Whispering-gallery modes in microring lasers made from conjugated polymers

Summary form only given. Stimulated emission has been reported in various semiconducting conjugated polymers, and the prospect of compact electrically pumped polymer lasers is exciting. Very recently, we were able to obtain unambiguous features of optically pumped laser emission from a poly[2,5-bis-(2´ethylhexyloxy)-p-phenylenevinylene] (BEH-PPV) film contained in a high-finesse Fabry-Perot cavity. Independent measurements revealed large optical gain that enables lasing in very small volumes, assuming that the suitable feedback is provided. Microcavities are easy to integrate and have the advantage that high Q values can be obtained even in very small and controllable mode volumes in which the current densities necessary for electrical pumping can in principle be achieved. We demonstrate threshold behavior of laser modes in two different microring configurations under optical excitation.