DESIGN AND ANALYSIS OF NANO-GAP ENHANCED SURFACE PLASMON RESONANCE SENSORS

Surface plasmon resonance (SPR) sensors are advantageous to other techniques of sensing chemical binding, offering quantitative, real-time, label-free results. Previous work has demonstrated the effectiveness of using dual-mode SPR sensors to differentiate between surface and background effects, making the sensors more robust to dynamic environments. This work demonstrates a technique that improves upon a previously optimized planar film dual-mode SPR sensor’s LOD by introducing a periodic array of subwavelength nano-gaps throughout the plasmon supporting material. First, general figures of merit for a sensor having an arbitrary number of modes are studied. Next, the mode effective index dispersion and magnetic field profiles of the two strongly bound modes found using a gap width of 20nm are analyzed. Qualitative analysis of the results demonstrates how such a design can enable better LODs in terms of each figure of merit. By optimizing a nano-gap enhanced sensor containing 20nm gaps, it is quantitatively demonstrated that the resulting modes improve upon almost every figure of merit, especially with respect to the orthogonality and magnitude of the sensitivity vectors, resulting in LODs approximately a factor of five less than the optimal planar design

Engineering strong-field phenomena : from attosecond pulse characterization to nanostructured electron emitters

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 141-149).Strong-field phenomena are a driving force behind the latest innovations in ultrafast science. As ultrafast laser sources improve in terms of peak pulse energy and wavelength tunability, applications that utilize high peak electromagnetic field strengths to generate attosecond pulses of both photons and electrons are becoming readily available. Furthermore, through the coupling of these optical fields to nanostructures that further enhance peak field strengths, a new generation of electron emitters and "light-speed" electronics are now emerging. This thesis explores two such areas in detail: the generation and characterization of attosecond pulses of light, and strong-field photoemission from nanostructures.by Phillip D. Keathley.Ph. D

Volkov transform generalized projection algorithm for attosecond pulse characterization

An algorithm for characterizing attosecond extreme ultraviolet pulses that is not bandwidth-limited, requires no interpolation of the experimental data, and makes no approximations beyond the strong-field approximation is introduced. This approach fully incorporates the dipole transition matrix element into the retrieval process. Unlike attosecond retrieval methods such as phase retrieval by omega oscillation filtering (PROOF), or improved PROOF, it simultaneously retrieves both the attosecond and infrared (IR) pulses, without placing fundamental restrictions on the IR pulse duration, intensity or bandwidth. The new algorithm is validated both numerically and experimentally, and is also found to have practical advantages. These include an increased robustness to noise, and relaxed requirements for the size of the experimental dataset and the intensity of the streaking pulse.United States. Air Force Office of Scientific Research (grant FA9550-12-1-0080)United States. Air Force Office of Scientific Research (grant FA9550-12-1-0499)Center for Free-Electron Laser ScienceGerman Science Foundation. Hamburg Centre for Ultrafast Imaging-Structure, Dynamics and Control of Matter at the Atromic ScaleUnited States. Department of Defense (National Defense Science & Engineering Graduate Fellowship (NDSEG) Program