Polarization control in GaN nanowire lasers.

We demonstrate polarization control in optically-pumped single GaN nanowire lasers fabricated by a top-down method. By placing the GaN nanowires onto gold substrates, the naturally occurring randomly orientated elliptical polarization of nanowire lasers is converted to a linear polarization that is oriented parallel to the substrate surface. Confirmed by simulation results, this polarization control is attributed to a polarization-dependent loss induced by the gold substrate, which breaks the mode degeneracy of the nanowire and forms two orthogonally polarized modes with largely different cavity losses.