A Family of Far‐Infrared‐Transmitting Glasses in the Ga–Ge–Te System for Space Applications

Abstract

Conditions of formation of bulk tellurium chalcogenide glasses, containing 70–80 at % Te associated to Ga and Ge are described. The characteristic temperatures are measured: the glass‐transition temperature, Tg, is situated in the range 140–185 °C and the difference Tx – Tg, where Tx is the onset crystallization temperature, is in the range 76–113 °C. Moreover, the optical transmission window is exceptional, ranging from 1.99 μm in the bandgap up to 28 μm in the phonon region.Developed within the framework of requirements for the Darwin mission (a search for and study of extrasolar planets), feasibility of infrared optical fibers formed from these glasses is studied. Drawing experiments are conducted with the glass Ga2‐Ge3Te15, which possesses the maximum Tx – Tg, and a first optical fiber is presented.

Structure, electronic, and vibrational properties of glassy Ga11Ge11Te78: Experimentally constrained densi

“…11,12 The spectra of molecules considered as essential for life (H 2 O, O 2 , CO 2 , and O 3 ) can be identified in the wavelength range 6-18 μm, extending the frequency range accessible to Se-based alloys. 13 Glass formation in the binary system Ge-Te is possible for compositions near GeTe 4 , but the difference between the glass temperature T g and crystallization temperature T x ( T ) is only 77 • C, and stable glasses cannot be prepared. 13,14 The glassy domain in the Ga-Ge-Te system is limited to a small region centered on the GeTe 4 -GaTe 3 pseudobinary line, and the alloy Ga 10 Ge 15 Te 75 is characterized by T g = 172 • C and T x = 285 • C ( T = 113 • C).…”

“…13 Glass formation in the binary system Ge-Te is possible for compositions near GeTe 4 , but the difference between the glass temperature T g and crystallization temperature T x ( T ) is only 77 • C, and stable glasses cannot be prepared. 13,14 The glassy domain in the Ga-Ge-Te system is limited to a small region centered on the GeTe 4 -GaTe 3 pseudobinary line, and the alloy Ga 10 Ge 15 Te 75 is characterized by T g = 172 • C and T x = 285 • C ( T = 113 • C). Stable samples of optical quality can be prepared, and fibers can be drawn.…”

“…Stable samples of optical quality can be prepared, and fibers can be drawn. Materials with this composition have an exceptionally broad IR window 13,14 (cutoff at 28 μm) and provided the first rewritable memory in thermally drawn fibers. 15 We describe the experimental techniques [x-ray diffraction (XRD), neutron diffraction (ND), extended x-ray absorption fine structure (EXAFS), and Raman spectroscopies] in Sec.…”

Glassy Materials and Light: Part 1

“…65-67 Segundo a aplicação desejada, como por exemplo sensoriamento espectral multibandas 68 ou lentes e sensores operando no IV distante (FWIR, Figura 11), [69][70][71] vidros de sulfetos são geralmente preferidos para os comprimentos de onda menores enquanto vidros de selenetos e teluretos serão usados para transmitir comprimentos de onda maiores, respectivamente. Por outro lado, é necessário considerar que estes dois últimos tipos de vidros, i.e., selenetos e teluretos, são opacos na região do visível devido à baixa energia da banda proibida, como pode ser observado na Figura 12.…”

Planar waveguide obtained by burying a Ge_22As_20Se_58 fiber in As_2S_3 glass

“…Chalcogenide glasses are transparent in the nearand mid-infrared regions of the spectrum (0:5-10 μm for sulfides, 0:8-12 μm for selenides, and up to 20 μm for tellurides [6,7]). The glasses have already been applied as different optical material, such as prisms, plates, filters, lenses, and coatings.…”