One-dimensional photonic crystals (PCs), when operating near the band edge in the dispersion diagram, inherently possess nearly polarization-independent angular selectivity-an angular transmission window around the normal direction with reflection for other angles. However, the incident light is mostly reflected at the PC-air interface due to large impedance mismatch. We show that the reflection may be sufficiently suppressed by utilizing a specially designed antireflection structure consisting of a PC having a different pitch from that of the host PC. The underlying mechanism is that the interfaces of the antireflection PC with the host PC and the air structure are selected such that the transverse impedance has a real value, which is positioned at the center of the thickness of a material film. Moreover, our structure provides a high-throughput wide angular transmission window, including the normal direction in both s and p polarizations. We develop an analytical model that captures the angular selectivity observed in numerical results. (C) 2016 Optical Society of America
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