Array of tiny quantum cascade lasers provides tunable mid-IR output

Quantum cascade lasers are the only semiconductor lasers that can operate at room temperature at 3-15μm. Although they have similar appearance with diode lasers, they have different operation principle. In a quantum cascade laser, the laser transition occurs between electron levels in the conduction band of a semiconductor superlattice. By changing the thicknesses of the quantum wells and barriers in the superlattice, one can engineer the energy levels to produce a laser transition at the desired wavelength. Quantum cascade lasers are more compact and portable than Fourier transform infrared spectrometers and are not costly as compared to laser diodes.