In this talk, we will share thoughts and perspectives on some of the driving factors, the challenges as well as the opportunities facing the future exploitation of the U.S. Operational Observing Systems data. In particular, the Big data challenge and the need to explore new and innovative ways to be able to exploit them.

The valley-dependent skew scattering of conduction electrons by impurities in two-dimensional a-T3 materials is studied. The interplay of Lorentz and Berry forces, which act on mobile electrons in position and momentum spaces respectively, is quantified. Interactions of electrons with ionized impurities at two valleys are observed in different scattering directions. Two zero- and first-order Boltzmann moment equations are used for calculating scattering-angle distributions of resulting skew currents, which are significantly enhanced by introducing microscopic inverse energy- and momentum-relaxation times to two moment equations.

nBn detector structure can be utilized to suppress the generation-recombination, tunneling and surface leakage dark currents mechanism as there is no p-n junction and the major carriers are blocked by the barrier in the conduction band. Here, we discuss various nBn structures in dual-band configuration where both n-type layers are absorber layers with two separate cutoff wavelengths. The valance band discontinuity that may arise and reduce the photoresponse of nBn detectors is removed by graded and delta-doped layers.

We introduce a new low cost material, suitable for detection in the SWIR range. Polycrystalline (Sb1-xBix)2Se3 thin film absorber layers are grown by co-evaporation with a thickness of 1-2 µm. It is shown that Bi can be incorporated into the crystal up to x=0.6, which allows to decrease the bandgap from ≈ 1.1 eV (x=0) to approximately 0.8 eV for detection of light with wavelengths up to 1550 nm. The thin film optoelectronic properties are investigated using Raman spectroscopy, transmission reflection measurements as well as photoluminescence spectroscopy. The crystal structure is determined using X-Ray diffraction.

In this paper, we investigate the structural quality of the mid-wavelength infrared InAsSb nBn photodetector with a 50% cut-off wavelength of 4.5 µm at room temperature. The structure is grown on multiple substrates, including GaSb, semi-insulating GaAs, and GeSi. The structural quality of the material has been investigated using non-contact, non-destructive electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM) for high-accuracy threading dislocation density (TDD) measurement, and time-resolved microwave reflectance (TMR) spectroscopy for minority carrier lifetime (τ) measurement. The combination of these two techniques enables a direct correlation between TDD and τ.

Development of High-Performance Graphene-PbSe Detector Technology for Mid-wave Infrared Applications Ashok K. Sood and John W. Zeller Magnolia Optical Technologies, 52-B Cummings Park, Suite 314, Woburn, MA 01801 Parminder Ghuman and Sachidananda Babu NASA Earth Science Technology Office, Greenbelt, MD 20771 Nibir K. Dhar U.S. Army Night Vision & Electronic Sensors Directorate, Fort Belvoir, VA 22060 Samiran Ganguly and Avik Ghosh Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 ABSTRACT High performance detector technology is being developed for sensing over the mid-wave infrared (MWIR) band for NASA Earth Science, defense, and commercial applications. The graphene-based PbSe detector technology involves the integration of graphene into PbSe photodetectors that combines the best of both materials, and allows for higher MWIR (2-5 μm) detection performance compared photodetectors using only PbSe material. The interfacial barrier

The Short and Mid Wave InfraRed (S-MWIR) rugged active detection system has been designed to be operated in the worst conditions with very low Size Weight and Power (SWaP) factor. The detection system is based on a single uncooled detector device implementing a Lead Sulphide (PbS) (SWIR) and Lead Selenide (PbSe) (MWIR) plate cells on the same package and an emitter based on a combination of standard silicon materials with Nano Amorphous Carbon (NAC) membrane. The S/MWIR detection system has been implemented on the Dust Sensor for the EXOMARS’20 mission for operation from 10ºC to -90ºC with two detector systems forward and backward for calculation the in-situ dust concentration on Mars surface.

