An image-sensor-based optical receiver fabricated in a standard 0.35-μm CMOS technology for free-space optical communications

We have developed an image-sensor-based optical receiver for free-space optical communications. In our scheme, each pixel has a function of an optical receiver as well as an image sensor. The functional mode can be selected pixel by pixel. The position of a communication target is detected from the image captured in the image sensor mode. Then, functional mode of the pixel receiving optical signals is changed to the optical receiver mode to start communication. We designed and fabricated a 50x50-pixel photo receiver in a standard 0.35 -μm CMOS technology, and fundamental operations were successfully verified. Total transimpedance gain of more than 200 kΩ and data rate of 30 Mbps and 50 Mbps for wavelength of 830 nm and 650 nm, respectively, were obtained.