Abstract

Inside a photonic crystal, the refractive index varies periodically on length scales of the order of a wavelength. This gives rise to a photonic band structure for light, analogous to the electronic band structure in semiconductors. The band structure is expected to have consequences for the radiation of a molecule embedded inside a photonic crystal due to spatial variations in the density of optical modes. To investigate this effect, we are measuring the spectrum and excited state life time of rhodamine dye in colloidal crystals. Surprisingly, only one experiment has been reported to date on fluorescence in photonic crystals [1]. In this experiment, dye was dissolved in the liquid. Thus chemical effects compound the interpretation. To avoid this, we have synthesized ~ 100 nm radius silica spheres in which rhodamine dye is incorporated and shielded inside. Furthermore, we have grown a whole series of crystals with a range of particle densities, with photonic strengths [2] comparable to those of ref. [1]. Synchrotron small-angle X-ray scattering experiments demonstrate that our crystals are highly ordered fcc single crystals [3].

© 1998 IEEE