Papers by Partha Banerjee
In this Chapter, we provide a brief review of the underlying nonlinear Schrödinger and associated... more In this Chapter, we provide a brief review of the underlying nonlinear Schrödinger and associated equations that model spatio-temporal propagation in one and higher dimensions in a nonlinear dispersive environment. Particular attention is given to fast adaptive numerical techniques to solve such equations, and in the presence of dispersion and nonlinearity management, saturating nonlinearity and nonparaxiality. A unique variational approach is also outlined which
Applied Optics, 2015
Fresnel transform implementation methods using numerical preprocessing techniques are investigate... more Fresnel transform implementation methods using numerical preprocessing techniques are investigated in this paper. First, it is shown that up-sampling dramatically reduces the minimum reconstruction distance requirements and allows maximal signal recovery by eliminating aliasing artifacts which typically occur at distances much less than the Rayleigh range of the object. Second, zero-padding is employed to arbitrarily scale numerical resolution for the purpose of resolution matching multiple holograms, where each hologram is recorded using dissimilar geometric or illumination parameters. Such preprocessing yields numerical resolution scaling at any distance. Both techniques are extensively illustrated using experimental results.
Adaptive Optics: Analysis and Methods/Computational Optical Sensing and Imaging/Information Photonics/Signal Recovery and Synthesis Topical Meetings on CD-ROM, 2007
Recently, 2D-Laplace analysis of recording and readout of edge-holograms was reported. Numerical ... more Recently, 2D-Laplace analysis of recording and readout of edge-holograms was reported. Numerical Laplace inversion was examined for simple test cases. In this paper, inversion algorithms are applied to examine beam shaping and distortion in photovoltaic and photorefractive materials.
IEEE Access, 2014
In recent years, multilayer photonic bandgap structures comprising stacks of alternating layers o... more In recent years, multilayer photonic bandgap structures comprising stacks of alternating layers of positive and negative index have been proposed for a variety of applications, such as perfect imaging, filters, sensors, coatings for tailored emittance, absorptance, etc. Following a brief review of the history of negative index materials, the performance of such stacks is reviewed, with emphasis on analysis of plane wave and beam propagation, and possible applications in sensing. First, the use of the transfer matrix method to analyze plane wave propagation in such structures to determine the transmittance and reflectance is developed. Examples of cases where the Bragg bandgap and the so-called zero <n> gap can be used for possible applications in sensing are illustrated. Next, the transfer matrix approach is extended to simulate the spatial evolution of a collection of propagating and nonpropagating TE and TM plane waves (or plane wave spectra) incident on such multilayer structures. The use of the complex Poynting theorem in checking the computations, as well as monitoring powers and the stored electric or magnetic energy in any section of the multilayer stack, is illustrated, along with its use in designing alternating positive and negative index structures with optimal gain to compensate for losses in the negative index material. Finally, the robustness of PIM-NIM stacks with respect to randomness in the dimensions of the PIM-NIM structure is examined. This should be useful in determining the performance of such structures when they are physically fabricated. INDEX TERMS Metamaterials, periodic structures, complex Poynting theorem, power box, beam propagation, transfer matrix method, Anderson localization.
Journal of Nanophotonics, 2011
We theoretically explored the feasibility of a tunable metamaterial using binary as well as core-... more We theoretically explored the feasibility of a tunable metamaterial using binary as well as core-shell nanoparticle dispersed liquid crystal cells in the infrared and optical regimes. Owing to the spatial variation of the permittivity of the liquid crystal host upon the application of a bias voltage, the host was decomposed into a layered medium and the effective refractive index recalculated for each layer due to the distribution of polaritonic and plasmonic nanoparticles. The scattering, extinction, and absorption of such a nanoparticle dispersed liquid crystal cell were also found. Depending on the applied voltage bias across the liquid crystal host, the types of nanoparticles used, and their radii and volume-filling fractions in the liquid crystal host, near-zero as well as negative index of refraction can be obtained over a range of frequencies, according to the effective medium theory.
