Ashok Sood - Academia.edu (original) (raw)
Papers by Ashok Sood
Mrs Bulletin, Jun 1, 2011
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium
Journal of the American Chemical Society, Apr 29, 2009
Proceedings of SPIE, Feb 8, 2007
ABSTRACT
Proceedings of SPIE, Aug 18, 2005
Low Cost Multi-color infrared (IR) sensors/focal plane arrays are required for surveillance and o... more Low Cost Multi-color infrared (IR) sensors/focal plane arrays are required for surveillance and other homeland security applications. These sensors require multi-color focal plane arrays (FPA) that will cover 3-5 (MWIR) and 8-14 (LWIR) micron bands. There has been a significant progress in developing HgCdTe on Silicon substrates [1,2]. Two-color IR FPA eliminate the complexity of multiple single color IR FPAs
Proceedings of SPIE, Sep 8, 2011
Proceedings of SPIE, Nov 4, 2004
High Speed Multi-Channel Fiber-Optic Transmitter (Tx) and Receiver (Rx) modules are needed for Ar... more High Speed Multi-Channel Fiber-Optic Transmitter (Tx) and Receiver (Rx) modules are needed for Army's Ground Vehicle Applications. The fiber optic network should take advantage of the high speeds (10 Gbps/channel) and have the ability to connect multiple systems and sensors using a rugged fiber-optic network capable of working with 100's of Gigabits of information. In addition, the network should provide redundant links between nodes so that in case one node goes out of service, the remainder of the network remains operational. In this paper we will present design, development and performance results for 1x12 Tx and Rx module operating at 10Gbps/channel. Each of the 1x12 modules is capable of providing 120 Gbps/Module operations for Army's Applications. Experimental results on 1x12 channel modules will include performance characteristics at 10 Gbps and will demonstrate high performance fiber-optical Tx and Rx Modules. We will also present architecture and simulation for a Fiber-Optic Network Card that has the capability to transmit and receive data, add and drop data at each node, and provide dual network redundancy. This network card includes Tx, Rx modules, serializer and deserializer (SERDES) and a cross bar switch. This architecture can be used as a building block for high-speed local area network for the U.S. Army's applications.
Proceedings of SPIE, Aug 31, 2006
This model was developed in matlab with I/O links to excel spreadsheets to add realistic and accu... more This model was developed in matlab with I/O links to excel spreadsheets to add realistic and accurate sensor effects to scene generator or actual sensor/camera images. The model imports scene generator or sensor images, converts these radiance images into electron maps and digital count maps, and modifies these images in accordance with user-defined sensor characteristics such as the response map, the detector dark current map, defective pixel maps, and 3-D noise (temporal and spatial noise). The model provides realistic line-of-sight motion and accurate and dynamic PSF blurring of the images. The sensor model allows for the import of raw nonuniformities in dark current and photoresponse, performs a user-defined two-point nonuniformity correction to calculate gain and offset terms and applies these terms to subsequent scene images. Some of the model's capabilities include the ability to fluctuate or ramp FPA and optics temperatures, or modify the PSF on a frame-by-frame basis. The model also functions as an FPA/sensor performance predictor and an FPA data analysis tool as FPA data frames can be input into the 3-D noise evaluation section of the model. The model was developed to produce realistic infrared images for IR sensors.
Proceedings of SPIE, May 13, 2011
ABSTRACT Quantum structured solar cells seek to harness a wide spectrum of photons at high voltag... more ABSTRACT Quantum structured solar cells seek to harness a wide spectrum of photons at high voltages by embedding low energy-gap wells or dots within a high energy-gap matrix. Quantum well and quantum dot solar cells have the potential to deliver ultra-high power conversion efficiencies in single junction devices, efficiencies that in theory can approach 45% in un-concentrated sunlight over a wide range of environmental conditions. In this paper, we will briefly review the theoretical underpinnings of quantum well and quantum dot photovoltaic devices, and summarize recent experimental efforts developing quantum-structured solar cell devices. In a specific example, test devices utilizing radiation-hard, III-V nitride materials have been built using both bulk and multiple quantum well (MQW) structures. Photovoltaic devices with an InGaN MQW structure are shown to outperform devices employing a thicker, bulk InGaN layer. These results, along with the underlying theoretical foundations, suggest that quantum well and quantum dot structures can enhance the performance of photovoltaic devices for a variety of defense applications.
