Design of a compact three-dimensional multimode interference phased array structures (3-D MMI PHASAR) for DWDM applications

Monolithic integration of three-dimensional multimode interference couplers with silicon photonic wires via self-profile transformation

“…Conventional MMI are often considered as a two-dimensional (2-D) planar structure, a combination of singlemode waveguides and a multimode waveguide with equal device height, performing one-dimensional (1-D) multimode interference. Although three-dimensional (3-D) MMI splitters have been theoretically studied to have large, dense port counts [5], the device fabrication is still challenging. Several approaches such as wafer bonding [6] and direct writing by the femtosecond lasers [7] were demonstrated, but these processes are generally complicated and have less tolerance during fabrication.…”