Manipulating light on wavelength scale

Light, at the length-scale on the order of its wavelength, does not simply behave as "light ray", but instead diffracts, scatters, and interferes with itself, as governed by Maxwell's equations. A profound understanding of the underlying physics has inspired the emergence of a new frontier of materials and devices in the past few decades. This thesis explores the concepts and approaches for manipulating light at the wavelength-scale in a variety of topics, including anti-reflective coatings, on-chip silicon photonics, optical microcavities and nanolasers, microwave particle accelerators, and optical nonlinearities.