We have recently shown the successful synthesis of zirconia nanoparticles that can be optimized for use in volume phase holography by a post-functionalization surface treatment. Here, we present further investigations on the surface modification treatment with the aim of providing tools to tailor the nanoparticle compatibility to the photocurable organic matrix. Highly crystalline ZrO2 nanoparticles with a mean diameter of 5nm are synthesized in multigram yield through a one-pot solvothermal reaction of zirconium (IV) n-propoxide in benzyl alcohol. It is shown that the yield of the ZrO2 nanoparticles and stability of the nanoparticle dispersions are strongly dependent on the synthesis temperature. Post-synthetic surface modification of ZrO2 nanoparticles using several aliphatic ligands with different surface binding groups such as carboxylate (-COO−), amine (−NH2), phosphate (−PO4) and methoxysilane (−SiOCH3) was performed in order to compare the binding ability of these functional groups to the nanoparticle surface and therefore provide a new rational approach for nanoparticle stabilization with organic ligands.

An all fiber linear frequency modulated continuous wave (FMCW) coherent laser radar system is under development with a goal to aide NASA's new Space Exploration initiative for manned and robotic missions to the Moon and Mars. Linear FMCW lidar has the capability of high resolution range measurements, and when configured into a multi-channel receiver system it has the capability of obtaining high precision vector velocity measurements. Precision range and vector velocity data are beneficial to navigating planetary landing pods to the pre-selected site and achieving autonomous, safe soft-landing. This paper discusses the design of a second generation prototype system under development at NASA Langley Research Center and presents preliminary performance data obtained from field experiments.

We have designed and grown a series of quantum dot semiconductor saturable absorber mirrors (QD-SESAMs) for a range of operating wavelengths, incorporating innovative design and processing features to optimise the device performance. Using a range of reflectivity studies, ellipsometric measurements and both time-integrated and time-resolved spectroscopic studies, we have conducted detailed investigations of device performance. Extensive modelling work of dielectric multilayers has been undertaken which supports our experimental findings and allows us to understand and design novel structures in order to improve and tailor device characteristics, including dielectric capping and non-normal incidence. We demonstrate samples designed for operation with the higher excited-states of the QDs which produced a self-starting train of mode-locked pulses with a temporal duration of 200 ps at a repetition rate of 78 MHz in a Nd:YVO4 solid-state laser. We also present SESAMs incorporating electronically coupled QD bilayers, allowing long wavelength operation.

A mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 320x256 pixel quantum well infrared photodetector (QWIP) dualband focal plane arrays (FPAs) have been demonstrated with excellent imagery. Currently, we are developing a 1024x1024 pixel simultaneous pixel co-registered dualband QWIP FPA. In addition, epitaxially grown self-assembled InAs/InGaAs/GaAs quantum dots (QDs) are exploited for the development of large-format FPAs. The Dot-in-a-Well (DWELL) structures were experimentally shown to absorb both 45° and normal incident light, therefore a reflection grating structure was used to enhance the quantum efficiency. The devices exhibit peak responsivity out to 8.1 microns, with peak detectivity reaching ∼ 1 × 1010 Jones at 77 K. The devices were fabricated into the first LWIR 640x512 pixel QDIP FPA, which has produced excellent infrared imagery with NETD of 40 mK at 60K operating temperature.

Combining novel highly-doped phosphate glasses and advanced fiber drawing techniques, we fabricated and tested single-frequency fiber lasers that generate powers of more than 2-W. We demonstrate enhanced performance employing active photonic crystal fiber compared to more conventional devices that are based on large core step-index fiber.

Through the integration of phosphate glass fiber gratings and highly-doped active phosphate glass fiber, we improve on optical, thermal, and mechanical behavior of our compact fiber lasers. Powerful and widely tunable phosphate glass distributed fiber lasers are presented and the possibility of cascading several grating structure for multiple wavelength generation is demonstrated. We also present results on phase-locking and coherently combining the output of up to 37 fiber cores into a single, near-Gaussian laser beam. To achieve exclusive oscillation of the fundamental in-phase supermode, several all-fiber laser cavities have been designed, numerically analyzed, fabricated, and tested. We will report on a 10-cm long monolithic all-fiber laser that emits more than 12-W of optical power and is based on combining the output of 19 active cores. All the cores are integrated within the same cladding and arranged in a two-dimensional isometric array.

