Coherent array of 900 semiconductor laser amplifiers

The design, fabrication, and testing of a two-dimensional array of 900 laser diode power amplifiers injected by a single semiconductor master oscillator is discussed. This array extends the results of the 200-emitter array reported on last year. The array consists of a stack of ten 100-emitter linear arrays. Nine of the 100-emitter arrays were successfully stacked and injected by a semiconductor master oscillator laser by way of a 1 to 10 semiconductor ridge- waveguide splitter and amplifier array. The tenth 100-emitter array was included in the stack but the fiber optic used to connect it to the 1 to 10 splitter broke before final strain-relief was added. The 900 amplifiers produced approximately 36 W of coherent power in the near field. Poor fill optics allowed only 15.6 W to be delivered to the far field of which 5.5 W were phase aligned into a narrow beam in one axis and into 5 major spots in the other axis. Improved optics and higher power emitters are the next steps in moving this array architecture to high power and brightness.