APPLIED PHYSICS: Smaller, Faster Midinfrared Lasers

Semiconductor lasers are small, efficient devices that are used widely as optical sources in telecommunication systems and CD-ROM and DVD optical memory drives. In his Perspective, Faist highlights the work by Paiella et al., who expand the range of operation of these devices substantially by demonstrating midinfrared lasers that emit picosecond pulses. Faist particularly stresses the innovative technique used by the authors, which may also allow new frequencies, for example in the terahertz frequency range, to be generated.