Photorefractive Optics, 2000
Physical Review A, 1998
We have developed a compact closed-form solution of the band transport model for high-contrast gr... more We have developed a compact closed-form solution of the band transport model for high-contrast gratings in photogalvanic crystals. Our solution predicts the effect of the photoconductivity and the electric field grating enhancement due to the photogalvanic effect. We predict a pronounced dependence of the steady-state photogalvanic current on the contrast of the interference pattern and an increase of holographic storage time due to the enhancement of the photoconductivity grating contrast. In the high contrast limit and a large photogalvanic effect the refractive index grating will be shifted from the position of the intensity modulation pattern, contrary to the usually adopted model of unshifted gratings. ͓S1050-2947͑98͒03610-5͔
Journal of the Optical Society of America B, 2005
Starting from the three-dimensional version of a standard photorefractive model (STPM), we obtain... more Starting from the three-dimensional version of a standard photorefractive model (STPM), we obtain a reduced compact set of equations for an electric field based on the assumption of a quasi-steady-state fast recombination. The equations are suitable for evaluation of a current induced by running gratings at small-contrast approximation and also are applicable for the description of space-charge wave domains. We discuss spatial domain and subharmonic beam formation in bismuth silicon oxide (BSO) crystals in the framework of the smallcontrast approximation of STPM. The experimental results confirming holographic current existence in BSO crystal are reported.
Optical Engineering, 1995
We have observed and explained three types of hexagon pattern formation in photo refractive cryst... more We have observed and explained three types of hexagon pattern formation in photo refractive crystal KNb0 3 :Fe. These are: (1) dynamic (laser induced), (2) semipermanent (holographically stored), (3) permanent (induced by a static domain grid) over a wide wavelength' range.
Applied Optics, 1998
Basic real-time programmable image-processing operations are accomplished by use of acousto-optic... more Basic real-time programmable image-processing operations are accomplished by use of acousto-optic ͑AO͒ cells. Instead of frequency-plane filters, the AO cells are placed directly behind the object. The onedimensional edge-enhancement results with one AO cell can be improved by use of two AO cells that are placed in tandem with contrapropagating sound. The dominant second-derivative operation obtained from the transfer function of the undiffracted order works like a one-dimensional Laplacian operator that enables improved edge enhancement.
We propose a technique in which intensity images are reconstructed from a digital hologram to pro... more We propose a technique in which intensity images are reconstructed from a digital hologram to provide inputs for the transport-of-intensity equation for unwrapped phase recovery. By doing this, we avoid shifting of the sample or the camera in the experiment, a method commonly employed while using the method of transport-of-intensity equation for phase retrieval. Computer simulations as well as experimental results have been demonstrated to verify the effectiveness of the proposed idea. The underlying numerical technique can also be viewed as an alternative to existing phase-unwrapping algorithms.
Propagation of optical fields is governed by the Helmholtz equation or the paraxial wave equation... more Propagation of optical fields is governed by the Helmholtz equation or the paraxial wave equation. Transport of intensity is a noninterferometric method to find the phase of an object by recording optical intensities at different distances of propagation. The transport of intensity equation results from the imaginary part of the complex paraxial wave equation and is equivalent to the principle of conservation of energy. The real part of the paraxial wave equation yields the Eikonal equation in the presence of diffraction. The amplitude and phase of the optical field must therefore simultaneously satisfy both the real and imaginary parts of the paraxial wave equation during propagation. In this paper, we demonstrate, with illustrative examples, how to exploit this to retrieve the phase through recursive calculations of the phase and intensity. This is achieved using the transport of intensity equation, which is solved using standard techniques, and the real part of the paraxial wave equation, or the transport of phase equation, which is solved using a Gauss–Seidel iterative method. Examples include calculation of the imaged phase induced through self-phase modulation of a focused laser beam in a liquid and the imaged phase of light reflected from a surface, which yields the 3D surface profile.
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Papers by Partha Banerjee