Mobile Self-Protection Resonant Beam SWIPT With Adaptive Phase Control

The Simultaneous Wireless Information and Power Transfer (SWIPT) technique heralds a new era for future Internet of Things (IoT) devices. Resonant Beam System (RBS) is emerging as a possible future for achieving long-range, high-power, and high-capacity SWIPT. However, ensuring human safety at higher power levels presents an unresolved issue. A novel approach to enhance safety utilizes self-mixing interference to minimize radiation exposure for invading objects. However, this design restricts the system to a predetermined position. Thus, the application of the system in mobile scenarios is still challenging. In this paper, we proposed an enhanced self-protection RBS with self-adaptive phase adjustment to support the mobility of the system. A phase adjuster is composed into the system which utilizes the linear Electro-optic effect (i.e. Pockels effect) to correct phase discrepancies. An Optical Phase-Locked Loop (OPLL) achieves self-adaptive functionality using its feedback loop. Based on the analytical model established in this paper, the proposed system does not compromise the safety of the original self-protection RBS but offers mobility. The SWIPT performance evaluations indicate a stable system output, with a spectral efficiency of approximately 13.77 bps/Hz and an electrical power output of 4.63 W over a distance of 6 m within a 5∘ field of view.