| Research Abstract |
In this research, firstly we analyzed the dispersion relation and the lifetime of photonic bands, and the frequency and the quality factor of localized defect modes in the pseudo-gap for photonic crystal slabs that can be fabricated on semiconductor substrates. We clarified the dispersion relation and the symmetry of photonic bands originating from plasmons for metallic photonic crystals in which very small group velocity of light is expected to be realized. Secondly we picked up the quadrature-phase squeezing as a representative example of quantum optical phenomena utilizing the second-order nonlinear optical effect. We clarified the enhancement effect due to the small group velocity by means of an approximate solution obtained by the Green function method. We also developed a numerical method to deal with the quantum fluctuation of the electromagnetic field in the linear approximation, and applied it to the photonic crystal slab.
In addition, we analyzed the superradiance, which is a cooperative light emission by a coherent polarization of matter, and examined the large Rabi splitting, partial relaxation of the population inversion of the electronic system, and the extraordinary atom-number dependence of the superradiant pulse shape caused by the photonic band gap. On the other hand, in cooperation with Dayton University, we fabricated waveguides made of LiNbO3 by the ion exchange method that has the second-order nonlinear susceptibility. We further fabricated one-and two-dimensional periodic patterns of a photoresist on the waveguide to make weakly modulated photonic crystal slabs, and examined their characteristics. We also synthesized new organic materials with the large second-order nonlinear susceptibility. We published two books from Springer Verlag and Morikita Publishing, in which the major works of the head investigator in the last ten years including the above-mentioned studies were collected.
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