Silk fibroin biopolymer films as efficient hosts for DFB laser operation

Abstract

Biopolymer hosts can be successfully used for the fabrication of multifunctional photonic devices due to their good optical properties, biocompatibility, remarkable mechanical properties and a wealth of chemical functionalization. Particularly, the silk fibroin (SF) biopolymer presents a wide range of suitable properties for photonic applications that were not fully exploited. In the present work, we demonstrate the operation of a distributed feedback (DFB) laser based on SF films doped with Rhodamine 6G (Rh6G) dye and films containing Rh6G and silica or silver nanoparticles. The SF grating structures were fabricated using a commercial blank digital versatile disc (DVD) as the template. The addition of silica or silver nanoparticles to the SF film led to enhanced emission due to the multiple scattering of light by the silica nanoparticles and a reduction of the emission linewidth. The laser wavelength was centered between approximate to 560 and approximate to 575 nm corresponding to the fourth-order diffraction of a 750 nm period of the SF grating. The results show that regenerated SF films are promising matrices for DFB lasers because of the excellent optical quality and large potential for biomedicine regarding biocompatibility and benign processing conditions.