Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “IR”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Comparison of 3D dose distributions for HDR {sup 192}Ir brachytherapy sources with normoxic polymer gel dosimetry and treatment planning system

Radiation fluence changes caused by the dosimeter itself and poor spatial resolution may lead to lack of 3-dimensional (3D) information depending on the features of the dosimeter and quality assurance of dose distributions for high–dose rate (HDR) iridium-192 ({sup 192}Ir) brachytherapy sources is challenging and experimental dosimetry methods used for brachytherapy sources are limited. In this study, we investigated 3D dose distributions of {sup 192}Ir brachytherapy sources for irradiation with single and multiple dwell positions using a normoxic gel dosimeter and compared them with treatment planning system (TPS) calculations. For dose calibration purposes, 100-mL gel-containing vials were irradiated at predefined doses and then scanned in an magnetic resonance (MR) imaging unit. Gel phantoms prepared in 2 spherical glasses were irradiated with {sup 192}Ir for the calculated dwell positions, and MR scans of the phantoms were obtained. The images were analyzed with MATLAB software. Dose distributions and profiles derived with 1-mm resolution were compared with TPS calculations. Linearity was observed between the delivered dose and the reciprocal of the T2 relaxation time constant of the gel. The x-, y-, and z-axes were defined as the sagittal, coronal, and axial planes, respectively, the sagittal and axial planes were defined parallel to the long axis of the source while the coronal plane was defined horizontally to the long axis of the source. The differences between measured and calculated profile widths of 3-cm source length and point source for 70%, 50%, and 30% isodose lines were evaluated at 3 dose levels using 18 profiles of comparison. The calculations for 3-cm source length revealed a difference of > 3 mm in 1 coordinate at 50% profile width on the sagittal plane and 3 coordinates at 70% profile width and 2 coordinates at 50% and 30% profile widths on the axial plane. Calculations on the coronal plane for 3-cm source length showed > 3-mm difference in 1 coordinate at 50% and 70% and 2 coordinates at 30% profile widths. The point source measurements and calculations for 50% profile widths revealed a difference > 3 mm in 1 coordinate on the sagittal plane and 2 coordinates on the axial plane. The doses of 3 coordinates on the sagittal plane and 4 coordinates on the axial plane could not be evaluated in 30% profile width because of low doses. There was good agreement between the gel dosimetry and TPS results. Gel dosimetry provides dose distributions in all 3 planes at the same time, which enables us to define the dose distributions in any plane with high resolution. It can be used to obtain 3D dose distributions for HDR {sup 192}Ir brachytherapy sources and 3D dose verification of TPS.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

IR fixed points in SU ( 3 ) gauge theories

We propose a novel RG method to specify the location of the IR fixed point in lattice gauge theories and apply it to the SU(3) gauge theories with N f fundamental fermions. It is based on the scaling behavior of the propagator through the RG analysis with a finite IR cutoff, which we cannot remove in the conformal field theories in sharp contrast to the confining theories. The method also enables us to estimate the anomalous mass dimension in the continuum limit at the IR fixed point. We perform the program for N f =16,12,8 and N f =7 and indeed identify the location of the IR fixed points in all cases.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

IR spectroscopic quantification of small molecule transport and desorption phenomena in polymers

