Excitonic detectors of infrared and submillimeter radiation

The theory of new type detectors based on the quenching of secondary emission in direct-gap semiconductors (lines of Raman light scattering due to interaction between free and bound excitons in the crystal, and also bands of edge radiation) caused by IR or submillimeter radiation is proposed. The results obtained are confirmed by the experiment performed for CdS crystal excited by ultraviolet radiation of mercury lamp, at liquid helium temperature.     

近红外高精度光辐射标准探测器的实验研究

在594nm和785nm两个波长上,用以低温辐射计标定过的陷阱探测器作为基准,对两个响应未知的陷阱探测器进行了绝对标准的传递。为此建立了一种辐射定标的新型测量光路,估算和分析了在光路调整时影响测量精度的关键环节,其中包括光功率传输效率以及光路色散效应的影响。分析了在传递过程中各主要环节的不确定度,总传递不确定度小于0 045%。     

Near infrared and charge transfer luminescence of Yb-doped LaPO4 at room temperature

The Yb³⁺-doped LaPO₄ was prepared by hydrothermal reaction under fine acidity control and identified by X-ray diffraction and FT-IR spectroscopy. The obtained powders crystallize in the monoclinic phase of LaPO₄. The spectroscopic study at room temperature (RT) of the Yb³⁺-doped LaPO₄ powder was investigated. Thus a wide band, characteristic of the fundamental ²F_5/2↔²F_7/2 transition in near infrared (NIR) range, has been located for La_(1−x)Yb_xPO₄ (x = 5, 10%). Four Stark levels of the ground ²F_7/2 state are located on the emission spectra between 976 nm and 1030 nm, after excitation at 925 nm. Low re-absorption of the 0-phonon transition was registered. Charge transfer band (CTB) luminescence of Yb³⁺, which is not observed in LaPO₄ in later works, was appeared under 266 nm excitation. In the UV–Visible spectra, double band typical for the CTB luminescence of Yb³⁺ are observed. The decay time dependence as a function of the concentration is also reported and compared to other works. The room temperature radiative lifetimes of the IR emission and charge transfer band luminescence are compatible with potential applications of this phosphor respectively as solid-state lasers and scintillators.