This document discusses fiber optic communication for long haul systems. It covers selecting optical fiber types for long haul communication links over 10km. It also discusses optical power and dispersion budget calculations. Components of long haul fiber optic systems include repeaters, optical fiber amplifiers, transmitters and receivers. Considerations for long haul include low loss, repeater spacing over 40km to reduce costs, splicing unbroken fiber in long lengths to minimize losses, structurally robust cabling, and field repairability without returning equipment to a lab. Security and privacy are also important due to the ability of fiber optics to prevent tapping. Power budget calculations account for losses like free space loss, receiver and atmospheric losses.