Visible light communications is an alternative method of indoor wireless communications that requires sensitive receivers. Ideally, single photon avalanche detectors (SPADs) could be used to create more sensitive receivers. However, the dead time, finite output pulse width, and photon detection efficiency of existing SPAD arrays limit their sensitivity and bandwidth. In this paper, an accurate equation for the impact of dead time on the sensitivity of a SPAD array is presented. In addition, the impact of the width of the output pulses on the on-off keying data rate is investigated. Finally, a comparison between receivers containing an avalanche photo-diode (APD) and a large array of SPADs shows that although the receiver containing the SPAD is more sensitive in the dark, the APD-based receiver is more sensitive in a normal operating condition. However, the models that predict the performance of both receivers suggest that newer SPAD arrays will enable significant improvements in receiver sensitivity.
Bibliographical note© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
- Avalanche photodiodes
- Mathematical model
- Optical receivers
Zhang, L., Chitnis, D., Chun, H., Rajbhandari, S., Faulkner , G., O'Brien, D. C., & Collins, S. (2018). A comparison of APD and SPAD based receivers for visible light communications. Journal of Lightwave Technology, 36(12), 2435-2442. https://doi.org/10.1109/JLT.2018.2811180