Two-stage injection locking of high-power semiconductor arrays

A new multistage diode-array injection-locking technique is demonstrated. This approach permits higher power extraction or higher overall gain to be achieved than possible with single-stage designs. Using two antireflectioncoated 40-stripe multiple-quantum-well diode arrays, we characterize the amplifier small-signal and saturated gain performance. More than 500 mWof power is achieved with single frequency and narrow linewidth in a nearly diffraction-limited far-field lobe. With small-signal inputs, an overall gain of 25 dB with 290-mW locked output is obtained.