Observation of sub-Bragg diffraction of waves in crystals
| Abstract | We investigate the diffraction conditions and associated formation of stop gaps for waves in crystals with different Bravais lattices. We identify a prominent stopgap in high-symmetry directions that occurs at a frequency below the ubiquitous first-order Bragg condition. This sub-Bragg diffraction condition is demonstrated by reflectance spectroscopy on two-dimensional photonic crystals with a centred rectangular lattice, revealing prominent diffraction peaks for both the sub-Bragg and first-order Bragg condition. These results have implications for wave propagation in 2 of the 5 two-dimensional Bravais lattices and 7 out of 14 three-dimensional Bravais lattices, such as centred rectangular, triangular, hexagonal and body-centred cubic. |
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| Authors | S. R. Huisman, R. V. Nair, A. Hartsuiker, L. A. Woldering, A. P. Mosk, and W. L. Vos |
| Year of publication | 2012 |
| Date published | 02/2012 |
| Journal | Phys. Rev. Lett. |
| Volume | 108 |
| Pages | 083901: 1-5 |
| Keywords | 2D crystals, 3D crystals, diffraction, photonic band gap, sub-Bragg |