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Advances in III-V semiconductor infrared absorbers and detectors
摘要： Advances in bulk III-V semiconductor material such as InGaAsSb and metamorphic InAsSb, as well as in a variety of type-II superlattices such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short to the very long wavelength infrared. We perform basic theoretical analysis to provide comparisons of different infrared materials. We also briefly report experimental results on a mid-wavelength InAs/InAsSb type-II superlattice unipolar barrier infrared detector and a focal plane array with significantly higher operating temperature than InSb.
关键词： unipolar barrier,MWIR,infrared detector,e-SWIR,LWIR,antimonide,type-II superlattice,nBn,effective mass
更新于2025-09-23 15:23:52
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Narrowband, infrared absorbing metasurface using polystyrene thin films
摘要： We present the results of an experimental investigation of polystyrene’s suitability as a dielectric material for designing narrowband, infrared metasurface-based absorbers. Our study included characterization of processing parameters of polystyrene films, such as surface roughness and film thickness, which are critical for device fabrication, and the dielectric properties, which we measured, using spectroscopic ellipsometry. Our results confirm that thin film polystyrene is a relatively low-loss dielectric material at long-wave infrared (LWIR) frequencies. Subsequently, this material was used as the dielectric substrate of a thin, narrowband, metasurface-based absorber at LWIR frequencies. The fabricated narrowband absorber demonstrates excellent performance in the LWIR band with absorptivity as high as 96% and a full-width-at-half-maximum bandwidth of 0:502 μm or 4.87%.
关键词： metasurface,infrared,absorber,polystyrene,narrowband,LWIR
更新于2025-09-23 15:21:01
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Crosstalk effect mitigation in black body warm-up cool-down calibration for Terra MODIS longwave infrared photovoltaic bands
摘要： The crosstalk phenomena in Terra MODerate-resolution Imaging Spectroradiometer (MODIS) midwave-to-longwave infrared (LWIR) photovoltaic (PV) bands (bands 27-30) have recently been individually studied and characterized, and a correction algorithm has been developed. The routine calibration of the four LWIR PV bands uses an onboard black body (BB) based on a quadratic model for the relationship between the at-aperture radiance and the background subtracted instrument response. While the crosstalk correction has been successfully applied in both the routine BB calibration (scan basis) to correct the crosstalk effect in the linear term and the Earth view (EV) radiance in our previous investigations on the bands 27–29, the most recent work on band 30 demonstrated a newfound necessity to include the impact of the crosstalk effect on the nonlinear term as well as the offset. In this paper, we analyze the calibration calculation under a variety of conditions consistent with the MODIS Collection 6 settings to examine the impact of the crosstalk effect in the two terms derived from the BB warm-up-cool-down (WUCD) calibration. We show that with correct account of the crosstalk effect in the WUCD calibration, the sudden changes and other abnormal features that have been observed in the two terms for many years are effectively and remarkably removed. In addition, imagery for bands 27–29 using the calibration result fully corrected for the electronic crosstalk effect shows further improvement over previous results that account for only the corrected linear term, whereas for the band 30 different testing scenes validate the previous fully corrected ?ndings.
关键词： crosstalk effect,LWIR photovoltaic bands,Terra MODIS,black body calibration,WUCD calibration
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tunable Narrowband Tm:YAP Laser using a Transversally Chirped Volume Bragg Grating
摘要： Tunable long wave infrared (LWIR) coherent sources emitting between 8 and 12 μm can be used for versatile remote gas sensing. In ref [1] we implemented a parametric oscillator in which wavelength tunability was achieved by temperature tuning of the crystal indices of refraction. It is well known that a similar wavelength range can be addressed by tuning the pump wavelength rather than the crystal temperature [2]. In addition, pump tuning can be significantly faster than temperature tuning. In this context we also need a narrow band spectrum to control the spectral output of the optical parametric oscillator, which is based on Vernier spectral filtering in doubly-resonant cavities. Seger and his team exhibited single longitudinal mode operation in a microlaser tuned with transversally chirped volume Bragg grating (TC-VBG) near 1 μm [3]. We show how this concept can be applied to a different laser emitting at 2 μm.
关键词： Tunable laser,LWIR,Tm:YAP,Narrowband,Volume Bragg Grating
更新于2025-09-12 10:27:22
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Electronic band structure of InAs/InAsSb type-II superlattice for HOT LWIR detectors
摘要： The InAs/InAs1?xSbx type-II superlattices (T2SLs) grown on GaSb bu?er layer and GaAs substrates have recently been applied for detectors for long wavelength infrared (LWIR) range and high operating temperature (HOT) conditions. The detailed modeling of T2SLs minibands structure required for detector’s design optimization process relies on accurate knowledge of the InAs1?xSbx bandgap and band edge position. The k?p (8 × 8 method) was used to analyze the valence band o?set (VBO) between InAs and InAs1?xSbx, and hence the InAs1?xSbx band edge position at required xSb composition. An increase of the VBO leads to the structure transformation from type-IIb to type-II superlattices. The required energy bandgap can be reached by changing the conduction band o?set (CBO) and the energy bandgap bowing parameter. The temperature dependence of the experimental results of InAs/InAs1?xSbx T2SLs energy bandgap was found to be comparable with theoretical one when energy bandgap bowing parameter is dependent on temperature. The proper ?tting of theoretically calculated and experimentally measured spectral response characteristics was shown.
关键词： Energy-band o?set,InAs/InAs1?xSbx type-II superlattice,T2SLs,LWIR,Infrared detectors
更新于2025-09-04 15:30:14
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SWIR-LWIR Photoluminescence from Sb-based Epilayers Grown on GaAs Substrates by using MBE
摘要： Utilizing Sb-based bulk epilayers on large-scale low-cost substrates such as GaAs for fabricating infrared (IR) photodetectors is presently attracting significant attention worldwide. For this study, three sample series of GaAsxSb1?x, In1?xGaxSb, and InAsxSb1?x with different compositions were grown on semi-insulating GaAs substrates by using molecular beam epitaxy (MBE) and appropriate InAs quantum dots (QDs) as a defect-reduction buffer layer. Photoluminescence (PL) signals from these samples were observed over a wide IR wavelength range from 2 μm to 12 μm in agreement with the expected bandgap, including bowing effects. In particular, interband PL signals from InAsxSb1?x and In1?xGaxSb samples even at room temperature show promising potential for IR photodetector applications.
关键词： SWIR,LWIR,IR detector,MWIR,Sb-based thin films
更新于2025-09-04 15:30:14