The Woodruff School

SUMMARY

Tailoring the spectral and directional radiative properties of engineered micro/nanostructures has enormous applications in photonics, microelectronics, and energy conversion systems. This thesis aims at (1) design and analysis of micro/nanostructures based on magnetic resonance and wave interference effects to achieve tunable coherent thermal emission or enhanced optical transmission; (2) microfabrication of the designed structures; and (3) measurement of the radiative properties of the fabricated samples using spectrometric techniques at temperatures from 300 K to 800 K. Magnetic polaritons have been recognized as a mechanism to achieve extraordinary optical transmission/absorption, through the comparison between an equivalent LC circuit model and the rigorous coupled-wave analysis (RCWA). With carefully tuned geometric parameters, the resonant frequencies can be favorably tailored for specific applications. A coherent emission source can be realized with deep gratings by excitation of magnetic polaritons and has been explained through the LC circuit model. Different from the surface plasmon/phonon polaritons, the magnetic polaritons are insensitive to the directions, and associated electromagnetic field is strongly localized. A test structure will be fabricated using a metallic slit array and a thin film separated by a spacer, and tested for coherent thermal emission. An asymmetric Fabry-Perot resonant cavity was studied as a potential coherent emission source based on the wave interference effect. The reflectance is measured at room temperature using a Fourier transform infrared spectrometer, and the emittance can be indirectly obtained from Kirchhoff�s law. A high-temperature emissometer was built to measure the thermal emission of fabricated samples at elevated temperatures. Cautions need to be taken for layered structures with nonuniform temperature distributions, and a generalized Kirchhoff�s law was deduced from the direct and indirect approaches. The results obtained from this thesis will facilitate the design and application of nanostructures in energy-harvesting systems.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Liping Wang

TIME:	Monday, February 21, 2011, 8:00 a.m.

PLACE:	Love Building, 109

TITLE:	Role of Magnetic Resonance and Wave Interference in Tailoring the Radiative Properties of Nanostructures

COMMITTEE:	Dr. Zhuomin Zhang, Chair (ME) Dr. Levent Degertekin (ME) Dr. Peter Hesketh (ME) Dr. David Citrin (ECE) Dr. Phillip First (Physics)

SUMMARY Tailoring the spectral and directional radiative properties of engineered micro/nanostructures has enormous applications in photonics, microelectronics, and energy conversion systems. This thesis aims at (1) design and analysis of micro/nanostructures based on magnetic resonance and wave interference effects to achieve tunable coherent thermal emission or enhanced optical transmission; (2) microfabrication of the designed structures; and (3) measurement of the radiative properties of the fabricated samples using spectrometric techniques at temperatures from 300 K to 800 K. Magnetic polaritons have been recognized as a mechanism to achieve extraordinary optical transmission/absorption, through the comparison between an equivalent LC circuit model and the rigorous coupled-wave analysis (RCWA). With carefully tuned geometric parameters, the resonant frequencies can be favorably tailored for specific applications. A coherent emission source can be realized with deep gratings by excitation of magnetic polaritons and has been explained through the LC circuit model. Different from the surface plasmon/phonon polaritons, the magnetic polaritons are insensitive to the directions, and associated electromagnetic field is strongly localized. A test structure will be fabricated using a metallic slit array and a thin film separated by a spacer, and tested for coherent thermal emission. An asymmetric Fabry-Perot resonant cavity was studied as a potential coherent emission source based on the wave interference effect. The reflectance is measured at room temperature using a Fourier transform infrared spectrometer, and the emittance can be indirectly obtained from Kirchhoff�s law. A high-temperature emissometer was built to measure the thermal emission of fabricated samples at elevated temperatures. Cautions need to be taken for layered structures with nonuniform temperature distributions, and a generalized Kirchhoff�s law was deduced from the direct and indirect approaches. The results obtained from this thesis will facilitate the design and application of nanostructures in energy-harvesting systems.