Coherent amplification characteristics of a GaAs phased array

The coherent amplification properties of antireflective coated GaAs diodes are considered for application to a phased array amplification scheme. The developmemt and design characteristics of a ten-element array system are discussed. An experimental diode array possessing good electrical and spectral match among diodes and excellent thermal dissipation is shown to provide optical gains, for main master laser modes, of at least 13 dB per array diode after coating. Temporal and spatial coherence within a GaAs laser spot, approximately 35 µ wide, is found to be adequate for array amplification purposes. The effects of array amplification on an incident coherent beam are evaluated by comparing predicted fringe patterns with observed interference patterns. The coherence of the incident beam is shown to be preserved during the amplification process.