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Full-Text Articles in Physics
Nonlinear Photoacoustics For Measuring The Nonlinear Optical Absorption Coefficient, Chandra S. Yelleswarapu, Sri-Rajasekhar Kothapalli
Nonlinear Photoacoustics For Measuring The Nonlinear Optical Absorption Coefficient, Chandra S. Yelleswarapu, Sri-Rajasekhar Kothapalli
Physics Faculty Publications
We report a novel photoacoustic Z-scan (PAZ-scan) technique that combines the advantages offered by the conventional Z-scan method and the sensitivity of the photoacoustic detection. The sample is scanned through the focused laser beam and the generated photoacoustic signal is recorded using a 10 MHz focused ultrasound transducer. Since the signal strength is directly proportional to the optical absorption, PAZ-scan displays nonlinear behavior depicting the nonlinear optical absorption of the material. Among many advantages, our experiments on mouse blood show that PAZ-scan can potentially be used as a standard technique to calibrate contrast agents used in theranostics in general and …
Enhancement Of Photoinduced Anisotropy And All-Optical Switching In Bacteriorhodopsin Films, Pengfei Wu, D.V.G.L.N. Rao, B. R. Kimball, M. Nakashima, B. S. Decristofano
Enhancement Of Photoinduced Anisotropy And All-Optical Switching In Bacteriorhodopsin Films, Pengfei Wu, D.V.G.L.N. Rao, B. R. Kimball, M. Nakashima, B. S. Decristofano
Physics Faculty Publications
Large enhancement of photoanisotropic effects is demonstrated in thin films of the biomaterial Bacteriorhodopsin by using two exciting beams of orthogonal polarization. The mechanism of the enhancement originates from optimization of direction-selected photoisomerization of the biomaterial controlled by the polarized exciting beams. The technique is applied for achieving an all-optical switch with the additional feature of output sign control.
Third‐Order, Nonlinear Optical Interactions Of Some Benzporphyrins, D.V.G.L.N. Rao, Francisco J. Aranda, Joseph F. Roach, David E. Remy
Third‐Order, Nonlinear Optical Interactions Of Some Benzporphyrins, D.V.G.L.N. Rao, Francisco J. Aranda, Joseph F. Roach, David E. Remy
Physics Faculty Publications
We measured third‐order, nonlinear optical susceptibility χ(3) for a series of tetrabenzporphyrins in solution in tetrahydrofuran at 532 nm using degenerate four‐wave mixing with picosecond pulses and obtained values of molecular second hyperpolarizability 〈γ〉. The corresponding macroscopic χ(3) values calculated for nine compounds with different substituent groups are four to five orders larger than CS2. For five of the compounds the χ(3) values are in the range 1.2–2.8×10−8 esu. Our experiments indicate that the nonlinearity is predominately electronic in origin with a response time faster than the 15 ps resolution of our system.