Laser oscillation from hexagonal crystals of a thiophene/phenylene co-oligomer

The characteristics of the unusually narrowed emission from hexagon BP1T crystals were investigated by photopumping them with a line laser beam. The wavelengths and strengths of the emission lines sensitively depended on the position and the angle of the crystal. The threshold of the excitation fluence decreases inversely proportional to the crystal length. We have concluded that the unusually narrowed emission is the laser oscillation by laser cavity resonance within a waveguide. The shape and size of the excitation laser beam play an important role in the laser oscillation. (c) 2006 American Institute of Physics.