Three step lithography to the fabrication of vertically coupled micro ring reson

A simple method to fabricate vertically coupled micro-ring resonators in amorphous silicon-on-insulator is created by a three-step lithography process. First, the linear loss at 1.55 \mu m of the a-Si:H film is calculated to be 0.2 +(-) 0.05 dB/cm. Then, the bottom line waveguide of Su-8 with a flat