A team at the Technical University of Vienna in Austria announced that it has constructed tunable distributed-feedback quantum cascade lasers with a peak emission at 9.35 µm. The surface-emitting devices may find applications in chemical sensing and pollution monitoring. The researchers grew layers of GaAs, AlGaAs and InGaAs by molecular beam epitaxy on a substrate of N-doped GaAs, and transferred a second-order Bragg grating into the surface with reactive ion etching. The temperature of the heat sink determined the wavelength of the 100-mW single-mode emission from the device, which the team described in the Oct. 2, 2000, issue of Applied Physics Letters.