OVERVIEW

Near-field optics has played a significant role in nanoscience and nanobiotechnology in the past 20 years and continues to be an active research area, especially when dealing with field localization and resonances in micro/nanostructures, with applications in biochemical sensing and nanolithography. The preceding two chapters have laid the foundation of electromagnetic waves in bulk materials and nanostructures. The present chapter offers a more detailed treatment of the energy transfer by electromagnetic waves in the near field, as well as the coupling between near-field phenomena and far-field characteristics. The applications include nanomanufacturing, energy conversion systems, and nanoelectronics thermal management.

Ernst Abbe in 1873 and Lord Rayleigh in 1879 studied the required angular separation between two objects for their images to be resolved. The resolution of a conventional microscope is diffraction limited such that the smallest resolvable distance is approximately 0.5 ?/ n, where ? is the wavelength in vacuum and n is the refractive index of the medium. Even with an immersion oil ( n ? 1.5), the imaging sharpness is rather limited to the order of wavelength. The concept of near-field imaging was first described by Synge ( Phil. Mag., 6, 356, 1928). This work elaborated the concept of using subwavelength aperture as small as 10 nm in diameter to introduce light to a specimen (e.g., a stained biological section), placed within 10-nm distance, which could move in its plane with a step size less than 10 nm. By measuring the transmitted...