Infrared two-photon-excited visible lasing from a DNA-surfactant- chromophore complex

Infrared two-photon-pumped and cavity-enhanced frequency upconversion lasing has been achieved in a novel DNA-surfactant-chromophore complex (DSCC) gel system, which is a new step toward producing a biological laser. Once the focused intensity of the 150 fs and ∼775 nm pump laser beam is higher than a certain threshold level, highly directional stimulated emission at ∼582 nm wavelength can be observed from a 1 cm long DSCC complex gel cell. With cavity feedback provided by the two optical windows, the pump threshold can be further reduced, the highly directional output lasing can be greatly enhanced, and the output spectral linewidth can be reduced to less than 1/5 of the spontaneous fluorescence spectral bandwidth.