Formation of guided Cherenkov radiation in silicon-based nanocomposites.
We use a monochromated 200 keV electron beam as a nanometer-resolution probe of the photonic density of states in bulk and nanoparticle Si/SiO(2) systems, observing infrared to ultraviolet waveguided Cherenkov modes in Si slabs, but none in SiO2. While isolated Si nanoparticles are too small to support Cherenkov radiation, we find high densities of Si nanoparticles in SiO2 support a damped form of the radiation, with the modes determined by the effective medium of the Si/SiO(2) mixture. The guided nature of the radiation is confirmed by the presence of a thickness-dependent cutoff.
School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850, USA.
Aycan
A
Yurtsever
Martin
M
Couillard
David A
DA
Muller