Previously, we have reported measurements of temperature-dependent surface resistivity of pure and multi-walled carbon nanotube (MWNCT) doped amorphous Polyvinyl Alcohol (PVA) thin films. In the temperature range from 22 °C to 40 °C with humidity-controlled environment, we found the surface resistivity to decrease initially, but to rise steadily as the temperature continued to increase. Moreover, electric surface current density (Js) was measured on the surface of pure and MWCNT doped PVA thin films. In this regard, the surface current density and electric field relationship follow Ohm’s law at low electric fields. Unlike Ohmic conduction in metals where free electrons exist, selected captive electrons are freed or provided from impurities and dopants to become conduction electrons from increased thermal vibration of constituent atoms in amorphous thin films. Additionally, a mechanism exists that seemingly decreases the surface resistivity at higher temperatures, suggesting a blocking effect for conducting electrons. Volume resistivity measurements also follow Ohm’s law at low voltages (low electric fields), and they continue to decrease as temperatures increase in this temperature range, differing from surface resistivity behavior. Moreover, we report measurements of dielectric constant and dielectric loss as a function of temperature and frequency. Both the dielectric constant and dielectric loss were observed to be highest for MWCNT doped PVA compared to pure PVA and commercial paper, and with frequency and temperature for all samples.
Previously, we have reported measurements of the temperature-dependent surface resistivity of pure and multi-walled carbon nanotubes doped Polyvinyl Alcohol (PVA) thin films. In the temperature range from 22 °C to 40 °C, with a humidity-controlled environment, we found the surface resistivity to decrease initially but to rise steadily as the temperature continued to increase. Correspondingly, we have measured the temperature-dependent pyroelectric coefficient of doped polyvinylidene difluoride (PVDF) thin films, very well. While the physical mechanism of the pyroelectric phenomenon in PVDF thin films is quite well known, the surface resistivity behavior of PVA thin films is not so well known. Here, we address this concern by reporting the electrical mechanistic phenomena that contribute to surface resistivity of pure and doped PVA thin films, and give preliminary surface resistivity detectivity and other relevant quality factors for infrared (IR) and motion sensors. Regarding the pyroelectric effect of doped PVDF thin films, we give materials Figures-of-Merit based on our measurements. In addition, pyroelectric and surface resistivity infrared fundamentals, IR sensor uniqueness, and innovative techniques are presented.
The detection of infrared radiation (IR) with pure and doped Polyvinylidene difluoride (PVDF) films has been well documented using the mechanism of pyroelectricity. Alternatively, the electrical properties of films made from Polyvinyl Alcohol (PVA) have received considerable attention in recent years. The investigation of surface resistivities of both such films, to this point, has received far less consideration in comparison to pyroelectric effects. In this research, we report temperature dependent surface resistivity measurements of commercial, and of multiwall carbon nanotubes (MWCNT), or Ag-nanoparticle doped PVA films. Without any variation in the temperature range from 22°C to 40°C with controlled humidity, we found that the surface resistivity decreases initially, reaches a minimum, but rises steadily as the temperature continues to increase. This research was conducted with the combined instrumentation of the Keithley Model 6517 Electrometer and Keithley Model 8009 resistivity test fixture using both commercial and in-house produced organic thin films. With the objective to quantify the suitability of PVDF and PVA films as IR detector materials, when using the surface resistivity phenomenon, instead of or in addition to the pyroelectricity, surface resistivity measurements are reported when considering bolometry. We find the surface resistivity of PVDF films to be in the range, which extends beyond the upper limit of our Keithley electrometer, but our measurements on PVA films were readily implemented.
In this research, the authors give an analysis of surface structural morphology and optical waveguide properties of
gadolinium oxide (Gd2O3) and gadolinium oxide europium doped (Gd2O3:Eu3+) films as prepared via the sol-gel and dip
coating methods under atmospheric and clean room conditions. After describing sol-gel preparation routines, the authors
further give observations of homogeneous surface morphological as characterized with scanning electron microscope
(SEM) techniques. In addition, FTIR measurements of the Gd2O3 and Gd2O3:Eu3+ films and sol gels were made to
monitor the decomposition and oxidation reactions that occur during processing. The samples' structural and resulting
optical properties were studied and compared according to film thickness and surface morphological features.
