon mode at k-E_in plane for d₁/d₂=1.0, d₁/d₂=2.0 and d₁/d₂=5.0

Fig. 3. Construction and optical simulation results of non-perfect spherical silver shell array with trumpet-shaped openings. (a) Schematic diagram of non-perfect spherical silver shell array with trumpet-shaped openings; (b) simulated absorption spectra at different opening angles ; (c) electric intensity distributions for TE₁ cavity plasmon mode at k-E_in plane for γ=0˚, γ=20˚ and γ=30˚

Fig. 4. Simulated absorption spectra for perfect ellipsoidal silver shell array, non-perfect spherical silver shell array and non-perfect ellipsoidal silver shell array

Fig. 5. Morphological characterization of experimental samples, experimental results and optical simulation results of samples. (a) Typical cross-sectional SEM image of sample fabricated by FIB; (b) SEM image of fabricated sample after ultrasonic treatment; (c) TEM image of PS microsphere array; (d) measured and simulated normalized transmission spectra for non-perfect ellipsoidal silver shell array; (e) transmission spectrum from experimental testing and Fano fitting result; (f) transmission spectrum from theoretical simulation and Fano fitting result