We have studied the reflectivity of CMOS-compatible three-dimensional silicon inverse woodpile photonic crystals at near-infrared frequencies. Polarization-resolved reflectivity spectra were obtained from two orthogonal crystal surfaces using an objective with a high numerical aperture. The spectra reveal broad peaks with maximum reflectivity of 67% that are independent of the spatial position on the crystals. The spectrally overlapping reflectivity peaks for all directions and polarizations form the signature of a broad photonic band gap with a relative bandwidth up to 16%. This signature is supported with stop gaps in plane-wave band-structure calculations and with the frequency region of the expected band gap.

Phys. Rev. B

Huisman, S. R., Nair, R. V., Woldering, L. A., Leistikow, M. D., Mosk, A., & Vos, W. L. (2011). Signature of a three-dimensional photonic band gap observed on silicon inverse woodpile photonic crystals. Phys. Rev. B, 83(20, Article number: 205313), 1–7. doi:10.1103/PhysRevB.83.205313