The application, continued performance, and degradation behavior of polymers often depends on their interaction with small organic or gaseous volatiles. Understanding the underlying permeation and diffusion properties of materials is crucial for predicting their barrier properties (permeant flux), drying behavior, solvent loss or tendency to trap small molecules, as well as their interaction with materials in the vicinity due to off-gassing phenomena, perhaps leading to compatibility concerns. Further, the diffusion of low Mw organics is also important for mechanistic aspects of degradation processes. Based on our need for improved characterization methods, a FTIR-based spectroscopic gas/volatile quantification setup was designed and evaluated for determination of the diffusion, desorption and transport behavior of small IR-active molecules in polymers. At the core of the method, a modified, commercially available IR transmission gas cell monitors time-dependent gas concentration. Appropriate experimental conditions, e.g. desorption or permeation under continuous flow or static gas conditions, are achieved using easily adaptable external components such as flow controllers and sample ampoules. This study presents overview approaches using the same IR detection methodology to determine diffusivity (desorption into a static gas environment, continuous gas flow, or intermittent desorption) and permeability (static and dynamic flow detection). Further, the challenges encountered for design and setup of IR gas quantification experiments, related to calibration and gas interaction, are presented. These methods establish desorption and permeation behavior of solvents (water and methanol), CO 2 off-gassing from foam, and offer simultaneous measurements of the permeation of several gases in a gas mixture (CO 2 , CO and CH 4 ) through polymer films such as epoxy and Kapton. They offer complementary guidance for material diagnostics and understanding of basic properties in sorption and transport behavior often of relevance to polymer degradation or materials reliability phenomena.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Ba 3 Fe 1.56 Ir 1.44 O 9 : A Polar Semiconducting Triple Perovskite with Near Room Temperature Magnetic Ordering

The crystal chemistry and magnetic properties for two triple perovskites, Ba 3 Fe 1.56 Ir 1.44 O 9 and Ba 3 NiIr 2 O 9 , grown as large, highly faceted single crystals from a molten strontium carbonate flux, are reported. Unlike the idealized A 3 MM 2 'O 9 hexagonal symmetry characteristic of most triple perovskites, including Ba 3 NiIr 2 O 9 , Ba 3 Fe 1.56 Ir 1.44 O 9 possesses significant site-disorder, resulting in a noncentrosymmetric polar structure with trigonal symmetry. The valence of iron and iridium in the heavily distorted Fe/Ir sites was determined to be Fe(III) and Ir(V) by X-ray absorption near edge spectroscopy (XANES). Density functional theory calculations were conducted to understand the effect of the trigonal distortion on the local Fe(III)O 6 electronic structure, and the spin state of iron was determined to be S = 5/2 by Mossbauer spectroscopy. Conductivity measurements indicate thermally activated semiconducting behavior in the trigonal perovskite. Magnetic properties were measured and near room temperature magnetic ordering (T N = 270 K) was observed for Ba 3 Fe 1.56 Ir 1.44 O 9 .

36 MATERIALS SCIENCE↗
DOE OSTI2015

Monitoring the Folding Kinetics of a β-Hairpin by Time-Resolved IR Spectroscopy in Silico

One of the most fundamental problems in modern biochemistry is protein folding. Time-resolved infrared (IR) spectroscopy in the amide I region is commonly used to monitor folding kinetics. However, associated atomic detail information on the folding mechanism requires simulations. In atomistic simulations structural order parameters are typically used to follow the folding process along the simulated trajectories. But, a rigorous test of the reliability of the mechanisms found in the simulations requires calculation of the time-dependent experimental observable, i.e., in the present case the IR signal in the amide I region. Here, we combine molecular dynamics simulation with a mixed quantum mechanics/molecular mechanics theoretical methodology, the Perturbed Matrix Method, in order to characterize the folding of a -hairpin peptide, through modeling the time-dependence of the amide I IR signal. The kinetic and thermodynamic data (folding and unfolding rate constants, and equilibrium folded- and unfolded-state probabilities) obtained from the fit of the calculated signal are in good agreement with the available experimental data [Xu et al. J. Am. Chem. Soc. 2003, 125, 15388 15394]. Furthermore, to the best of our knowledge, this is the first report of the simulation of the time-resolved IR signal of a complex process occurring on a long (microsecond) time scale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

In Situ Attenuated Total Reflectance Infrared Spectroelectrochemistry (ATR-IR-SEC) for the Characterization of Molecular Redox Processes on Surface-Proximal Doped Silicon ATR Crystal Working Electrodes

