Two-dimensional symmetric multimode interferences in silicon square waveguides

Symmetric interference in two-dimensional multimode silicon waveguides is experimentally investigated. For a 100×100 μm² cross section, 2700-μm-long waveguide fabricated on silicon-on-insulator substrate, an 8×8 matrix of replicated images with high contrast ratio is demonstrated for 1530-1570 nm wavelength range. Symmetric interference results in reduced device length, and the actual device length is consistent with the theoretical expectation. The device also exhibits stable imaging in terms of good loss uniformity, and low wavelength and polarization dependencies among the replicated images.