A three-dimensional photonic crystal operating at infrared wavelengths

The ability to confine and control light in three dimensions would have important implications for quantum optics and quantum-optical devices: the modification of black-body radiation, the localization of light to a fraction of a cubic wavelength, and thus the realization of single-mode light-emitting diodes, are but a few examples(1-3). Photonic crystals-the optical analogues of electronic crystal-provide a means for achieving these goals. Combinations of metallic and dielectric materials can be used to obtain the required three-dimensional periodic variations in dielectric constant, but dissipation due to free carrier absorption will limit application of such structures at the technologically useful infrared wavelengths(4), On the other hand, three-dimensional photonic crystals fabricated in low-loss gallium arsenide show only a weak 'stop band' (that is, range of frequencies at which propagation of light is forbidden) at the wavelengths of interest(5), Here we report the construction of a three-dimensional infrared photonic crystal on a silicon wafer using relatively standard microelectronics fabrication technology, Our crystal shows a large stop band (10-14.5 mu m), strong attenuation of light within this band (similar to 12 dB per unit cell) and a spectral response uniform to better than 1 per cent over the area of the 6-inch wafer.