Mid-wavelength infrared (MWIR) avalanche photodiodes (APDs) were fabricated using Indium Arsenide- Gallium Antimonide (InAs-GaSb) based strain layer superlattice (SLS) structures. They were engineered specifically to have either electron or hole dominated ionization. The gain characteristics and the excess noise factors were measured for both devices. The electron dominated p+-n−-n APD with a cut-off wavelength of 4.13 μm at 77 K had a maximum multiplication gain of 1800 measured at -20 V while that of the hole dominated n+-p--p structure with a cut-off wavelength of 4.98 μm at 77 K was 21.1 at -5 V at 77 K. Excess noise factors were measured between 1-1.2 up to a gain of 800 and between 1-1.18 up to a gain of 7 for electron and hole dominated APDs respectively.

The past success of lidar instruments in space combined with potentials of laser remote sensing techniques in improving measurements traditionally performed by other instrument technologies and in enabling new measurements have expanded the role of lidar technology in future NASA missions. Compared with passive optical and active radar/microwave instruments, lidar systems produce substantially more accurate and precise data without reliance on natural light sources and with much greater spatial resolution. NASA pursues lidar technology not only as science instruments, providing atmospherics and surface topography data of Earth and other solar system bodies, but also as viable guidance and navigation sensors for space vehicles. This paper summarizes the current NASA lidar missions and describes the lidar systems being considered for deployment in space in the near future.

Four samples of (Y1−xCex)3(Al1−y Gay)5O12 (where x=0.01, 0.02 and y=0, 0.5) were synthesized via the simple, efficient combustion synthesis method in order to determine the effect of substituting Ga3+ for Al3+ on the temperature-dependent fluorescent lifetime. X-ray diffraction shows that the Ga-doped samples have longer lattice constants and transmission electron microscopy data show that each sample consists of nanocrystallites which have agglomerated in micron-sized particles. Photoluminescence data reveal that the addition of gallium into the YAG:Ce matrix induces a red shift in the absorption spectra and a blue-shift in the emission spectra. The laser-induced fluorescent lifetime was determined as a function of temperature over the range of 0-125°C using two different emission filters. Increasing the amount of dopant ultimately results in a decrease of the fluorescent lifetime. The quenching temperatures for the Ga-doped samples were lower than the samples without gallium. The results of this work show that combustion synthesis is viable method for making highly luminescent, nanocrystalline TGPs. In addition, these results show that the quenching temperature of YAG:Ce can be altered by substituting ions which alter the location of the charge transfer state and by changing the morphology of the sample.

A new, patent-pending method of cooling high-power laser diode arrays has been developed which leverages advances in several areas of materials science and manufacturing. This method utilizes multi-layer ceramic microchannel coolers with small (100's of microns) integral water channels to cool the laser diode bar. This approach is similar to the current state-of-the-art method of cooling laser diode bars with copper microchannel coolers. However, the multi-layer ceramic coolers offer many advantages over the copper coolers, including reliability and manufacturing flexibility. The ceramic coolers do not require the use of deionized water as is mandatory of high-thermal-performance copper coolers.

Experimental and modeled data is presented that demonstrates thermal performance equal to or better than copper microchannel coolers that are commercially available. Results of long-term, high-flow tests are also presented to demonstrate the resistance of the ceramic coolers to erosion. The materials selected for these coolers allow for the laser diode bars to be mounted using eutectic AuSn solder. This approach allows for maximum solder bond integrity over the life of the part.

A fiber based lidar system is developed which simplifies the processing of linear FM pulses by using a modulated local oscillator power in the coherent detector. Experiments were conducted on lidar systems with direct, heterodyne and simplified homodyne detection to compare receiver sensitivity. A field experiment using the homodyne system verified the sensitivity estimation on a building target at 370-m range.

