Effect of surface truncation on mode density in photonic crystals

The effect of surface truncation on the electromagnetic density of modes (DOM) in photonic crystals (PCs) is investigated theoretically. It shows that for PCs with surface truncation parameter τ≠0 or τ≠0.5, the DOM has asymmetric properties on the two edges of the first bandgap in normal incidence. Moreover, DOM at band edges has much larger values in the PC with appropriate truncation than that in the PC without truncation. Also, the effect of surface truncation on a band-edge laser is discussed, and the case of the oblique incident is also discussed.