Three types of reflection-mode InGaAs/GaAs photocathodes with varied component emission layer were epitaxial grown by MOCVD, in which one sample is a thin emission layer InGaAs/GaAs photocathode, and the other two samples are the conventional thickness emission layer InGaAs/GaAs photocathodes and their emission layers are divided into three 0.6μm thickness sublayers and a 0.04μm varied component layer is introduced between sublayers in one of them, aims to form a gradual change structure between the sublayer interfaces. The test results after activation experiments show that a photocathode with multiple emission sublayers and varied component layer between them have the best spectral response, meanwhile, by fitting spectral response curves, the obtained electron diffusion length and electron surface escape probability of the ones are increased, which causes the higher integral sensitivity and long-wave response.

Today, aircraft post sales revenue exceeds from sales of a new aircraft and for these reasons there is an intense battle within Aerospace industry to capture larger share of aftersales market. BOEING projects that after sales revenue will exceed by US $2.5 trillion over next 20 years. We believe IOT, 5G network and Machine Learning will bring revolution in this after-sales market where smart sensor will be increasingly used for predictive diagnostic. Two years back we demonstrated a proof of concept for a novel use of a Federal Aviation Administration qualified sensor for application in Aircraft’s Health Management program. In this paper, we present controlled laboratory data and demonstrate feasibility of using this sensor as an add on to existing aircraft's for preventative maintenance.

Due to the weak acoustic phonon interaction, graphene is a promising material to overcome the limitation of metal-based Schottky barrier devices. However, these devices suffered from the low absorption rate of light due to the single-layer structure of graphene. In this presentation, based on the strong absorption in the infrared range and its in-situ growth property at silicon substrate, we demonstrated that, using graphene nanowalls (GNWs) as the electrode of Schottky barrier and absorption materials, an infrared photodetector with high responsivity could be obtained. With in-situ grown graphene nanowalls, we obtained perfect schottky junction with ideal factor near 1.0, which show high-performance including good responsivity and large linear dynamic range. Furthermore, metal particles were adopted to modify the interface barrier height between GNWs and slicon, so room-temperature high detectivity in infrared was obtained, and response in THz and mid-infrared were also observed.

This study describes parametric modeling of near-infrared (NIR, 0.7-0.9 µm) and shortwave infrared (SWIR, 0.9-1.7 µm) absorbance spectra, which is for optimizing NIR-SWIR reflectance of dyed fabrics with respect to given illuminations and background environments. The parametric models are linear combinations of gaussian functions, which are for modeling dyes in fabric whose absorption spectra span the NIR/SWIR spectral range. In general, decomposition of an absorbance spectrum in terms of linear combinations of gaussain functions is not unique. This suggests investigatng what are optimal linear combinations of gaussian functions for modeling given spectra. Prototype modeling is applied to NIR/SWIR absorbing dyes, and their mixtures, in fabric samples, which consist of a cotton blend. The results of this study demonstrate parametric modeling using linear combinations of gaussian functions for simulating NIR/SWIR absorbance spectra, which are for variable dye and dye blend concentr

Double-layer gold (Au) gratings have been fabricated on silicon wafers using soft ultraviolet-nanoimprint lithography. The thickness of benzocyclobutene spacer between the two layers of the Au grating was appropriately designed to produce a Fabry-Perot (F-P) cavity resonance. Fourier transform infrared spectroscopy demonstrated that our double-layer grating enhanced the transmission of the transverse magnetic (TM) polarized light by the F-P cavity resonance modes, whereas attenuating the transmission of the transverse electric (TE) polarized light. As a result, the extinction ratio of the double-layer grating, defined as the ratio of TM to TE transmission was as eight times higher as that of the single-layer Au grating in a mid-wave infrared (MWIR) region of 3.5-6 μm. This result was evidenced by our multiple-layer model based on a transfer matrix theory. The radiometric characterization was performed to compare the linear polarization performances of the single- and double-layer Au gratings. As compared to the single-layer Au grating, the double-layer Au grating produced MWIR imageries with both a higher extinction ratio (~86) and a higher degree of linear polarization (~0.94). These double-layer Au gratings with superior polarization sensitivity can be used as a microgrid polarizer for the next generation high-performance polarimetric imagers.

