Demonstration of 1Kx1K long-wave and mid-wave superlattice infrared focal plane arrays
Author(s):
S. D. Gunapala;
D. Z. Ting;
C. J. Hill;
J. Nguyen;
A. Soibel;
S. B. Rafol;
S. A. Keo;
J. M. Mumolo;
M. C. Lee;
J. K. Liu;
B. Yang;
A. Liao
Show Abstract
Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for
remote sensing and imaging applications. Currently, we are working on Superlattice detectors, multi-band Quantum
Well Infrared Photodetectors (QWIPs), and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for
high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper, we will discuss the
demonstration of long-wavelength 1Kx1K QDIP FPA, 1Kx1K QWIP FPA, the first demonstration of the megapixelsimultaneously-
readable and pixel-co-registered dual-band QWIP FPA, and demonstration of the first mid-wave and
long-wave 1Kx1K superlattice FPA. In addition, we will discuss the advantages of III-V material system in the context
of large format infrared FPAs.
Barrier engineering in superlattices and quantum dots for higher operating temperature
Author(s):
Sanjay Krishna
Show Abstract
The third generation of infrared detectors has seen a lot of emphasis been placed on Higher Operating Temperature
(HOT) devices. In our research group, we are investigating barrier engineering in two promising material systems
namely the type II strained layer superlattices and quantum dots in a well (DWELL) heterostructure. In this paper, we
will outline some of our recent approaches to use barrier engineering to obtain a lower dark current and higher operating
temperature in these devices.
Performance of InAsSb-based infrared detectors with nBn design
Author(s):
S. A. Myers;
A. Khoshakhlagh;
J. Mailfert;
P. Wanninkhof;
E. Plis;
M. N. Kutty;
H. S. Kim;
N. Gautam;
B. Klein;
E. P. G. Smith;
S. Krishna
Show Abstract
Our group is investigating nBn detectors based on bulk InAs(1-x)Sb(x) absorber (n) and contacts (n) with an AlAs(1-x)Sb(x)
barrier (B). The wide-band-gap barrier material exhibits a large conduction band offset and small valence band offset
with respect to the narrow-band-gap absorber material. An important matter to explore in this design is the barrier
parameters (material, composition and doping concentration) and how they effect the operation of the device. This paper
investigates AlAs(1-x)Sb(x) barriers with different compositions and doping levels and their effect on detector
characteristics, in particular, dark current density, responsivity and specific detectivity.
Study of strain balance in long wavelength infrared InAs/GaSb superlattice materials
Author(s):
H. J. Haugan;
G. J. Brown;
S. D. Pacley;
L. Grazulis;
S. T. Fenstermaker
Show Abstract
The epitaxial growth parameters optimized for mid wavelength infrared (MWIR) InAs/GaSb superlattice (SL)
growth are not necessarily the best parameters for very long wavelength infrared (VLWIR) SL growth. While the cutoff
wavelength of the SL structure can be easily extended from a MWIR to a VLWIR spectral range by increasing InAs
layer thickness with a fixed GaSb layer thickness, the structural and optical properties of SLs are changing as well, and
these changes are not necessarily beneficial to the material quality of VLWIR SLs. For instance, tensile strain in the SL
rapidly increases as InAs layer thickness increases. This impacts the interface growth processes used to strain balance
the average lattice constant of the SL to match the GaSb substrate, the interface engineering in a VLWIR SL is very
different than that in a MWIR SL. Using a baseline SL design of 16 monolayers (MLs) InAs/7 MLs GaSb, a systematic
study of controlling the Sb/As background pressure and shutter sequence during interface formation was performed in
order to minimize tensile strain in the VLWIR SLs. The effect of various shutter sequences on the SL morphological
quality and their impact on optical spectral response is reported. By inserting 0.5 MLs of InSb-like interfaces, using a
migration-enhance-epitaxy technique, in the baseline SL design, while maintaining a total SL period of 23 MLs, we
achieved a high structural quality, strain balanced LWIR SL with a photoresponse onset at 15 μm.
Intersubband transitions in GaN-based quantum wells: a new materials platform for infrared device applications
Author(s):
Roberto Paiella;
Kristina Driscoll;
Yan Li;
Yitao Liao;
Anirban Bhattacharyya;
Christos Thomidis;
Lin Zhou;
David J Smith;
Theodore D Moustakas
Show Abstract
Due to their large conduction-band offsets, GaN/AlGaN quantum wells can accommodate intersubband transitions at
record short wavelengths throughout the mid-infrared and into the near-infrared spectral regions. As a result, they are
currently the subject of extensive research efforts aimed at extending the spectral reach and functionality of intersubband
optoelectronic devices. Here we review our recent work in this area, based on GaN/AlGaN quantum-well samples
grown by molecular beam epitaxy on sapphire substrates. In particular, we have investigated the intersubband
absorption properties of a wide range of structures, including isolated and coupled quantum wells. Furthermore, we
have developed a new class of ultrafast all-optical switching devices, based on intersubband cross-absorption saturation
in GaN/AlGaN quantum-well waveguides operating at fiber-optic communication wavelengths. Strong self-phase
modulation of ultrafast optical pulses has also been measured in these waveguides, revealing a large refractive-index
nonlinearity which is related to the same intersubband carrier dynamics. Finally, we have demonstrated optically
pumped intersubband light emission from GaN/AlN quantum wells resonantly excited with a pulsed OPO. The
measured room-temperature output spectra are peaked near 2 μm, which represents a new record for the shortest
intersubband emission wavelength from any quantum-well materials system.
