Thesis (Ph. D.) -- California Institute of Technology, 2010. / Title from home page (viewed 03/02/2010). Advisor and committee chair names found in the thesis' metadata record in the digital repository. Includes bibliographical references.

Plasmonics is an important branch of optics and photonics, focusing on the electromagnetic response of metals or other materials with free carriers. This field has recently experienced a significant expansion due to its importance for applications. Plasmonics has shown great promises in green energies, biosensing, nanolasers, and imaging. The main advantage of plasmonics stems from the existence of unique excitations, referred to as plasmons, representing collective response of the free carriers to the electromagnetic field. While plasmons, both in the bulk and on the surface of the metals, have been known for decades, the recent advances in nano fabrication and material sciences at nano scale have enabled versatile engineering of these modes. Focus of my dissertation is surface plasmons whose properties can be tailored by judiciously nano-patterning metal films and surfaces. Such patterned structures, referred to as metasurfaces, are the main tool to control and boost the light-matter interaction. Appropriately designed metasurfaces provide many-fold electromagnetic energy enhancement on the surface which can be used to amplify numerous surface effects such as SEIRA and nonlinear optical phenomena, facilitate spectroscopy, and enhance absorption of light. In this thesis, I report approaches to shape and engineer the confinement, mode profile, and lifetime of the surface modes. I also investigate how the dielectric environment affects the properties of the modes. The effect of the geometry and topology of the nano patterns on the optical response of metasurfaces is also studied. Finally I study how manipulating symmetries of metasurfaces can be used to tailor polarization state of light and lifetime of the modes using an ultrathin metasurface, instead of bulky traditional optical elements. %The symmetry manipulation results in the plasmonic analogue of Electromagnetically Induced Transparency, a well-known phenomenon in atomic physics. The work summarized in this thesis has brought marked advances in understanding the physics behind the collective surface waves in nano-structured metasurfaces. It paves new avenues for engineering structures with desirable properties. The immediate application of my findings is the compactification of optical elements, and envisioning next-generation plasmonic-based on-chip devices. / text

This dissertation presents novel techniques applied to double nanohole (DNH) optical tweezer with the idea of characterizing and developing capabilities of nanoaperture trap, for single molecule and nanoparticle analysis. In addition, an alternative approach for fabrication of double nanoholes using template stripping is presented. The strength of the DNH tweezer was characterized quantitatively in terms of trap stiffness using two techniques: autocorrelation of Brownian-induced intensity fluctuations and trapping transient. These experimental techniques have, for the first time, been applied to an aperture based trap used for trapping Rayleigh particles in the range of few nanometres. These techniques can be used for calibration and comparison of the aperture based traps among themselves and with other nano-optical tweezers. A statistical technique based on the parameters, time-to-trap and the transient jump due to optical trapping was used for sensing the concentration, size and refractive index of the nanoparticles. The time-to-trap showed a linear dependence with particle size and a -2/3 power dependence with particle concentration, which is in agreement with the diffusion theory based on simple microfluidic considerations. The transient jump in the trapping signal at the trapping instant scales empirically as the Clausius–Mossotti factor for different refractive index particles. The ability of the DNH tweezer to hold small Rayleigh particles with high efficiency and also the increased sensitivity of the transmission signal to the trapped particle during detection makes it favourable for studying the dynamics and interactions of biomolecules. In this direction, the unzipping of the hairpin DNA and its interaction with the tumour suppressor p53 transcription protein, which suppresses the unzipping, were detected using double nanohole optical tweezer. The energy associated with the suppression of unzipping was found to be close to the binding energy of p53-DNA complex. The mutant p53 inability to supress the unzipping of the DNA was also confirmed, showing the ability of the DNH tweezer to distinguish between the mutant p53 and the wild-type. An extraordinary acoustic Raman (EAR) technique was used to study the vibrational modes of ssDNA molecule. The resonant vibrational modes were found to be in the sub 100 GHz range and could be tuned based on the base sequence and length of the DNA strand. The vibrational modes were verified using 1-D lattice vibration theory. Finally, an alternative approach of template stripping for fast and cheaper fabrication of DNH is presented. The template strip process can be used reliably for mass production of gold slide containing DNH’s and also results in cost reduction by 70 % for a single gold slide. Also, we have successfully used this approach to transfer DNH structure to the tip of the cleaved fiber, which would make the DNH tweezer module more compact and scalable. This would open up opportunities for many other applications for single molecule and nanoparticle analysis such as transfer of molecules in-situ to other biomolecular solution for studying their interactions and many others. / Graduate

No description available.

