Optical thickness changes in freshly deposited layers of lead telluride

Evans, C.S.; Hunneman, Roger; Seeley, J. S.

doi:10.1088/0022-3727/9/2/022

Cited by 16 publications

(6 citation statements)

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“…Currently, it dominates the material selection for the design of infrared thin-film interference filters operating in the long wavelength infrared both at room and reduced temperature. The combination of its high index (above 5.5 in the spectral range of long wavelength infrared at room temperature) and its advantage of a negative temperature coefficient of refractive index (À2.0 Â 10 À3 K À1 ) make it much superior to other infrared coating materials [11][12][13][14][15][16][17].…”

Section: Properties and Applications Of Pbtementioning

confidence: 99%

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Li¹,

Xie²,

Zhang³

et al. 2019

Coatings and Thin-Film Technologies

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The greater value of refractive index for high-index layers in thin-film interference filters operating in the infrared has an incomparable advantage. Lead telluride (PbTe), which is much superior to other infrared high-index coating materials due to its high index and advantage of fundamental absorption edges, has played an important role in filters employed in the infrared radiometer and other instruments launched in space atmosphere sounding research projects. In this chapter, we summarized some recent achievements in the investigations into another infrared high-index coating material-lead germanium telluride (Pb 1Àx Ge x Te), a pseudo-binary alloy of PbTe and GeTe. It can be revealed that the layers of Pb 1Àx Ge x Te exhibit the tunable optical properties, such as temperature coefficient of refractive index and fundamental absorption edge, as well as mechanical properties, such as the hardness and Young's modulus, corresponding to its intrinsic ferroelectric phase transition. Some important applications in thin-film interference filters were also demonstrated for its tremendous potential, such as a stable narrow bandpass interference filter without temperature-induced wavelength shift and a tunable infrared short wavelength cutoff filter. Furthermore, it is also revealed that electron beam evaporation is a more effective congruent-transfer technique to deposit the layers of Pb 1Àx Ge x Te.

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Section: Properties and Applications Of Pbtementioning

confidence: 99%

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Li¹,

Xie²,

Zhang³

et al. 2019

Coatings and Thin-Film Technologies

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“…There is currently no prescribed method to address how the effects of these defects interact with the energy band structure on cooling, and hence currently remains an anomaly in this area of thin-film fabrication and materials science. The consequence of maintaining stoichiometry under high vacuum therefore particularly requires the use of PbTe layers to be deposited with either non-stoichiometric source material containing Tellurium enrichment [23] or stoichiometric source material deposited within a partial pressure of oxygen [24] , both of which exhibit similar spectral properties on cooling.…”

Section: Multilayer Materials Propertiesmentioning

confidence: 99%

“…This infrared region contains many features from astrophysical objects, the measurements of which determine the temperature, abundance of minerals, chemical composition, and grain size distribution from circumstellar dust and gas disks which are crucial to theories on the formation of planetary systems. Some of the key atomic and molecular absorption lines are located in this region at 24 0-0 S(0)], together with many silicate dust and neutral gas features throughout the 15-40 μm range, some of which are heated by stellar radiation and re-emit at longer Q-band wavelengths [10] . Star formation and evolution of galaxies often occur in heavily dust obscured regions, where mid-to far-infrared measurements provide the best means of observation.…”

Section: Introductionmentioning

confidence: 99%

Cooled optical filters forQ-band infrared astronomy (15-40 μm)

et al. 2016

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With a growing interest in mid-and far-infrared astronomy using cooled imaging and spectrometer instruments in highaltitude observatories and spaceflight telescopes, it is becoming increasingly important to characterise and assess the spectral performance of cooled multilayer filters across the Q-band atmospheric window. This region contains spectral features emitted by many astrophysical phenomena and objects fundamental to circumstellar and planetary formation theories. However extending interference filtering to isolate radiation at progressively longer wavelengths and improve photometric accuracy is an area of ongoing and challenging thin-film research. We have successfully fabricated cooled bandpass and edge filters with high durability for operation across the 15-30 μm Q-band region. In this paper we describe the rationale for selection of optical materials and properties of fabricated thin-film coatings for this region, together with FTIR spectral measurements and assessment of environmental durability.

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“…Lead Telluride (PbTe) is an exceptional semiconductor material that has been investigated extensively for mid-infrared optical filters for many years [7]. It is an extraordinary material for the following reasons [8]; the high refractive index when used with an appropriate lowindex dielectric results in one of the highest practical known index contrasts (n H /n L ) to achieve a prescribed spectral filtering function with the minimum number of layers and maximize throughput.…”

Section: Introductionmentioning

confidence: 99%

Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared

Stolberg-Rohr¹,

Hawkins²

2015

Opt. Express

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Abstract:The ability of narrow bandpass filters to discriminate wavelengths between closely-separated gas absorption lines is crucial in many areas of infrared spectroscopy. As improvements to the sensitivity of infrared detectors enables operation in uncontrolled high-temperature environments, this imposes demands on the explicit bandpass design to provide temperature-invariant behavior. The unique negative temperature coefficient (dn/dT<0) of Lead-based (Pb) salts, in combination with dielectric materials enable bandpass filters with exclusive immunity to shifts in wavelength with temperature. This paper presents the results of an investigation into the interdependence between multilayer bandpass design and optical materials together with a review on invariance at elevated temperatures. ©2015 Optical Society of America

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Optical thickness changes in freshly deposited layers of lead telluride

Cited by 16 publications

References 0 publications

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Infrared High-Index Coating Materials, PbTe and Pb1−xGexTe: Properties and Applications

Cooled optical filters forQ-band infrared astronomy (15-40 μm)

Spectral design of temperature-invariant narrow bandpass filters for the mid-infrared

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