Hendrik Schön and co-workers grew the single tetracene crystal from the vapour phase and surrounded it with field-effect transistors to produce electron- and hole-rich regions in the crystal. By applying a 5 V potential difference across the crystal, the team caused the positive and negative charges to flood across the crystal and recombine, producing a burst of photons that initiated the lasing process. The cleaved ends of the crystal act as the reflecting endpoints of the laser cavity, amplifying the emission to produce yellowy-green light with a wavelength of 575.7 nm.

Schön and coworkers believe they can reduce the optical losses in their present system to substantially lower the threshold current density needed for laser action. This will bring a room temperature continuous tetracene-based laser another step closer.

The group previously demonstrated the fractional quantum Hall effect in tetracene crystals (Science 288 2338), and the new organic laser is the latest in a string of achievements from Schön and his colleagues.