Measurement of radiative and guided modes in silicon-on-insulator photonic crystal slabs

The dispersion of photonic modes in silicon-on-insulator patterned waveguides containing line defects is fully investigated both above and below the light-line. Quasi-guided (radiative), as well as truly guided, modes are probed by means of angle- and polarization-resolved micro-reflectance and attenuated total reflectance measurements. The presence of a supercell repetition leads to the simultaneous excitation of defect and bulk modes, which are folded in a reduced Brillouin zone. The measured dispersion is in very good agreement with full 3D calculations based on expansion on the waveguide modes, indicating that a deep understanding of the propagation properties of patterned silicon-on insulator waveguides is achieved.