The present research focused on the systematic study of the fabrication of gadolinium oxide (Gd2O3) and gadolinium oxide:europium (Gd2O3:Eu3+) thin films via the sol-gel and dip coating methods under normal laboratory conditions in a methanol solvent medium to determine if thin films of comparable quality could be produced. The thin films were synthesized via the sol-gel method by the hydrolysis of gadolinium acetylacetate in two different solvent mediums, absolute ethanol and methanol. The europium doped gadolinium oxide sol-‐gels were prepared to have a final concentration of 0.01 M europium nitrate. Ordinary microscope glass slides (borosilicate glass or BSG) were used as the substrate. The substrates were cleaned and coated using the dip coating apparatus to prepare thin films that consisted of 5, 10, 30 and 50 layers. The cast films were annealed at 300°C and 500°C by direct insertion in a furnace operated under atmospheric conditions. The resulting film thickness and effective refractive indices were determined and compared. Finally, we present the introductory results of gadolinium oxide thin films as a waveguide.
In this work, we have determined the dielectric and conductance properties of multi-wall carbon nano-tubes (MWCNT) in polyvinylidene fluoride (PVDF) nanocomposite thin films as a function of temperature and frequency. Samples, ranging from 15 - 280 microns in thickness, were measured in the temperature range from 21 to 90°C and in frequencies from 50Hz to 110MHz. The samples were prepared by the solution casting technique. Measures indicate that at constant temperatures, the real dielectric constant decreases at lower frequencies, stays steady at low frequencies but rise at higher frequencies over towards the strong resonance. The dielectric loss, a particular concern as it is inversely related to the conductance, decreases also at lower frequencies but rise at higher frequencies with a steeper slope in each case. Additionally, we have measured the pyroelectric coefficient in the same temperature range, compared the pyroelectric coefficient results with previous measures made on silver nanoparticle in PVDF thin films and provided preliminary evidence of the causative microscopic response mechanism. Our MWCNT:PVDF thin films yield higher figures of merit than that indicated by pure PVDF thin films and results indicate a usage of MWCNT:PVDF thin films in infrared uncooled sensors and vidicon technology.
Using a solution casting technique, for sample preparation, pyroelectric multi-walled
carbon nanotubes in polyvinylidene fluoride composite films have been fabricated, to
allow the characterization of both the pyroelectric and dielectric properties of such
composites. The properties measured include: (1) dielectric constants and (2) pyroelectric
coefficient as a function of temperature. From the foregoing parameters, figures-of-merit,
for infrared detection and thermal-vidicons, were calculated. The results indicated
figures-of-merit of composite film were higher than pristine polyvinylidene fluoride
films. Additionally, composite films, composed of pyroelectric Lithium tantalate
[(LiTaO3), LT] ceramic particles and silver nanoparticles incorporated into
polyvinylidene fluoride-trifluoroethylene [PVDF-TrFE) 70/30 mol%] copolymer matrix,
have been prepared. The results indicate that silver nanoparticles incorporated lithium
tantalate:polyvinylidene fluoride-trifluoroethylene composite films may have application
for un-cooled infrared sensor.
Power harvesting is the process of extracting useful electrical energy from ambient low grade energy sources such as solar energy, mechanical energy, and thermal energy using smart materials as transducers. These materials have the ability to convert one form of energy into another. This paper aims at thermal-electrical energy converters based on a pyroelectric effect for energy harvesting, and examines its possible use in ultralow power devices and sensor modules. The present work investigates theoretically the energy harvesting capacity of pyroelectric samples fabricated in our laboratory and commercially available pyroelectric elements/transducers by capturing thermal energy of pavements. The single- and polycrystalline elements: triglycine selenate; lithium tantalate; modified lead zirconate titanate; modified lead titanate; modified lead metaniobate; and pyroelectric polymer nanocomposites such as Portland cement; nanocarbon fibers; polymer-lithium tantalate embedded with silver nanoparticles; and others were characterized for applicable performance parameters. The modeling and numerical simulation of energy harvesting capacity of these samples with the available pavement's temperature-profile data over an extended period of time were investigated. The results indicate that the electrical energy harvesting via pyroelectricity is a feasible technique for powering autonomous low-duty electric devices.Based on our analysis of a single electric-energy harvesting unit, the triglycine selenate elements shall perform better than others with regard to the amount of voltage and energy densities extracted with respect to time. Possible future work and concepts of developing promising multidomain energy harvesters or hybrid harvesters are also briefly discussed.
Ferroelectric oxide ceramics have been investigated as possible alternatives to highly sensitive triglycine
sulfate (TGS) crystals for their use in room temperature infrared detectors. In this paper dielectric and
pyroelectric properties of some ceramics based on modified lead titanate and others are presented. The
figures-of-merit of these ceramics calculated using the measured dielectric and pyroelectric data are
presented. The relative advantages and disadvantages of the principal ceramic systems are also compared
with existing materials reported in the literature.
