Stable Lasing in Azobenzene Polyelectrolyte with Polarization Gratings as Distributed Feedback

An easy and reliable method to fabricate stable distributed feedback (DFB) miniature lasers is demonstrated. Durable polymer lasers are fabricated via a simple and fast patterning procedure, resulting in polarization gratings in azobenzene-fluorophore films. The azobenzene-containing polyelectrolyte matrix provides not only DFB via the inscribed polarization grating, but also hinders fluorophore deterioration, leading to laser devices which can withstand tens of thousand pulses without encapsulation. The application of different dyes and changes in the spatial grating frequency allows tuning of the laser wavelength over a spectral range of at least 640–870 nm. By simple rewriting of the grating with another spatial period it is possible to tune the emission wavelength. Lasing in the 1st diffraction order is achieved for at least two laser dyes with an efficiency of up to 0.7%. The arrays of lasers spatially emitting at different wavelengths could be constructed by doping the matrix with different fluorophores. An application of polarization gratings (a common feature of azobenzene-containing materials) as DFB structures for lasing paves the way for further improvement of laser performance.