In parallel with the effort to improve the efficiency of Quantum cascade lasers (QCL) for high power continuous wave (CW) operations, the peak power in pulsed mode operation can be easily scaled up with larger emitting volumes, i.e., processing QCLs into broad area lasers. However, as the emitter width increases, multi-mode operation happens due to poorer lateral mode distinguishability. By putting a two dimensional photonic crystal distributed feedback (PCDFB) layer evanescently coupled to the main optical mode, both longitudinal and lateral beam coherence can be greatly enhanced, which makes single mode operation possible for broad area devices. For PCDFB laser performance, the linewidth enhancement factor (LEF) plays an important role in controlling the optical coherence. Being intersubband devices, QCLs have an intrinsically small LEF, thus serves better candidates over interband lasers for PCDFB applications. We demonstrate electrically pumped, room temperature, single mode operation of photonic crystal distributed feedback quantum cascade lasers emitting at λ ∼ 4.75 μm. Ridge waveguides of 50 μm and 100 μm width were fabricated with both PCDFB and Fabry-Perot feedback mechanisms. The Fabry-Perot device has a broad emitting spectrum and a broad far-field character. The PCDFB devices have primarily a single spectral mode and a diffraction limited far field characteristic with a full angular width at half-maximum of 4.8 degrees and 2.4 degrees for the 50 μm and 100 μm ridge widths, respectively.

The Atmospheric Laser Doppler Instrument (ALADIN) is the payload of the ADM-AEOLUS mission, which will make direct measurements of global wind fields. It will determine the wind velocity component normal to the satellite velocity vector. The instrument is a direct detection Doppler Lidar operating in the UV, which will be the first of its kind in space.

ALADIN is now in its final construction stage: the integration of the Flight Model is on-going. Most of the subsystems have been integrated; the payload performance and qualification test campaign will commence.

This paper describes the ALADIN the development status and the results obtained at this stage. This regards the receiver performance, the telescope development and the challenges of the laser.

The paper will also provide insights on the ATLID instrument design which is the backscatter lidar for the EarthCARE mission. This lidar program is starting its detailed design phase.

The ALADIN and ATLID instruments are developed by EADS Astrium Satellites for the European Space Agency.

Recently, various nanoscale materials, devices, and systems with remarkable properties have been developed, with numerous unique applications in chem.-bio sensors, nanophotonics, and nanobiotechnology. This presentation covers satellite and aerial remote sensing science and methodologies employing nanotechnology based advanced sensor systems to improve performance, resolutions, and security. Increased demand on monitoring, surveillance due to global war on terrorism, weather prediction, and environmental pollution detection and monitoring have necessitated geospatial sensing with high accuracy, speed, and authenticity. Plasmonic interactions on the nanoscale and nanophotonics have produced new phenomena and technologies surpassing the realms of possibilities with conventional photonics and electronics. These new technologies could include high spatial resolution near-field imaging, high efficiency information processing and transferring, high capacity optical data storage, flexible- and high contrast displays, and precise detection, control and manipulation of nanoscale devices and integrated systems. Elements utilizing refractive or diffractive surfaces have found applications in novel sub-wavelength nanostructures satellites. The nanophotonics structures coupled with lightweight structures and advanced nanotechnology based sensors have resulted in launching of nano-satellites by several countries. The use of nanophotonics in space through the combination of micro, nano, integrated and fibre-optic technologies is to reduce susceptibility of the system to EMI, reduction in the weight of the signal cables (< 1/20 of electrical), higher information transmission capacity (GHz), reduced weight and volume, opto-isolation of critical spacecraft subsystems, high speed optical processing of RF and microwave signals, low propagation loss, and enhanced security encryption capabilities. Carbon Nanotubes (CNTs) based field emission electron gun (FEG) employ low voltage for emission and are actively researched as cold cathode microwave generation devices. CNTs based composites provide light-weight and compact platform with mechanical and thermal robustness. Such satellite system can be placed in low Earth orbit (LEO) to medium Earth orbit (MEO) as multi-sensor satellite imagers with panchromatic, multi-spectral, area and hyper spectral sensors on a single focal plane array (FPA), to achieve medium to high resolution (2.5m to 15m) spatial sampling, wide swaths (up to 45km) and noise equivalent reflectance (NER) values of less than 0.5%. An evaluation of security risks, vulnerability, and strategies is presented for communications technologies used in gathering, processing, storing, and disseminating global environmental micro and nano sensors and satellite data.

