We have demonstrated low-threshold two-dimensional photonic crystal lasers with self-assembled InAs/GaAs quantum dots. Coupled cavity designs of whispering gallery modes are defined in square lattice photonic crystal slabs. Our lasers showed a small 120 µW input pumping power threshold. Actual absorption power is evaluated to be less than 20 µW. Our lasers show high spontaneous emission coupling (β) factors0.1. The mode volumes are expected to be 0.7-1.2 times cubed wavelength by our modelling. Based on threshold analysis, 80 QDs are the effective number of QDs defined as the number of QDs needed to make PC cavities transparent if they are on maximum optical field points. Using the same analysis we found that single quantum dot lasing is likely to occur both by proper alignment of the single quantum dot relative to geometries of photonic crystals and by using sharp QD emission lines in high-Q localized modes.

We have designed, fabricated and characterized efficient optical resonators and low-threshold lasers based on planar photonic crystal concept. Lasers with InGaAsP quantum well active material emitting at 1550 nm were optically pumped, and room temperature lasing was observed at threshold powers below 220 µW. Porous high quality factor cavity that we have developed confines light in the air region and therefore our lasers are ideally suited for investigation of interaction between light and matter on a nanoscale level. We have demonstrated the operation of photonic crystal lasers in different ambient organic solutions, and we have showed that planar photonic crystal lasers can be used to perform spectroscopic tests on femtoliter volumes of analyte.