Emission characteristics and performance comparison of polyfluorene lasers with one- and two-dimensional distributed feedback

We report the fabrication of optically pumped solid-state polymer lasers based on the semiconducting polymer poly(9,9-dioctyl-fluorene) (PFO) using resonator structures that offer one- and two-dimensional distributed feedback. The lasers are readily fabricated by solution deposition of thin polymer films on top of suitable grating microstructures etched into fused silica substrates. The devices operate in the blue spectral region, are highly efficient (slope efficiencies as high as 7.8% are demonstrated), and exhibit very low threshold energies for oscillation (0.8 nJ per pulse). The operating characteristics of the lasers are investigated in detail. The transverse mode profiles and divergence of the output beams are measured and correlated with the internal lasing modes and the feedback mechanism present in the resonators. Additionally, broadband tuning of the emission wavelength over a range of ∼ 40 nm is demonstrated by controlling the supported resonant frequency of the laser cavities.