Abstract
Thin films of organic semiconductors have been subjected to extensive studies in the last two decades due to applications in photonics and optoelectronics. In this paper, we investigate wavelength tuning phenomena based on fluorene-cored oligomers (T3). We studied the optical properties of oligofluorene vacuum-deposited thin films and found that they show high optical anisotropy but become optical isotropic after annealing at a temperature around the glass-transition temperature. The results indicate the molecular reorientation in thin films after annealing. Using this property, we investigated the influence of molecular orientation on stimulated emission properties of organic thin films. Employing such properties, we have also demonstrated continuous tuning of the stimulated emission wavelength of a slab waveguide within one sample. Finally, we employed T3 thin film for laser application. We have also demonstrated the wavelength tuning of the organic laser with DFB structures.