Terahertz time-domain study of a pseudo-simple-cubic photonic lattice

A pseudo-simple-cubic photonic crystal lattice was fabricated in silicon. The phase-shift spectra and the amplitude spectra of the transmitted electromagnetic wave are studied by Terahertz time-domain spectroscopy measurements. The {π} phase shifts between Fabry-Perot modulation peaks are clearly observed. Our results are in good correspondence with transfer-matrix calculations. The dispersion curves were qualitatively extracted from the frequency dependence of the phase shifts. The gradient of the phase shift becomes large at the band-gap edges. This suggests that the group velocity is correspondingly small near the Brillouin-zone boundary.