Abstract
A distributed feedback-based flexible laser with broadband tunability was fabricated using a green conjugated copolymer (CP) poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-diphenylene-vinylene-2-methoxy-5-{2-ethylhexyloxy}-benzene)] (PFO-co-PPV-MEHB) as an active medium. The CP was embedded in a solid-state host polymer made of commercially available ethylene vinyl acetate/terpene phenol (1%) [EVA-TPR (1%), or EVA] composite to retain the transparency and efficiency of the solution. To design a suitable distributed feedback (DFB) system, we calculated the effective Bragg length (Λeff) for the CP/EVA composite. The absorption, fluorescence, transmission, and reflectance of the PFO-co-PPV-MEHB films were measured experimentally. The experimental data were used to calculate the refractive index and other properties of the CP/EVA composite. The Λeff of the DFB system was chosen based on the fluorescence region and the change in Bragg length (ΔΛeff) for tunability resolution of wavelength (Δλ). A flexible aluminum master grating was selected. The DFB film was either embossed or molded on the CP/EVA composite. The CP/EVA (DFB) composite was pumped by pulsed Nd: YAG laser (3rd harmonics). Bending (strain) of the active media was used for wavelength tuning. The emitted laser had a full-width half maximum (FWHM) of 1.5 ± 0.5 nm, and the range of tunability was 45 nm (495–535 nm). The solid-state DFB active media is stable up to 3000 compressions.
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•The spectral and amplified spontaneous emission (ASE) properties of a CP/EVA film were studied.•The film showed a high optical gain coefficient of 53.76 cm−1 and a low optical loss coefficient of 3.89 cm−1.•A distributed feedback-based (DFB) flexible laser with broadband tunability was fabricated.•The DFB showed a reversible laser tunability in a range of 495–535 nm.•The DFB film does not deteriorate in performance up to 7.5 × 103 operations.