Proceedings of SPIE, May 5, 2006
ABSTRACT
Proceedings of SPIE, Feb 10, 2011
EO Sensors are being developed for a variety of Military Systems Applications. These include UV, ... more EO Sensors are being developed for a variety of Military Systems Applications. These include UV, Visible, SWIR, MWIR and LWIR Nano Sensors. In this paper, we will discuss growth and characterization of ZnO Nanowires on a variety of substrates that include Silicon, ZnO and ...
Proceedings of SPIE, Sep 8, 2011
In recent years a substantial amount of research has focused on the mechanical and electro-optica... more In recent years a substantial amount of research has focused on the mechanical and electro-optical properties of ZnO nanowires (NWs). Initially, a significant portion of the work involved developing either single NWs or NW arrays for photo detection at ultraviolet (UV) wavelengths, and the innovation and performance of such devices have subsequently and progressively advanced. In addition, several new areas of ZnO NW research have since appeared, with energy harvesting at the forefront. The piezoelectric potential of nanowires has been a source of considerable interest, and novel concepts have been reported, including devices that convert thermal energy and sound waves into electrical power. In this paper we will address recent work (mostly published within the past couple years) on both ZnO NW based UV photodetectors and energy harvesting, seeking in the process to identify notable and innovative features that are advancing ZnO NW technology and nanodevice performance.
SPIE eBooks, Aug 1, 2010
SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared f... more SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared focal plane arrays that will cover the spectral band from 0.4 to 1.6 microns. The attractive features of SiGe based foal plane arrays take advantage of silicon based technology that promises small feature size, low dark current and compatibility with the low power silicon CMOS circuits for signal processing. This paper will discuss performance characteristics for the SiGe based VIS-NIR Sensors for a variety of defense and commercial applications using small unit cell size and compare performance with InGaAs, InSb, and HgCdTe IRFPA's. We will present results on the approach and device design for reducing the dark current in SiGe detector arrays. We will discuss electrical and optical properties of SiGe arrays at room temperature and as a function of temperature. We will also discuss future integration path for SiGe devices with other Silicon-based technology for defense and Commercial Applications.
Proceedings of SPIE, Sep 26, 2007
The ZnO nanostructures can be implemented in optoelectronic applications, piezoelectric pressure ... more The ZnO nanostructures can be implemented in optoelectronic applications, piezoelectric pressure sensors, Spintronic devices, transducers and biomedical applications [1-8]. Use of these nanostructures, will also allow building of nanoscale nanosensors, nanocantilevers, field-effect transistors and nanoresonators for a variety of military, homeland security and, commercial applications. In this paper we review growth and characterization of ZnO nanowires on a variety of
Proceedings of SPIE, Feb 9, 2006
GaN /AlGaN transistors are being developed for a variety of RF electronic devices that will event... more GaN /AlGaN transistors are being developed for a variety of RF electronic devices that will eventually replace GaAs-and silicon-based devices for commercial and military applications. In this paper, we present results from the optimization of the growth conditions for GaN/AlGaN ...
