Polycrystalline MgAl2O₄ spinel for infrared and terahertz region windows

Transparency of the polycrystalline magnesium-aluminate spinel (MAS) in both the infrared and terahertz regions is evaluated and compared with other frequency-used window materials by Fourier transform infrared spectroscopy and terahertz time-domain spectroscopy. The MAS material exhibits higher transmissivity in both the infrared and terahertz regions than other materials. Excellent flexural strength also ensures that it can be subject to the atmospheric pressure. Therefore, this material is suitable to be applied as a broadband transparent window in the infrared synchrotron radiation pump-terahertz time-domain spectroscopy probe experimental platform which works in the low-temperature and high-vacuum conditions. Our work provides a groundwork for the understanding of the native properties of the polycrystalline MAS. The result suggests a new window material to be employed in the low-temperature and high-vacuum conditions.