Germanium Single Crystals for Photonics

Germanium (Ge) is a system-forming material of IR photonics for the atmospheric transparency window of 8–14 µm. For optics of the 3–5 µm range, more widespread silicon (Si), which has phonon absorption bands in the long-wave region, is predominantly used. A technology for growing Ge single crystals...

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Main Authors: Grigory Kropotov, Vladimir Rogalin, Ivan Kaplunov
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Crystals
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Online Access:https://www.mdpi.com/2073-4352/14/9/796
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author Grigory Kropotov
Vladimir Rogalin
Ivan Kaplunov
author_facet Grigory Kropotov
Vladimir Rogalin
Ivan Kaplunov
author_sort Grigory Kropotov
collection DOAJ
description Germanium (Ge) is a system-forming material of IR photonics for the atmospheric transparency window of 8–14 µm. For optics of the 3–5 µm range, more widespread silicon (Si), which has phonon absorption bands in the long-wave region, is predominantly used. A technology for growing Ge single crystals has been developed, allowing the production of precision optical parts up to 500 mm in diameter. Ge is used primarily for the production of transparent optical parts for thermal imaging devices in the 8–14 µm range. In addition, germanium components are widely used in a large number of optical devices where such properties as mechanical strength, good thermal properties, and climatic resistance are required. A very important area of application of germanium is nonlinear optics, primarily acousto-optics. The influence of doping impurities and temperature on the absorption of IR radiation in germanium is considered in detail. The properties of germanium photodetectors are reported, primarily on the effect of photon drag of holes. Optical properties in the THz range are considered. The features of optical properties for all five stable isotopes of germanium are studied. The isotopic shift of absorption bands in the IR region, caused by phonon phenomena, which was discovered by the authors for the first time, is considered.
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spelling doaj-art-10a738bffcc44ecab0f41fd4d10b7fe72025-08-20T01:55:28ZengMDPI AGCrystals2073-43522024-09-0114979610.3390/cryst14090796Germanium Single Crystals for PhotonicsGrigory Kropotov0Vladimir Rogalin1Ivan Kaplunov2Tydex LLC, St. Petersburg 194292, RussiaIEE RAS, St. Petersburg 191186, RussiaApplied Physics Department, Tver State University, Tver 170100, RussiaGermanium (Ge) is a system-forming material of IR photonics for the atmospheric transparency window of 8–14 µm. For optics of the 3–5 µm range, more widespread silicon (Si), which has phonon absorption bands in the long-wave region, is predominantly used. A technology for growing Ge single crystals has been developed, allowing the production of precision optical parts up to 500 mm in diameter. Ge is used primarily for the production of transparent optical parts for thermal imaging devices in the 8–14 µm range. In addition, germanium components are widely used in a large number of optical devices where such properties as mechanical strength, good thermal properties, and climatic resistance are required. A very important area of application of germanium is nonlinear optics, primarily acousto-optics. The influence of doping impurities and temperature on the absorption of IR radiation in germanium is considered in detail. The properties of germanium photodetectors are reported, primarily on the effect of photon drag of holes. Optical properties in the THz range are considered. The features of optical properties for all five stable isotopes of germanium are studied. The isotopic shift of absorption bands in the IR region, caused by phonon phenomena, which was discovered by the authors for the first time, is considered.https://www.mdpi.com/2073-4352/14/9/796germanium (Ge)single crystalIR and THz opticslasernonlinear opticsacousto-optics
spellingShingle Grigory Kropotov
Vladimir Rogalin
Ivan Kaplunov
Germanium Single Crystals for Photonics
Crystals
germanium (Ge)
single crystal
IR and THz optics
laser
nonlinear optics
acousto-optics
title Germanium Single Crystals for Photonics
title_full Germanium Single Crystals for Photonics
title_fullStr Germanium Single Crystals for Photonics
title_full_unstemmed Germanium Single Crystals for Photonics
title_short Germanium Single Crystals for Photonics
title_sort germanium single crystals for photonics
topic germanium (Ge)
single crystal
IR and THz optics
laser
nonlinear optics
acousto-optics
url https://www.mdpi.com/2073-4352/14/9/796
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AT vladimirrogalin germaniumsinglecrystalsforphotonics
AT ivankaplunov germaniumsinglecrystalsforphotonics