Intermediate high index layer for laser mode tuning in organic semiconductor lasers.

We modified the optical properties of organic semiconductor distributed feedback lasers by introducing a high refractive index layer consisting of tantalum pentoxide between the substrate and the active material layer. A thin film of tris-(8-hydroxyquinoline) aluminium doped with the laser dye 4-dicyanomethylene-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran was used as the active layer. By varying the intermediate layer thickness we could change the effective refractive index of the guided laser mode and thus the laser wavelength.

Organic semiconductor distributed feedback laser fabricated by direct laser interference ablation.

We use a pulsed, frequency tripled picosecond Nd:YAG laser for holographic ablation to pattern a surface relief grating into an organic semiconductor guest-host system. The resulting second order distributed feedback lasers exhibit laser action with laser thresholds being comparable to those obtained with resonators structured by standard lithographic techniques. The details of the interference ablation of tris-(8-hydroxyquinoline) aluminum (Alq(3)) doped with the laser dye 4- dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) are presented and discussed.