Pyroelectric infrared Lithium tantalite [(LiTaO3), LT] ceramic particles and silver nanoparticles have
been incorporated into a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70/30 mol%]
copolymer matrix to form composite films. The films were prepared using solvent casting method.
Electrical properties such as the dielectric constant, dielectric loss, and pyroelectric coefficient have been
measured as a function of temperature. In addition, materials' figures-of-merit have also been calculated
to assess their use in infrared detectors. The results show that the fabricated silver nanoparticles
incorporated lithium tantalite: polyvinylidene
fluoride-trifluoroethylene composite films may have a good
potential for uncooled infrared sensor applications.
Pyroelectric infrared radiation detectors are one of kind thermal sensors, operating at ambient temperature,
unlike semiconductor detectors, which require cooling. They also have a uniform spectral response in a
wide range of wavelengths, including the main band of infrared transmission of the earth's atmosphere.
Recently, 0-3 composites consisting of ferroelectric ceramic particles dispersed in a ferroelectric polymer
have stimulated interest due to their good mechanical flexibility and strength, and excellent piezoelectric
and pyroelectric properties. Lithium tantalite [(LiTaO3), LT] ceramic particles have been incorporated into
a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70/30 mol%] copolymer matrix to form
composite films. The films were prepared using solvent casting method with the LT powder
homogeneously dispersed in the P(VDF-TrFE) copolymer matrix with various volume fractions. Electrical
properties such as the dielectric constant, dielectric loss, and pyroelectric coefficient have been measured as
a function of temperature as well as frequency. In addition, materials' figures-of-merit have also been
calculated to assess their use in infrared detectors. The results show that the fabricated lithium tantalite:
polyvinylidene fluoride-trifluoroethylene composite films have a good potential for uncooled infrared
sensor applications operating at moderate temperatures.
We continue a study of the equivalence particle principle applied to an optical spatial soliton which is a "narrow filament" that maintains its existence in a waveguide. Using this principle, expressions for acceleration, spatial frequency, spatial period and other variables for a spatial soliton can be derived from the solution of basic Nonlinear Schrödinger Equation. These results agree well with numerical simulations of the Modified Nonlinear Schrödinger Equation. If the expression of the acceleration is bounded in some cases this means the spatial soliton propagates with a swing effect. We go one step further in this theoretical study to investigate the effects of the swing effect with power law included in the Modified Nonlinear Schrödinger Equation.
KEYWORDS: Data modeling, Mathematical modeling, Differential equations, Solids, Data mining, Mining, Analytical research, Weapons of mass destruction, Process modeling, Algorithm development
We present a novel mathematical framework for Data Mining blogger text entries and converting latent conceptual
information into analytical predictive equations. These differential equations are conceptual models of the blogger's
topic and state-of-mind transition dynamics. The mathematical framework is explored for its value in characterization of
topic content and topic tracking as well as identification and prediction of topic dynamic changes.
We present a novel algorithm taking measurements of time, solar irradiance, wind speed, peak wind speed, temperature gradient, and relative humidity to derive a predictive differential equation for mean Cn2. Our method derives individual control terms and forcing functions by modeling macro-structure, micro-structure, and fine structure terms independently. The final model is suitable for analysis and able to be used as a baseline expectation model for in situ battlefield use for predictive optical correction or slewing, and possibly for mitigating the effects of wind shear on artillery shells downrange.
Lead magnesium niobate-lead titanate,
Pb(Mg, Nb)O3-PbTiO3 is a piezoelectric, ferroelectric crystal at room temperature with large electromechanical coefficient. The crystals were grown by PbO-B2O3 flux method. Typically the crystals were colorless and transparent, but a small fraction of them were Brown/reddish colored and show interesting photoluminescence (PL) properties. The PL studies were conducted under XeCl (308nm) excitation and under Argon Ion (Ar+) laser excitation. The excitation with 308nm gave broad PL centered at 500nm and intense emission at 710nm. The emission at 710nm in colorless crystals is very weak. The excitation with Ar+ laser coinciding with electronic absorption in brown samples gave rich and sharp PL particularly with 514.5 nm excitation. The PL with
514.5nm-Ar+ laserexcitation, consisted of intense anti stokes emission in addition to intense red and near infrared emission, is a result of photo-transfer optically stimulated luminescence (PT-OSL). This involved electron-hole recombination at photoinduced
magnetic polaron site. The PL emissions and the centers identified are the followings: 718nm emission due to magnetic polaron and 360nm emission due to cooperative emission from two polarons, Fe-R line at 660nm due to Fe3+ coupled to a cation; 380nm and 399nm due to Pb2+ clusters and Nb5+ center; 630 and 860 nm due to 6p→6s transition of Pb3+ and 760nm due to isolated Fe3+ ions. Raman spectrum of brown samples revealed the presence of nano particles/wires of orthorhombic β PbO. The FTIR spectrum gives evidence of significant amount of hydroxyl impurity.
