Optical Spectra of High-Temperature Superconductors

摘要

This paper complements our recent survey [1] of experimental and theoretical work on the optical spectra of high-temperature superconductors. The emphasis is laid on experiments involving single crystals and good textured ceramic samples. Data have been collected on chemically doped samples, as well as on samples in which carriers are created by photodoping. One of the most remarkable consequences is the observation of a photoinduced superconductivity and a phase separation of photoexcited carriers. The theory has offered a few main suggestions but they have all failed to produce the magic formula for understanding the optical response. Nevertheless, bipolaron models seem somewhat closer to reality. Future experimental, theoretical, and practical developments are considered.