Single photon emission and detection at the nanoscale utilizing semiconductor nanowires
Author(s):
Michael E. Reimer;
Maarten P. van Kouwen;
Maria Barkelid;
Moïra Hocevar;
Maarten H. M. van Weert;
Rienk E. Algra;
Erik P. A. M. Bakkers;
Mikael T. Björk;
Heinz Schmid;
Heike Riel;
Leo P. Kouwenhoven;
Val Zwiller
Show Abstract
We report recent progress toward on-chip single photon emission and detection in the near infrared utilizing semiconductor nanowires. Our single photon emitter is based on a single InAsP quantum dot embedded in a p-n junction defined along the growth axis of an InP nanowire. Under forward bias, light is emitted from the single quantum dot by electrical injection of electrons and holes. The optical quality of the quantum dot emission is shown to improve when surrounding the dot material by a small intrinsic section of InP. Finally, we report large multiplication factors in excess of 1000 from a single Si nanowire avalanche photodiode comprised of p-doped, intrinsic, and n-doped sections. The large multiplication factor obtained from a single Si nanowire opens up the possibility to detect a single photon at the nanoscale.
Performance improvement of AlN/GaN-based intersubband detectors thanks to quantum dot active regions
Author(s):
Daniel Hofstetter;
Joab Di Francesco;
Esther Baumann;
Fabrizio Raphael Giorgetta;
Prem Kumar Kandaswamy;
Aparna Das;
Sirona Valdueza-Felip;
Eva Monroy
Show Abstract
Since the operating mode of 1.55 μm AlN/GaN-based intersubband photodetectors is based on optical rectification, both
the excited state lifetime and the lateral displacement of the carriers play an important role for performance optimization.
We thus show here results of an improved detector generation based on a novel type of active region. Thanks to the use
of quantum dots instead of quantum wells, a factor of 60 could be gained in terms of maximum responsivity. In addition,
the maximum performance was achieved at a considerably higher temperature of 160 K instead of 80 K as typically seen
for quantum wells.
Geiger-mode avalanche photodiode focal plane arrays for three-dimensional imaging LADAR
Author(s):
Mark A. Itzler;
Mark Entwistle;
Mark Owens;
Ketan Patel;
Xudong Jiang;
Krystyna Slomkowski;
Sabbir Rangwala;
Peter F. Zalud;
Tom Senko;
John Tower;
Joseph Ferraro
Show Abstract
We report on the development of focal plane arrays (FPAs) employing two-dimensional arrays of InGaAsP-based
Geiger-mode avalanche photodiodes (GmAPDs). These FPAs incorporate InP/InGaAs(P) Geiger-mode avalanche
photodiodes (GmAPDs) to create pixels that detect single photons at shortwave infrared wavelengths with high
efficiency and low dark count rates. GmAPD arrays are hybridized to CMOS read-out integrated circuits (ROICs) that
enable independent laser radar (LADAR) time-of-flight measurements for each pixel, providing three-dimensional
image data at frame rates approaching 200 kHz. Microlens arrays are used to maintain high fill factor of greater than
70%. We present full-array performance maps for two different types of sensors optimized for operation at 1.06 μm
and 1.55 μm, respectively. For the 1.06 μm FPAs, overall photon detection efficiency of >40% is achieved at <20 kHz
dark count rates with modest cooling to ~250 K using integrated thermoelectric coolers. We also describe the first
evalution of these FPAs when multi-photon pulses are incident on single pixels. The effective detection efficiency for
multi-photon pulses shows excellent agreement with predictions based on Poisson statistics. We also characterize the
crosstalk as a function of pulse mean photon number. Relative to the intrinsic crosstalk contribution from hot carrier
luminescence that occurs during avalanche current flows resulting from single incident photons, we find a modest rise
in crosstalk for multi-photon incident pulses that can be accurately explained by direct optical scattering.
Infrared spectroscopy of thin layers under ultra-high vacuum conditions
Author(s):
Annemarie Pucci
Show Abstract
We summarize recent results from in-situ infrared spectroscopic studies of nanofilm growth. These studies, performed
under ultra-high vacuum conditions with sub-monolayer sensitivity, exploited the relationship between morphology and
structure on the one side and, on the other side, vibrational excitations and plasmonic ones. The studies were performed
within various projects ranging from astronomy and high-energy physics to organic electronics and plasmonics. The
results represent examples the description of which needs theoretical models beyond the use of Fresnel's formulae, the
assumption of abrupt interfaces, and the use optical databases for bulk materials. For example, at the SiO-Si interface Si-
O-Si bridges with Si-O bonds longer than in the bulk are formed which can be identified via their special vibration
signals at unusually low vibration frequencies. From a thickness of about 1 nm on, the infrared spectra show typical SiObulk
features. The lowered vibrational frequencies are attributed to changes in the average distribution of Si-O bond
length close to the interface. On the diamond (100) surface, during Cr deposition, we observed the formation of a
conducting nanocrystalline fcc phase of chromium. At a certain thickness, the nanocrystalline phase makes a phase
transition to the typical bulk chromium phase. Cr is a preferred material for electric contacts in single-crystal diamond
detectors the performance of which sensitively depends on the conductivity of the deposited Cr contact. On organic
semiconductor layers metallization may be accompanied by an intermixing at the metal-semiconductor interface. Such
intermixing can be observed as the appearance of new excitation features.
cQED enhanced light detection and emission in electrically contacted quantum dot micropillars
Author(s):
S. Reitzenstein;
C. Kistner;
T. Heindel;
C. Schneider;
M. Lermer;
T. Braun;
S. Höfling;
L. Worschech;
A. Forchel
Show Abstract
The quest for efficient light sources and light detectors is a driving force in the development of semiconductor
quantum dot (QD) devices. Self assembled QDs in bulk material are characterized by high quantum efficiency
and can act as single photon emitters. However, they suffer from a poor light in- and outcoupling efficiency. We
demonstrate highly efficient QD-micropillar based light detectors and single photon emitters exploiting cavity
quantum electrodynamics (cQED) effects. An advanced fabrication technique allows us to realize ultra sensitive
and wavelength selective light detectors as well as triggered, electrically driven single photon sources with photon
outcoupling efficiencies exceeding 60 %.
