Versatile Spectral Imaging With an Algorithm-Based Spectrometer Using Highly Tuneable Quantum Dot Infrared Photodetectors

Abstract

reconstructing the spectral shape of materials in the MWIR and LWIR wavelengths using only experimental photocurrent measurements from quantum dot infrared photodetectors (QDIPs). The algorithm theory and implementation will be described, followed by an investigation into this algorithmic spectrometer's performance. Compared to the QDIPs utilized in an earlier implementation, the QDIPs used have highly varying spectral shapes and four spectral peaks across the MWIR and LWIR wavelengths. It has been found that the spectrometer is capable of reconstructing broad spectral features of a range of band pass infrared filters between wavelengths of 4µm and 12µm as well as identifying absorption features as narrow as 0.3µm in the IR spectrum of a polyethylene sheet.Index Terms-Algorithmic spectrometer, hyperspectral imaging, multispectral imaging, quantum dot infrared photodetectors.

Implementation of an algorithmic spectrometer using Quantum Dot Infrared Photodetectors

“…5 also shows the reconstructions achieved in Ref. [3] using a QDIP with 40 DWELL periods and QDs doped with 1 electron/dot was used. This QDIP has significantly different spectral shapes compared to QDIP0.…”

“…The lattice matched GaAs/AlGaAs material system minimises strain accumulation in the DWELL enabling growth of up to 80 repeats of InAs-GaAs-AlGaAs DWELL with high detectivity, D Ã of 2 Â 10 10 cm Hz 1/2 /W [3]. The structures used in this work, shown in Fig.…”

“…We will now focus on implementation of the IRAS using in a similar manor to that reported in [2,3,6,7]. Details of the algorithm can be found in Refs.…”

“…They exhibited peak absorption wavelengths varying from 5.7 lm to 6.8 lm as the bias was varied from 0.2 V to À1.0 V. Using these set of spectral responses they were able to reconstruct the power spectrum of a black body with a polystyrene filter although they were less successful in resolving the smaller absorption characteristics of the polystyrene filter. More recently Vines et al [3] reported a successful reconstruction of a polyethylene filtered black body power spectrum by using the algorithm proposed by Sakoglu et al with QDIPs that exhibited a more varied set of spectral responses with the peak absorption wavelength varying from 5.5 lm to 10 lm. The magnitude of the power spectrum within the wavelength range of 4.0-12 lm was successfully reconstructed and the large absorption feature of $0.3 lm at 5.8 lm was clearly resolved.…”

Application of Neural Networks to Matlab Analyzed Hyperspectral Images for Characterization of Composite Structures

“…Common problems in the area of hyperspectral analysis involving data relevancy include optimal selections of wavelength, number of bands, and spatial and spectral resolution. Despite the fact that hyperspectral image analysis is used to perform index analysis in hyperspectral and multispectral satellite imagery, it is assumed that it can be used for image comparison of similar or processed images, of completely different origin [11][12][13][14][15].…”