BROADBAND MID-INFRARED SOLID-STATE LASERS Broadband Mid-Infrared Lasers

A survey of broadband Co2+and Cr2+-based lasers is presented. These mid-IR sources, operating in the very interesting “molecular fingerprint” region between ∼1.6 and 3.5μm offer the broadest bandwidth from all solid-state vibronic lasers. The emphasize is made on Cr2+-doped lasers, which have not only the widest and the highest gain, but also operate at room-temperature and produce the shortest pulses of only several optical cycles around 2.5μm directly from the resonator. Ten years after their invention, Cr2+-doped lasers have come of age and emerge in applications, demanding high power and extreme bandwidth. The paper reviews advances in the existing and novel Cr2+-based lasers, such as mixed Cr2+:ZnSxSe1−x, Cr2+:CdMnTe and Cr2+:CdZnTe lasers, which are likely to extend these features even further, and briefly describes a number of novel and yet upcoming applications. The first steps towards electrically pumped nanocrystalline lasers are described and the underlying physics is outlined.