Azobenzene Lasers Tuned Over a 200 nm Range




An application of red emitting rod-like dyes similar to Pyridine 1 in an epoxy-based oligomeric azobenzene system leads to optically pumped distributed feedback (DFB) lasers tunable over a spectral range of 200 nm. DFB structures in azobenzene films doped with laser dyes are created by a reliable and simple holographic technique using Lloyd's interferometer. In this way, surface relief gratings serving as DFBs can be routinely inscribed in 1 min time, which protect laser dyes from bleaching. The emitting wavelength of the laser device can be tuned by small adjustments of the interference pattern period in Lloyd's interferometer, by film thickness, and by changing the laser dye. The fabricated miniature lasers emit from 680 to 875 nm. In addition to laser devices emitting at the 2nd diffraction order, devices fabricated with a grating period of ca. 250 nm emitting at the 1st diffraction order are also demonstrated. The lasers support several tens of thousands of pulses without encapsulation and have an efficiency of up to 0.6% in the case of a laser working in the 1st diffraction order.