In situ mid-infrared spectroscopy is a powerful technique for understanding the mechanism of CO 2 reduction (CO 2 R) catalysts because it enables the direct detection of catalytic intermediates and products. Moreover, spectroelectrochemistry (SEC), the coupling of spectroscopy with electrochemistry, allows spectroscopic changes to be correlated with applied potentials to reveal potential-dependent intermediates that are often relevant to photoelectrochemical reactions. Hybrid photoelectrodes, comprised of a narrow bandgap semiconductor, like silicon (Si), with a covalently-linked molecular catalyst, are a promising platform for sunlight-driven catalysis, but characterization of the catalytic mechanism(s) is challenging under photoelectrochemical conditions, particularly when the catalyst is present in monolayer or less concentrations. Here, we have developed a new strategy to use multiple-reflection attenuated total reflectance IR spectroscopy (ATR-IR) coupled with electrochemistry to characterize catalysts directly integrated with a semiconductor surface under applied potential. We show that by surface-proximal n-type or p-type doping of the top ~100-200 nm of the crystal surface, Si ATR crystals can be used simultaneously as the internal reflection element and semiconductor working electrode for ATR-IR-SEC measurements. The surface-proximal doping strategy yields a quasi-equipotential surface with excellent infrared transparency that would have been compromised by free carrier absorption if the crystal was uniformly doped. This approach permits the catalytically-active functionalized surface to be directly probed without modification and overcomes signal-to-noise limitations of other strategies that use separately deposited working electrodes on Si ATR crystals. Proof-of-concept ATR-IR-SEC spectra were collected during the reduction and oxidation of monolayers of Re- and Ru-based transition metal carbonyl complexes, respectively, verifying the viability of the technique to probe redox processes associated with CO 2 R catalysts on Si electrode surfaces with high sensitivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Distinct Mechanisms and Hydricities of Cp*Ir-Based CO 2 Hydrogenation Catalysts in Basic Water

Transition metal-catalyzed reversible hydrogenation of CO 2 to formate in aqueous solutions under ambient conditions is an attractive environmentally friendly strategy for the storage and transportation of H 2 in a liquid chemical form. Here, mechanistic details for the CO 2 hydrogenation by a series of pentamethylcyclopentadienyl iridium(III) (Cp*Ir) complexes with picolinamidate ligands are investigated through density functional theory and kinetic isotope effects (KIEs) calculations. Additionally, adopting a speciation approach at a pH of 8.2, CO 2 hydrogenation mechanisms of 37 distinct protonation states and conformers of Cp*Ir type complexes are investigated. This imposes a challenging test for the computational modeling in terms of providing a consistent correlation with experimental kinetics and KIE studies of multiple catalysts instead of a single complex. Overall, H 2 heterolysis to generate an iridium hydride intermediate was demonstrated to be the rate determining step, which proceeds via distinct pathways depending on the stereoelectronic properties of the ligand. A peculiar iridium dihydride route was also uncovered, which could be optimized to accelerate the H 2 heterolysis. We have further computed the thermodynamic and kinetic hydricities of 74 complexes with [Cp*Ir(L)(H)] q ( q = -1, 0, 1 depending on the ligand charge by deprotonation or protonation events) general formula. Hydricity values do not show any noticeable correlation with the thermodynamics (Δ G ) of [Cp*Ir(L)(HCO 2 – )] formation but exhibit linear correlation with the kinetics (Δ G ‡ ) of electrophilic CO 2 attack to iridium hydride species, especially when the charges and local structural effects of the metal hydrides are considered. Insights gained in this study on (i) the factors determining the preferred pathway for the rate-limiting H 2 heterolysis step, (ii) the correlation between thermodynamic hydricity and the kinetics of CO 2 insertion to iridium hydride species, and (iii) mechanistic analysis via combination of free energy profiles and KIE studies for a series of iridium catalysts will provide guidelines for the design of next-generation catalysts for the reversible H 2 storage through CO 2 utilization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

CO Oxidation on Ir 1 /TiO 2 : Resolving Ligand Dynamics and Elementary Reaction Steps

