: Hyunho Jung, Kyungtaek Min, Heonsu Jeon, Sunghwan Kim

: Adv. Opt. Mater. 4, 1738 (2016)

Here, we report the use of optically activated silk bio-ink for the realization of a physically transient DFB laser, utilizing a simple and entirely green spin-coating process on a large area 1D fused silica grating. Sodium fluorescein, a dye used for diagnostics in ophthalmology and optometry, was used to activate silk bio-ink optically.The resulting DFB structure showed single mode lasing at the wavelength of 555 nm and had a threshold of 13.6 mJ cm−2. Under optical pumping, the lasing output power was continuously degraded, an intrinsic limitation of organic lasers. We were able to remove the used and degraded silk active layer by dipping in water for a few seconds and the washed fused silica grating could then become a new DFB laser after spin-coating the silk bio-ink. The threshold and the differential external quantum efficiency remained steady under the repetitive washing and recoating process. In addition, the chemosensing capability of the physically transient silk DFB laser was investigated using hydrochloride vapor as a model analyte.