Lateral confinement in macroporous silicon photonic crystal waveguides

Abstract

Macroporous silicon photonic crystals (PCs) are known as easy and low-cost two-dimensional PC demonstrators with patterns of very high aspect ratios. Slab waveguides can be created in these crystals by modulating the pore diameter during the etching process. In this work, we demonstrate the feasibility of light confinement in the periodicity plane by using an in-filling technique. In-filling of ~0.6μm period macroporous silicon PCs with polymer is achieved over a depth approaching 15μm. The optical properties of in-filled crystals are compared experimentally with those of the original crystals. An excellent agreement is found between the results of measurements and numerical simulations. The combination of the in-filling technique with the modulation of the pore diameter during the etching process opens the way toward linear PC waveguides buried in macroporous silicon. The guiding properties of this new type of PC waveguide are analysed using a full three-dimensional plane-wave model with the supercell method.