Low-Threshold and Broadly Tuneable Organic Lasers Based on Star-Shaped Oligofluorene Truxenes
A family of star-shaped truxene-core fluorene-oligomers are introduced. Key photophysical features of two long arm members, T3 and T4, including their absorption and emission spectra, and solid-state photoluminescence quantum yields are studied. To inspect their potential as gain media for lasers, optical gain and loss coefficients are measured with amplified spontaneous emission from thin film waveguides. Ellipsometry measurements are performed to examine whether the thin films are amorphous or crystalline, and to determine the optical constants, i.e. refractive indices and extinction coefficients. The refractive indices of the gain media are important parameters in designing distributed feedback lasers. Low threshold surface emitting DFB lasers, optically pumped by a Q-switched microchip laser, are demonstrated with these oligofluorene truxenes, with broad tunability in the blue spectral region.
KeywordsOrganic Semiconductor Loss Coefficient Amplify Spontaneous Emission Pump Intensity Laser Threshold
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