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This PDF file contains the front matter associated with SPIE
Proceedings Volume 7095, including the Title Page, Copyright
information, Table of Contents, Introduction (if any), and the
Conference Committee listing.
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Hybrid and Nanoparticle Materials for Radiation Environments
In this paper we present the preliminary experimental characterization of electronic devices based upon Germanium
nano-crystals (nc-Ge) embedded in thick SiO2 films grown on a Si substrate. The samples were prepared using Ge
ion implantation followed by thermal annealing. Typical diameter of the nc-Ge is shown to be in the range of 4-
10nm. Gold (Au) contacts were deposited on the top of the oxide surface allowing measurements of the electronic
properties.
We present preliminary experimental results of electronic properties of the nc-Ge based devices including
current-voltage (I-V) and capacitance-voltage (C-V) curves of the nano-devices while illuminated by white light and
an external laser at a wavelength of 532nm for various levels of intensity. The characterization curves were also
obtained at different temperatures.
The proposed technology of devices based on nc-Ge was proven to be insensitive to high doses of irradiation by
neutrons in a research nuclear reactor, which suggests that these nc-Ge devices can be used under extreme working
conditions such as strong cosmic radiation appearing in outer space.
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A revolutionary family of cost-effective, lightweight, self-cleaning and anti-contamination coatings is being investigated
to mitigate lunar dust on critical power and optical systems, including solar photovoltaic power systems, radiators, and
other components needed for lunar exploration as well as optical instruments and sensors. Dust contamination is a
serious problem for equipment and vehicles since Lunar "weathering" has left the lunar soil has fine texture compared to
terrestrial dust particle size distributions. The electrostatic charging of the lunar surface is caused by its interaction with
the local plasma environment and solar UV and X-rays induced photoemission of electrons. The lunar thermal
environment poses unique challenges to coatings since it is characterized by large temperature variations, long hot and
cold soak times, and reduced heat rejection capability due to the presence of the lunar regolith. We are attempting to
design an integrated approach to solving the dust problems associated with its many elements This presentation will
discuss the properties, as a function of ionizing radiation, temperature and space contamination effects, for both
hydrophilic and hydrophobic coating self-cleaning approaches as well as a new approach which incorporates various
catalytic mechanisms (stoichiometric, photocatalytic and electrocatalytic) for decontamination in the lunar environment.
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Although metal halide anti-reflective (AR) coatings are widely used by manufacturers of electronics equipment, high
application temperatures mean that they can only easily be applied to glass substrates. Screens made from plastics
materials can be coated but the process requires additional steps to prevent damaging the substrate.
A new, easily applied anti-reflective coating has been designed which can be applied to both plastic and glass substrates.
The single layer coating applied to an acrylic substrate has proven to be better performing than current commercial single
layer anti-reflective coatings. This performance has been achieved from an amorphous fluoropolymer solution which is
dip coated onto the substrate.
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Infrared photodetectors with spectrally selective response are highly desirable for applications such as hyper-spectral
imaging and gas sensing. Owing to the ability of photonic density of states modification and dispersion engineering,
photonic crystals appear to be one of the most promising platforms for infrared photodetectors with spectrally-selective
absorption enhancement. We report here the latest advances on 1D and 2D dielectric photonic crystal structures for
infrared photodetectors, based on defect mode, bandedge effect and the guided mode resonance/Fano effects. High
spectral selectivity and tunability is feasible with defect mode engineering, making photonic crystal defect cavities a
promising nanophotonic platform for the spectrally selective infrared sensing and hyper-spectral imaging, with the
incorporation of quantum well or quantum dot infrared photodetector heterostructures.
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NASA's Phoenix Mars lander employs a suite of instruments to investigate the properties of the planet's North polar
region. A Robotic Arm is used to retrieve subsurface samples for analysis, and a Robotic Arm Camera mounted on the
wrist of the arm provides images of the surface and of material in the scoop. The RAC and the Optical Microscope both
utilize LEDs, which enable the generation of true color imagery and provide higher illumination levels at lower power
levels than the incandescent lamps used on a predecessor instrument. Although red, green and blue LEDs were
available when the instruments were being developed, the manufacturers had not tested the devices in all the
environments the spacecraft would encounter. This paper details the results of a series of tests conducted to qualify the
lamps for the temperature, vibration, and radiation environments they would encounter during the mission.
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Rare-earth-doped fibers, such as Er3+- and Yb3+-doped aluminosilicates can be advantageous in space-based systems
due to their stability, their high-bandwidth transmission properties and their lightweight, small-volume properties. In
such environments the effect of ionizing-radiation on the optical transmission of these fibers is of paramount importance.
