  Sub-threshold measurements of a photonic crystal (PC) microcavity laser
operating at 1.3 microns show a linewidth of 0.10 nm, corresponding to a
quality factor Q ~ 1.3x10^4. The PC microcavity mode is a donor-type mode in a
graded square lattice of air holes, with a theoretical Q ~ 10^5 and mode volume
Veff ~ 0.25 cubic half-wavelengths in air. Devices are fabricated in an
InAsP/InGaAsP multi-quantum well membrane and are optically pumped at 830 nm.
External peak pump power laser thresholds as low as 100 microWatts are also
observed.
