Gigabit data rates are becoming relevant for several applications areas, including computer interconnections, trunk telecommunications, and phased-array radar control. LED's, lasers, p-i-n FET's, photoconductors, and avalanche photodiodes are candidate components. Silicon NMOS, bipolar, GaAs FET, and heterojunction bipolar logic IC technologies are all appropriate and no obstacles are apparent to prevent direct modulation to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sim10-20</tex> Gbit/s. Wavelength multiplexing will impact strongly in several applications enabling complex new system architectures. Increasing speed and complexity will drive technology to higher optoelectronic integration levels.