Flexible random laser from a porous polymer film

Abstract

Flexible random lasers have attracted a great deal of interest due to their potential in light-weight, flexible optical sensors and devices. Among many alternatives, flexible thin film random lasers are very interesting because they can be easily fabricated via a simple solution-based process. Herein, we demonstrate a dye-doped porous polyvinyl alcohol film that can work as a flexible random laser source under optical pumping. The film is fabricated by a drop cast technique and has a nearly circular shape with a diameter of ∼5 mm. Owing to the inverted photonic glass structure that is air voids in the polymer matrix, light emission from dye molecules is multiple scattering and lasing emission is achieved. In the central area, the film laser works reliably with the lasing threshold of ∼166μJ/mm2 and lasing wavelength of around 595 nm. In the edge area, the lasing properties are more fluctuated indicating that the structure may not be uniform. It is found that the lasing wavelength in the edge area is 4.5 nm red-shifted compared to that in the central area of the film. Interestingly, the thin film laser can operate well under bending conditions with a minor change in the lasing wavelength.