Prof. Devulapalli V. Rao Profile

Prof. Devulapalli V. Rao

Distinguished Professor of Physics at Univ of Massachusetts Boston

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Author

Publications (24)

Proceedings Article | 12 April 2013 Paper

Transient Fourier holography with bacteriorhodopsin films for breast cancer diagnostics

Devulapalli Rao, Sri-Rajasekar Kothapalli, Pengfei Wu, Chandra Yelleswarapu

Proceedings Volume 8598, 85980K (2013) https://doi.org/10.1117/12.2020227

KEYWORDS: Image processing, Mammography, Diffraction, Holography, Spatial frequencies, Image enhancement, Beam splitters, Diffraction gratings, Breast cancer, Holograms

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Proceedings Article | 15 June 2011 Paper

Fourier phase contrast multimodal optical microscopy for real time display of phase and fluorescence at the same time

Chandra Yelleswarapu, Bhargab Das, Alexey Veraksa, D. V. G. L. Rao

Proceedings Volume 8090, 809006 (2011) https://doi.org/10.1117/12.889375

KEYWORDS: Luminescence, Phase contrast, Liquid crystals, Image filtering, Image enhancement, Optical filters, Microscopes, Microscopy, Spatial frequencies, Spatial filters

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Proceedings Article | 22 February 2011 Paper

Photoacoustic Z-scan for the measurement of third-order nonlinear absorption coefficient

Chandra Yelleswarapu, Sri-Rajasekhar Kothapalli, D. V. G. L. Rao

Proceedings Volume 7917, 79171I (2011) https://doi.org/10.1117/12.875470

KEYWORDS: Absorption, Photoacoustic spectroscopy, Nonlinear optics, Transient nonlinear optics, Signal to noise ratio, Physics, Transducers, Biomedical optics, Refraction, Signal generators

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Proceedings Article | 11 February 2011 Paper

In-line digital holographic microscopy based on intensity measurements at two planes

Bhargab Das, Chandra Yelleswarapu, D. V. G. L. N. Rao

Proceedings Volume 7904, 790403 (2011) https://doi.org/10.1117/12.875449

KEYWORDS: Holograms, Digital holography, 3D image reconstruction, Image processing, Microscopy, Holography, Charge-coupled devices, Cameras, Phase shifts, Diffraction gratings

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Proceedings Article | 13 September 2007 Paper

Completely passive nonlinear transmission system using a nonlinear absorbing medium and azobenzene films

Chandra Yelleswarapu, D. V. G. L. N. Rao, Brian Kimball

Proceedings Volume 6653, 665312 (2007) https://doi.org/10.1117/12.733176

KEYWORDS: Complex systems, Polarization, Absorption, Molecules, Polarizers, Anisotropy, Laser beam diagnostics, Transmittance, Beam splitters, Nonlinear optics

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Proceedings Article | 29 September 2006 Paper

The complex optical response of arrays of aligned multiwalled carbon nanotubes

Keith Gregorczyk, Brian Kimball, Joel Carlson, Asher Pembroke, Krzysztof Kempa, Zhifeng Ren, Chandra Yelleswarapu, Thomas Kempa, Glynda Benham, Y. Wang, Wenzhi Li, A. Herczynski, Jacob Rybczynski, D. V. G. L. N. Rao

Proceedings Volume 6321, 63210G (2006) https://doi.org/10.1117/12.680765

KEYWORDS: Antennas, Solar energy, Carbon nanotubes, Polarization, Visible radiation, Chromium, Photovoltaics, Electromagnetic radiation, Microwave radiation, Polarizers

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Proceedings Article | 18 August 2005 Paper

Spectroscopic studies of arrays of multiwalled carbon nanotubes

Brian Kimball, Joel Carlson, Asher Pembroke, Krzysztof Kempa, Z. Ren, Pengfei Wu, Chandra Yelleswarapu, Thomas Kempa, Glynda Benham, Y. Wang, A. Herczynski, Jakub Rybczynski, Z. Huang, D. V. G. L. N. Rao