NIRS was applied to analyze healthy human muscles in vivo, and we found that NIRS produces reliable, reproducible and robust spectral “fingerprints” of individual muscles, that can be successfully discriminated by chemometric analysis and predictive models. Investigations have been thus extended to verify if the same technique is able to distinguish healthy muscles from muscle affected by spasticity. Clinical neurophysiology methods explore only the neurogenic mechanism of spasticity, whether a quick, non-invasive, easy-to-use method for evaluating the overall muscle changes in spastic patients is lacking. We investigated whether NIRS is able to distinguish healthy from spastic muscles, and spastic muscles before and after botulinum toxin treatment. To do this, we collected Vis-SWIR spectra from affected and unaffected upper limb muscles at fixed time interval before and after treatment. We found that Vis-SWIR reflectance spectroscopy discriminate spastic from healthy muscles as well a

Nowadays, the Shack-Hartmann aberrometer is one of the most widely used devices for measuring optical aberrations of the human eye. These aberrometers are used in fundus cameras to measure aberrations inherent to the human eye. This article shows the validation of an experimental Shack-Hartmann aberrometer, which in the future will be used as the optimized adaptive optics arm of an eye fundus camera. The validation is done by a statistical analysis between the aberrations obtained from our experimental system and a commercial aberrometer. This analysis will be performed from the most common aberrations of the human eye, i.e., myopia and astigmatism.

In the pulsed laser ranging system based on time-of-flight measurement, since different targets have different reflection characteristics, the intensity of the echo will affect the leading edge moment received by the range finder, thus affecting the result of the ranging. The pulse width of the echo is positively correlated with the light intensity, so the pulse intensity can be used to characterize the light intensity and correct the leading edge time. This paper proposes a leading edge time correction model based on pulse width.And the leading edge moment acquisition experiment under different echo intensities is carried out by using polarizing plates. The model is fitted and validated by experimental data. The experimental results show that the correction model can effectively correct the error caused by the echo light intensity of the pulsed laser ranging system, thus improving the accuracy of ranging. Keywords: laser ranging, pulse width, leading edge time correction

Infrared (IR) focal plane arrays (FPAs) needed for Earth Science applications have always been among the most challenging in IR detector technology due to the rigorous material growth, device design and fabrication demands. Future small satellite missions will present even more challenges for IR FPAs, as operating temperature must be increased so that cooler (and radiator) volume, mass, and power can be reduced. To address this critical need, we are working on following three technologies, 1) type-II superlattice (T2SL) barrier infrared detector (BIRD), 2) resonator pixel technology, which uses nanophotonics light trapping techniques to achieve strong absorption in a small detector absorber volume, thereby enabling enhanced QE and reduced dark current, 3) high dynamic range 3D Readout IC (3D-ROIC), which integrates a digital reset counter with a conventional analog ROIC to provide a much higher effective well capacity than previously achievable.

In this work, we design and produce 1280x1024 format InGaAs based planar type detectors with 15µm pixel pitch. We have obtained diffusion current limited low dark current (~10fA) and high responsivity (1.08A/W at 1.55µm) values at room temperature conditions. Moreover, dark current modeling is performed using diffusion, generation & recombination (GR) and trap assisted tunneling (TAT) current mechanisms. Ideality factor is extracted from forward bias characteristics. Excellent match between modeling and experimental data is reached. Also, temperature dependency of dark current is studied in 10 – 60C ranges. The area and perimeter related dark current components are differentiated using test detectors with changing diameters that are placed next to the detector array structure. Experimental data shows good agreement with theoretical expectations.

This paper reviews recent progress in extended wavelength (EW) InGaAs photodetectors at Teledyne Judson Technologies (TJT). Up to just recent years, EW InGaAs detectors generally had performance below the corresponding SWIR HgCdTe per Rule-07 for the same cutoff wavelength and operating temperature. The performance gap between the two materials became larger as the cutoff wavelength increases. However, the recent progress in both EW InGaAs material growth and detector fabrication has resulted in dramatic improvement of EW InGaAs detector performance. The performance gap is becoming much smaller at some wavelengths, while at other wavelengths, EW InGaAs even exceeds SWIR HgCdTe per Rule-07. We will present recent detector performance data taken from EW InGaAs, as well as SWIR HgCdTe photodetectors, manufactured at TJT. An in-depth analysis of dark current density at reverse biases, as well as shunt resistance-area product at zero bias (R0A), over a broad temperature range, is performed.