Proceedings of SPIE, Sep 8, 2011
ABSTRACT High resolution imaging in the UV band has a lot of applications in Defense and Commerci... more ABSTRACT High resolution imaging in the UV band has a lot of applications in Defense and Commercial Applications. The shortest wavelength is desired for spatial resolution which allows for small pixels and large formats. UVAPD's have been demonstrated as discrete devices demonstrating gain. The next frontier is to develop UV APD arrays with high gain to demonstrate high resolution imaging. We also disuses our recent efforts on development of APD's using MOCVD of GaN/ AlGaN. We present an analytical model that can predict sensor performance in the UV band using p-i-n or APD detectors with and without gain and other detector and sensor parameters for a desired UV band of interest. SNR's can be modeled from illuminated targets at various distances with high resolution under standard MODTRAN atmospheres in the UV band using detector arrays with unity gain and with high gain APD along with continuous or pulsed UV lasers.
Proceedings of SPIE, Oct 6, 2011
Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a ... more Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense Applications including Unattended Ground Sensor Applications. Several different nanomaterials are being evaluated for these applications. These include ZnO nanowires that have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under
Proceedings of SPIE, Aug 31, 2006
ABSTRACT
Proceedings of SPIE, Aug 19, 2010
SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared f... more SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared focal plane arrays that will cover the spectral band from 0.4 to 1.6 microns. The attractive features of SiGe based foal plane arrays take advantage of silicon based technology that promises small feature size, low dark current and compatibility with the low power silicon CMOS circuits for signal processing. This paper will discuss performance characteristics for the SiGe based VIS-NIR Sensors for a variety of defense and commercial applications using small unit cell size and compare performance with InGaAs, InSb, and HgCdTe IRFPA's. We will present results on the approach and device design for reducing the dark current in SiGe detector arrays. We will discuss electrical and optical properties of SiGe arrays at room temperature and as a function of temperature. We will also discuss future integration path for SiGe devices with other Silicon-based technology for defense and Commercial Applications.
Proceedings of SPIE, Oct 22, 2004
Multi-color infrared (IR) focal planes are required for high performance sensor applications. The... more Multi-color infrared (IR) focal planes are required for high performance sensor applications. These sensors will require multi-color focal plane arrays (FPA) that will cover various wavelengths of interest in MWIR/LWIR and LWIR/VLWIR bands. There has been a significant progress in ...
Mrs Bulletin, Jun 1, 2011
IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium
Journal of the American Chemical Society, Apr 29, 2009
Proceedings of SPIE, Feb 8, 2007
ABSTRACT
Proceedings of SPIE, Aug 18, 2005
Low Cost Multi-color infrared (IR) sensors/focal plane arrays are required for surveillance and o... more Low Cost Multi-color infrared (IR) sensors/focal plane arrays are required for surveillance and other homeland security applications. These sensors require multi-color focal plane arrays (FPA) that will cover 3-5 (MWIR) and 8-14 (LWIR) micron bands. There has been a significant progress in developing HgCdTe on Silicon substrates [1,2]. Two-color IR FPA eliminate the complexity of multiple single color IR FPAs
Proceedings of SPIE, Sep 8, 2011
Proceedings of SPIE, Nov 4, 2004
High Speed Multi-Channel Fiber-Optic Transmitter (Tx) and Receiver (Rx) modules are needed for Ar... more High Speed Multi-Channel Fiber-Optic Transmitter (Tx) and Receiver (Rx) modules are needed for Army's Ground Vehicle Applications. The fiber optic network should take advantage of the high speeds (10 Gbps/channel) and have the ability to connect multiple systems and sensors using a rugged fiber-optic network capable of working with 100's of Gigabits of information. In addition, the network should provide redundant links between nodes so that in case one node goes out of service, the remainder of the network remains operational. In this paper we will present design, development and performance results for 1x12 Tx and Rx module operating at 10Gbps/channel. Each of the 1x12 modules is capable of providing 120 Gbps/Module operations for Army's Applications. Experimental results on 1x12 channel modules will include performance characteristics at 10 Gbps and will demonstrate high performance fiber-optical Tx and Rx Modules. We will also present architecture and simulation for a Fiber-Optic Network Card that has the capability to transmit and receive data, add and drop data at each node, and provide dual network redundancy. This network card includes Tx, Rx modules, serializer and deserializer (SERDES) and a cross bar switch. This architecture can be used as a building block for high-speed local area network for the U.S. Army's applications.
