Towards Optical Excitation of Liquid-Dispersed Carbon Nanotubes inside Hollow-Core Photonic Bandgap Fiber

Abstract

This thesis is a study of the excitation of liquid-suspended carbon nanotubes (CNTs) confined in an optical waveguide. Desirable optical properties such as narrow emission and excitation bandwidths, as well as wide selectivity over the near-infrared spectrum, warrant the exploration of using CNTs as a gain medium in fiber-integrated lasers. Because of the necessity of liquid suspension to achieve high intensity fluorescence from CNTs, Hollow-core photonic bandgap fiber (HCPBF) was filled with common solvents, deionized water and deuterium dioxide(D2 O) to create an opto-fluidic waveguide. D2 O Liquid-HCPBFs with operational bandgaps in the near-infrared spectrum using telecom-wavelength HCPBFs drop to around half of their hollow-core transmission intensity due to propagating though a higher refractive index medium but still maintain a small mode-area. Preserving refractive- index scaling laws, the characteristics of hollow-core wavguides that make them desirable for engineering photon-particle interactions are maintained in the liquid-core counterparts. The interaction of the fiber mode with nano-scale suspended particles was first tested with indocyanine green, a fluorescent dye, due to its simple preparation and overlapping emission and excitation spectra with the bandgap of the liquid-HCPBFs. Within the Liquid-HCPBF, the fraction of fluorescence for ICG collected was an order of magnitude greater than that of collection efficiencies measured for dye samples contained in cuvettes. Following the results of the ICG dye, CNT solutions dominant with CNT chiralities within the Liquid-HCPBF bandgap were prepared and characterized. Initial Liquid-HCPBF with CNTs were began but the investigation with CNTs remains open.