Vertical trident coupler for 3D optical interconnection

A vertical trident coupler for 3D optical circuit was demonstrated. This is novel interlayer directional-type coupler between crystalline Si and amorphous-Si:H wire waveguides. The trident structure can manage both easiness of fabrication and high coupling even with relatively thick interlayer distances. In experiment, this trident coupler realized low coupling loss (coupling efficiency) of 0.58dB (87%) at 1550 nm wavelength and almost constant coupling loss of around 0.5dB within the wavelength range from 1530 nm to 1610 nm.