Let there be white light: supercontinuum generation by ultrashort laser pulses

Three centuries after Newton's experiments on the decomposition of white light into its spectral components and the synthesis of white light from various colors, nonlinear-optical transformations of ultrashort laser pulses have made it possible to produce an artificial white light with unique spectral properties, controlled time duration, and a high spectral brightness. Owing to its broad and continuous spectrum, such radiation is called supercontinuum. The laser generation of white light is an interesting physical phenomenon and the relevant technology is gaining in practical implications - it offers novel solutions for optical communications and control of ultrashort laser pulses, helps to achieve an unprecedented precision in optical metrology, serves to probe the atmosphere of the Earth, and suggests new strategies for the creation of compact multiplex light sources for nonlinear spectroscopy, microscopy, and laser biomedicine. Here, we provide a review of physical mechanisms behind the laser generation of white light, examine its applications, and discuss the methods of generation of broadband radiation with controlled spectral, temporal, and phase parameters.