Identifying the rate-controlling steps and the evolution of the ligand environment throughout the catalytic cycle on supported single-atom catalysts is crucial to bridge the gap between heterogeneous and homogeneous catalysis. Here we identified the rate-controlling elementary steps for CO oxidation on TiO 2 -supported Ir single atoms and isolated the corresponding intermediate Ir complexes. Kinetic measurements, operando spectroscopy, and quantum-chemical calculations indicate that the reaction mechanism has two kinetically relevant steps, CO adsorption/oxidation and O 2 dissociation. By varying the reaction conditions, three Ir 1 complexes (states) along the reaction cycle were isolated and identified using in situ spectroscopy. Furthermore, we show that all the intermediate Ir 1 states share a common CO ligand that does not turn over. Finally, this study provides atomic level details on the active, intermediate complexes and reaction cycle of supported single-metal-atom catalysts, thereby offering future possibilities to control the ligand environment and reactivity.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Direct Observation by Rapid-Scan FT-IR Spectroscopy of Two-Electron-Reduced Intermediate of Tetraaza Catalyst [Co II N 4 H(MeCN)] 2+ Converting CO 2 to CO

In the search for the two-electron-reduced intermediate of the tetraaza catalyst [Co II N 4 H(MeCN)] 2+ (N 4 H = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene) for CO 2 reduction and elementary steps that result in the formation of CO product, rapid-scan FT-IR spectroscopy of the visible-light-sensitized catalysis, using Ir(ppy) 3 in wet acetonitrile (CD 3 CN) solution, led to the observation of two sequential intermediates. The initially formed one-electron-reduced [Co I N 4 H] + --CO 2 adduct was converted by the second electron to a transient [Co I N 4 H] + --CO 2 - complex that spontaneously converted CO 2 to CO in a rate-limiting step on the second time scale in the dark under regeneration of the catalyst (room temperature). The macrocycle IR spectra of the [Co I N 4 H] + --CO 2 - complex and the preceding one-electron [Co I N 4 H] + --CO 2 intermediate show close similarity but distinct differences in the carboxylate modes, indicating that the second electron resides mainly on the CO 2 ligand. Vibrational assignments are corroborated by 13 C isotopic labeling. The structure and stability of the two-electron-reduced intermediate derived from the time-resolved IR study are in good agreement with recent predictions by DFT electronic structure calculations. This is the first observation of an intermediate of a molecular catalyst for CO 2 reduction during the bond-breaking step producing CO. The reaction pathway for the Co tetraaza catalyst uncovered here suggests that the competition between CO 2 reduction and proton reduction of a macrocyclic multi-electron catalyst is steered toward CO 2 activation if the second electron is directly captured by an adduct of CO 2 and the one-electron-reduced catalyst intermediate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Electrospun Ti–Zr Oxide Heterostructures Enable Strongly Anchored Ultralow-Ir Anodes for Durable Acidic Oxygen Evolution

Proton-exchange-membrane water electrolysis (PEMWE) requires acidic oxygen-evolution-reaction (OER) anodes that combine high activity, high durability, and low Ir loading. Here, we report a Ti-Zr composite electrospun oxide (ESO) nanorod support that enables ultralow-Ir anodes for high-performance PEMWE. Zr-containing Ti oxide heterostructures stabilize anatase-rich TiO2, tune the local oxygen-coordination environment, and strengthen interfacial anchoring of IrOx under acidic anodic conditions. The electrospun nanorod network further creates an open, mechanically coherent catalyst layer that improves Ir utilization, ionomer penetration, and mass transport. At an anode loading of 0.2 mgIr cm-2, the optimized Ir/TiZr20-ESO anode delivers a PEMWE mass activity of 0.99 A mgIr-1 at 1.45 V, 28.3 and 43.0 times higher than commercial Ir black and commercial IrO2/TiO2, respectively. The same anode reaches 3.0 and 4.0 A cm-2 at 1.75 and 1.83 V, respectively, and sustains 2000 h operation at 2.0 A cm-2. Also, accelerated stress tests up to 525 hours over 31,500 cycles confirm promising long-term durability, with an insignificant performance decay of 0.4 μV per cycle. Density functional theory indicates that the Ti-Zr oxide heterostructure suppresses Ti demetallation and strengthens IrO2 interfacial binding, rationalizing the improved high-current-density stability.

