Infrared optical response of strongly correlated cuprates: the effects of topological phase separation

We examine the effects of electron inhomogeneity on IR optical conductivity of cuprates. Nanoscopic electron inhomogeneity is believed to be inherent property of doped cuprates throughout the phase diagram beginning from electron-hole droplets in insulating parent system and ending by a topological phase separation in electron-hole bose liquid (EHBL) phase. A simple model of metal-insulator composite and effective medium theory has been used to describe the static phase separation effects. The low-frequency dynamics of topological EHBL phase in a random potential in underdoped regime has been discussed in a quasiparticle approximation within the memory function formalism. The effects of static and dynamic nanoscopic phase separation are believed to describe the main peculiarities of the optical response of doped cuprates in a wide spectral range.