Liquid crystal tuning of InGaAsP photonic crystal membrane type nanocavities

We demonstrate mode-dependent tuning of liquid crystal (4-pentyl-4’cyanobiphenyl, 5CB, Merck) infiltrated into InGaAsP photonic crystal (PhC) membranes with embedded InAs quantum dots when the temperature or the power of an incident laser is varied. The cavity modes can be tuned in opposite directions and exhibit a sudden change at the clearing temperature. The mechanism relies on the existence of both ordinary and extraordinary refractive indices of the liquid crystal arising from specific molecular alignment inside the PhC holes. For high laser powers, large and reversible tuning of cavity modes is observed which is tentatively attributed to temperature induced liquid transport