ABSTRACT
Control experiments were performed to improve the slope conversion efficiency of the organic distributed feedback laser by varying the dissolution solvents of the laser gain layer, a conjugated polymer poly(2-methoxy-5-(2ʹ-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) in this work. The distributed feedback configuration of the laser was prepared by holographic photopolymerisation of the polymer/liquid crystal (HPDLC) mixture. Experimental results showed that the tetrahydrofuran (THF) solvent cast laser gain layer had a lower lasing threshold (0.28 μJ/pulse) and a higher slope conversion efficiency (7.8%) than that of the xylene solvent cast laser gain layer (0.5 μJ/pulse, 4.9%). Thin film waveguide characterisation demonstrated that the THF-cast film possessed a smaller waveguide loss (5.3 cm−1) and larger net gain (17.1 cm−1) than the xylene-cast film (8.3 cm−1, 15.7 cm−1). Absorbance and photoluminescence spectra indicated that the THF-cast film showed brighter luminescence at 620 nm and larger absorbance at 532 nm, indicating that the interchain interactions of the MEH-PPV is different, which plays the vital role in improving the optical performance of our organic DFB lasers.
GRAPHICAL ABSTRACT
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Disclosure statement
No potential conflict of interest was reported by the authors.