25 ENERGY STORAGE↗
DOE OSTI2018

Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts

Supported single atoms provide the best utilization of noble metals and provide an opportunity to design new heterogeneous catalysts. However, identification of the active single atoms structure is required for understanding the reaction mechanism and guiding catalyst design. We used in-situ infrared spectroscopy, in-operando x-ray adsorption spectroscopy and quantum chemical calculations to show that Ir(CO)/MgAl2O4 is the active single atom complex for low temperature CO oxidation and Ir(CO)(O) is the most stable intermediate. In contrast to poisoning of nanoparticles by CO, the formation of Ir(CO) on single atoms results in a different reaction mechanism and high activity for low temperature CO oxidation. This is due to the ability of single atoms to coordinate with multiple ligands, where CO, in Ir(CO)(O), acts as a facilitator by lowering the reaction barrier between gas phase CO and adsorbed O (Eley-Rideal mechanism).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

New insulating antiferromagnetic quaternary iridates M La 10 Ir 4 O 24 (M=Sr, Ba)

Recently, oxides of Ir 4+ have received renewed attention in the condensed matter physics community, as it has been reported that certain iridates have a strongly spin-orbital coupled (SOC) electronic state, J eff = ½, that defines the electronic and magnetic properties. The canonical example is the Ruddlesden-Popper compound Sr 2 IrO 4 , which has been suggested as a potential route to a new class of high temperature superconductor due to the formal analogy between J eff = ½ and the S = ½ state of the cuprate superconductors. The quest for other iridium oxides that present tests of the underlying SOC physics is underway. In this spirit, here we report the synthesis and physical properties of two new quaternary tetravalent iridates, M La 10 Ir 4 O 24 (M = Sr, Ba). The crystal structure of both compounds features isolated IrO 6 octahedra in which the electronic configuration of Ir is d 5 . As a result, both compounds order antiferromagnetically despite the lack of obvious superexchange pathways, and resistivity measurement shows that SrLa 10 Ir 4 O 24 is an insulator.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Elastic, magnetic and electronic properties of iridium phosphide Ir 2 P

Cubic (space group: Fm3¯m) iridium phosphide, Ir 2 P, has been synthesized at high pressure and high temperature. Angle-dispersive synchrotron X-ray diffraction measurements on Ir 2 P powder using a diamond-anvil cell at room temperature and high pressures (up to 40.6 GPa) yielded a bulk modulus of B 0 = 306(6) GPa and its pressure derivative B 0 '= 6.4(5). Such a high bulk modulus attributed to the short and strongly covalent Ir-P bonds as revealed by first – principles calculations and three-dimensionally distributed [IrP 4 ] tetrahedron network. Indentation testing on a well–sintered polycrystalline sample yielded the hardness of 11.8(4) GPa. Relatively low shear modulus of ~64 GPa from theoretical calculations suggests a complicated overall bonding in Ir 2 P with metallic, ionic, and covalent characteristics. Additionally, a spin glass behavior is indicated by magnetic susceptibility measurements.

36 MATERIALS SCIENCE↗
DOE OSTI2016

IR-Live: fabrication of a low-cost plastic microfluidic device for infrared spectromicroscopy of living cells

Water is a strong mid-infrared absorber, which has hindered the full exploitation of label-free and non-invasive infrared (IR) spectromicroscopy techniques for the study of living biological samples. To overcome this barrier, many researchers have built sophisticated fluidic chambers or microfluidic chips wherein the depth of the liquid medium in the sample compartment is limited to 10 μm or less. We report an innovative and simple way to fabricate plastic devices with infrared transparent view-ports enabling infrared spectromicroscopy of living biological samples; therefore the device is named “IR-Live”. Advantages of this approach include lower production costs, a minimal need to access a micro-fabrication facility, and unlimited mass or waste exchange for the living samples surrounding the view-port area. We demonstrate that the low-cost IR-Live in combination with microfluidic perfusion techniques enables long term (>60 h) cell culture, which broadens the capability of IR spectromicroscopy for studying living biological samples. To illustrate this, we first applied the device to study protein and lipid polarity in migrating REF52 fibroblasts by collecting 2-dimensional spectral chemical maps at a micrometer spatial resolution. Then, we demonstrated the suitability of our approach to study dynamic cellular events by collecting a time series of spectral maps of U937 monocytes during the early stage of cell attachment to a bio-compatible surface.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