MERTIS-thermal infrared imaging of Mercury: advances in mid-IR remote sensing technology for planetary exploration
Author(s):
Gabriele E. Arnold;
Harald Hiesinger;
Jörn Helbert;
Gisbert Peter;
Ingo Walter
Show Abstract
MERTIS (MErcury Radiometer and Thermal infrared Imaging Spectrometer) is part of ESA's BepiColombo Mercury
Planetary Orbiter mission to the innermost planet of the Solar system. MERTIS is designed to identify rock-forming
minerals, to map the surface composition, and to study the surface temperature variations with an uncooled
microbolometer detector in the hot environment of Mercury. MERTIS is an advanced IR instrument combining a pushbroom
IR grating spectrometer (TIS) with a radiometer (TIR) sharing the same optics, instrument electronics and in-fight
calibration components for a wavelength range of 7-14 and 7-40 μm, respectively. First results of the ongoing
MESSENGER project at Mercury have shown a more complex geology and higher variability of features than
previously thought. The MESSENGER studies have demonstrated the need to gain global high-resolution mid-IR
spectral and temperature data to achieve a better understanding of the planetary genesis. The MERTIS measurements
will acquire this currently missing data set. This article gives a summary of the instrument requirements and its design.
We are reporting on the actual instrument development progress, and the status of system and subsystem qualification
efforts.
MERTIS: understanding Mercury's surface composition from mid-infrared spectroscopy
Author(s):
Jörn Helbert;
Harald Hiesinger;
Ingo Walter;
Thomas Säuberlich;
Alessandro Maturilli;
Mario D'Amore;
Jörg Knollenberg;
Eckehard Lorenz;
Gisbert Peter;
Gabriele E. Arnold
Show Abstract
The Mercury Radiometer and Thermal Infrared Imaging Spectrometer MERTIS on the joint ESA-JAXA mission
BepiColombo to Mercury is combining a spectrometer using an uncooled microbolometer in a pushbroom mode with a
highly miniaturized radiometer.
A full development model of MERTIS is now available. So, after three flybys of Mercury by the MESSENGER mission
and with the Planetary Emissivity Laboratory at DLR in Berlin that can routinely obtain infrared emission spectra at high
temperatures it is a good time to review the MERTIS science requirements and the performance in perspective of our
new knowledge of Mercury.
MERTIS: shutterless background signal removal
Author(s):
Thomas Säuberlich;
Carsten Paproth;
Jörn Helbert
Show Abstract
MERTIS (MERcury Thermal infrared Imaging Spectrometer) is an advanced infrared remote sensing instrument that is
part of the ESA mission BepiColombo to planet Mercury. The enabling technology that allows sending the first
spectrometer for the thermal infrared spectral range to Mercury is an uncooled microbolometer. One of the challenges is
the calibration of the instrument. Radiometric and spectroscopic breadboard models of MERTIS were used to develop
proper calibration methods.
In the context of the calibration we are reporting on the ongoing efforts to separate non-scene and scene signal portions
from each other. The non-scene signal portion is contained in the raw image data sets and is usually the dominating
signal contribution. The conventional method to measure the non-scene signal contributions using a shutter or spaceview
and perform a time-interpolation is compared to an approach using linear pixel-to-pixel relations in which
information from the outer regions of the image matrix is used for the estimation of the non-scene signal components of
the inner regions where additional scene signal components exist. The results of both methods are discussed in terms of
noise or errors of the extracted scene information. The proposed method could be used without further instrument
modifications offering a functional redundancy which is important to keep alive the MERTIS operation in the case of a
breakdown of the mechanically stressed high-speed shutter device.
MERTIS: system theory and simulation
Author(s):
Carsten Paproth;
Thomas Säuberlich;
Herbert Jahn;
Jörn Helbert
Show Abstract
The deep-space ESA mission BepiColombo to planet Mercury will contain the advanced infrared remote sensing
instrument MERTIS (MErcury Radiometer and Thermal infrared Imaging Spectrometer). The mission has the
goal to explore the planets inner and surface structure and its environment. With MERTIS investigations of
Mercury's surface layer within a spectral range of 7-14μm shall be conducted to specify and map Mercury's
mineralogical composition with a spatial resolution of 500m. Due to the limited mass and power budget the
used micro-bolometer detector array will only have a temperature-stabilization and will not be cooled.
The theoretical description of the instrument is necessary to estimate the performance of the instrument
especially the signal to noise ratio. For that purpose theoretical models are derived from system theory. For a
better evaluation and understanding of the instrument performance simulations are performed to compute the
passage of the radiation of a hypothetical mineralogical surface composition through the optical system, the
influence of the inner instrument radiation and the conversion of the overall radiation into a detector voltage
and digital output signal. The results of the simulation can support the optimization process of the instrument
parameters and could also assist the analysis of gathered scientific data. The simulation tool can be used as well
for performance estimations of MERTIS-like systems for future projects.