We have observed nanosecond electrical and optical pulsations from photorefractive lithium-niobate optical fibers using
CW green and blue low-power lasers. Fourier spectra of the pulsations have a maximum at ~900 MHz with peaks
separated by ~30MHz. We consider free-space and fiber supported illumination of the fiber crystal. Strong nonlinear
enhanced backscattering with phase conjugation was observed from bulk crystals and crystal fibers along the C-axis. Model
of transformation of CW laser irradiation of ferroelectric crystals into periodic nanosecond electrical and optical pulsations
is suggested. This model includes combinations of photorefractive, pyroelectric, piezoelectric, and photogalvanic
mechanisms of the holographic grating formation and crystal electrical charging. Possible applications of these short
photo-induced
electrical pulses for modulation of holographic beam coupling, pulsed electrolysis, electrophoresis, focused
electron beams, X-ray and neutron generation, and hand-held micro
X-ray devices for localized oncology imaging and
treatment based on our advanced sensor work are discussed.
Barium titanate crystals were grown by top seeded solution growth technique, nominally pure and also 0.05% and 1% Cr3+ impurity. We have conducted electron paramagnetic resonance (EPR) and photo-EPR studies at room temperature to investigate the role of Cr3+ impurity in photoinduced electron transfer. Nominally pure crystals contained Fe3+ as impurity, and its EPR is consistent with work reported by previous investigators. The Cr3+ doped crystals also contained Fe3+ impurities. It was observed that the site symmetry and the strength of the axial field parameter for Fe3+ complex were significantly different in Cr3+ doped crystals compared to nominally pure BaTiO3. The EPR spectra of Cr3+ were distinguished using the hyperfine structure of odd isotope 53Cr (I=3/2). By Photo-EPR technique we observe that in the presence of Cr3+, Fe3+ is not significantly photosensitive. In contrast Cr3+ exhibited higher photosensitivity in the presence of Fe3+. This was monitored by locking the magnetic field to 1/2↔1/2 transition of Cr3+, and recording intensity as a function of time, under insitu laser illumination. In lightly doped crystals the intensity of Cr3+ signal is sharply reduced immediately after switching the laser OFF showing non-exponential decay. In heavily doped crystals photo-EPR signal clearly shows that the fast decay of Cr3+ was followed by slow and steady build up of Cr3+ signal. The growth of Cr3+ signal was attributed to photoinduced decoupling of Cr3+ dimers. Thus, by doping BaTiO3 with Cr3+ more efficient grating formation can be achieved and time dependent phenomena are observed.
Electron paramagnetic resonance (EPR) under the conditions of in situ laser illumination of the sample in the microwave
cavity, called photo-EPR is an excellent method to detect photo induced electron transfer in real time. We report Photo-
EPR results on the formation of clusters of magnetic ions in 0.67Pb(Mg1/3Nb2/3)O3. 0.33PbTiO3 (PMN-PT) on
illumination with blue laser at room temperature .The Photo EPR signal with g=2.00, agrees with Pb3+ formation. The
PMN-PT crystals 2-6mm size grown using PbO flux method were clear and transparent: and the upper part of the melt
yielded pink colored crystals containing a few hundred PPM of Fe3+ as seen by EPR Signal at g=4.3. The large linewidth
(~45 Gauss) of the photo-EPR signal and the presence of Fe3+ in the sample suggests the possibility of magnetic ion
cluster formation on blue laser excitation. When the photo-magnetic centers were produced in magnetic field of 7.5KG,
the signal was 30% more than that produced under switch-OFF condition of magnet having a remnant field of only 50G.