GaN/AlGaN Avalanche Photodiode Detectors for High Performance Ultraviolet Sensing Applications Ashok K. Sood and John W. Zeller Magnolia Optical Technologies, Inc., 52-B Cummings Park, Suite 314, Woburn, MA 01801 Parminder Ghuman and Sachidananda Babu NASA Earth Science Technology Office, Greenbelt, MD 20771 Russell D. Dupuis School of Electrical & Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332 ABSTRACT Detection of ultraviolet (UV) bands offers increased spatial resolution, small pixel sizes, and large format arrays, thus benefitting a variety of NASA, defense, and commercial applications. AlxGa1-xN semiconductor alloys, which have attracted much interest for detection in the UV spectral region, have been shown to enable high optical gains, high sensitivity with the potential for single photon detection, and low dark current performance in ultraviolet avalanche photodiodes (UV-APDs). We are developing GaN/AlGaN UV-APDs with large pixel sizes that d

A high sensitivity infrared (IR) thermometry system for a precise real-time temperature measurement and control in domestic induction cooktops is presented. The system includes an InGaAs PIN photodiode and preamplifier which detects the IR radiation emitted from the bottom of the cookware and the glass-ceramic top. For a precise temperature control with a maximum temperature error of 5°C a cookware emissivity measurement system is included. The accuracy and the validity of our model have been confirmed within the range of cooking temperatures from 60°C to 250°C with experimental measurements performed with the proposed system.

A diamond-like carbon thin film was deposited on the outer face of the germanium (Ge) window to protect the infrared lenses from a harsh environment in automotive application. Infrared transmittance and residual stress of a tetrahedral amorphous carbon (ta-C) thin film by a filtered cathodic vacuum arc (FCVA) source were investigated to increase the lifetime of a Ge window. They were found to have a trade-off relation about the change of the substrate pulse voltage. By introducing methane gas in FCVA deposition process, a hydrogenated ta-C (ta-C:H) thin film of which both IR transmittance and residual stress was improved could be obtained. A Ge window coated with ta-C:H thin film with 1.43 m thickness showed anti-reflection effect in long-wave infrared. The hardness of ta-C:H thin film on Ge window was higher than 30 GPa. Adhesion, severe abrasion, temperature, humidity and salt solubility tests were carried out in accordance with MIL-C-48497A.

Ashok K. Sood, Gopal G. Pethuraja, John W. Zeller, and Roger E. Welser Magnolia Optical Technologies, Inc, 52-B Cummings Park, Suite 314, Woburn, MA 01801 Magnolia Optical Technologies, Inc, 251 Fuller Road, CESTM B-250, Albany NY 12203 Harry Efstathiadis CNSE, SUNY Polytechnic Institute, 257 Fuller Road, Albany, NY 12203 Priyalal Wijewarnasuriya U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783 Nibir K. Dhar U.S. Army Night Vision & Electronic Sensors Directorate, Fort Belvoir, VA 22060 Infrared (IR) technology plays critical role in various military and civilian applications include target acquisition, surveillance, night vision, homing, and tracking. IR sensors and systems operating from near-infrared (NIR) to long-wave infrared (LWIR) spectrum are being developed for these defense and commercial system applications. Performance of the IR systems is significantly limited by the signal loss due to reflection on the IR substrates and optical components.

Diabetic Foot Ulcers (DFU) are one of the common complications of Diabetes Mellitus, which have high associated costs and may affect severely the patients’ quality of life. Changes in skin temperature is one of the early signs of its development, this can be assessed using Infrared Thermal (IRT) imaging. A decision support system using machine learning classifiers was developed and applied to plantar IRT images of 39 active DFU patients. The DFU ulcers can be neuro-ischemic or ischemic. The system showed an 81.25% accuracy on correctly identifying the DFU type.

