Grating formation in bi-layered DNA-complex devices: application to thin-film tunable dye lasers

Interaction of some organic dyes with DNA induces fluorescence enhancement through intercalation or groove binding, stimulating the development of compact tunable thin-film dye lasers. We have demonstrated amplified spontaneous emission (ASE), laser emission and its tuning via distributed feedback (DFB) with a dynamic grating formed in DNA-surfactant complexes doped with cyanine or hemicyanine dyes. The formation of semi-persistent (or quasi-dynamic) grating is more preferable in order to realize stable and easily tunable laser sources, so we fabricated bi-layered devices composed of a DNA-CTMA layer doped with pyridine 1 (Py1) and an PMMA layer including an azo dye, Disperse Red 1 (DR1). Under simultaneous excitation of the azo layer with interfering two beams for grating formation and the emission layer with another beam as pumping, we observed laser emission from the device. The oscillation wavelength was controlled by varying the incident beam angles allowing the fast tuning suitable to applications. Furthermore, monolithic DNA device having two functions of lasing and grating formation would be more promising. DNA-CTMA complex had been considered to be a poor matrix for grating inscription, but we found that doping of an azo-carbazole compound made it possible to inscribe gratings with relatively high diffraction efficiency and with fast response which could be applicable to monolithic tunable laser system.