Image Sensing Technologies: Materials, Devices, Systems, and Applications IX

The high operating temperature (HOT) BIRD focal plane arrays (FPAs) offer the same high performance, uniformity, operability, manufacturability, and affordability advantages as InSb. However, mid-wavelength infrared (MWIR) HOT-BIRD FPAs can operate at significantly higher temperatures (>150K) than InSb FPAs (typically 80K). Moreover, while InSb has a fixed cutoff wavelength (~5.4 µm), the HOT-BIRD offers a continuous adjustable cutoff wavelength, ranging from ~4 µm to >15 µm, and is therefore also suitable for long wavelength infrared (LWIR) as well. The LWIR detectors based on the BIRD architecture has also demonstrated significant operating temperature advantages over those based on traditional p-n junction designs. Two 6U SmalSat missions CIRAS (Cubesat Infrared Atmospheric Sounder) and HyTI (Hyperspectral Thermal Imager) are based on JPL’s T2SL FPAs.

The detection of Nd: YAG laser emission at 1.064 microns is important for a number of applications such as active infrared imaging and space LIDAR. We propose a silicon photodetector and avalanche photodetector (APD) based on micro-scaled photonic structures, comprising with holes arrays filled with SiO2 to yield optical diffraction and light trapping. With 3D electromagnetic modeling, we design and optimize the hole size and their spacing in a hexagonal array. The optimized structure theoretically yields 26.0% absorption at 1.064 microns, which is about 50 times higher than the planar structure, in addition to 18% dark current reduction.

The detection and resolution of multiple, few photon, laser return pulses of nanosecond width and separation is presented via a novel high bandwidth, avalanche photodiode (APD) design. The intended application requires signal amplification to detect the anticipated low photon pulses. Consequently, a HgCdTe avalanche photodiode (APD) was chosen to provide high (~ 500 to 1000) gain at ~ 16 to 20 V with low excess noise factor. To fulfill the application, the APD requires ~ 1GHz or higher Bandwidth (BW). A detector architecture has been chosen for achieving intended bandwidth. The APD has an absorber region cutoff wavelength of 2.5 um and a gain region cutoff wavelength of 3.5 um.

We have successfully tested simultaneously 2.4 Micron Wavelength, Extended InGaAs Photodiodes having diameters of 20, 30, 40, 50, 100, 150, 200, 250 and 290 Micron, coupled with a Single Mode Fiber using Hydrogen (H), Helium (He), and Iron (Fe) Ions which collectively make up over 90% of the Galactic Cosmic Rays (GCR). During radiation, the devices were maintained at dry ice temperature, reverse biased at 100 mV, and their leakage current was continuously monitored in-situ during the run. After the radiation run was completed, all nine devices were monitored for any change in their leakage current at 100 mV and room temperature for several weeks to monitor any annealing effects that may occur. All devices were found to be fully functional at the normal operating conditions and at both dry ice and room temperature. We did not observe any post radiation annealing effect for leakage current at room temperature and 100 mV bias for any of the devices after several weeks of data logging

We are developing III-Nitrite material based deep UV (200 nm – 280 nm) APD. The wide bandgap AlXGa1-XN material system enables design of highly efficient, radiation-hard detectors for operating at high temperatures without coatings. We will present results on characteristics from materials to device. The results showed high quality and high Al composition AlxGa1-xN have spectral response in deep UV spectral range. The proposed DUV-APD and its array will have space and commercial applications including UV spectroscopy, portable chemical and biological identification systems.