Research in solid-state nanophotonics and quantum optics has been recently pushing the limits in semiconductor microcavity design. High quality microcavities that confine light into small volumes are now able to drastically alter the local density of states (LDOS). Plasmonic systems can provide smaller effective confinements, however it is unclear if the benefits of confinement are good enough to balance material losses due to non-radiative processes. This thesis presents a compendium of techniques for calculating photonic Green functions in various lossy, inhomogeneous magneto-dielectric systems. Subsequently we derive a rigorous theory of quantum light-matter interactions, valid in both weak and strong coupling limits, and show how the classical photonic Green function is developed to calculate Purcell factors, Lamb shifts, and the near and far field spectra from a single photon emitter. Using these techniques, this work investigates the classical and quantum optical properties of a variety of inhomogeneous structures, including their coupling to single photon emitters. This includes examining Purcell factors above negative index slabs and showing the convergence of many slow-light modes leads to a drastic increase in the LDOS along with large Lamb shifts. The optical trapping of metallic nanoparticles is examined above a negative index slab and a silver half-space, showing the importance of interparticle coupling on the optical forces. Then the interaction between a quantum dot and a metallic nanoparticle is studied where far-field strong coupling effects are observed only when the metallic nanoparticle is considered beyond the dipole approximation. Finally, this work addresses the issue of the LDOS diverging in lossy materials, which necessitates a description of spontaneous emission beyond the dipole approximation; the ``local field problem'' in quantum optics is revisited and generalized to include local field corrections for use in any photonic medium. The strength of finite-difference time-domain techniques is demonstrated in a number of cases for the calculation of regularized Green functions in lossy inhomogeneous media. This thesis presents a comprehensive study of Green function approaches to model classical and quantum light-matter interactions in arbitrary nanophotonic structures, including quantum dots, semiconductor microcavities, negative index waveguides, metallic half-spaces and metallic nanoparticles. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2012-04-26 15:25:53.178

Plasmonics is a promising field of nanophotonics dealing with light interaction with metallic nanostructures. In such material systems, hybridizationof photons and collective free-electron oscillation can result in sub-wavelength light confinement. The strong light-matter interaction can be harnessed for,among many applications, high-density photonic integration, metamaterial design, enhanced nonlinear optics, sensing etc. In the current thesis work, we focus on experimental fabrication and characterization of planar plasmonic metamaterials and waveguide structures. The samples are fabricated based on the generic electron beam lithography and characterizations are done with our home-made setups. Mastering and refinement of fabrication techniques as well as setting up the characterization tools have constituted as a majorpart of the thesis work. In particular, we experimentally realized a plasmonic absorber based on a 2D honeycomb array of gold nano-disks sitting on top of a reflector through a dielectric spacer. The absorber not only exhibits an absorption peak which is owing to localized surface plasmon resonance and is insensitive to incidence’s angle or polarization, but also possesses an angle- and polarization-sensitive high-order absorption peak with a narrow bandwidth. We also demonstrated that the strong light absorption in such plasmonic absorbers can be utilized to photothermally re-condition the geometry of gold nanoparticles. The nearly perfect absorption capability of our absorbers promises a wide range of potential applications, including thermal emitter, infrared detectors, and sensors etc. We also fabricated a plasmonic strip waveguide in a similar metal-insulator-metal structure. The strip waveguide has a modal confinement slightly exceeding that of the so-called plasmonic slot waveguide. We further thermally annealed the waveguide. It is observed that the propagation loss at 980 nm has been decreased significantly,which can be attributed to the improvement in gold quality after thermal annealing. / <p>QC 20140203</p>

Nanophotonics has been proposed to design low latency and high bandwidth Network-On-Chip (NOC) for future Chip Multi-Processors (CMPs). Recent nanophotonic NOC designs adopt the token-based arbitration coupled with credit-based flow control, which leads to low bandwidth utilization. This thesis proposes two handshake schemes for nanophotonic interconnects in CMPs, Global Handshake (GHS) and Distributed Handshake (DHS), which get rid of the traditional credit-based flow control, reduce the average token waiting time, and finally improve the network throughput. Furthermore, we enhance the basic handshake schemes with setaside buffer and circulation techniques to overcome the Head-Of-Line (HOL) blocking. The evaluations show that the proposed handshake schemes improve network throughput by up to 11x under synthetic workloads. With the extracted trace traffic from real applications, the handshake schemes can reduce the communication delay by up to 55%. The basic handshake schemes add only 0.4% hardware overhead for optical components and negligible power consumption. In addition, the performance of the handshake schemes is independent of on-chip buffer space, which makes them feasible in a large scale nanophotonic interconnect design.

Thesis (Ph. D.)--University of North Texas, May, 2008. / Title from title page display. Includes bibliographical references.

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Adibi, Ali; Committee Member: Bhatti, Pamela; Committee Member: Callen, William; Committee Member: Gaylord, Thomas; Committee Member: Zhou, Hao-Min. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed September 08, 2009). PDF text: xiii, 129 p. : ill. (some col.) ; 36 Mb. UMI publication number: AAT 3352411. Includes bibliographical references. Also available in microfilm and microfiche formats.