Dye-doped organic distributed-feedback lasers with index and surface gratings: the role of pump polarization and molecular orientation

The dependence of the laser threshold of organic distributed-feedback (DFB) lasers having index and surface gratings on the pump polarization angle is studied and examined. A model is developed to describe the relationship between the fluorophore orientational distribution and the number of photons emitted into the laser mode. Experimental data fitted with this model demonstrate that the fluorophores are isotropically oriented in the plane of the sample. The polarization dependence of the laser threshold is then used in conjunction with the measured pump intensity dependence of the emission intensity to explain the pump polarization selectivity of the laser emission of these structures. The effect of the above phenomena on future applications is discussed. (C) 2004 Optical Society of America