Proceedings Volume 5931, 59310X (2005) https://doi.org/10.1117/12.617968

KEYWORDS: Antennas, Carbon nanotubes, Light sources, Diffraction, Spectroscopy, Light, Lithography, Optical properties, Polarization, Polarizers

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SPIE Journal Paper | 1 July 2005 Open Access

Nonlinear optical Fourier filtering technique for medical image processing

Sri-Rajasekhar Kothapalli, Pengfei Wu, Chandra Yelleswarapu, Devulapalli Rao

JBO, Vol. 10, Issue 04, 044028, (July 2005) https://doi.org/10.1117/12.10.1117/1.1953287

KEYWORDS: Mammography, Spatial frequencies, Optical filters, Image processing, Beam controllers, Nonlinear filtering, Image filtering, Spatial light modulators, Medical imaging, Image enhancement

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Proceedings Article | 8 October 2004 Paper

Diffraction effects in honeycomb arrays of multiwalled carbon nanotubes

Brian Kimball, Joel Carlson, Diane Steeves, Krzysztof Kempa, Zhifeng Ren, Pengfei Wu, Thomas Kempa, Glynda Benham, Y. Wang, Wenzhi Li, A. Herczynski, Jacob Rybczynski, Devulapali Rao

Proceedings Volume 5515, (2004) https://doi.org/10.1117/12.559752

KEYWORDS: Diffraction, Polarization, Antennas, Carbon nanotubes, Optical properties, Light scattering, Visible radiation, Scattering, Lithography, Plasma enhanced chemical vapor deposition

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Proceedings Article | 24 November 2003 Paper

Optical properties of honeycomb arrays of multiwalled carbon nanotubess

Brian Kimball, Joel Carlson, Krzysztof Kempa, Wenzhi Li, Zhifeng Ren, Pengfei Wu, Devulapalli Rao, Jacob Rybczynski, Michael Giersig, Zhongping Huang, David Carnahan, Diane Steeves, Michael Sennett

Proceedings Volume 5224, (2003) https://doi.org/10.1117/12.508016

KEYWORDS: Diffraction, Silicon, Polarization, Optical properties, Light scattering, Carbon nanotubes, Reflectivity, Visible radiation, Photonic crystals, Scattering

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Proceedings Article | 16 January 2002 Paper

Evaluation of experimental laser-induced-damage assessment techniques for solid state nonlinear optical elements

Brian Kimball, Kenneth Altshuler, Samuel Cohen, Barry DeCristofano, Masato Nakashima, Appaji Panchangam, Devulapalli Rao, Pengfei Wu

Proceedings Volume 4462, (2002) https://doi.org/10.1117/12.452741

KEYWORDS: Modulation, Laser damage threshold, Sensors, Laser induced damage, Imaging systems, Optical components, Image resolution, CCD image sensors, Line scan image sensors, Absorption

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Proceedings Article | 16 January 2002 Paper

Numerical simulations of solvent effects on optical transmission processes for zinc porphyrins

Masato Nakashima, Landa Hoke, Brian Kimball, Gregory Kowalski, Barry DeCristofano, Paula Rosenof, Desai Rao, Devulapalli Rao

Proceedings Volume 4462, (2002) https://doi.org/10.1117/12.452720

KEYWORDS: Picosecond phenomena, Transmittance, Nonlinear optics, Zinc, Quantum efficiency, Numerical simulations, Absorption, Thermal effects, Thermal modeling, Laser beam propagation

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Proceedings Article | 29 November 2000 Paper

Solvent effect on optical limiting of zinc tetrabenzoporphyrin compounds

Brian Kimball, Masato Nakashima, Barry DeCristofano, N.K.M. Naga Srinivas, P. Premkiran, Desai Rao, Appaji Panchangam, Devulapalli Rao

Proceedings Volume 4106, (2000) https://doi.org/10.1117/12.408513

KEYWORDS: Absorption, Picosecond phenomena, Optical limiting, Data modeling, Zinc, Nonlinear optics, Molecules, Solids, Chlorine, Sensors

