Different Bandgaps of Transmission and Emission Spectra in Artificial Opal
Kai Song, Renaud Vallee, Koen Clays and Andre Persoons
The spontaneous emission of fluorophores embedded in a photonic crystal was studied. Two samples with different structures were prepared: dye uniformly infiltrated structure and nano-engineered sandwich-like structure. For the later, we could exclude the presence of fluorophores at the surface of the crystal. For both structures, it was found that the stopband in the transmission spectrum was deeper than the stopband in the emission spectrum. We conjecture that the omnidirectional propagation of the emission from a point source in an incomplete photonic band gap material is the cause of the shallower stopband in emission.