Recent Progress in Transition-Metal-Doped II–VI Mid-IR Lasers

Recent progress in transition metal (TM)-doped II-VI semiconductor materials (mainly Cr²⁺:ZnSe) makes them the sources of choice for laser when one needs a compact continuous wave (CW) system with tunability over 1.9-3.1 mum, output powers up to 2.7 W, and high (up to 70%) conversion efficiency. The unique combination of technological (low-cost ceramic material) and spectroscopic characteristics make these materials ideal candidates for new regimes of operation such as microchip and multiline lasing. This paper reviews these nontraditional Cr-doped middle-infrared (mid-IR) lasers as well as describes emerging Fe²⁺:ZnSe lasers having potential to operate at room temperature (RT) over the spectral range extended to 3.7-5.1 mum. In addition to being wideband semiconductors, effective RT mid-IR lasing TM-doped II-VI media also hold potential for direct electrical excitation. This paper shows the initial steps toward achieving this goal by studying Cr²⁺-Co²⁺- and-doped quantum dots. We have demonstrated a novel method of TM-doped II-VI quantum dots fabrication based on laser ablation in liquid environment. TM-doped II-VI quantum dots demonstrated strong mid-IR luminescence. It opens a new pathway for future optically and electrically pumped mid-IR lasers based on TM-doped quantum confined structures.