Nanophotonics with and without photons

Abstract

This chapter considers a variety of optical and light—matter interaction phenomena in the context of classical and quantum electrodynamics. All propagation phenomena are emphasized as wave-optical process where the photon notion is not necessary to be involved into consideration. All phenomena related to light emission and inelastic scattering do need photons for their interpretation. However, elastic scattering fully merges with the description based on classical electrodynamics, and spontaneous emission and inelastic scattering can be calculated using classical electrodynamics approach. Here merging of quantum and classical description is enabled by means of the operational definition of photon density of states based on the properties of a classical oscillator affected by space topology and local environment. This accordance of quantum and classical presentations is remarkably demonstrated by elaboration of the optical nanoantenna conception. The quantum-classical convergence is appreciated for new discovered phenomena of light–matter interaction in complex structures. Here the lately discovered phenomenon of changing light wavelength in a cavity is treated as possible inelastic photon scattering promoted by high photon local density of states in a tunable cavity, an analog to Purcell effect known for spontaneous emission probability.