This critical observation is a clear pointer to the formation of photo-induced magnetic polarons at room temperature,
which are essentially clusters of ferromagnetically, coupled Fe3+ , Pb3+ and trapped electrons. The cluster formation and
decay exhibited fast optical response with growth and decay time less than or equal to 100msec. These observations show that PMN-PT
having excellent electromechanical properties can also be used for photomagnetic switching and real time holography
with fast grating response using Pb2+ <--> Pb3+ process. PMN-PT would have additional advantage compared to other
photo-refractive materials: due to possibility that the grating contrast can be manipulated by external magnetic field.
We have measured the rc (effective electrooptical coefficient) of pure and doped Ferroelectric Lithium Niobate (LN) using a single beam, null detection polarimeter. The polarimeter is adjustable between two adaptive optics configurations--an iris hard stop beam pattern on the one hand and a diffractive optics generated top-hat beam on the other. We clearly show the need to control thermal heating of LN due to the transmitted laser beam. The required heating control has been implemented using a fabricated metallic heat sink called a "Cold Finger." In addition to its electrooptical properties, LN possesses a combination of unique piezoelectric, pyroelectric, and photorefractive properties. These properties make it suitable for applications in optical devices as frequency doublers, modulators, switches, and filters in communication systems and holographic recording medium. We present the classical microscopic anharmonic oscillator description for generating Pockels coefficients, and briefly describe the polarimetry measurement system. Here, the growth of pure and iron doped lithium Niobate is also described using an Automatic Diameter Control Czochralski Design growth technique. The results of growth, electrooptic measurements, adaptive optics implementation and some physical properties are compared and presented.
The one-particle type temporal soliton exists by maintaining a balance between dispersive linear contributions on the one hand and non-linear effects on the other. The linear contributions occur from processes such as group velocity and polarization mode dispersion. The nonlinear features occur from Kerr, or power law non-Kerr behavior. In addition, a variety of perturbations, such as damping, Brillouin scattering, and Raman effects exist to alter the simple soliton solution. In this paper, we review the propagation of temporal solitons in power law non-Kerr media. This is developed through the higher nonlinear Schroedinger's equation (HNLSE). Also, the fundamentals of multiple-scales are presented that will be used to yield quasi-stationary solitons when perturbations are present. In waveguides, the one-particle type spatial soliton exists by maintaining a balance between the linear propagational diffraction and non-linear self-focusing, while possibly being subjected to a variety of perturbations. Here, we use a spatial optical soliton solution to the nonlinear Schroedinger equation in an inhomogeneous triangular refractive index profile as a small index perturbation to illustrate the oscillation property within a two dimensional waveguide. We determine, from the motion of spatial soliton, its effective acceleration, period of oscillation, and compare results with the Gaussian refractive index profile. Such spatial solitons behave as point masses existing in a Newtonian gravitational potential hole.
Ferroelectric Lithium Niobate (LN) possesses a combination of unique electrooptic, piezoelectric, pyroelectric, and photorefractive properties. These features make it suitable for applications in optical devices-as modulators, switches, and filters in communication systems and holographic recording medium, etc. Here, the growth of lithium Niobate doped with iron and doubly doped with iron and manganese ions will be described. The growth technique will be through Automatic Diameter Control Czochralski Design. From these grown crystals, critical electrooptical coefficients using null detection polarimetry are provided. The results of growth, electrooptic measurements, and some physical properties are compared and presented. Also, the use of doped LN crystals in devices is discussed.
Short pulse spectral content becomes modified while propagating in dispersive media. However, in dispersive nonlinear media, optical pulses resulting in solitary waves maintain their existence if proper balance is established between nonlinear self-phase modulation on the one hand and linear dispersion on the other. Such invariance pulse shape is critical for data transfer reliability in telecommunication technologies. Robust solitary waves that emerge from collisions unaltered are called solitons. During propagation of optical solitons in inhomogeneous media their trajectories are observed to deviate from straight-line paths to that of oscillatory behavior. Here, we use a spatial optical soliton solution to the nonlinear Schrödinger equation in an inhomogeneous triangular refractive index profile as a small index perturbation to illustrate the oscillation motion. We determine the effective acceleration, give the period of oscillation, and compare results with the Gaussian refractive index profile. Such spatial solitons behave as point masses existing in a Newtonian gravitational potential hole. This novel transverse oscillatory behavior, occurring for various refractive index profiles, results from an effectively bounded acceleration.
Albert Lim, Holger Jaenisch, James Handley, Miroslav Filipovic, Graeme White, Alex Hons, Cor Berrevoets, Gary Deragopian, Jeffrey Payne, Mark Schneider, Matthew Edwards
We present here a novel concept for achieving real-time super-resolution ground-based imagery for small aperture telescopes. We explore the combination of existing stacking and registration software in conjunction with real-time equation based Data Models. Our research indicates that for anisoplanatic imagery, a real-time video/software enhanced analog to conventional speckle imaging is possible. This paper highlights the technique and theory for creating such a system.
