Shabbir Mian - Academia.edu (original) (raw)

Papers by Shabbir Mian

Supplemental Material, NM_NT_SI_rev for C-Si hybrid photonic structures by full infiltration of c... more Supplemental Material, NM_NT_SI_rev for C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters by Valentina Robbiano, Salvatore Surdo, Alessandro Minotto, Giancarlo Canazza, G Mattia Lazzerini, Shabbir M Mian, Davide Comoretto, Giuseppe Barillaro, and Franco Cacialli in Nanomaterials and Nanotechnology

Nanomaterials and Nanotechnology, 2018

Loading of one-dimensional (1-D) porous silicon photonic crystals (PS-PhCs), known as rugate filt... more Loading of one-dimensional (1-D) porous silicon photonic crystals (PS-PhCs), known as rugate filters, with luminescent materials is generally limited by the potential for (undesired) “pore clogging,” in relation to the size of the nanoparticles (e.g. quantum dots) or molecular species, and so far mainly restricted to small molecular weight materials or small nanocrystals, or in situ polymerized dyes. Here we report the infiltration 1-D PS-PhCs with a green-emitting commercial luminescent polymer (F8BT, poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,8-diyl)]), with a molecular weight of approximately 46 kDa across their whole depth (approximately 7.5 μm), thereby showing that pore clogging is not a concern for these structures. We also characterize the modification of the photoluminescence (PL) and decay rates, and investigate the detailed inner morphology of the filters with the help of (scanning) transmission electron microscopy. We observe both suppression (...

2018 Conference on Laboratory Instruction Beyond the First Year of College, 2018

The Physics Teacher, 2015

Constructing ray diagrams to locate the image of an object formed by thin lenses and mirrors is a... more Constructing ray diagrams to locate the image of an object formed by thin lenses and mirrors is a staple of many introductory physics courses at the high school and college levels, and has been the subject of some pedagogy-related articles. Our review of textbooks distributed in the United States suggests that the singular approach involves drawing principle rays to locate an object's image. We were pleasantly surprised to read an article in this journal by Suppapittayaporn et al. in which they use an alternative method to construct rays for thin lenses based on a “tilted principle axis” (TPA). In particular, we were struck by the generality of the approach (a single rule for tracing rays as compared to the typical two or three rules), and how it could help students more easily tackle challenging situations, such as multi-lens systems and occluded lenses, where image construction using principle rays may be impractical. In this paper, we provide simple “proofs” for this alternat...

Aps March Meeting Abstracts, Mar 1, 1996

AIP Conference Proceedings, 2005

2015 Conference on Laboratory Instruction Beyond the First Year, 2015

Organic and Hybrid Photonic Crystals, 2015

We report the modification of the photoluminescence (PL) and decay rates of two different green-e... more We report the modification of the photoluminescence (PL) and decay rates of two different green-emitting conjugated polymers incorporated into photonic crystals with the stop-bands spectrally tuned on their emission. We observe both suppression (in the stop-band) and enhancement (at the high-energy band-edge) of the photoluminescence. Time-resolved measurements also reveal a concomitant modification of the emission lifetime that is enhanced at the band-edge and suppressed within the stop-band, thus confirming a variation of the radiative decay rate of the excitations in such photonic nanostructures. We propose two examples of fluorescent photonic composite systems. The first consists of a hybrid Si-organic system, obtained by infiltration of the polymer inside a rugate filter (a 1D photonic crystal). The second example is a fully organic system obtained by self-assembling of solvent-compatible microspheres-polymer system for obtaining a synthetic opal (a 3D photonic crystal) with a uniform distribution of the emitting material across the photonic structure.

Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37088), 2000

Summary form only given.This work demonstrates the use of interference effects in enhancing the c... more Summary form only given.This work demonstrates the use of interference effects in enhancing the coupling of an input laser beam into the tight cross-section of a periodically segmented KTiOPO/sub 4/ waveguide yielding a three fold increase in its SHG output. In combination with the differential heating technique reported earlier, the use of this technique can result in compact blue laser sources meeting the minimum power requirements for several applications.

Rayleigh-Brillouin scattering spectra of Eu^3+ and Pr^3+ doped alumino-silicate glasses have been... more Rayleigh-Brillouin scattering spectra of Eu^3+ and Pr^3+ doped alumino-silicate glasses have been measured to investigate the physical properties of the alumino-silicate glasses with different Eu^3+ and Pr^3+ concentrations. The applications of the spectra with various Eu^3+ and Pr^3+ concentrations have resulted in valuable information for understanding the glass structures and optical properties of glasses. Values of the elastic and photo-elastic

ABSTRACT Brillouin scattering spectra of rare earth doped glasses have been measured to investiga... more ABSTRACT Brillouin scattering spectra of rare earth doped glasses have been measured to investigate the differences of optical properties of soda magnesia alumina silicate glasses with different Eu3+ and Pr3+ concentrations. Measurements of Brillouin frequency shifts and intensities along with refractive indexes and densities allow us to calculate the acoustic sound velocities, elastic and photoelastic constants. The physical significance of the changes in elastic and photoelastic constants as a function of rare earth content and type is discussed. The results on elastic constants show that the glasses become harder with increasing concentration of the high coordinated rare earth modifiers. From Carleton's model, the Lorentz-Lorenz effect dominates P12, while the atomic effect dominates P44 in our glasses. The increase in both the bond polarisability parameter and Poisson's ratio with the rare earth concentration indicates the enhancement in polarisability and ionicity of these glasses.