Proceedings of SPIE, Aug 31, 2006
This model was developed in matlab with I/O links to excel spreadsheets to add realistic and accu... more This model was developed in matlab with I/O links to excel spreadsheets to add realistic and accurate sensor effects to scene generator or actual sensor/camera images. The model imports scene generator or sensor images, converts these radiance images into electron maps and digital count maps, and modifies these images in accordance with user-defined sensor characteristics such as the response map, the detector dark current map, defective pixel maps, and 3-D noise (temporal and spatial noise). The model provides realistic line-of-sight motion and accurate and dynamic PSF blurring of the images. The sensor model allows for the import of raw nonuniformities in dark current and photoresponse, performs a user-defined two-point nonuniformity correction to calculate gain and offset terms and applies these terms to subsequent scene images. Some of the model's capabilities include the ability to fluctuate or ramp FPA and optics temperatures, or modify the PSF on a frame-by-frame basis. The model also functions as an FPA/sensor performance predictor and an FPA data analysis tool as FPA data frames can be input into the 3-D noise evaluation section of the model. The model was developed to produce realistic infrared images for IR sensors.
Proceedings of SPIE, May 13, 2011
ABSTRACT Quantum structured solar cells seek to harness a wide spectrum of photons at high voltag... more ABSTRACT Quantum structured solar cells seek to harness a wide spectrum of photons at high voltages by embedding low energy-gap wells or dots within a high energy-gap matrix. Quantum well and quantum dot solar cells have the potential to deliver ultra-high power conversion efficiencies in single junction devices, efficiencies that in theory can approach 45% in un-concentrated sunlight over a wide range of environmental conditions. In this paper, we will briefly review the theoretical underpinnings of quantum well and quantum dot photovoltaic devices, and summarize recent experimental efforts developing quantum-structured solar cell devices. In a specific example, test devices utilizing radiation-hard, III-V nitride materials have been built using both bulk and multiple quantum well (MQW) structures. Photovoltaic devices with an InGaN MQW structure are shown to outperform devices employing a thicker, bulk InGaN layer. These results, along with the underlying theoretical foundations, suggest that quantum well and quantum dot structures can enhance the performance of photovoltaic devices for a variety of defense applications.
Proceedings of SPIE, May 5, 2006
ABSTRACT
Proceedings of SPIE, Feb 10, 2011
EO Sensors are being developed for a variety of Military Systems Applications. These include UV, ... more EO Sensors are being developed for a variety of Military Systems Applications. These include UV, Visible, SWIR, MWIR and LWIR Nano Sensors. In this paper, we will discuss growth and characterization of ZnO Nanowires on a variety of substrates that include Silicon, ZnO and ...
Proceedings of SPIE, Sep 8, 2011
In recent years a substantial amount of research has focused on the mechanical and electro-optica... more In recent years a substantial amount of research has focused on the mechanical and electro-optical properties of ZnO nanowires (NWs). Initially, a significant portion of the work involved developing either single NWs or NW arrays for photo detection at ultraviolet (UV) wavelengths, and the innovation and performance of such devices have subsequently and progressively advanced. In addition, several new areas of ZnO NW research have since appeared, with energy harvesting at the forefront. The piezoelectric potential of nanowires has been a source of considerable interest, and novel concepts have been reported, including devices that convert thermal energy and sound waves into electrical power. In this paper we will address recent work (mostly published within the past couple years) on both ZnO NW based UV photodetectors and energy harvesting, seeking in the process to identify notable and innovative features that are advancing ZnO NW technology and nanodevice performance.
