Described herein are embodiments of transferring electromagnetic energy that includes providing a first electromagnetic resonator structure receiving energy from an external power supply, said first resonator structure having a first mode with a resonant frequency ω1, an intrinsic loss rate Γ1, and a first Q-factor Q1=ω1/(2Γ1), providing a second electromagnetic resonator structure being positioned distal from said first resonator structure and not electrically wired to the first resonator structure, said second resonator structure having a second mode with a resonant frequency ω2, an intrinsic loss rate Γ2, and a second Q-factor Q2=ω2/(2Γ2), and transferring electromagnetic energy from said first resonator structure to said second resonator structure over a distance D that may be smaller than each of the resonant wavelengths λ1 and λ2 corresponding to the resonant frequencies ω1 and ω2, respectively. The electromagnetic resonator structures may be designed to have Q1>100 and Q2>100. The absolute value of the difference of said angular frequencies ω1 and ω2 may be smaller than the magnitude of the coupling rate, κ.