In the recent two decades, Cr²⁺:ZnSe crystals have been widely used as a gain media for 2∼3 μm mid-infrared lasers. However, it still remains a huge challenge for researchers to meet more and more requirements on the crystals with high qualities and large sizes. In this work, one Cr²⁺:ZnSe single crystal with a diameter of about 15 mm was successfully grown by chemical vapor transporting (CVT) with NH₄Cl in a closed quartz ampoule without any seed. The transmission of as-grown crystal is up to 70% in the UV-VIS-NIR region and is with an intense characteristic absorption of Cr²⁺ near 1770 nm. The X-ray photoelectron spectroscopy (XPS) shows that the incorporation of chlorine anions does not significantly affect the valence distribution of components in the crystal. The mid-infrared photoluminescence spectra show a strong and broad emission band centered at 2400 nm with a width of 600 nm under the 1770 nm laser excitation at room temperature. The calculated cross sections of absorption and emission were 1.31×10⁻¹⁸ and 1.4×10⁻¹⁸ cm², respectively. The measured photoluminescence decay time was about 6.9 μs at room temperature. It is confirmed that the method of CVT with NH₄Cl is suitable for the growth of Cr²⁺:ZnSe single crystals, which are expected to have a promising prospect in mid-infrared laser applications in further.

中文翻译：

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用NH ₄ Cl化学气相传输生长的中红外Cr ²⁺：ZnSe单晶的光学性质。

在最近的二十年中，Cr ²⁺：ZnSe晶体已被广泛用作2〜3μm中红外激光器的增益介质。然而，对于研究人员来说，要满足对高质量和大尺寸晶体越来越多的要求仍然是一个巨大的挑战。在这项工作中，一个直径约为15 mm的Cr ²⁺：ZnSe单晶通过在不带任何晶种的密闭石英安瓿瓶中用NH ₄ Cl进行化学气相传输（CVT）成功地生长了。生长中的晶体在UV-VIS-NIR区域的透射率高达70％，并具有强烈​​的Cr ²⁺吸收特性在1770海里附近 X射线光电子能谱（XPS）表明，氯阴离子的掺入不会显着影响晶体中组分的化合价分布。在室温下，在1770 nm激光激发下，中红外光致发光光谱显示出以2400 nm为中心，宽为600 nm的强且宽的发射带。计算的吸收和发射截面分别为1.31×10 ^-18和1.4×10 ^-18 cm ²。室温下测得的光致发光衰减时间约为6.9μs。证实了用NH ₄ Cl进行CVT的方法适合于Cr ²⁺的生长。：ZnSe单晶，有望进一步在中红外激光应用中具有广阔的前景。