****Technical Abstract**** Measurements of the spectrum of the microwave field pattern at the output surface and on a line along the length of disordered samples generated by a source moved to points on a grid over the sample's input surface will provide a comprehensive picture of waves transport. Related measurements will be carried out using laser light and a spatial light modulator and CCD camera. The analyses of these measurements will be supplemented with finite difference time domain numerical simulations. This research will advance four distinct perspectives on wave transport and the relationships between them: the spatial structure of (1) modes and (2) transmission eigenchannels, as well as the variation with position of (3) the local diffusion coefficient, and (4) the field speckle pattern for both diffusive and localized waves. Wave statistics determined in single samples will guide applications to focusing, imaging, and enhanced transmission in random systems. The joint experimental, theoretical and numerical study of fundamental and applied aspects of propagation using microwave radiation and light will provide and ideal learning experience for the undergraduate, graduate, and high school students and the postdoctoral fellow involved in this research. The work will strengthen the photonics initiative at CUNY and foster photonic technological in the New York City area.
The manner in which waves propagate in random media affects our ability to communicate and image and to create electronic and photonics devices. The study of waves in multiply-scattering systems is all the more challenging because of the twin difficulties of probing the interior of scattering samples and measuring the full scattered field. In this project, we will measure the wave pattern generated by sources of microwave radiation and light at various positions on the output of disordered samples as well as microwave radiation in the interior of such samples. This full set of measurements will allow us to determine the natural modes of oscillation as well as the specific transmission channels for waves in each random sample as well as the position dependent flux and intensity of the wave and the nature of fluctuations of intensity throughout the sample. The work will enable optimal focusing through and within random systems and will yield nearly complete transmission even in ordinarily opaque systems. The use of both microwave and laser measurements for challenging fundamental and applied problems will advance the education and careers of graduate students, undergraduates, high school students and a postdoctoral fellow involved in the research. The success of this work will strengthen the CUNY Photonic Center established to enhance the technological base of the New York City metropolitan area.
