Theory of resonantly enhanced near-field imaging

We investigate the fundamental issues of power transfer and far-field retrieval of subwavelength information in resonantly enhanced near-field imaging systems. It is found that high-quality resonance of the imaging system, such as that provided by dielectric resonators, can drastically enhance the power transfer from the object to the detector or the working distance. The optimal power transfer condition is shown to be the same as the critical coupling condition for resonators. The combination of a dielectric planar resonator with a solid immersion lens is proposed to project resonantly enhanced near-field spatial frequency components into the far field with the same resolution limit as that for solid immersion microscopy, but with much improved signal power throughput or working distance for resonant spatial frequencies. (C) 2007 Optical Society of America.