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

Stolberg-Rohr, T.; Hawkins, Gary

doi:10.1364/oe.23.000580

Cited by 19 publications

(15 citation statements)

References 30 publications

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“…In this paper we utilize the elevated temperature measurements from a comprehensive repository of historic spaceflight bandpass filters, previously described in [5] to derive a new, realistic and practical data set of thermal-optical properties ( ) for embedded polycrystalline thin films of PbTe and ZnSe within a multilayer. We further consider the application of other alternative Pb-salts (PbSe, PbS) to broaden the range of temperature-invariance towards shorter wavelengths, and present the first reported thin film SWIR bandpass filter at 3.0 µm exhibiting temperature-invariance and utilizing the negative thermo-optical expansion of lead sulphide (PbS).…”

Section: Lh Lmentioning

confidence: 99%

“…We previously conducted a systematic investigation into the design of temperature-invariant narrow bandpass filters, from which we demonstrated the thermo-optical properties of PbTe films accessible from literature sources were insufficient to accurately predict the temperature-induced wavelength shift of PbTe/ZnSe multi-cavity narrow bandpass filters across an elevated temperature range 20-200 ºC [5]. Thus, an improved and refined understanding of thin film thermo-optical properties is essential to simulate, and gain control of the behavior of bandpass temperature-invariance demanded by non-cooled infrared optical systems [6].…”

Section: Introductionmentioning

confidence: 99%

“…The thermo-optical expansion coefficient ( ) is a crucial term, as it is primarily this material property that is responsible for the wavelength shift with temperature exhibited by any optical thin film multilayer. In a binary material narrow bandpass filter, we showed in [5] that the center wavelength shift with temperature obeys the linear relation in Eq. (1).…”

Section: Introductionmentioning

confidence: 99%

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Determination of the embedded thermo-optical expansion coefficients of PbTe and ZnSe thin film infrared multilayers

Hawkins¹,

Stolberg-Rohr²

2015

Opt. Express

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This paper reports the first derived thermo-optical properties for vacuum deposited infrared thin films embedded in multilayers. These properties were extracted from the temperature-dependence of manufactured narrow bandpass filters across the 4-17 µm mid-infrared wavelength region. Using a repository of spaceflight multi-cavity bandpass filters, the thermo-optical expansion coefficients of PbTe and ZnSe were determined across an elevated temperature range 20-160 °C. Embedded ZnSe films showed thermo-optical properties similar to reported bulk values, whilst the embedded PbTe films of lower optical density, deviate from reference literature sources. Detailed knowledge of derived coefficients is essential to the multilayer design of temperature-invariant narrow bandpass filters for use in non-cooled infrared detection systems. We further present manufacture of the first reported temperature-invariant multi-cavity narrow bandpass filter utilizing PbS chalcogenide layer material.

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Section: Lh Lmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determination of the embedded thermo-optical expansion coefficients of PbTe and ZnSe thin film infrared multilayers

Hawkins¹,

Stolberg-Rohr²

2015

Opt. Express

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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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“…These designs are especially constructed to generate alternate layer expansion coefficients that add up to zero. We have also performed research for the development of temperature-invariant behaviour in uncooled and high-temperature (20-200 °C) applications [27,28] .…”

Section: Temperature-invariant Narrow Bandpass Filtersmentioning

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

Cited by 19 publications

References 30 publications

Determination of the embedded thermo-optical expansion coefficients of PbTe and ZnSe thin film infrared multilayers

Determination of the embedded thermo-optical expansion coefficients of PbTe and ZnSe thin film infrared multilayers

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

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

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