MERTIS: using diffractive optical elements for geometrical calibration
Author(s):
M. Bauer;
D. Griessbach;
T. Säuberlich;
M. Scheele;
A. Schischmanow
Show Abstract
Geometrical sensor calibration is essential for space applications based on high accuracy optical measurements, in this
case for MERTIS. The goal is the determination of interiour sensor parameters. A conventional method is to measure the
line of sight for a subset of pixels by single pixel illumination with collimated light. To adjust angles which define the
line of sight of a pixel a manipulator construction is used.
A new method for geometrical sensor calibration is presented using Diffractive Optical Elements (DOE) in connection
with laser beam equipment. This method is especially used for 2D-sensor array systems but can also be applied to the
thermal infrared push-broom imaging spectrometer MERTIS.
Diffractive optical elements (DOE) are optical microstructures which are used to split an incoming laser beam with a
dedicated wavelength into a number of beams with well-known propagation directions. As the virtual sources of the
diffracted beams are points at infinity, the object to be imaged is similar to the starry sky which gives an image invariant
against translation. This particular feature allows a complete geometrical sensor calibration with one image avoiding
complex adjustment procedures which means a significant reduction of calibration effort.
MERTIS: reflective baffle design and manufacturing
Author(s):
T. Zeh;
C. Gal;
S. Kaiser;
G. Peter;
I. Walter;
J. Helbert;
J. Jachlewski;
K. Multhaup;
H. Hiesinger
Show Abstract
Optical instruments for remote sensing applications frequently require measures for reducing the amount of external,
unwanted stray light in the optical instrument path. The reflective planet baffle design and manufacturing process for the
thermal infrared imaging spectrometer MERTIS onboard of ESA's cornerstone mission BepiColombo to Mercury is
presented. The baffle has to reflect the unwanted solar flux and scattered IR radiation, and minimize the heat load on the
instrument.
Based on optical stray light simulations and analyses of different baffle concepts the Stavroudis principle showed the
best performance and the smallest number of internal reflections. The setup makes use of the optical properties of
specific conic sections of revolution. These are the oblate spheroid, generated by rotating an ellipse about its minor axis,
and the hyperboloid of one sheet, obtained by the rotation of a hyperbola around its conjugate axis.
Due to the demanding requirements regarding surface quality, low mass and high mechanical stability, electroforming
fabrication was selected for the baffle. During manufacturing, a layer of high strength nickel alloy is electrodeposited
onto a diamond turned aluminum mandrel. The mandrel is subsequently chemically dissolved. Not only the baffle, but
also the baffle support structure and other mating components are electroformed. Finally, the baffle and support structure
are assembled and joined by an inert gas soldering process. After the optimum baffle geometry and surface roughness
has been realized, the remaining total heat flux on the baffle is only dependent on the selection of the appropriate, high
reflective coating.
MERTIS: optics manufacturing and verification
Author(s):
Andreas Gebhardt;
Ralf Steinkopf;
Sebastian Scheiding;
Stefan Risse;
Christoph Damm;
Thomas Zeh;
Stefan Kaiser
Show Abstract
The MERTIS reflective infrared optics can be beneficial implemented as diamond turned aluminium mirrors coated with
a thin gold layer. The cutting processes allow the manufacturing of both, the optical surface and mechanical interfaces, in
tight tolerances. This is one of the major advantages of metal optics and was consequently used for the MERTIS sensor
head optics.
This paper describes the entire process chain of the MERTIS spectrometer optics including the manufacturing methods
for the mirrors and for the spherical grating, the coating with sputtered gold for infrared reflectivity as well as the
alignment and the verification of the spectrometer optics.
Technologies supporting radiative science
Author(s):
Robert A. Bauer;
George J. Komar;
Philip M. Larkin;
Keith E. Murray;
Michael P. Pasciuto;
Amy L. Walton
Show Abstract
Technology investments made over the past decade by the NASA Earth Science Technology Office
(ESTO) have enabled the current mission concept of the Climate Absolute Radiance and Refractivity
Observatory (CLARREO) mission. Early investments include the Far-Infrared Spectroscopy of the
Troposphere (FIRST) instrument, which today is being used as a testbed to demonstrate new detectors
under development. Current investments, aimed at the CLARREO goals of high absolute accuracy and onorbit
international measurement standards traceability, include a prototype hyperspectral imager, extended
blocked impurity band detectors for far-infrared detection, and a high-accuracy blackbody.
Far-IR measurements at Cerro Toco, Chile: FIRST, REFIR, and AERI
Author(s):
Richard P. Cageao;
J. Ashley Alford;
David G. Johnson;
David P. Kratz;
Martin G. Mlynczak
Show Abstract
In mid-2009, the Radiative Heating in the Underexplored Bands Campaign II (RHUBC-II) was conducted from Cerro
Toco, Chile, a high, dry, remote mountain plateau, 23°S , 67.8°W at 5.4km, in the Atacama Desert of Northern Chile.
From this site, dominant IR water vapor absorption bands and continuum, saturated when viewed from the surface at
lower altitudes, or in less dry locales, were investigated in detail, elucidating infrared (IR) absorption and emission in the
atmosphere. Three Fourier Transform InfraRed (FTIR) instruments were at the site, the Far-Infrared Spectroscopy of the
Troposphere (FIRST), the Radiation Explorer in the Far Infrared (REFIR), and the Atmospheric Emitted Radiance
Interferometer (AERI). In a side-by-side comparison, these measured atmospheric downwelling radiation, with
overlapping spectral coverage from 5 to 100μm (2000 to 100cm-1), and instrument spectral resolutions from 0.5 to
0.643cm-1, unapodized. In addition to the FTIR and other ground-based IR and microwave instrumentation,
pressure/temperature/relative humidity measuring sondes, for atmospheric profiles to 18km, were launched from the site
several times a day. The derived water vapor profiles, determined at times matching the FTIR measurement times, were
used to model atmospheric radiative transfer. Comparison of instrument data, all at the same spectral resolution, and
model calculations, are presented along with a technique for determining adjustments to line-by-line calculation
continuum models. This was a major objective of the campaign.
