Focusing Leaky Waves: A Class of Electromagnetic Localized Waves with Complex Spectra

Abstract

Focusing light's energy in the near field, beyond the diffractive limit, is key to progress in fields as diverse as microscopy, electronics, telecommunication, wireless power transfer, and ablation and tomography in medicine. The authors address the problem by considering a specific class of partially guided waves, known as ``leaky'' waves. Interestingly, only the subclass of backward leaky waves is found to be useful here. Qualitative and quantitative assessments furnish general design rules, and a simple but efficient leaky-wave device is proposed for generating limited-diffraction beams and pulses in the millimeter-wave range, where few experiments have been performed.