This book explores the applications of plasmonic gold nanorods (GNRs) in early cancer diagnostics and treatment by engineering the light focusing properties. On account of polarisation-dependent excitation efficiency of GNRs and their three-dimensionally random orientations, radially polarised beams are advantageous over linearly polarised beams because they can generate focal fields with the similar strength in three dimensions. Meanwhile, the energy density is studied to provide comprehensive understanding of light-matter interaction. Investigations into two-photon excited fluorescence...