Infrared detectors overview in the short-wave infrared to far-infrared for CLARREO mission
Author(s):
M. Nurul Abedin;
Martin G. Mlynczak;
Tamer F Refaat
Show Abstract
There exists a considerable interest in the broadband detectors for CLARREO Mission,
which can be used to detect CO2, O3, H2O, CH4, and other gases. Detection of these species
is critical for understanding the Earth's atmosphere, atmospheric chemistry, and systemic
force driving climatic changes. Discussions are focused on current and the most recent
detectors developed in SWIR-to-Far infrared range for CLARREO space-based instrument to
measure the above-mentioned species. These detector components will make instruments
designed for these critical detections more efficient while reducing complexity and associated
electronics and weight. We will review the on-going detector technology efforts in the SWIR
to Far-IR regions at different organizations in this study.
A high-accuracy blackbody for CLARREO
Author(s):
Harri Latvakoski;
Mike Watson;
Shane Topham;
Deron Scott;
Mike Wojcik;
Gail Bingham
Show Abstract
The NASA climate science mission Climate Absolute Radiance and Refractivity Observatory (CLARREO), which is to
measure Earth's emitted spectral radiance from orbit for 5 years, has an absolute accuracy requirement of 0.1 K (3σ) at
220 K over most of the thermal infrared. To meet this requirement, CLARREO needs highly accurate on-board
blackbodies which remain accurate over the life of the mission. Space Dynamics Laboratory is developing a prototype
blackbody that demonstrates the ability to meet the needs of CLARREO. This prototype is based on a blackbody design
currently in use, which is relatively simple to build, was developed for use on the ground or on-orbit, and is readily
scalable for aperture size and required performance. We expect the CLARREO prototype to have emissivity of ~0.9999
from 1.5 to 50 μm, temperature uncertainties of ~25 mK (3σ), and radiance uncertainties of ~10 mK due to temperature
gradients. The high emissivity and low thermal gradient uncertainties are achieved through cavity design, while the SItraceable
temperature uncertainty is attained through the use of phase change materials (mercury, gallium, and water) in
the blackbody. Blackbody temperature sensor calibration is maintained over time by comparing sensor readings to the
known melt temperatures of these materials, which are observed by heating through their melt points. Since blackbody
emissivity can potentially change over time due to changes in surface emissivity (especially for an on-orbit blackbody)
an on-board means of detecting emissivity change is desired. The prototype blackbody will include an emissivity
monitor based on a quantum cascade laser to demonstrate the concept.
Ordered/disordered broadband antireflective structures for near-infrared detector applications
Author(s):
Young Min Song;
Eun Sil Choi;
Gyeong Cheol Park;
Sung Jun Jang;
Jae Su Yu;
Yong Tak Lee
Show Abstract
This study reports broadband antireflective subwavelength structures (SWS) on various semiconductor materials for
near-infrared detector applications. Two fabrication methods are proposed, i.e., a lenslike shape transfer and an overall
dry etch process of Ag nanoparticles. These methods provide relatively simple, fast, inexpensive process steps, which is
applicable for practical device applications. The fabricated SWS showed extremely lower reflectance spectra compared
to that of flat surface in the near-IR range, indicating good agreement with the simulation results. We also propose
amorphous silicon SWS on InGaAs photodetector to enhance the absorption efficiency.
Measurement of trace gases in East Asia from satellite infrared radiometer
Author(s):
Fumie Kataoka;
Yasushi Mitomi
Show Abstract
Measurement of trace gases from satellite is useful technique to grasp the atmospheric information on a regional scale. In
recent years, exhaust gas emitted by developing country has become a huge social issue. It greatly affects global
environmental problems. In this study, we focused on Nitrous Oxide (N2O) in East Asia. N2O has a strong radiative
forcing and has gotten a lot of attention as the greenhouse effect and ozone-depleting gases recently. We conducted the
sensitivity analysis of N2O using the infrared spectral radiances measured by Tropospheric Emission Spectrometer (TES),
which was launched on NASA's EOS Aura satellite in July 2004. Based on these result, we selected retrieval channel
and tried to retrieve the troposheric profile of N2O. In this paper, we will present the preliminary result.
1.5 to 5 micron radiometer for spectral contrast of objects in changing backgrounds in real time (Background Discrimination Radiometer or BDR)
Author(s):
Dario Cabib;
Amir Gil
Show Abstract
A digital FLIR (Forward Looking Infrared camera) in the 1.5 to 5 micron range can measure the contrast of selfemission
of objects with respect to their background in real time: however, when such a measurement is carried out in a
narrow spectral range through an interference filter the amount of unfiltered stray photons from the environment
reaching the detector contributes a significant part of the total signal with respect to the filtered photons from the object
of interest. The result is a significant reduction of dynamic range of the measurement and of the ability of the FLIR to
measure large variation of signal in real time.
A somewhat more advantageous instrument to measure the contrast of an object against its background in real time is
proposed here: it is a non-imaging single-detector, 1.5 to 5 micron radiometer (BDR). A classical example of application
is measuring the radiant intensity contrast of an airplane or missile in the background of sky during its flight. The
instrument is built so that it can measure this contrast in one narrow or wide wavelength range as function of time or in
successive wavelength ranges to provide contrast information in absolute units of irradiance (Watts/cm2) in different
regions of the spectrum. Several filters can be accommodated in a wheel to provide the spectral capability. The reason
for the ability of such configuration to avoid the dynamic range problem of the FLIR is the fact that in this detection
method the detector is AC coupled and the electronic amplification acts only on the difference between the source and
background signals.