SPIE eBooks, Aug 1, 2010
SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared f... more SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared focal plane arrays that will cover the spectral band from 0.4 to 1.6 microns. The attractive features of SiGe based foal plane arrays take advantage of silicon based technology that promises small feature size, low dark current and compatibility with the low power silicon CMOS circuits for signal processing. This paper will discuss performance characteristics for the SiGe based VIS-NIR Sensors for a variety of defense and commercial applications using small unit cell size and compare performance with InGaAs, InSb, and HgCdTe IRFPA's. We will present results on the approach and device design for reducing the dark current in SiGe detector arrays. We will discuss electrical and optical properties of SiGe arrays at room temperature and as a function of temperature. We will also discuss future integration path for SiGe devices with other Silicon-based technology for defense and Commercial Applications.
Proceedings of SPIE, Sep 26, 2007
The ZnO nanostructures can be implemented in optoelectronic applications, piezoelectric pressure ... more The ZnO nanostructures can be implemented in optoelectronic applications, piezoelectric pressure sensors, Spintronic devices, transducers and biomedical applications [1-8]. Use of these nanostructures, will also allow building of nanoscale nanosensors, nanocantilevers, field-effect transistors and nanoresonators for a variety of military, homeland security and, commercial applications. In this paper we review growth and characterization of ZnO nanowires on a variety of
Proceedings of SPIE, Feb 9, 2006
GaN /AlGaN transistors are being developed for a variety of RF electronic devices that will event... more GaN /AlGaN transistors are being developed for a variety of RF electronic devices that will eventually replace GaAs-and silicon-based devices for commercial and military applications. In this paper, we present results from the optimization of the growth conditions for GaN/AlGaN ...
Proceedings of SPIE, Sep 8, 2011
ABSTRACT High resolution imaging in the UV band has a lot of applications in Defense and Commerci... more ABSTRACT High resolution imaging in the UV band has a lot of applications in Defense and Commercial Applications. The shortest wavelength is desired for spatial resolution which allows for small pixels and large formats. UVAPD's have been demonstrated as discrete devices demonstrating gain. The next frontier is to develop UV APD arrays with high gain to demonstrate high resolution imaging. We also disuses our recent efforts on development of APD's using MOCVD of GaN/ AlGaN. We present an analytical model that can predict sensor performance in the UV band using p-i-n or APD detectors with and without gain and other detector and sensor parameters for a desired UV band of interest. SNR's can be modeled from illuminated targets at various distances with high resolution under standard MODTRAN atmospheres in the UV band using detector arrays with unity gain and with high gain APD along with continuous or pulsed UV lasers.
Proceedings of SPIE, Oct 6, 2011
Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a ... more Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense Applications including Unattended Ground Sensor Applications. Several different nanomaterials are being evaluated for these applications. These include ZnO nanowires that have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under
Proceedings of SPIE, Aug 31, 2006
ABSTRACT
Proceedings of SPIE, Aug 19, 2010
SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared f... more SiGe based focal plane arrays offer a low cost alternative for developing visible-near-infrared focal plane arrays that will cover the spectral band from 0.4 to 1.6 microns. The attractive features of SiGe based foal plane arrays take advantage of silicon based technology that promises small feature size, low dark current and compatibility with the low power silicon CMOS circuits for signal processing. This paper will discuss performance characteristics for the SiGe based VIS-NIR Sensors for a variety of defense and commercial applications using small unit cell size and compare performance with InGaAs, InSb, and HgCdTe IRFPA's. We will present results on the approach and device design for reducing the dark current in SiGe detector arrays. We will discuss electrical and optical properties of SiGe arrays at room temperature and as a function of temperature. We will also discuss future integration path for SiGe devices with other Silicon-based technology for defense and Commercial Applications.
Proceedings of SPIE, Oct 22, 2004
Multi-color infrared (IR) focal planes are required for high performance sensor applications. The... more Multi-color infrared (IR) focal planes are required for high performance sensor applications. These sensors will require multi-color focal plane arrays (FPA) that will cover various wavelengths of interest in MWIR/LWIR and LWIR/VLWIR bands. There has been a significant progress in ...