High Speed Electro-Absorption Modulator for Long Range Retroreflective Free Space Optics

In this letter, we present the design and implementation of a pixelated electro-absorption modulator-based modulating retroreflector (MRR) for high-speed optical wireless communications. The modulator is based on a multiple quantum well structure embedded in an asymmetric Fabry–Perot cavity. This MRR was used in an outdoor link, operating at 150 Mb/s with a bit error rate (BER) of <inline-formula> <tex-math notation="LaTeX">$1.22\times 10^{-6}$ </tex-math></inline-formula> at a range of 200 m. The system was also tested in laboratory-controlled conditions achieving a data rate of 200 Mb/s with a BER of <inline-formula> <tex-math notation="LaTeX">$2\times 10^{-4}$ </tex-math></inline-formula>. To the best of our knowledge, this is the fastest retroreflective free-space optics demonstration in both the indoor and outdoor environments.