We present here the instrument's design and its calibration algorithm1.
Advances in modeling the obstruction in the HIRDLS optical train and resulting data
Author(s):
John Gille;
Charles Cavanaugh;
Christopher Halvorson;
Craig Hartsough;
Bruno Nardi
Show Abstract
A piece of plastic film came loose during launch and blocked most of the optical aperture. The largest remaining
problem in correcting the measured radiances is the removal of the signals from this blockage. The present method is
briefly described, followed by an outline of a new version, called the (ST)3 method. It relies on more understanding of
the behavior of the blockage signals acquired in previous work. The method involves Scaling and Time interpolating the
signals, Shifting them to align features, and Translating them to recover the scaled value at the reference angle. The
residuals are represented by empirical orthogonal functions, coefficients of which may be Substituted from other
channels. Finally, allowance for long-term Temporal changes in the blockage signals are being developed. Results for a
day in the middle of the mission are presented, as well as their effects on water vapor retrievals.
In-orbit health and performance of operational AVHRR instruments
Author(s):
M. K. Rama Varma Raja;
Douglas Battles;
Xiangqian Wu;
Helmut Bauch;
Fangfang Yu;
Robert W. Lambeck;
Ninghai Sun;
Abelardo Perez Albinana;
Francois Montagner
Show Abstract
The Advanced Very High Resolution Radiometer (AVHRR) instruments on board NOAA-18, MetOp-A and NOAA-19
satellites are key components of the current operational NOAA-EUMETSAT Initial Joint Polar System (IJPS) and are
routinely monitored. Overall, the results of trending analysis show that the AVHRR instruments on NOAA-18/19 and
MetOp-A are functioning well outperforming the channel noise specification limits. The backup NOAA-17 AVHRR
functioned well for the on-orbit period prior to the onset of scan motor failure around April 11, 2010. The sun-earthsatellite
geometry driven seasonality is exhibited by temperature measurements from thermistors on various instrument
housing components including blackbody with the exception of patch temperature which is typically maintained stable.
The only electrical measurement which exhibits seasonality is patch power. It is shown that the seasonality has no
significant adverse impact on AVHRR radiometric performance. On the other hand the space view is adversely affected
by intermittent periodic lunar signals and ubiquitous low frequency variability presumably connected to space clamping
mechanism. Based on this it is suggested that the AVHRR channel noise estimation should be based on blackbody view.
Finally, the temporal stability of the monitored parameters and the smaller or comparable magnitudes of seasonal
variability in most of the instrument housekeeping measurements as compared to their orbital variability confirm the
good health of AVHRR instruments on-board NOAA-18/19 and MetOp-A.
The multi-spectral imager on board the EarthCARE spacecraft
Author(s):
Abelardo Pérez Albiñana;
Robert Gelsthorpe;
Alain Lefebvre;
Maximillian Sauer;
Erich Weih;
Klaus-Werner Kruse;
Ralf Münzenmayer;
Guy Baister;
Mark Chang
Show Abstract
Clouds and aerosols are important atmospheric elements that strongly influence the weather and climate on planet Earth.
The European Space Agency (ESA) is currently developing, in co-operation with the Japan Aerospace Exploration
Agency (JAXA) the EarthCARE satellite mission with the objective of improving the understanding of the cloudaerosols-
radiation interactions within the Earth's atmosphere. It is foreseen that the data provided by the EarthCARE
satellite will allow the improvement of the currently available numerical prediction models, and therefore the quality of
the weather forecast and climate evolution predictions.
The payload of the EarthCARE satellite consists of a Cloud Profiling Radar (CPR), a Backscatter Lidar (ATLID), a
Broadband Radiometer (BBR), and a Multi-spectral Imager (MSI). The MSI instrument will provide images of the earth
in 7 spectral bands in the visible and infrared parts of the spectrum, with a spatial ground resolution of 500 m and an
image width on the ground of 150 km. This paper provides a description of the MSI instrument and its expected
performance.
A highly integrated micropayload for broadband infrared spectrometry (HIBRIS)
Author(s):
Marco Esposito;
Sandro Hannemann;
Scott Moon;
Dmitris Lampridis;
Max Collon;
Marco Beijersbergen
Show Abstract
We present a highly integrated payload suite which consists of the following instruments: a hyperspectral imager
covering the wavelength range from 0.7 μm up to 5μm, and a thermal infrared radiometric imaging spectrometer.
The payload design is the result of a design study that was performed in the context of the development of space
exploration technologies under ESA contracts. The payload is broadly applicable to environmental research and
for a number of remote sensing mission scenarios. All instruments have imaging capability and have been chosen
such that they profit from close integration. HIBRIS is a combination of the hyperspectral NIR spectrometer,
considered as generic instrument being part of many missions, and the radiometric micro-bolometer in the
thermal infrared spectrum. A linear variable filter (LVF) concept is implemented in the NIR range that avoids
the use of gratings which are usually limited to one decade of spectral range or less. The thereby rather compact
design does allow the integration of multiple instruments within a rather limited volume envelope. The suite
also makes use of a microcooler and the most advanced NIR detector technologies. The use of an LVF drives
the spectral resolution of the instruments to 1% of the wavelength. The SNR is satisfactory in the most part
of the spectrum for LEO EO missions. Current activities at cosine Research have focused on the design and
performance of uncooled microbolometers, linear filters, light shielding baffles, beam splitters for shared optical
paths, and the thermal design of HIBRIS.
