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Abstract:As an application of organic semiconductor distributed feedback (DFB) lasers we demonstrate their use as excitation sources in Raman spectroscopy. We employed an efficient small molecule blend, a high quality resonator and a novel encapsulation method resulting in an improved laser output power, a reduced laser line width and an enhanced power stability. Based on theses advances, Raman spectroscopy on selected substances was enabled. Raman spectra of sulfur and cadmium sulfide are presented and compared with the ones excited by a helium-neon laser. We also fabricated a spectrally tunable organic semiconductor DFB laser to optimize the Raman signals for a given optical filter configuration.

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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. With this technique we were able to tune the laser emission range between 613 nm and 667 nm. For high index layer thicknesses higher than 40 nm the laser operated on the TE(1)-mode rather than the fundamental TE(0)-mode.