Photonics in the twenty-first century

Photonics is a broad topic describing light based systems that are part of a wide range of technologies which have recently emerged in commercial systems. The central effort has been associated with signal processing for fibre optics, as this necessitates developments of lasers, pulse coding, multi-wavelength transmission and repeater units that function simultaneously and independently for as many as 100 carrier wavelengths, before wavelength-dependent separation, detection and routing. This is a phenomenal achievement that enables all modern communication. The chapter explains the simplicity of the concepts and design of examples of the technology. There are also far more complex proposals, such as early stage examples of invisibility cloaking, and recent progress with advances in photonics in medicine for both diagnostics and treatment.