IR mass-resolved spectroscopy of complexes without chromophore: Cyclohexanol·(H{sub 2}O){sub n}, n = 1–3 and cyclohexanol dimer

Mass-resolved IR spectra of cyclohexanol-water clusters and cyclohexanol dimer in supersonic expansions are presented for the first time. A combination of ns and fs IR lasers made possible recording such spectra without inclusion of a chromophore or a messenger atom. Furthermore, employment of the recently developed IR{sup 3} technique [I. León, R. Montero, F. Castaño, A. Longarte, and J. A. Fernández, J. Phys. Chem. A 116, 6798 (2012)] allowed us to discriminate between the contribution of different species to the IR spectrum. Comparison of the experimental spectra with the predictions at the M06-2X/6-311++G(d,p) calculation level confirmed the assignment of the spectrum of cyclohexanol·(H{sub 2}O){sub 1} to a structure in which water is accepting a proton from cyclohexanol's OH group, and those of cyclohexanol·(H{sub 2}O){sub 2,3} to structures with cyclic hydrogen bond networks. A comparative analysis of the results obtained with those reported on other aromatic alcohols is also offered.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Morin transition temperature in (0001)-oriented α-Fe{sub 2}O{sub 3} thin film and effect of Ir doping

The structural properties and Morin transition in c-plane-oriented α-Fe{sub 2}O{sub 3} and Ir-doped α-Fe{sub 2}O{sub 3} thin films have been investigated. The enhancement of the Morin transition temperature (T{sub M}) in α-Fe{sub 2}O{sub 3} film by Ir doping has been demonstrated. The T{sub M} in the c-plane-oriented α-Fe{sub 2}O{sub 3} thin film was determined from the temperature-dependent in-plane magnetization and change of coercivity (H{sub c}); this T{sub M} value was found close to that of bulk α-Fe{sub 2}O{sub 3}. The spin directions of non-doped and Ir-doped α-Fe{sub 2}O{sub 3} at room temperature were also estimated from conversion electron Mössbauer spectroscopy measurements. We confirmed that Ir doping dramatically enhances the T{sub M} of α-Fe{sub 2}O{sub 3} thin film.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

A DFT study on the adsorption of CO and CO{sub 2} molecules on Pt{sub 4} and Ir{sub 4} clusters

We analyze the electronic structure and adsorption binding energy of CO and CO{sub 2} molecules adsorbed on Ir{sub 4} and Pt{sub 4} clusters by using Density functional theory (DFT). It is found that the Ir{sub 4} cluster has more adsorption binding energy than Pt{sub 4} cluster. We show that the Ir and Ir - supported materials are good catalytic materials and could be useful for gas sensor applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Tunable parametric amplifier for mid-IR application based on highly nonlinear chalcogenide material

A novel dispersion controlling technique towards attaining tunable parametric amplification based on highly nonlinear photonic crystal fibers has been investigated. Selective infiltration of the liquid into the air-holes leads to alter the zero dispersion wavelength towards a broader parametric gain in the mid-IR spectrum by only changing the temperature of the system externally. The dispersion profile specially the zero dispersion wavelengths can be well tuned around the pumping wavelength, thereby generating several hundred nanometer parametric bandwidth in near-IR to mid-IR region. The tunability of the photonic crystal fibers (PCFs) can also be useful for generating new frequencies in both the red- and blue-shifted regions far from the pumping wavelength. Our numerical calculations reveal that we could achieve very wide band fiber optic parametric amplifier both in the communication wavelength and in the IR region. Also two different types of PCFs can be used to achieve same broadband wavelength spectra however with a tradeoff between the fiber lengths and pump power.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