For the present work, gamma-radiation experiments were conducted in which un-pumped Yb3+ and Er3+ doped sample
fibers were irradiated with a Cobalt-60 source under different dose-rate and temperature conditions. In-situ spectral
transmittance data over the near IR was monitored during the irradiations for total doses of up to tens of krad (Si). It was
found that there was a dose-rate dependence in which higher rates resulted in more photodarkening. Higher temperatures
were not found to significantly affect the rate of photodarkening at the dose rates used.
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The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel
materials when subjected to the synergistic effects of the harsh space environment for several months. In this paper, a
few materials and components from NASA Langley Research Center (LaRC) that have been flown on MISSE 6 mission
will be discussed. These include laser and optical elements for photonic devices. The pre-characterized MISSE 6
materials were packed inside a ruggedized Passive Experiment Container (PEC) that resembles a suitcase. The PEC was
tested for survivability due to launch conditions. Subsequently, the MISSE 6 PEC was transported by the STS-123
mission to International Space Station (ISS) on March 11, 2008. The astronauts successfully attached the PEC to
external handrails and opened the PEC for long term exposure to the space environment. The plan is to retrieve the
MISSE 6 PEC by STS-128 mission in 2009.
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The tolerance of a hybrid array (HA) to total ionizing dose (TID) radiation continues to be a major
performance consideration for space based imaging systems. In an effort to improve TID performance, HA
manufacturers have begun to utilize circuit design techniques to enhance the TID tolerance of readout
integrated circuits (ROICs). This paper will report on the radiometric and TID radiation characterizations of a
HA that utilizes radiation-hardened-by-design (RHBD) techniques. This paper will not describe the design
techniques used. Instead, characterization data are presented that demonstrate a HA TID tolerance of over 25
units of total ionizing dose (UTID). This result is compared with the performance of devices with ROICs
processed at commercial foundries that do not make use of RHBD techniques. The HA described in this paper
represents a state-of-the-art device; the ROIC was designed to be low noise, high gain, and radiation tolerant.
While design techniques were utilized to enhance its TID hardness, no special fabrication processes were used.
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Greenhouse gases, such as carbon dioxide, carbon monoxide, and methane, can be remotely monitored through optical
spectroscopy at ~2 micron wavelength. Space based LIDAR sensors have become increasingly effective for greenhouse
gas detection to study global warming. The functionality of these LIDAR sensors can be enhanced to track global wind
patterns and to monitor polar ice caps. Such space based applications require sensors with very low sensitivity in order
to detect weak backscattered signals from an altitude of ~1000km. Coherent detection allows shot noise limited
operation at such optical power levels. In this context, p-i-n photoreceivers are of specific interest due to their ability to
handle large optical power, thereby enabling high coherent gain. Balanced detection further improves the system
performance by cancelling common mode noise, such as laser relative intensity noise (RIN).
We demonstrate a low-noise InGaAs balanced p-i-n photoreceiver at 2μm wavelength. The photoreceiver is
comprised of a matched pair of p-i-n photodiodes having a responsivity of 1.34A/W that is coupled to transimpedance
amplifier (TIA) having an RF gain of 24dB (transimpedance = 800Ω) and input equivalent noise of 19pA/√Hz at 300K.
The photoreceiver demonstrates a 3dB bandwidth of 200MHz. Such bandwidth is suitable for LIDAR sensors having 20
to 30m resolution. The photoreceiver exhibits a common mode rejection ratio of 30dB and optical power handling of
3dBm per photodiode.
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Recent progress in development and nonlinear optical device application of germano-silicate optical fibers incorporated
with noble metal nanoparticles are presented. Novel macro-optical properties, such as linear absorption, resonant optical
nonlinearity, and optical limiting properties of the fibers fabricated by modified chemical vapor deposition and solution
doping techniques are experimentally and theoretically demonstrated based on surface plasmon resonance effect and
nonlinear confinement of the noble metal nanoparticles. Applications of the fibers for all-optical signal gating with the
cascaded long period gratings and for a new method to determine the third-order susceptibility of optical fibers are
discussed.