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Proceedings Article | 4 October 1999 Paper

Optical power limiting in some azulenic compounds

Brian Kimball, Masato Nakashima, Barry DeCristofano, Appaji Panchangam, Sriraj Bhadra, Devulapalli Rao, Francisco Aranda, Alfred Asato, Robert Liu

Proceedings Volume 3798, (1999) https://doi.org/10.1117/12.363879

KEYWORDS: Absorption, Four wave mixing, Saturable absorption, Nonlinear optics, Picosecond phenomena, Transmittance, Chromophores, Nd:YAG lasers, Polarizability, Molecules

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Proceedings Article | 4 October 1999 Paper

Optical power limiting in ZnO crystals

Francisco Aranda, Meckie Harris, Michael Callahan, John Bailey, Michael Suscavange, David Bliss, Brian Kimball, Masato Nakashima, Barry DeCristofano, Devulapalli Rao

Proceedings Volume 3798, (1999) https://doi.org/10.1117/12.363878

KEYWORDS: Crystals, Zinc oxide, Nonlinear crystals, Absorption, Wide bandgap semiconductors, Sensors, Picosecond phenomena, Silicon, Laser crystals, Refraction

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Proceedings Article | 16 October 1998 Paper

Third-order nonlinear optics of some azulenic donor-acceptor compounds

Brian Kimball, Masato Nakashima, Barry DeCristofano, Francisco Aranda, Devulapalli Rao, Alfred Asato, Robert Liu

Proceedings Volume 3473, (1998) https://doi.org/10.1117/12.328180

KEYWORDS: Molecules, Absorption, Sensors, Picosecond phenomena, Nonlinear optics, Four wave mixing, Refractive index, Saturable absorption, Beam splitters, Signal detection

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Proceedings Article | 2 January 1998 Paper

Photonic applications of bacteriorhodopsin

Devulapalli Rao, Francisco Aranda, Joby Joseph, Joseph Akkara

Proceedings Volume 3211, (1998) https://doi.org/10.1117/12.345549

KEYWORDS: Modulation, Absorption, Fourier transforms, Proteins, Semiconductor materials, Semiconductors, Optical recording, Data processing, Genetic engineering, Molecular photonics

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The photochromic protein bR is receiving much attention as an interesting alternative to conventional inorganic semiconductor based materials for a variety of applications in optical recording and information processing. Recent advances in genetic engineering techniques for tailoring molecular properties without degrading of its inherent mechanical and thermal stability make it an outstanding photonic material. Some of the photonic applications already demonstrated by our group are reviewed. We exploit the parallel processing of optics and the real-time nature of bR films for the implementation of several photonic applications. We reported a convenient method to obtain all-optical light modulation in bacteriorhodopsin films using a degenerate four-wave mixing geometry. Chemically stabilized films of bacteriorhodopsin in a polymer matrix for which the life time of the excited M state is tens of seconds are used to demonstrate all-optical light intensity modulation. Small intensities of order mW/cm2 are used in the modulation experiments. The fast photochemical transition from M to B permits reasonably fast modulation speeds independent of the slow thermal M to B relaxation time. The experimental system can also be viewed as an all-optical switch, that uses molecular states in a bacteriorhodopsin thin film, where a low power blue pulse turns on a signal red beam. All-optical logic gates are implemented with wild- type and chemically stabilized films of bacteriorhodopsin using a two-color backward degenerate four- wave mixing geometry. The sensitivity of each bR film is markedly different due to the large differences in the saturation intensity. Red light is used to form a grating due to the B to M transition and blue light is used to form a grating due to the fast photochemical transition from M to B. Each of the two wavelengths in the experimental system acts as an input to the all-optical gate and the phase conjugate signal beam bears the output of the gate. To establish the origin of the nonlinearity we studied the intensity dependence of the self-focusing and self-defocusing properties of wild-type bR in water solution using the Z-scan technique with low power cw lasers at two wavelengths on either side of the absorption band. Our measurements indicate that the sign of the nonlinearity depends on the wavelength and the magnitude depends on the fluence of the incident laser beam. The observed self-defocusing and focusing is not due to the intrinsic electronic nonlinearity. The observations can be explained in terms of the Kramers-Kronig dispersion relation that relates the real and imaginary parts of the complex index of refraction to the absorption spectrum.We developed an optical pattern recognition system using Optical Fourier Transform with bR films. The photoinduced dichroism and its dependence on light intensity allows one to use the bR film as a real-time self-adaptive spatial filter at the FT plane. We also demonstrate flow disturbance visualization and beam shaping.

