2025/04/23 by Enokidani, Umi, Matsuhara, Hideo, Nakagawa, Takao +8
#FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM)
paper · doi:10.48550/arxiv.2504.16388
We have been developing a CdZnTe immersion grating for a compact high-dispersion mid-infrared spectrometer (wavelength range 10--18 μm, spectral resolution R = λ/Δλ> 25,000, operating temperature T < 20 K). Using an immersion grating, the spectrometer size can be reduced to 1/n (n: refractive index) compared to conventional diffraction gratings. CdZnTe is promising as a material for immersion gratings for the wavelength range. However, the refractive index n of CdZnTe has not been measured at T < 20 K. We have been developing a system to precisely measure n at cryogenic temperatures (T ∼ 10 K) in the mid-infrared wavelength range. As the first result, this paper reports the temperature dependence of n of CdZnTe at the wavelength of 10.68 μm. This system employs the minimum deviation method. The refractive index n of CdZnTe is measured at temperatures of \( T = 12.57, 22.47, 50.59, 70.57, and 298 K \). We find that n of CdZnTe at λ= 10.68 μm is 2.6371 ± 0.0022 at 12.57 ± 0.14 K, and the average temperature dependence of n between 12.57 ± 0.14 K and 70.57 ± 0.23 K is Δn/ΔT = (5.8 ± 0.3) × 10-5 K-1.