Abstract:Two-dimensional photonic crystals of dielectric spheres with a 2.1 μm diameter have been fabricated by arranging individual spheres using a micromanipulation technique in a scanning electron microscope. A buildup of photonic bands from whispering gallery modes has been observed as the number of spheres increased, by measuring the transmission spectra for lattices composed of various numbers of spheres. The photonic band dispersion curves were experimentally obtained for a finite system made of 91 spheres from … Show more
“…Such a PBG was calculated using the whispering gallery mode-coupling model. 21 This model explains reasonably well the observed far-field transmission spectra and their angular dependence. Moreover, this theory predicts considerable broadening of the minima bandwidth due to light leakage to the substrate.…”
Section: Discussionsupporting
confidence: 67%
“…19 Colloidal PhCs can be directly deposited on the surface of the light emitting film using the well-controllable LangmuirBlodgett ͑LB͒ technique. 20 When compared to micromanipulation 21 or colloidal self-assembly, 19 the LB method offers large area coatings and precision in terms of depositing the required number of monolayers of spheres.…”
A light source on the surface of a slab of 2+1-dimensional photonic crystal has been prepared by the Langmuir–Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals. The directional enhancement of the light emission intensity in the spectral range of the photonic bandgap has been revealed through the comparative examination of the angle-resolved transmission, diffraction, and photoluminescence spectra of the prepared structures. Changes in the emission spectrum have been tentatively explained in terms of the acceleration of the radiative recombination due to the increase in the local field strength at photonic bandgap resonance and changes in the emission diagram—as arising from the wavelength dependence of the topology of the local field pattern.
“…Such a PBG was calculated using the whispering gallery mode-coupling model. 21 This model explains reasonably well the observed far-field transmission spectra and their angular dependence. Moreover, this theory predicts considerable broadening of the minima bandwidth due to light leakage to the substrate.…”
Section: Discussionsupporting
confidence: 67%
“…19 Colloidal PhCs can be directly deposited on the surface of the light emitting film using the well-controllable LangmuirBlodgett ͑LB͒ technique. 20 When compared to micromanipulation 21 or colloidal self-assembly, 19 the LB method offers large area coatings and precision in terms of depositing the required number of monolayers of spheres.…”
A light source on the surface of a slab of 2+1-dimensional photonic crystal has been prepared by the Langmuir–Blodgett deposition of a colloidal crystal on top of a thin film containing CdTe nanocrystals. The directional enhancement of the light emission intensity in the spectral range of the photonic bandgap has been revealed through the comparative examination of the angle-resolved transmission, diffraction, and photoluminescence spectra of the prepared structures. Changes in the emission spectrum have been tentatively explained in terms of the acceleration of the radiative recombination due to the increase in the local field strength at photonic bandgap resonance and changes in the emission diagram—as arising from the wavelength dependence of the topology of the local field pattern.
“…One approach is based on consideration of 2D PhC, the PBG of which is calculated by coupling of whispering gallery mode resonances of individual spheres in the 2D crystal. 10 The lowest wavelength resonance in this model appears at D / Ϸ 0.9, which corresponds to the 545 nm minimum in our case ͑Fig. 1͒.…”
mentioning
confidence: 99%
“…Moreover, no spectroscopic evidence has been demonstrated to prove the formation of a 3D lattice in LB multilayers. 9 On the other hand, optical spectra of 2D hexagonal sphere crystals were studied only at wavelengths shorter than the sphere diameter, 10,11 i.e., in the range of their 2D PBG.…”
“…8,9 These minima were associated with excitation of optical eigenmodes of 2D PhC, which propagate in plane of a monolayer. The aim of this work is to demonstrate that similar effect can be observed in thin opal films.…”
Diffraction in the face centered cubic lattice cannot explain some minima observed in the transmission spectra of self-assembled opal films. Here, we compared them with minima observed in the transmission spectra of a hexagonal close packed monolayer of spheres of the same diameter. The identity of the sphere packing on the surface of the opal film and in the sphere monolayer was demonstrated by the light diffraction at the sample surfaces. It was shown that excitation of surface propagating modes in the opal film is responsible for the formation of additional minima in opal film transmission. (C) 2008 American Institute of Physics. (DOI: 10.1063/1.2920443
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