Fabrication and measurements on coupled photonic crystal cavities

Quasi-three dimensional photonic crystals can be realized by fabricating thin membranes of high index material hanging in air patterned with sub-micron holes to create a photonic band gap for optical confinement in plane and total internal reflection for out of plane confinement. Introducing defects into the photonic crystal gives rise to defect states in the form of small confined modes. By embedding an active gain medium like quantum dots into the membrane makes it possible to realize lasers with ultra-small mode volumes and low thresholds. Unfortunately single cavity photonic crystal lasers have also a low output power. A promising way to increase the output power while keeping a low threshold is to couple a large number of cavities. We successfully fabricated several coupled cavity systems and measured on them in order to investigate the behaviour of the coupled systems and the interaction between coupled cavities depending on their relative coupling to each other.