The impact of high dielectric constant on photonic bandgaps in PbSe nanocrystal-based photonic crystal slabs

Abstract

A detailed study was carried out to understand the photonic crystal design rules with very high dielectric constant (ε>13), based on plane wave expansion and finite difference time-domain (FDTD) techniques. It is found that the optimal dielectric constant contrast is indeed the one between conventional semiconductors (ε=12-14) and air. Either too high or too low contrast can lead to the reduction of complete photonic bandgap. With very high bulk dielectric constant (ε=20-25), PbSe nanocrystal quantum dots (NQDs) are suitable for air hole based PC structure with large TE gap. On the other hand, NQD backfilled photonic crystals with tunable bandgap is proposed based on the control of packing density of NQDs inside the air holes of photonic crystal structures. Both theoretical and experimental results on the integration process are reported.