Safety Analysis of Long-Range and High-Power Wireless Power Transfer using Resonant Beam

Wen Fang, Hao Deng, Qingwen Liu, Mingqing Liu, Qingwei Jiang, Liuqing Yang, Georgios B. Giannakis

Research output: Contribution to journalArticlepeer-review


Resonant Beam Charging (RBC) is a promising Wireless Power Transfer (WPT) technology to realize long-range and high-power charging for electronic devices. However, the safety mechanism of the RBC system has not been investigated so far. In this paper, we propose an analytical model based on electromagnetic field analysis for evaluating the performance of the RBC system with external object invasion, such as the benchmark for the WPT safety, irradiance on the invading object. For the RBC system with 5m transmission distance and 1W output electric power, the safety numerical analysis of radiation illustrates that the maximum irradiance on the invading object is 0.81W/cm<sup>2</sup>, which is approximately 1/10 compared with 8.22W/cm<sup>2</sup> for the comparable laser charging system. Particularly, the peak irradiance on the invading object of the RBC system satisfies the Maximum Permissible Exposure (MPE) requirement for human skin, which is 1W/cm<sup>2</sup> in the standard Safety of Laser Products IEC 60825-1. Hence, the RBC system can realize skin-safe WPT with Watt-level power over meter-level distance.

Original languageEnglish (US)
Article number9422160
Pages (from-to)2833-2843
Number of pages11
JournalIEEE Transactions on Signal Processing
StatePublished - 2021

Bibliographical note

Funding Information:
Manuscript received November 6, 2020; revised February 27, 2021 and April 9, 2021; accepted April 19, 2021. Date of publication May 3, 2021; date of current version May 28, 2021. The associate editor coordinating the review of this manuscript and approving it for publication was Dr. An Liu. This work was supported in part by the National Key R&D Program of China under Grants 2020YFB2103900 and 2020YFB2103902, and in part by the National Natural Science Foundation of China under Grants 61771344 and 62071334. (Corresponding authors: Qingwen Liu; Hao Deng.) Wen Fang, Qingwen Liu, Mingqing Liu, and Qingwei Jiang are with the College of Electronic and Information Engineering, Tongji University, Shanghai 200000, China (e-mail:;;;

Publisher Copyright:
© 1991-2012 IEEE.


  • Laser beams
  • Laser excitation
  • Power lasers
  • Pump lasers
  • Receivers
  • Safety
  • Transmitters
  • resonant beam charging
  • Electromagnetic field analysis
  • wireless power transfer
  • inherent safety


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