The Lunar Orbiter Laser Altimeter (LOLA) is one of six instruments on the Lunar Reconnaissance Orbiter (LRO) with the objectives to determine the global topography of the lunar surface at high resolution, measure landing site slopes and search for polar ices in shadowed regions. The LOLA laser transmitter is a passively q-switched cross-Porro resonator. The flight laser beryllium bench houses two oscillators (a primary oscillator and a cold spare). The two oscillators are designed to operate sequentially during the mission. The secondary laser will be turned on if the primary laser can no longer provide adequate scientific data products. All components used in the laser have space flight heritage. In this paper we will summarize the development effort of the LOLA laser including the material choice, design criteria and contamination control as applied to the flight laser build.

In this paper we present results on the optimization of multilayered a-SiC:H heterostructures for wavelength-division (de) multiplexing applications. The non selective WDM device is a double heterostructure in a glass/ITO/a-SiC:H (p-i-n) /a-SiC:H(-p) /a-Si:H(-i')/a-SiC:H (-n')/ITO configuration. The single or the multiple modulated wavelength channels are passed through the device, and absorbed accordingly to its wavelength, giving rise to a time dependent wavelength electrical field modulation across it. The effect of single or multiple input signals is converted to an electrical signal to regain the information (wavelength, intensity and frequency) of the incoming carriers. Here, the (de) multiplexing channels is accomplished electronically, not optically. This approach has advantages in terms of cost since several channels share the same optical components; and the electrical components are typically less expensive than optical ones. An electrical model gives insight into the device operation

Si-rich SiOX strip-loaded waveguide with silicon (Si) nanocrystals contributed amplified spontaneous emission at 750-850 nm with associated spectral linewidth of 140 nm is characterized. By using variable stripe length (VSL) method we demonstrate the optical gain and loss coefficients of 65 and 5 cm−1, respectively, for such a waveguide amplifier. The optical gain and loss coefficients are observed by fitting the one dimensional amplifier equation. The small-signal power gain of 18.4 dB at wavelength of 805 nm under He-Cd laser pumping of 40 mW at 325 nm is obtained from the SiO2/SiOX/SiO2 waveguide amplifier with length of 1 cm.

Research results on high energy/power ns pulsed fiber lasers are discussed in this paper. Modulation schemes for a seed laser in getting various optical waveforms, high power operation of fiber amplifiers, nonlinearity mitigation in high power fiber lasers, and trade-offs have been addressed. It shows experimentally that ns pulses can be achieved by direct modulation of a semiconductor seed laser and an energy level of sub-mJ were demonstrated. 23 % wall plug efficiency was achieved for a compact laser module.

An 1.5 micron pulsed Coherent Doppler LIDAR system using all fiber optical components has attracted attention for remote wind sensing application because of its eye-safety, reliability and easy deployment. We report on our key technologies such as fiber based MOPA (Master Oscillator Power Amplification) transmitter, high peak power optical amplification and a real-time signal processing. Some performance results and applications are also provided.

Investigations on standing wave (SW) interferometry come in focus of interest in the course of ongoing miniaturization of high precision length measurement systems. A key problem within these efforts is the development of a transparent ultra-thin photodetector for sampling the intensity profile of the generated SW. Group III-materials are promising candidates to ensure a good photodetector performance combined with the required optical transparency. In this work, we report on the interrelation of strain and dislocation density along with the influence of the structural properties on the sensitivity of double-heterostructure III-nitride photodetectors grown by molecular beam and metal organic vapour phase epitaxy.

We demonstrate a highly strained InGaAs/GaAs VECSEL operating at 1173 nm with more than 8.5 W output power and tunable over 40 nm. High-efficiency yellow-orange emission is then achieved by intra-cavity frequency doubling. Over 5 W of CW output power in the 585-589 nm spectral regions is achieved. This compact low-cost high-power yellow-orange laser provides an innovative alternative for sodium guidestar lasers or other medical / communication applications.