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Novel Photonic Devices for Space-Based Applications I
We develop a dual-charged-fluid model is to explore the surface-acoustic-wave (SAW) dragged photocurrents
of one-dimensional (1D) confined-state carriers in a steady state. The proposed model takes into account the
quantum confi;nement, the tunneling escape of SAW-dragged 1D carriers, the inelastic capture of two-dimensional
continuous-state carriers and the induced self-consistent space-charge field. The numerical results demonstrate
a high optical gain due to suppressed recombination of 1D carriers in a region between an absorption strip
and a surface gate. Using a discrete model, we calculate the responsivity for the SAW-dragged photocurrent
in a quantum well as functions of the gate voltage, photon flux, SAW power and frequency and temperature,
respectively. A high responsivity (~103 Amp/Watt) is shown for high gate voltages and SAW powers, as well as
for low photon fluxes and SAW frequencies.
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The fragile nature of alumina and the intrinsic Al2O3 barrier layer at the pore bases has hindered its use in optoelectronic
devices. In this work, these issues have been addressed by the development of a nanoporous alumina template directly on
a silicon substrate with platinum electrodes at the pore bases. This template was then used to perform dc galvanostatic
electrochemical deposition of II-VI semiconductor heterostructure nanowires that were then used to fabricate pixilated
detector arrays.
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Novel Photonic Devices for Space-Based Applications II
To optimize the photodetector based on quantum-dot (QD) structures, we develop and exploit a model of the roomtemperature
QD photodetector. Using analytical modeling and Monte-Carlo simulations, we investigate photoelectron
kinetics, i.e. capture and transit processes, as functions of selective doping of a QD structure, its geometry, and electric
field applied. Results of our simulations demonstrate that the photoelectron capture is substantially enhanced in strong
electric fields. Detailed analysis shows that effects of the electric field on electron capture in the structures with barriers
are not sensitive to the redistribution of electrons between valleys. Thus, most data find adequate explanation in the
model of hot-electron transport in the potential relief of quantum dots. We also show that the photoelectron kinetics is
very sensitive to potential barriers of intentionally or unintentionally charged quantum dots. The capture processes can
be substantially suppressed by a proper choice of the geometry of a QD structure and modulation doping. The suggested
model is in agreement with the available experimental results. Manageable kinetics will allow one to employ QDIP as an
adaptive detector with changing parameters.
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A hyper-spectral quantum dot infrared photodetector (QDIP) based on doublecavity
comb filter is reported. The hyperspectral QDIP uses a double cavity comber filter
and a novel transparent conductive carbon nanotube (CNT) thin-film network as the
electrode. By tuning the bias of the transparent electrode coated on the membrane, the
cavity length and corresponding passband of the filter can be changed accordingly with
low optical loss. Such MEMS-based hyper-spectral QDIP would also enable quick
spectral scan of IR characteristics of chemical and biological materials.
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Launch vehicles and other satellite users need launch services that are highly reliable, less complex, easier
to test, and cost effective. Being a very small molecule, hydrogen is prone to leakage through seals and
micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of
hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of
cryogenic fluids in spaceport facilities, launch vehicle industry and aerospace agencies are currently
relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh
several hundred kilograms. Therefore, there is a critical need for miniaturized sensors and instruments
suitable for use in space applications.
This paper describes a novel multi-channel integrated nano-engineered optical sensor to detect hydrogen
and monitor the temperature. The integrated optic sensor is made of multi-channel waveguide elements
that measure hydrogen concentration in real Time. Our sensor is based on the use of a high index
waveguide with a Ni/Pd overlay to detect hydrogen. When hydrogen is absorbed into the Ni/Pd alloy
there is a change in the absorption of the material and the optical signal in the waveguide is increased.
Our design uses a thin alloy (few nanometers thick) overlay which facilitates the absorption of the
hydrogen and will result in a response time of approximately few seconds.
Like other Pd/Pd-Ni based sensors the device response varies with temperature and hence the effects of
temperature variations must be taken into account. One solution to this problem is simultaneous
measurement of temperature in addition to hydrogen concentration at the same vicinity. Our approach
here is to propose a temperature sensor that can easily be integrated on the same platform as the hydrogen
sensor reported earlier by our group. One suitable choice of material system is silicon on insulator (SOI).
Here, we propose a micro ring resonators (MRR) based temperature sensor designed on SOI that
measures temperature by monitoring the output optical power.
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The NASA Goddard Fiber Optics Team in the Electrical Engineering Division of the Applied Engineering and
Technology Directorate designed, developed and integrated the space flight optical fiber array hardware for the Lunar
Reconnaissance Orbiter (LRO). The two new assemblies that were designed and manufactured at GSFC for the LRO
exist in configurations that are unique in the world for the application of ranging and LIDAR. Described here is an
account of the journey and the lessons learned from design to integration for the Lunar Orbiter Laser Altimeter and the
Laser Ranging Application on the LRO.
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