We present an ultra-compact carbon dioxide detection scheme using a single silicon waveguide ring resonator. The comb-like CO2 absorption line spectrum around 1580 nm wavelength can closely match the comb spectrum of an appropriately designed ring resonator. By actively correlating the ring spectrum with the CO2 absorption lines, a specific detection signal can be generated. In this demonstration, the ring resonator is designed to match the carbon dioxide vibronic lines in the range from 1575 to 1585 nm. We demonstrate that such a device can detect carbon dioxide. It is promising for applications in astronomy and remote atmospheric sensing.

We have successfully tested 5 to 8 GHz bandwidth, Uncooled, Extended InGaAs 2.2 um Wavelength, Linear Optical Receivers, coupled with a Standard Single Mode Fiber for 1 GeV/n Helium, 1 GeV/n Iron, and Gamma Rays. These devices find multiple applications in outer-space for Coherent Rapid Doppler Shift LIDAR, Long Wavelength Gravitational Wave Sensing, as well as Inter-Planetary and Earth-to-Moon Coherent Communication Links. Pre- and Post- radiation results were measured for: (1) Leakage Current Vs. Voltage for the Photodiodes; (2) Responsivity (Quantum efficiency) in A/W for Photodiodes; (3) Optical Return Loss (ORL) for Photodiodes; (4) Bandwidth of the PIN+TIA; and (5) TIA Drive current.

A multimode interference sensor to measure curvature and temperature was demonstrated. A structure of single-mode – multimode – single-mode, coated with polydimethylsiloxane (PDMS) was manufactured. Bending laboratory results showed that the proffered sensor has a sensitivity of -0.9835 nm/m-1 at a curvature range from 0 m-1 to 1.3652 m-1. The laboratory temperature response was -119 pm/°C at a temperature range from 30 °C to 60 °C, showing an improvement in temperature response. The sensitivity reported in the literature for multimode fiber-based sensors are around 12 pm/°C and below 50 pm/°C for low temperatures, and around 100 pm/°C for high temperature sensing applications.

The potential for operating in a very low signal-to-noise ratio (SNR) environment makes single-photon detectors (SPD) an attractive option for many applications. Some of the applications include Lidar/Ladar sensors utilized in mapping and autonomous navigation using near-infrared (NIR) lasers and detectors. In this paper, the characterization of several NIR lasers using InGaAs SPD’s demonstrates the sensitivity and limits of the SPD sensor, as well as the potential to generate repeatable fractional level photons for credible testing of these types of sensors. In particular, the time correlations between pulses are examined; illustrating both dark count rate of the detector and the effect of convolving detector and intrinsic laser noise together.

The demand for non-mechanical approaches to beam-steering has led to several electro-optic approaches. One with great potential integrates liquid crystal (LC) as a cladding layer to a planar waveguide for continuous two dimensional steering. The birefringence of LC is leveraged to tune the refractive index of the guided mode, while efficient coupling with a freespace beam is accomplished with a “tapered gap” prism coupler. The out-coupled beam can be steered to follow a path or address random points with sub millisecond response times. This device architecture presents a challenge for modeling and simulation with a large parameter space. Experimental successes have motivated a custom MATLAB model that couples LC and waveguide physics to accomplish predictive steering amplitude via ray tracing, coupling efficiency and bandwidth calculations and validation of empirical results. The model allows us to optimize parameters that maximize the field of regard and throughput efficiency.

Nowadays there is a great interest in the study of arrays formed by the combination of long period gratings and Bragg gratings in cascade (CLBG). In this work, an analysis and modeling of CLBG using the Transfer Matrix method was performed for the case of two gratings in series for any one fiber. We analyzed the variation of the FWHM of the reflectance and transmittance spectra for different values of the difference of the refractive indexes of the core and the perturbation of the grating, using the typical core refractive index of an SMF-28 as reference value. For smaller index difference a narrow intensity peak was observed. After, the number of perturbations was varied, when there is a greater number of perturbations in the grating, there is greater intensity in reflectance, however, this dependence is not a linear function. Such results were obtained under the maximum tunning-reflectivity for the grating.

In oil and gas fields, gas leakage is one of the major concerns, as it causes serious economical, safety, and health consequences. This requires a frequent and periodic inspections of all equipment which either store or transport gases, such as gas pipelines and gas storage tanks. In this paper, a real-time leak detection and localization system which can operate fully autonomously either in a drone or a mobile robot is suggested.