Investigation of group delay, loss, and disorder in a photonic crystal waveguide by low-coherence reflectometry

The authors propose highly resolved optical low-coherence reflectometry for investigating low-loss photonic crystal slab waveguides. This technique allows a fast, reliable, and straightforward measurement of the group delay and propagation losses for both TE and TM polarizations. The agreement with theory is very good. These measurements reveal effects related to structural disorder. The versatility and deep physical insight of this measurement technique will play a key role in the study of slow-light devices such as photonic crystal waveguides.