Known laser diode selections are limited to those designed for high power applications (high gain) or those designed for stable single mode operation in an external cavity (low gain). Exponential gain of laser diodes implemented according to embodiments of the present invention is improved (i.e., optimized) to provide both high output power and stability in an external cavity. This is accomplished by controlling the number of quantum wells, light confinement factor, and the transparency current of the laser diode.