Porous silicon: A photonic material for all seasons

Porous silicon has a number of demonstrated optical properties that are ideal for a broad range of applications in photonics and optoelectronics research. Technologies based on the tunability of the optical properties of porous silicon such as the refractive index and the ability to grow monolithic multi-layered structures has emerged as new focus of research. In this paper we report on developments relating to porous silicon based microcavities and Bragg reflectors, which have significant implications for a diverse range of applications. Fabrication of a one-dimensional photonic crystal with photonic band-gap is demonstrated. We have also fabricated microcavity structures that exhibit cavity resonances with sub-nanometer line-widths and very high Q-factors (> 7300). Such structures could be useful as both passive and active devices such as narrow bandpass filters and environmental sensors.