Spaceborne laser transmitters for remote sensing applications
Author(s):
Anthony W. Yu;
Steven X Li;
Mark A Stephen;
Anthony J Martino;
Jeffrey R Chen;
Michael A Krainak;
Stewart Wu;
Haris Riris;
James B Abshire;
David J Harding;
Graham R Allan;
Kenji Numata
Show Abstract
NASA Goddard Space Flight Center (GSFC) has been engaging in Earth and planetary science remote sensing
instruments development for many years. The latest instrument was launched in 2008 to the moon providing the most
detailed topographic map of the lunar surface to-date. NASA GSFC is preparing for several future missions, which for
the first time will perform active spectroscopic measurements from space. In this paper we will review the past, present
and future of space-qualified lasers for remote sensing applications at GSFC.
Next generation infrared sensor instrumentation: remote sensing and sensor networks using the openPHOTONS repository
Author(s):
Stephen So;
Evan Jeng;
Clinton Smith;
David Krueger;
Gerard Wysocki
Show Abstract
We describe our novel instrumentation architectures for infrared laser spectrometers. Compact, power
efficient, low noise modules allow for optimized implementation of cell phone sized sensors using
VCSELs, diode, and quantum cascade laser sources. These sensors can consume as little as 0.3W with full
laser temperature (<0.001K/Hz1/2) and current control (<2ppm/Hz1/2 noise), photodiode preamplification
(<2pA/Hz1/2 noise floor, 1MΩ transimpedance), and digital lock-in amplification with 3 independent
channels. We have implemented sensors based on laser absorption spectroscopy, photoacoustic
spectroscopy, and Faraday rotation spectroscopy using the openPHOTONS systems, with performance
rivaling standalone laboratory measurement instrumentation. Additionally, as openPHOTONS is an open
source software repository, this instrumentation can be quickly adapted to new optical configurations
and applications. Such modules allow the development of flexible sensors, whether implementing
closed path spectrometers, open path perimeter monitoring, or remote backscatter based sensors. This
work is also the enabling technology for wireless sensor networks (WSN) of precision sensors, a
desirable sensing paradigm for long term, wide area, precision, temporally and spatially resolved
studies. This approach can complement existing remote sensing and mapping technologies including
satellite observations and sparse networks of flux towers.
Applications of quantum cascade lasers in chemical sensing
Author(s):
Sheng Wu;
Andrei Deev;
Yongchun Tang
Show Abstract
We show new results in modulating and modifying Quantum Cascade (QC) lasers to make them more
suitable for chemical sensing spectroscopy. Spectroscopy results using QC lasers are demonstrated with
whispering gallery mode CaF2 disc/ball, saturated absorption in hollow waveguide and direct chemical
analysis in water.
Advanced optoacoustic sensor designs for environmental applications
Author(s):
Cinzia Di Franco;
Angela Elia;
Vincenzo Spagnolo;
Pietro Mario Lugarà;
Gaetano Scamarcio
Show Abstract
We will report on the design and realization of optoacoustic sensors based on commercial quantum cascade lasers for
environmental analysis applications. Different configurations will be described: i) sensors based on resonant
photoacoustic cells, a "standard" H cell and an innovative T-cell; ii) sensor based on quartz enhanced photoacoustic
spectroscopy. We will analyze the results obtained in the detection of nitric oxide.
Calibration of far-IR and sub-mm detectors traceable to the international system of units
Author(s):
Ralf Müller;
Berndt Gutschwager;
Christian Monte;
Andreas Steiger;
Jörg Hollandt
Show Abstract
Precision power measurement of electromagnetic radiation is required to establish metrological applications, e.g. remote
sensing. The Physikalisch-Technische Bundesanstalt (PTB), as the national metrology institute of Germany, has started
to determine the spectral responsivity of detectors for THz radiation. In this work, the THz spectral range denotes the
wavelength range from 60 μm to 300 μm, corresponding to 5 THz to 1 THz, which is traditionally the overlap between
far-IR and the sub-mm range.
Traceability of power measurement to the international system of units (SI) has been missing in the THz region in the
past. The PTB establishes this traceability by using two complementary optical approaches, source- and detector-based
radiometry. Both methods have been successfully prototyped. These primary investigations led to the design of a new
measurement facility for the determination of THz radiant power and the responsivity calibration of THz detectors
traceable to the SI.
NPP Visible/Infrared Imaging Radiometer Suite (VIIRS) radiometric calibration emissive bands: tested performance
Author(s):
Eric Johnson;
Karen Galang;
Courtney Ranshaw;
Brendan Robinson
Show Abstract
The Visible/Infrared Imaging Radiometer Suite (VIIRS) collects radiometric and imagery data in 22 spectral bands
within the visible and infrared spectrum ranging from 0.4 to 12.5 μm. This paper describes the radiometric uncertainty
requirements for the 7 VIIRS thermal emissive bands and the calibration methodology employed to meet these
requirements, including the on-board calibration subsystems and the retrieval algorithm for generating calibrated
radiance from instrument data. The instrument characteristics contributing to uncertainties in retrieved radiance are
presented based on results from the recently completed pre-launch test program. The final roll-up of these uncertainties
relative to the absolute radiometric requirements are shown, and compared against the results obtained from the radiance
retrieval algorithm exercised during thermal-vacuum testing for a NIST traceable Blackbody Calibration Source.
