Whispering-gallery-mode microring laser using a conjugated polymer

We observed laser emission in whispering gallery modes using a microring composed of a semiconducting polymer poly[2,5-bis-(2^′-ethylhexyloxy)-$p$ -phenylenevinylene coated on an etched fiber under transient and quasisteady-state pumping conditions. The threshold for laser oscillation was 1 ${\mathrm{mJ/cm}}^{\mathrm{2}}$ (0.1 ${\mathrm{MW/cm}}^{\mathrm{2}})$ and 30 ${\mathrm{\mu J/cm}}^{\mathrm{2}}$ (300 ${\mathrm{MW/cm}}^{\mathrm{2}})$ for nanosecond and femtosecond excitation, respectively. The laser output showed superlinear dependence on the excitation energy above the threshold. The demonstration of lasing under quasisteady-state pumping shows the possibility to develop electrically pumped polymer lasers.