Spatially resolved polarisation measurement in photonic crystal cavity

A lasing mode in a single-cell photonic crystal cavity is characterised by measuring spatially resolved polarisation. A polarisation state is measured at each small element of area (50 x 50 mum) in the lasing mode. The observed set of polarisation compares well with the computed electric field direction of the quadrupole mode. This polarisation study demonstrates a significant advance to unambiguously identify a lasing mode in a photonic crystal cavity.