Improving plasmonic nanoantennas for optical limiting

In this dissertation, the nanoantenna is used for the application of optical limiting. The strong local electromagnetic field enhancement in the small gap of the dipole nanoantenna gives it the ability to enhance nonlinear absorption. The first part of this dissertation will emphasize improving plasmonic nanoantennas. An annealing method, which can reduce the loss of gold nanoantennas and improve the plasmonic resonance, is described. By annealing the nanoantenna for two minutes at 400 degree Celsius, the Drude electron relaxation rate due to the grain boundaries is decreased by the factor of 3.2. In the second part of the dissertation, the laser damage threshold of the interaction between a short pulse laser and the nanoantenna is discussed. Thermal expansion occurs when the nanoantenna absorbs the laser energy at the resonance wavelength. To help avoid this damage, a dielectric film covering on the top of nanoantennas can be applied to increase the nanoantenna damage threshold by six times. This dissertation concludes with a discussion of the organic film (4, 4\u27-bis(diphenylamino)stilbene, BDPAS) deposition experiment and the z-scan measurement re of BDPAS thin film with nanoantennas. The z-scan result describes the 40 times enhancement of two photon absorption from the BDPAS thin film with nanoantennas