The potential of the blue laser device is being recognized for its development into a commercial lighting system using about a tenth of the power and with a thousand times the operating lifetime of a comparable conventional system. This work introduces the subject at a level suitable for graduate students. It covers the basic physics of light emitting diodes (LEDs) and laser diodes (LDs) based on gallium nitride and related nitride semiconductors, and gives an outline of their structural, transport and optical properties, and the relevant device physics. It begins with the fundamentals, and...