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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.