Spirals, a family of beautiful and elegant geometrical curves with fascinating methematical properties, are present everywhere in the universe on a vast range of scales: nautilus, hurricanes, galaxies, etc. Here we applied such delightful curves to our laser cavity designs.

By connecting a spiral semiconductor micro-structure to a straight one, we achieved a coupled-cavity design, in which the spiral section enhances the mode-selectivity that would facilitate single-mode operation of Quantum Cascade lasers and potentially other types of semiconductor lasers. The photo shows the topview of a laser with such a cavity design. The surface of the device is covered with gold for conducting electric current. That's why the photo is titled "The Golden Spiral."