An experimental study of strongly modified emission in inverse opal photonic crystals

Abstract

We present the first experiments that demonstrate strong angle-independent modification of spontaneous emission spectra from laser dyes in photonic crystals, made of inverse opals in titania. We show that both the fluorescence quantum efficiency and weak disorder play a key role in interpreting the experimental data. We compare the angle-independent emission spectra of dye in photonic crystals with spectra from such crystals with much smaller lattice spacings, for which emission is in the long wavelength limit. The ratio of emission power spectra shows inhibition of emission up to a factor $ 5 over a large bandwidth of 13% of the first order Bragg resonance frequency. The inhibition shifts to increasing wavelength with the lattice parameter, confirming the photonic nature of the phenomenon. The center frequency and bandwidth of the inhibition agree with the calculated total density of states, but the measured inhibition of the vacuum fluctuations is much larger. This result is confirmed by experiments using different dyes. We likely probe the strongly modulated local photonic density of states, due to the spatially nonuniform distribution of dye molecules over the unit cell.

Cavity quantum electrodynamics with three-dimensional photonic band gap crystals

“…where P is the rate of excitation of the emitters [38]. If the quantum efficiency is low then γ rad ≪ γ nrad , hence γ tot → γ nrad so that γ tot is independent of the LDOS.…”

“…Consequently the cw intensity I(ω eg ) of the emitters becomes proportional to γ rad , hence I(ω eg ) is then an excellent probe of the LDOS. If one studies the cw intensity I(ω eg ) to obtain information on the crystal's LDOS, care must be taken to distinguish spectral features from several other effects, such as angular effects related to photonic bandstructures, as well as the angledependent excitation and the angle-dependent collection efficiency [38,43]. To interpret results in terms of the LDOS, the observed intensity spectrum I(ω eg ) is normalized to a reference that employs the same light sources in the same chemical environment.…”

Spatial distribution of the emission intensity in a photonic crystal: Self-interference of Bloch eigenwaves

“…The angular distribution of the far-field intensity depends on the topology of the iso-frequency surface of the crystal at the emission frequency (21)(22). In what follows, an infinite two-dimensional square lattice of air holes in a polymer background is considered.…”

“…In figure 8 the comparison of the "geometrical optics" (22) and "wave optics" (21) approximations of the far-field emission intensity is given. A normalized inverse Gaussian curvature of the iso-frequency surface Ω = 0.333 is presented in the top panel.…”

“…Light emission in a photonic crystal has attracted a substantial attention both in theoretical [1,2,3,4,5,6,7,8,9,10,11,12] and experimental [13,14,15,16,17,18,19,20,21,22] studies. To a large extend this interest is due to potential perspectives of the emission modification and control provided by photonic crystals.…”