Ludwig-Maximillians University researchers believe they have taken a crucial step towards making an electrically-pumped organic polymer laser. They have used an array of miniature gold discs as a diffraction grating to try and eliminate some of the problems that have held back current-driven devices.
Their laser is built on a glass substrate with a 110 nm thick ITO (indium-tin-oxide) layer covered with a 2D grating of 110 nm diameter gold nanodiscs. This is covered with a 460 nm layer of a LPPP polymer. Gold was chosen as the metal as it doesn’t oxidise and the gold on ITO setup allows the layers to be used as distributed feedback (DFB) mirrors.
The device is pumped by 30 femtosecond pulses from a regeneratively amplified Ti:Sapphire laser emitting at 400 nm. Feedback comes from second-order diffraction from the nanodisc grating.
With a pump pulse energy of 2.7 nJ the laser gives a strong emission at 492 nm and the team believe they can tune the laser’s emission with by variations in the thickness of the LPPP layer.