A polymer film with ultra-broadband optical gain characteristics

Abstract

Miniaturization of the tunable laser equipment is an important factor for further development in various optoelectronic technologies. To realize the compact tunable laser devices, an optical gain medium having a broadband optical gain characteristic is required. In this study, we propose a promising strategy for preparing an optical gain film that exhibits a ∼250 nm gain bandwidth in the visible wavelength region. This film consists of a polymer matrix co-doped with organic luminescent molecules that form a complex of the excited state, i.e., exciplex. The exciplex state can co-exist with the monomolecular exciton state, leading to broadband (400–650 nm) optical gain with a large Stokes shift. Optically pumped lasing action is also possible when the film is combined with an optical resonator. This strategy would be useful for developing a compact tunable laser device without active medium replacement.