Phase conjugate techniques for diode laser brightness enhancement

Diode laser arrays provide a compact, high power, high efficiency source of monochromatic light and are finding many applications in all solid-state mini and micro-laser systems. Unfortunately, the preferred modes of operation of free-running, conventional gain-guided laser arrays involve the simultaneous oscillation of many array transverse modes1. This results in an undesirable broadened twin-lobe output in the far field which is generally several times the diffraction limit of the emitting region. This leads to poor focussability which in turn severely limits the efficiency of launching into optical fibers, coupling into planar waveguides and longitudinal pumping of solid-state micro-lasers.