Design and Construction of a Raman Microscope for Nano-Plasmonic Structures

• Main Author: Alshehab, Maryam Habeeb
• Other Authors: Berini, Pierre
• Format: Others
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2018
• Subjects: Nanoantenna; Graphene; Raman Spectroscopy; Plasmonics
• Online Access: http://hdl.handle.net/10393/38127; http://dx.doi.org/10.20381/ruor-22382

Nanometallic structures efficiently convert light to surface plasmon-polaritons (SPPs) localized to ultra-small volumes. Such structures can provide highly enhanced fields and are of interest in applications involving plasmon-enhanced nonlinear optics. In this study, the devices consist of rectangular gold nanoantennas on a graphene layer on a SiO2/Si substrate. The nanoantennas are used to exploit SPPs to enhance the interaction between graphene and light. Specifically, plasmon-enhanced Raman scattering from graphene is of interest. Here, the nanoantennas are spectrally-aligned with a Stokes wavelength of graphene. With the addition of a second laser source, stimulated Raman scattering can be achieved. The first laser source pumps the sample’s atoms and molecules into virtual excited states and the second one stimulates emission of a photon and relaxation to a higher mode of the ground state. This work involves designing and constructing a stimulated and spontaneous Raman microscope and also a reflectance measurement tool. Within the framework of this thesis, Raman scattering enhancement in graphene based on plasmonic resonant enhancement of the Stokes emission is demonstrated, providing a maximum cross-sectional gain of approximately 500 per antenna. This work also shows the normalized reflectance response of the nanoantenna structures of different length and width and how their resonant wavelengths shift.