Improved UV to IR band detector performance through advanced nanostructured antireflection coatings Ashok K. Sood, John W. Zeller, Adam W. Sood, 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 B250, Albany NY 12203 Parminder Ghuman and Sachidananda Babu NASA Earth Science Technology Office, Greenbelt, MD 20771 Sarath Gunapala. Alexander Soibel and David Ting Center for Infrared Photodetectors, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91030 Latika S. Chaudhary and Harry Efstathiadis College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, 257 Fuller Road, Albany, NY 12203 ABSTRACT The performance of optical and imaging systems may be limited considerably by losses due to reflection of signals off substrates and optical components. Nanoengineered optical layers offering tunable refractive index p

NRL is developing new materials that transmit across wide wavelength ranges and will present recent results. MILTRAN is a new optical ceramic that transmits visible through LWIR and is well suited as an internal lens element. NRL-series moldable glasses transmit SWIR through LWIR and may be bonded to each other in an adhesive-free thermal process. NRL-200-series glasses transmit visible through MWIR and expand the glass map for multispectral lens designs. These new materials enable greater flexibility for designers of lenses for advanced defense applications and potentially reduce the size, weight and cost of next-generation optics.

Microbolometers are the detectors most used in infrared imaging systems. The current trend is to transition to low size, weight, and power (low SWaP) imaging systems. Seebeck nanoantennas are considerably faster than traditional bolometers. Also, since the thermoelectric elements provide an output voltage no bias is needed for operation, reducing the power requirements of the whole imaging system. In this work a multipolarized Seebeck nanoantenna is analyzed as a potential infrared pixel, their responsivity and detectivity are calculated from Multiphysics simulations for different pixel sizes.

A scalable, low cost, low power, and small footprint uncooled mid-wave infrared (MWIR) sensing technology capable of measuring thermal dynamics with high spatial resolution can be of great benefit to space and satellite applications such as remote sensing and earth observation. Conventional photodetectors designed to absorb MWIR band wavelengths have often been based on HgCdTe material and typically require cooling. However, through integration of bilayer graphene functioning as a high mobility channel with HgCdTe material in photodetectors, higher performance detection over the 2-5 μm MWIR band may be enabled and facilitated primarily by thus limiting recombination of photogenerated carriers in these detectors. This high performance MWIR band detector technology is being developed and tested for NASA Earth Science, defense, and commercial applications. Graphene bilayers on Si/SiO2 substrates are doped with boron using a spin-on dopant (SOD) process and then transferred onto HgCdTe

Adding a charge blocking layer at the anode of organic photodiodes suppresses the current when forward biased. This simple structure can substitute thin film transistors as a switch when scaled into an array. However, the mechanism of the structure is still unknown. Meanwhile we observe a slow turn on when reverse biased, this indicates small and large signal injection dominated by different recombination mechanisms. Here, we developed a numerical model simulating this three-layer structure and compared against experimental data to describe the carrier dynamics and elucidate the physics dominant in this switchable photodiode.

Capabilities of neuromorphic (event) based sensors for atmospheric turbulence spatio-temporal dynamics characterization and refractive index structure parameter (Cn2) sensing are investigated by recording features of a building in 7km distance using an optical telescope with attached event camera. Synchronously the refractive index structure parameter was measured with a commercial scintillometer. A processing technique is developed to compare the distribution-width of events generated by a vertical edge of the building within a given time-span to the measured strength of turbulence. It is shown that this method can be used to characterize the turbulence strength.

Mobile mapping becomes a more and more important and interesting field of sensing technologies and their application scenarios. Concerning ground base solutions, known fields of application range from the detection of the surface condition of roads to the digitization of entire railroad lines. This work summarizes the state-of-the-art mobile mapping technologies in the framework of detection and digitization concerning georeferenced condition monitoring. Various sensing systems will be compared with regard to their applications, applicability, limitations and technological aspects. The aim is to clearly identify technical shortcomings with regard to the application case of road detection in the forestry sector and lay the foundation for subsequent research and development work for multimodal sensing systems in that field.

