Mid-infrared light emission from a Fe²⁺:ZnSe polycrystal using quantum cascade laser pumping

We report the realization of light emission from a Fe²⁺ doped ZnSe polycrystal with efficient pumping from a quantum cascade (QC) laser. The QC laser photon energy is near the absorption edge of the Fe²⁺:ZnSe with less than ∼60 meV Stokes' shift. The Fe²⁺:ZnSe polycrystal shows an absorption band of ∼2.2 – 5 μm in the mid-infrared (mid-IR) at room temperature, which narrows down to ∼2.4–4.2 μm at 80 K. Clear photoluminescence (PL) from 4.5 μm to 6 μm are observed throughout the temperature range of 300 K to 80 K. At room temperature, the luminescence lifetime is about 0.38 ± 0.1 μs which increases up to 101 ± 2 μs at 118 K. This system transfers energy stored in the upper state of a QC laser with ∼ps lifetime to the Fe²⁺:ZnSe with 10⁵ to 10⁸ times longer lifetime, at the cost of minute photon energy losses.