Attenuation of optical transmission within the band gap of thin two-dimensional macroporous silicon photonic crystals

The transmissivity within the photonic band gap of two-dimensional photonic crystals of macroporous silicon is reported as a function of crystal thickness. Measurements were carried out for crystals of nominally 1, 2, 3, and 4 crystal layers using a commercial parametric source, with a wavelength tunable from 3 to 5 mu m. For wavelengths well within the 3-5 mu m photonic band gap, attenuation of approximately 10 dB/crystal layer is obtained, in agreement with calculations based on plane wave expansion methods. For these materials, one should be able to achieve photonic crystal functionality in many applications with very small crystal volumes. (C) 1999 American Institute of Physics. [S0003-6951(99)01046-3].