We present a method for simulating CCD focal plane array (FPA) images of extended deep sky objects using Data Modeling. Data Modeling is a process of deriving functional equations from measured data. These tools are used to model FPA fixed pattern noise, shot noise, non-uniformity, and the extended objects themselves. The mathematical model of the extended object is useful for correlation analysis and other image understanding algorithms used in Virtual Observatory Data Mining. We apply these tools to the objects in the Messier list and build a classifier that achieves 100% correct classification.
< 869.47 -3.27 41.37 602.25 10053.48 620.0042>
We propose a novel approach for index-tagging Virtual Observatory data files with descriptive statistics enabling rapid data mining and mathematical modeling. This is achieved by calculating at data collection time 6 standard moments as descriptive file tags. Data Change Detection Models are derived from these tags and used to filter databases for similar or dissimilar information such as stellar spectra, photometric data, images, and text. Currently, no consistent or reliable method for searching, collating, and comparing 2-D imagery exists. Traditionally, methods used to address these data problems are disparate and unrelated to text data mining and extraction. We explore the use of mathematical Data Models as a unifying tool set for enabling data mining across all data class domains.
We have developed the all-optical EO-modulator using a pulsed photogalvanic power supply driven by light illumination (coherent and incoherent). Generated by ferroelectric crystal with the photogalvanic effect (Fe-doped LiNbO3), electrical pulses were used for driving a standard EO-modulator, based on transversal EO effect in Bi12SiO20 (BSO) crystals. Both parallel and serial connections of photogalvanic crystal (LN), BSO and oscilloscope were tested. The depth of EO-modulation was very sensitive to the impedance of the connected cables, which implies the existence of transmission-line resonances. Secondly, a more compact version of EO self-modulation is realized with green (wavelength λ=532 nm, P=100mW) solid-state CW laser. In this case, reflection of the CW laser from the LN crystal was modulated in time. Pulsating optical reflection was correlated with the pulsating electrical signals. We report both modes of operation: (1) as pulsed high-voltage power supply, and (2) as compact-pulsed optical modulator. We have described these pulsations using model of photogalvanic effect and ferroelectric emission.
The growth of lithium niobate doped with iron and doubly doped with Iron and Manganese ions with optimum growth parameters by using automatic diameter control Czochralski system designed is briefly described. The results of investigation of optical and some physical properties of these crystals are presented and compared with pure LN crystals.
Salicylidene-aniline (SA) derivatives have been synthesized and characterized for optical and nonlinear optical properties. The substituents used as methyl (-CH3), chloro (-Cl), and nitro (-NO2) groups. These substituent groups show a variation in their electro-negativity characteristics and hence have the capacity to perturb the electrons system in the parent ring structure of the salicylidene-aniline compound. Material characterization has been done using various analytical tools namely: DSC, FTIR, UV-VIS and GC/MS. The nonlinear optical characterization has been done using the Kurtz powder efficiency method. The nonlinear refractive index and the third order susceptibility have been determined using the Z-Scan method in solution using ethanol as the solvent. The Kurtz powder efficiency measurements using urea as standard gives the values as 0.7 for 3-Cl SA, 0.8 3-NO2 SA and 1.0 for the 3-CH3 SA derivative. The results of single bulk crystals grown using the Bridgman-Stockbarger method are reported.
Photonics/laser related technologies and applications rely on a steady supply of device quality single crystals. For more than a decade, the main focus has been on high performance nonlinear optical materials that comply with device manufacturing and end-use conditions such as high performance, high thermal, mechanical and chemical stability. To this end a variety of organic and semi-organic NLO materials have been successfully synthesized, purified and grown into bulk single crystals. In the process of growing bulk single crystals, various novel techniques and processes have been developed. In this presentation, results of synthesis and crystal growth processing of the various NLO materials such as methyl-(2,4-dinitrophenyl)-aminopropionate: 2-methyl-4-nitroaniline (MAP:MNA), L-arginine phosphate, L-Histidine tetrafluoroborate, L-arginie tetrafluoroborate and other isomorphs, pure and doped Bismuth silicon oxide, pure and doped Lithium niobate crystals will be discussed including challenges faced, novel techniques and experimental set-ups developed in growing large high quality crystals.
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