Keywords:thermoplasmonics, localized temperature spot, temperature gradient
Illuminated plasmonic metal nanostructures can efficiently convert light into heat at nanoscale dimensions. The heat generated in the nanostructure can be, similarly to light, strongly localized in deep sub-wavelength volumes. Despite the localized heating, generating localized nanoscale temperature spots is challenging due to the diffusive spread of heat which, because the plasmonic nanostructures typically have a much larger thermal conductivity than the surrounding environment, tends to make the temperature uniform within the nanostructure. We tackled this challenge by fully exploiting the photothermal response of free-standing sub-wavelength nanocones under continuous wave illumination. In this respect, a 3D finite element method model was employed to obtain the 3D electric field, heat and temperature distributions. The results demonstrate the possibility to generate deep sub-wavelength localized temperature spots and strong temperature gradients within the nanocone and how size, shape, surrounding environment material, incoming wavelength and polarization provide a way to control and tune the photoinduced temperature gradient.