Radiation Protection Dosimetry, 2001

A new thermoluminescence glow curve deconvolution (GCD) function is introduced which accurately d... more A new thermoluminescence glow curve deconvolution (GCD) function is introduced which accurately describes first order thermoluminescence (TL) curves. The new GCD function is found to be accurate for first order TL peaks with a wide variety of the values of the TL kinetic parameters E and s. The 3-parameter Weibull probability function is used with the function variables being the maximum peak intensity (Im), the temperature of the maximum peak intensity (Tm) and the Weibull width parameter b. An analytical expression is derived from which the activation energy E can be calculated as a function of Tm and the Weibull width parameter b. The accuracy of the Weibull fit was tested using the ten reference glow curves of the GLOCANIN intercomparison program and the Weibull distribution was found to be highly effective in describing both single and complex TL glow curves. The goodness of fit of the Weibull function is described by the Figure of Merit (FOM) which is found to be of comparable accuracy to the best FOM values of the GLOCANIN program. The FOM values are also comparable to the FOM values obtained using the recently published GCD functions of Kitis et al. It is found that the TL kinetic analysis of complex first-order TL glow curves can be performed with high accuracy and speed by using commercially available software packages.

Journal of the Optical Society of America B, 1996

Journal of Applied Physics, 2007

We report on electroabsorption (EA) and built-in voltage (VBI) measurements of polymer light-emit... more We report on electroabsorption (EA) and built-in voltage (VBI) measurements of polymer light-emitting diodes with the general structure ITO/PEDOT:PSS/emitting polymer/LiF∕Ca∕Al where ITO is indium tin oxide, PEDOT:PSS is poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate), and the emitting polymer is either poly(9,9-dioctylfluorene), poly(9, 9-dioctyl-fluorene-alt-bis-N,N′-(4-butyl-phenyl)-bis-N,N′-phenyl-1, 4-phenylenediamine), or poly(9,9-dioctylfluorene-alt-N-(4-butylphenyl)-diphenylamine). We find that the EA nulling voltage, i.e., the dc bias at which the EA signal vanishes, depends on the frequency of the ac voltage and on the incident photon wavelength. Such dependence poses a problem for accurate measurement of the built-in voltage (VBI), which is the voltage generated between the electrodes upon equilibration of the Fermi levels through the heterostructure. We find that the EA signal is mixed with a smaller intensity signal which can be ascribed to excited ...

Journal of Applied Physics, 1995

We have investigated optical nonlinearities using a beam that has a transverse elliptic Gaussian ... more We have investigated optical nonlinearities using a beam that has a transverse elliptic Gaussian profile. The popular single-beam technique known as Z-scan complimented with optical limiting experiments are analyzed in this study. A geometric optics model including both nonlinear refraction and absorption is developed in the aberration-free approximation. We have found good agreement between theory and experimental data taken from a lead silicate glass where the elliptic beam had an eccentricity of about 0.98.

Applied Physics Letters, 2012

We investigate the functionalization of gold anodes with azobenzene-based self-assembled monolaye... more We investigate the functionalization of gold anodes with azobenzene-based self-assembled monolayers (AZO-SAM) and the influence of such functionalization on the external quantum efficiency (EQE) of polyfluorene-based light-emitting diodes (LEDs). Photoluminescence and electroluminescence measurements show that the AZO-SAMs do not modify the shape of the emission spectrum of the active layer. Instead, AZO-SAMs enhance the EQE of LEDs by an order of magnitude (from 0.018% to 0.18%) and decrease the turn-on voltage from 7.9 V to 6.2 V by reducing the injection barrier at the anode, thus promoting a better balance between hole and electron populations in the active layer.

Applied Physics Letters, 1999

We show that optical interference of two input beams coupled into a periodically segmented KTiOPO... more We show that optical interference of two input beams coupled into a periodically segmented KTiOPO4 waveguide can increase the efficiency of the generated second harmonic by a factor of three over coupling a single beam with the same total power. A simple model based on two interfering Gaussian beams indicates that the second harmonic output increases by enhancing the coupling of the fundamental energy into the waveguide. A Mach–Zehnder interferometer scheme is used to demonstrate this effect. The variation of the second harmonic power with the fundamental input power of the interfering beams shows excellent qualitative agreement between experimental results and the model presented.