Proceedings Article | 24 October 1997 Paper

Optical logic operations using photoinduced anisotropy in bacteriorhodopsin films

Joby Joseph, Francisco Aranda, Devulapalli Rao, Joseph Akkara, Barry DeCristofano

Proceedings Volume 3159, (1997) https://doi.org/10.1117/12.279449

KEYWORDS: Polarization, Molecules, Logic, Laser beam diagnostics, Dichroic materials, Proteins, Absorption, Molecular electronics, Polarizers, Anisotropy

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Proceedings Article | 10 October 1997 Paper

Optical power limiting in solid state porphyrin polycarbonate composites

Francisco Aranda, Devulapalli Rao, Brian Kimball, Barry DeCristofano, Masato Nakashima, Joseph Akkara, Debra Trantolo, Y. Hsu

Proceedings Volume 3146, (1997) https://doi.org/10.1117/12.279303

KEYWORDS: Absorption, Composites, Solid state physics, Molecules, Saturable absorption, Eye, Laser damage threshold, Metals, Sensors, Thin films

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Proceedings Article | 7 October 1996 Paper

Nonlinear absorption of tetrabenzporphyrins

Francisco Aranda, Desai Rao, Devulapalli Rao, Masato Nakashima, Barry DeCristofano

Proceedings Volume 2853, (1996) https://doi.org/10.1117/12.253474

KEYWORDS: Absorption, Molecules, Picosecond phenomena, Thin films, Molecular aggregates, Glasses, Saturable absorption, Polymethylmethacrylate, Sensors, Chromophores

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Proceedings Article | 7 October 1996 Paper

Optical power limiting in solutions of polyphenylquinoxalines

Brian Kimball, Masato Nakashima, Joseph Roach, Adam Jaglowski, Francisco Aranda, Devulapalli Rao

Proceedings Volume 2853, (1996) https://doi.org/10.1117/12.253475

KEYWORDS: Absorption, Scattering, Refraction, Light scattering, Polymers, Transmittance, Saturable absorption, Nonlinear optics, Optics manufacturing, Opacity

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Proceedings Article | 3 October 1996 Paper

All-optical logical gates with bacteriorhodopsin films

Devulapalli Rao, Francisco Aranda, Desai Rao, Z. Chen, Joseph Akkara, Masato Nakashima

Proceedings Volume 2897, (1996) https://doi.org/10.1117/12.252925

KEYWORDS: Proteins, Photonics, Molecular photonics, Genetics, Optical computing, Data processing, Thin films, Switches, Logic, Four wave mixing

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Proceedings Article | 1 September 1996 Paper

Applications of bacteriorhodopsin films for optical modulation and logic operations

D. V. G. L. N. Rao

Proceedings Volume 2778, 2778AK (1996) https://doi.org/10.1117/12.2316069

KEYWORDS: Modulation, Logic, Absorption, Physics, Proteins, Molecules, Switching, Logic devices, Phase conjugation, Switches

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Proceedings Article | 1 April 1992 Paper

Self-focusing in bioengineered polymers

George Fischer, Joseph Akkara, Francisco Aranda, Joseph Roach, David Kaplan, D. Ghosh Roy, Devulapalli Rao

Proceedings Volume 1626, (1992) https://doi.org/10.1117/12.58122

KEYWORDS: Polymers, Neodymium, Nonlinear optics, Chromium, Ruby lasers, Four wave mixing, Refractive index, Laser beam propagation, High power lasers, Liquids

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Showing 5 of 24 publications

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