Tunable and Robust Mid-Infrared Saturable Absorber Employing Tungsten Doping Cadmium Oxide

摘要

Mid-infrared (MIR) pulsed lasers operating at 2-5 & mu;m have important applications in communication, sensing, and medicine. However, the lack of robust MIR saturable absorbers (SAs) remains a major obstacle. Here, a semiconductor material cadmium oxide (CdO) film with high laser-induced damage threshold (800 nm, 134 mJ cm-2) and broadband saturable absorption (2.0-3.9 & mu;m) is investigated. The effective tuning of the nonlinear optical response of CdO is demonstrated by adjusting the carrier concentration via a tungsten (W)-doping scheme. The saturable absorption is improved and carrier relaxation process is accelerated after increasing the W-dopant level. Based on these findings, the robust CdO-SAs with customizable parameters are realized and Q-switched lasers with decreasing pulse width from 372 to 254.3 ns are obtained at 2 & mu;m. The design flexibility provided by CdO opens up a large parameter space that enables the continuous improvement of compact and high-performance MIR ultrafast lasers. @@@ A mid-infrared CdO based saturable absorber with high laser-induced damage threshold and broadband saturable absorption is demonstrated. Based on a tungsten-doping scheme, the effective tuning of the nonlinear optical response of CdO and customizable parameters of Q-switched lasers are realized. The design flexibility provided by CdO opens up a large parameter space that enables the improvement of mid-infrared ultrafast lasers.image

关键词