The Air Force has played a leading role in the development of coherent semiconductor diode lasers since 1985. Because of their high efficiency and small size, these lasers have great potential for use in a variety of applications. In order to advance the technical base in the area of semiconductor lasers, the Air Force has awarded many development contracts as well as established a strong in-house modelling and characterization capability. This paper discusses the various techniques for achieving high-power, coherent, semiconductor laser sources. Among these are the use of broad area, single stripe sources, linear edge emitting arrays, surface emitting arrays, external cavities, and a phase conjugate master oscillator power amplifier system. The various techniques and their relative merits are discussed.