New Regimes of Excitation and Mid-IR Lasing of Transition Metal Doped II–VI Crystals
Recent progress in transition-metal doped II–VI semiconductor materials (mainly Cr2+:ZnSe and ZnS) make them the laser sources of choice when one needs a compact system with continuous tunability over 2–3.1 μm, output powers up to 2W, and high (up to 70%) conversion efficiency. The unique combination of technological (low-cost ceramic material) and spectroscopic characteristics (ultrabroadband gain bandwidth, high óproduct and high absorption coefficients) make these materials ideal candidates for “non-traditional” regimes of operation such as microchip and multi-line lasing. This chapter reviews these non-traditional Cr-doped mid-IR lasers as well as describes emerging Fe2+:ZnSe lasers having the potential to operate at room temperature over the spectral range extended to 3.7–5.1 μm. In addition to effective RT mid-IR lasing transition-metal doped II–VI media, being wide band semiconductors, hold the potential for direct electrical excitation. This work shows the initial steps toward achieving this goal by studying Cr2+ ion excitation into the upper laser state 5E via photoionization transitions as well as via direct electrical excitation.
Keywords: Transition-metal doped II–VI; Cr2+:ZnSe; Fe2+:ZnSe; tunable mid-infrared lasers; photoluminescence; electroluminescence; photo-conductance.
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