  The topological characteristics, including invariant topological orders, band
inversion, and the topological edge mode (TEM) in the photonic insulators, have
been widely studied. Whether people can take advantage of intriguing
topological modes in simple one-dimensional systems to implement some practical
applications is an issue which people are increasingly concerned about. In this
work, based on a photonic dimer chain composed of ultra-subwavelength
resonators, we verify experimentally that the TEM in the effective second-order
parity-time (PT) system is immune to the inner disorder perturbation, and can
be used to realize the long-range wireless power transfer (WPT) with high
transmission efficiency. To intuitively show the TEM can be used for WPT, a
power signal source is used to excite the TEM. It can be clearly seen that two
LED lamps with 0.5-W at both ends of the structure are lighted up with the aid
of TEMs. In addition, in order to solve the special technical problems of
standby power loss and frequency tracking, we further propose that a WPT system
with effective third-order PT symmetry can be constructed by using one
topological interface mode and two TEMs. Inspired by the long-range WPT with
TEMs in this work, it is expected to use more complex topological structures to
achieve energy transmission with more functions, such as the WPT devices whose
direction can be selected flexibly in the quasiperiodic or trimer topological
chains.
