Silicon-based photonic crystals

We introduce the concept of silicon-based photonic crystals with the main focus on the macroporous silicon material system. photonic crystals are the optical analog to electronic semiconductors. Due to their periodic modulation of the refractive index they exhibit a band-structure for photons propagating in the Photonic crystal. This photonic band structure and in particular the photonic band-gap provide a number of interesting effects for both fundamental research as well as applied physics. These effects include, e.g., forbidden propagation of photons for certain frequencies or a huge reduction of the group velocity. The macroporous silicon material system allows the fabrication of photonic crystals with high dielectric contrast and a variety of patterns as well as defect incorporation using lithographic prestructuring and subsequent photoelectrochemical etching. The etching process will be discussed and experimental results of two-and three-dimensional photonic crystals based on macroporous silicon will be presented and their optical properties will be explored.