A Gbps Building-to-Building VLC Link Using Standard CMOS Avalanche Photodiodes

Abstract

A building-to-building free-space visible-light-communication link over more than 72 m link distance is presented. The link employs a dual data/clock optical channel from two 680-nm vertical-cavity surface-emitting laser laser-diodes. The receivers are implemented using custom bandwidth-enhanced avalanche photodiodes (APD) in Austria-Micro-Systems 0.35 μm complementary-metal-semiconductor-oxide technology. The APD receiver uses resistive linearization to allow for improved bias voltage control in the soft-breakdown region as well as increased signal-to-noise ratio by around 6 dB. A simple amplifier-based architecture is employed with no equalization or transimpedance-amplifier use. Measurement results show an on–off-keying data rate of 2 Gb/s and forward-error-correction-compliant bit error rate below 3.8 × 10−3.

Keywords

• FSO
• VLC
• avalanche photodiodes
• laser diodes.