This course explains the physics behind modern optical communication systems at high data rates. The first half of this course covers information theory and light propagation over fiber optic waveguide channels; semiconductor laser sources and detectors; high speed digital optic links; and dense wavelength division multiplexing methods and devices. The second half of this course covers quantum optical information theory; coherent systems and quantum correlations; optical solition-based communication; squeezed light and noise limitations; de-phasing and de-coherence; teleportation and secure communication system protocols; and cryptography and chaotic optics.