Enhancement of Optical Properties in Artificial Metal-dielectric Structures

The thesis consists of 7 self-contained chapters. Following the introductory Chapter 1, in Chapter 2, I analyze the enhancement of radiation in HMMs by going beyond usual “effective medium” model and discovering many interesting phenomena that augment and, in some cases, contradict the established results. I discover that Purcell enhancement of radiation is always present in metal dielectric structures and that it results from the direct coupling of the energy into the free electron motion in the metal that leads to quenching of the radiative lifetime. In Chapter 3, I study the so-called hyperlensing purportedly capable of imaging sub-wavelength objects. I analyze the imaging properties of HMMs by using newly developed Eigen-mode approach as well as by transfer matrix method. In Chapter 4, I study arrays of subwavelength resonant features made form metals and dielectrics. In this arrays mid-infrared fields get greatly enhanced which is extremely important for applications in sensing. I establish that to achieve the strongest enhancement, one still needs to use metals, due to high free carrier density in them. That makes the metals preferred in fluorescence or Raman sensing. The subject of Chapter 5 is also related to the mid-infrared region where I explore the light manipulation with metasurface consisting of metal-isolator metal (MIM) resonators. Based on theoretical analysis and simulation performed by me, a metasurface was designed and fabricated using nanoimprint method and later analyzed using Fourier Transform Infrared Spectrometry. Chapter 6 is dedicated to a new material that can be greatly broaden the range of features attainable in metal dielectric structure – a two-dimensional MoS2. An origami-inspired self-folding approach is used to reversibly transform MoS2 into functional 3D optoelectronic devices. We demonstrated that the 3D self-folded MoS2 structures show enhanced light interaction and are capable of angle-resolved photodetection. Chapter 7 deals with periodically poled lithium niobate for frequency conversion for a novel application – development of non-magnetic optical isolator – a key component for application in optical communications and especially in integrated optics. The nonmagnetic isolator based on frequency converter was proposed, designed, fabricated and tested showing excellent performance characteristics in terms of isolation ratio exceeding 20dB

Nanoscale heat transfer - from computation to experiment

Heat transfer can differ distinctly at the nanoscale from that at the macroscale. Recent advancement in computational and 5 experimental techniques has enabled a large number of interesting observations and understanding of heat transfer processes at the nanoscale. In this review, we will first discuss recent advances in computational and experimental methods used in nanoscale thermal transport studies, followed by reviews of novel thermal transport phenomena at the nanoscale observed in both computational and experimental studies, and discussion on current understanding of these novel 10 phenomena. Our perspectives on challenges and opportunities on computational and experimental methods are also presented.University of Notre Dame (Startup fund)United States. Dept. of Energy. Office of Basic Energy Sciences (Solid-State Solar-Thermal Energy Conversion Center