Pre-launch characterization of the WISE payload
Author(s):
Harri Latvakoski;
Joel Cardon;
Mark Larsen;
John Elwell
Show Abstract
The Wide-field Infrared Survey Explorer (WISE), launched on December 14, 2009, is a NASA-funded Explorer mission
that is providing an all-sky survey in the mid-infrared with far greater sensitivity and resolution than any previous IR
survey mission. The WISE science payload is a cryogenically cooled infrared telescope with four 1024x1024 infrared
focal plane arrays covering from 2.8 to 26 μm, which was designed, fabricated, and characterized by Utah State
University's Space Dynamics Laboratory. Pre-launch charaterization included measuring focus, repeatability, response
non-linearity, saturation, latency, absolute response, flatfield, point response function, scanner linearity, and relative
spectral response. We will provide a brief overview of the payload, discuss the overall characterization approach, review
several pre-launch characterization methods in detail, and present selected results from ground characterization and early
on-orbit performance.
Aberrations of a transparent sphere
Author(s):
Gonzalo Paez;
Marija Strojnik;
Claudio Ramirez
Show Abstract
We present a ray trace through the sphere in support of sub-aperture testing of the shape of a transparent sphere,
used as a volume (density) standard. The radius of curvature for a sub-aperture may be determined after finding
zero for the defocus aberration, localizing the back focal plane.
Image splitter for mid-infrared bi-spectral analysis of flames
Author(s):
Antonio Ortega-Martinez;
Gonzalo Paez;
Marija Strojnik
Show Abstract
We propose and evaluate an optical "image splitter" by which we can capture two simultaneous infrared images of a
single object, using a single detector. With this device, we can perform experiments in which we are interested to
observe transitory phenomena in two different spectral bands, without losing the spatial information of the test subject.
We also present experimental results of using this array for mid-infrared flame analysis.
Oxygen saturation with simulated breathing
Author(s):
Camille Vazquez-Jaccaud;
Gonzalo Paez;
Marija Strojnik
Show Abstract
We describe a systematic procedure to arrive at the optimal wavelengths for monitoring oxygen delivery to and its
consumption in an organ. On the basis of the signal-to-noise optimization study, we propose several high
performance 2-D wavelength intervals within the therapeutic window. Furthermore, we find that at least one of the
traditional wavelength choices falls near the interval of decreased performance, providing a possible explanation for
the occasional failure of currently used devices.
Tunable filter imager for JWST: etalon opto-mechanical design and test results
Author(s):
D. Touahri;
P. Cameron;
C. Evans;
C. Haley;
Z. Osman;
A. Scott;
N. Rowlands
Show Abstract
The Tunable Filter Imager of the James Webb Space Telescope will be based on blocking filters and a tunable Fabry-
Perot etalon with an average resolution of about 100. It will operate in two wavelength bands from 1.6 μm to 2.5 μm and
from 3.1 μm to 4.9 μm at a cryogenic temperature of about 35K. It will respectively be used to study the First Light and
re-ionization of the universe by surveying Lyman-alpha sources and to provide an in-depth study of proto-planetary
systems as well as giant planets of nearby stars.
The Tunable Filter Imager (TFI) is designed to image a sky field of view of 2.2' by 2.2' (magnified to 4.6 deg. x 4.6 deg.
at the etalon). Its tunable etalon has an aperture of 56 mm. It operates at low orders 1 and 3 for the two wavelength bands
which reduces the number of blocking filters to a number of eight. The etalon gap tuning between 2.5 μm and 5.5 μm is
provided by piezoelectric actuators and will be servo controlled by using capacitive displacement sensors.
In this paper, we present the etalon's opto-mechanical design that allows us to achieve the stringent requirements in
terms of resolution over a wide infrared wavelength band, and operation at low gap at cryogenic temperature. Cryogenic
test results will be shared as well.
Micro-controller based fall detector to assist recovering patients or senior citizens
Author(s):
Francisco Páez;
Lars Asplund
Show Abstract
Senior citizens and patients recovering from surgery or using strong medications with severe side effects
tend to fall unexpectedly. The consequences of such an uncontrolled fall could be worse than the original
malady, especially when there is no communication with the care-takers. We describe a fall-detector device
capable of distinguishing falls from normal daily activities. Based on three-axis accelerometer and
advanced data processing, the microcontroller emits an alarm requesting help in the case of a physical fall.
We design and construct the fall-detector prototype for either inside or outside use. In order to determine
the device performance, fifty instances of each fall event have been evaluated; all of them detected as fall
event. In the case of daily activities, the only movement that produces an alarm is the transition from
standing up to lying in 5% of the occurrences.
The Astro-Comb project
Author(s):
G. Schettino;
C. Baffa;
E. Giani;
M. Inguscio;
E. Oliva;
A. Tozzi;
P. Cancio Pastor
Show Abstract
An Optical Frequency Comb-based apparatus, to be used as a calibration system of the IR GIANO astronomical spectrograph, is the aim of the Astro-Comb project. We plan to obtain, starting from a comb repetition rate of 100 MHz, a final calibration spectrum of lines equally spaced by 16 GHz over the spectral range from 1 μm to 2 μm. Such a system is able to overcome some limits of the present day calibrators, allowing to complement a high resolution spectrograph, such as GIANO, for precision measurements like the detection of extra-solar rocky planets.
Simultaneous measurement of multiple parameters using a single fiber Bragg grating
Author(s):
Mahesh Kondiparthi
Show Abstract
A novel approach for simultaneous measurement of chirp (any parameter that can induce strain gradient on
FBG) and temperature using a single FBG is proposed. Change in reflectivity at central wavelength of FBG reflection &
Bragg wavelength shifts induced due to temperature were used for chirp & temperature measurements respectively.
Theoretical resolution limit for chirp and temperature using an Optical Spectrum Analyzer (OSA) with 1pm wavelength
resolution and >58dB dynamic range are 12.8fm and 1/13 oC respectively.