Rapid developments in infrared (IR) and electro-optical (EO) systems are crucial to further enhance the intelligence, surveillance, and reconnaissance (ISR) capabilities of platforms. The operational conditions of these platforms are getting harsher each day and new technologies must be adapted into these EO/IR systems swiftly to keep up with these challenges. While the performance requirements are increasing, the size, weight, and power (SWaP) constraints are becoming more stringent, especially in airborne platforms such as UAVs. Advancements in the technology of the components of such systems will be evaluated to shed light into the future of these systems.

Non-degenerate two-photon absorption (ND-2PA) across the indirect gap of silicon is theoretically and experimentally investigated in the current work. We present measurements of the 2PA coefficient of bulk silicon using femtosecond pump and probe pulses in the IR and mid-IR range. Enhancement of ND-2PA was observed from the results of our measurements with increasing non-degeneracy. This can be utilized when designing sensitive silicon-based mid-IR detectors. Modeling of the 2PA was performed by considering three theoretical pathways across the band structure of silicon for the two photons and a phonon, and the most dominant processes are determined by comparison to our measurements.

THz testing has been recently proposed to identify altered or damaged ICs. This method is based on the fact that a modern field-effect transistor (FET) with a sufficiently short channel can serve as a terahertz detector. The response can be recorded while changing the THz radiation parameters and location and compared to a trusted one for classification. We measured the THz response of original and damaged ICs for classification using different Transfer Learning models as a method of deep learning. We have achieved the highest classification accuracy of 98%.

The challenges of size, weight, power consumption, and the cost of federated sensor systems for defense applications can be mitigated by exploring solutions derived from collaborative activities across government, industry, and academia. But sensor integration is illusive. For example, new vehicles are almost always developed by a single prime contractor; sensors are often identified as Contractor Furnished Material or Government Furnished Equipment and acquired by the “Prime.” This approach leads to federate architectures; sensor upgrades or new additions often show the “Christmas tree” effect, where sensors are more or less “hung” on the platform. This talk will explore novel approaches to integrating sensors needed to provide enhanced or new capabilities. Integrated sensors can support multiple missions performed by a single platform alone or with other manned or unmanned platforms, using common standards emerging from the DoD and Industry.

The paper aims to use new monolithic polarizing image sensors for surface inspection of technical surfaces. Therefore, the approach that specific materials will polarize light should be used. In these investigations the degree of polarization of small water drops were observed and processed in different wavelength ranges. Due to the characteristics of the special setup the waterdrops can be detected in the most cases. Especially the blue wavelength range will increase the stability of the detection. As a support for the visualization of the polarizing characteristics a special image presentation software was developed.

We have developed a wafer-scale, low SWaP-C enabling Metamaterial Spectrometer (MMS) device for MWIR hyperspectral imaging. Each MMS chip couples a narrow passband Distributed Bragg Stack filter, with a sub-wavelength dielectric resonator metasurface which can be pixelated into spectral channels, with independently engineerable center wavelengths and bandwidths. The metasurface resonators are engineered to accept light across a wide angle-of-incidence cone while being integrated directly into existing focal plane array (FPA) detectors. This eliminates the need for collimating optics, thereby reducing the SWaP requirements. Potential commercial applications of the hyperspectral MMS include environmental monitoring, medical diagnostics, antiterrorism, forensics, and food safety.

Quantum technologies provide new base capabilities which open up new frontiers in sensing, networking, and computation. In all cases, working with systems at the limits set by nature requires high degrees of integration of complex systems to realize practical results. Jake will discuss the promise quantum systems in diverse areas from particle physics to drug discovery, and highlight the many challenges to be overcome and the ways in which the nascent field of quantum engineering can tackle these challenges.

Superconducting nanowires operating at temperatures of a few degrees Kelvin can be biased so that a single photon--even one in the infrared--will initiate a sudden transition into a resistive state that is easily sensed by conventional amplifiers. The resulting signal preserves photon-arrival timing at the few-picosecond level and adds virtually no readout noise. Imagers are now being developed in this technology for a range of future applications. In this talk, I will present the current state-of-the-art of this technology.