Visible spectrum waveguiding in bulk CMOS

Abstract

Waveguiding across the visible spectrum in an unmodified bulk CMOS chip is reported. The chip is fabricated in a standard CMOS process, and a simple wet etch removes metal in predetermined locations to expose glass rib waveguides. A modified Euler bend is introduced to improve bend radii by nearly an order of magnitude in the rib waveguides, and upper-bound losses are measured at visible wavelengths. These losses range from 6.2 dB/cm at 450 nm to 3.2 dB/cm at 650 nm and represent the lowest losses reported at visible wavelengths in unmodified bulk CMOS.