High-efficiency dual-layer grating coupler for vertical fiber-chip coupling in two polarizations.

Efficient coupling between optical fibers and high-index-contrast silicon waveguides is essential for the development of integrated nanophotonics. Herein, a high-efficiency dual-layer grating coupler is demonstrated for vertical polarization-diversity fiber-chip coupling. The two waveguide layers are orthogonally distributed and designed for - and -polarized fiber modes, respectively.

Ultra-broadband Bragg concave diffraction grating designs on 220-nm SOI for wavelength demultiplexing.

The appropriate broadband design of a de/multiplexer can significantly increase the channel number and consequently the transmission capacity of a wavelength division multiplexing system. Herein, we present the first ultra-broadband Bragg concave diffraction grating (CDG) on a 220-nm silicon-on-insulator, covering most of the E, S, C, L, and U telecommunication wavebands spanning from 1.425 to 1.