Expanding high reflection range in a dielectric multilayer reflector by disorder and inhomogeneity

A systematical study is presented on the impact of disorder and inhomogeneity on the high reflection range (HRR) in a one-dimensional binary dielectric multilayer reflector for various incident angles. It is found that the introduction of disorder can expand the HRR for both transverse electric (TE) and transverse magnetic (TM) waves, irrespective of the incident angle. The HRR is found to become wider as the degree of disorder increases, until the effect becomes saturated. On the other hand, for the TE wave only, the introduction of inhomogeneity may broaden the width of the HRR regardless of the incident angle. While for the TM wave, the effect of inhomogeneity depends on the angle of incidence, and it can expand the HRR only for the case of a small incident angle. The phenomenon is expected to find significant applications in the optimal design of broadband binary dielectric omnidirectional reflectors.