Broadband multimode waveguide bend in the SOI platform

In this paper, we present a design and experimental demonstration of a 90o broadband multimode waveguide bend that supports the propagation of multiple modes on a silicon-on-insulator (SOI) platform. In order to achieve efficient mode multiplexing, we utilize trapezoidal-shaped subwavelength grating (SWG) segments, which are bridged by adiabatically tapered radial strips to form a gradient curvature bend. Using a 220 nm SOI wafer, our unique design of the multimode bend has a radius of 10 μm and only requires a single full etch step. We report successful experimental demonstration of a multimode waveguide bend that supports at least 4 modes, across a broad bandwidth of 100 nm, centered at 1550 nm. This work offers a promising potential for broadband mode-division multiplexers.