Giga-Bit Transmission Between an Eye-Safe Transmitter and Wide Field-of-View SiPM Receiver

Published in IEEE Access with Dr Wajahat Ali as first author, and my first open-access paper.

Abstract

In this paper, the performance of a wide field of view VLC receiver that includes a silicon photomultiplier (SiPM) is reported. In particular, a receiver field of view of ±45° and On-Off keying data rates of 1.8 Gbps are demonstrated in 500 lux of ambient light. These results are achieved by combining optical absorption filters with a 6 mm by 6 mm SiPM. By absorbing ambient light between 450 nm and 750 nm these filters ensure that the SiPM is not saturated and reduces the transmitter power needed to support the required data rate. Unlike other optical filters the performance of absorption filters is not sensitive to angle of incidence. Consequently, the FOV is explained by a combination of the changes to the receiver’s projected area, the path length of light in the filters and reflections from the filter surfaces. In addition, the results of the calculations, described by the IEC 62471:2006 safety standard, needed to determine the eye safety of a transmitter are reported. These calculations and the resulting irradiance levels available in a representative office scenario are used to show that data rates of more than 1 Gbps could be achieved with eye safe transmitters.

Key Findings

The paper sets out how to design 405 nm transmitters for SiPM receivers, checks their eye safety against IEC 62471:2006, and measures the performance they achieve. Absorption filters give the receiver its wide FOV because, unlike interference filters, they work the same at any angle of incidence. They block the 450 nm to 750 nm light from white LED luminaires, so the SiPM stays out of saturation in a lit office.