Detailed complex investigations of the spectral and physical characteristics for cubic Bi,G%0,-Nd3+ crystals were made. An analysis of absorption, luminasoence, and stimulated emission spectra for ,F3/2 + 4111/2 and 4F3/2 -r 4113/2 transitions were carried out. The luminescence lifetime of the metastable state, inter-multiplet and "Stark" luminescence branching coefficients, luminescence quantum efficiency, luminescence line width, spontaneous transition probabilities and stimulated-emission transition cross-sections were determined. The temperature dependence of the stimulated-emission (4F3/2 + 4111/2) excitation threshold was investigated and interpreted. Preliminary conclusions on the activator centre structure of Nd3+ ions in Bi,Ge,O,, were made, and informations on the extent of the vibronic spectra of Bi4Gg0,, crystals were obtained. xapaKTepmTm K Y~H~~C K O~O KptlcTanna Bi,Ge,O,,-Nd3+. IIpoBenea a~a n~3 cnew 9emH ~n 5 i ABYX nepexoAoB 4F3/2 -*I11/2 II 4F3/2 +4113/2. B pa6ol.e 6b1nl1 OnpeAeneHbI: npOBeAeHbI AeTaJIbHbIe KOMIIJIeKCHbIe HCCJIeAOBaHH5i CIIeKTpanbHO-rpH3HseCKIlX

Absorption and luminescence of a concentration series of (Bi1−x Prx)4Ge3O12 single crystals are investigated. The intensity analysis of Pr3+ spectral lines in Bi4Ge3O12 crystals shows that the Judd‐Ofelt approach is inadequate. Therefore experimental methods are applied to obtain the main spectroscopic characteristics. The study of probabilities of non‐radiative transitions from different states of activator ions allowed to estimate the luminescence quantum yield from the metastable 3P0 state of Pr3+ ions in Bi4Ge3O12 crystals. 4Ge3O12Pr3+ crystals are promising active media for cryogenic and room temperature lasers in the visible spectral region.

Optical biomedical imaging in short wave infrared (SWIR) range within 0.9–1.7 μm is a rapidly developing technique. For this reason, there is an increasing interest in cost-effective and robust hardware for hyperspectral imaging data acquisition in this range. Tunable-filter-based solutions are of particular interest as they provide image processing flexibility and effectiveness in terms of collected data volume. Acousto-optical tunable filters (AOTFs) provide a unique set of features necessary for high-quality SWIR hyperspectral imaging. In this paper, we discuss a polarizer-free configuration of an imaging AOTF that provides a compact and easy-to-integrate design of the whole imager. We have carried out image quality analysis of this system, assembled it and validated its efficiency through multiple experiments. The developed system can be helpful in many hyperspectral applications including biomedical analyses.

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