This chapter addresses optical communications, in particular optical fiber based-communications. Optical communication systems are evaluated using the "eye pattern" measurement, which is an oscilloscope trace showing the detected signal as a function of the transmission rate. When the signals come in cleanly, an open eye pattern is observed. Pulse shaping will continue to be an integral part of optics-based communications. A number of communication-specific pulse shapers have been described in the scientific literature. Beyond the acousto-optic modulators and liquid-crystal spatial light modulators, one finds descriptions of micro-optomechanical modulators and other micro-electro-mechanical devices designed to take the wavelength-dispersed input spectrum and modulate each wavelength and send the information taking advantage of WDM and OCDMA. For long-haul communication, there is a need to transmit high-energy pulses for hundreds to thousands of kilometers without the need for repeaters. It is likely that optical satellite links will help the longest-distance communication, given the much lower dispersion of air compared to optical fibers.