**1. Introduction**

The back bone of numerous applications in the recent years is the plasmonic nano-antennas especially in the optical spectral regions due to their unique properties, as high enhancement and subwavelength confinement of the electrical field. One of the attractive application is the treatment of the cancer cells where the diffusion of heat could be controlled via plasmonic nano-antennas and hence the temperature is confined in the diseased tissue. Nano-antennas are consisting of adjacent metallic nano-particles with nano-scales gaps (in particular the bowtie shape) which have excessively strong field confinement and enhancement in the gap region. The generated field is invested in various applications that are depending on near field enhancement produced by plasmonic optical nano-antennas (PONAs) such as cancer treatment. The heat produced and the thermal diffusion in the plasmonic structure are not richly investigated might be due to the shortage in the experiments. Vigorous potentials are conducted into the development of new techniques for the controlled temperature at the nano-scale and the destroying cell by the temperature rise due to the converting heat is also included.

In this chapter we try to high light on the important aspects of the interaction of laser light with proposed cancer cells. A case study was designed and studied represented by a plasmonic bowtie nano-antenna. First of all, we have to design a suitable cell of nano-antenna considering the dimensions in nano scale. The second step is to select the shape because it represents the enhanced field source in addition to an appropriate noble metal due to the application of plasmonic bow-tie nano- antennas is conducted inside the human body. The wavelength of the laser used should be selected depending on the resonance frequency because the absorption is regarded the first step of the plasmonic generation. The field distribution is quite important to kill the diseased cells so, the angle of laser incidence and the distance to the tissue play the essential role in the effective process. The virtual tissue is irradiated by two laser wavelengths (532, 1064) nm through a single bowtie nano-antenna, The absorption of EM field that is transferred to heat in the human body depending on the incident EM power density is measured via SAR. It is written as Eq. (1) [1].

$$SAR = \sigma \left| E \right|^2 / 2\,\rho\left(\text{Kg } / \text{w}\right) \tag{1}$$

Where:

σ = conductivity of the tissue-simulating material (S/m).

E = total Root Mean Square (RMS) field strength (V/m).

ρ = mass density of tissue-simulating material (kg/m3).

From the thermal energy deposited on the proposed tissue, the temperature elevation could be estimated as the following equation:

$$dQ = \rho \, V \, C \, dT \tag{2}$$

Where:

Q = the thermal energy (J).

V = the volume (m3).

C = the specific heat (J /K. kg).

T = the temperature in Kelvin (K).

Both sides in the equation could be divided by (ρ V dt), then the terms are rearranged, so the following equation could be written as:

$$(\mathbf{dQ} \,/\, d\mathbf{t}) \,/\,\rho \,\mathbf{V} = \mathbf{C}.d\mathbf{T} \,/\, d\mathbf{t} \tag{3}$$

The specific absorption rate and the temperature elevation detection via the time period calculation are the main considered parameters. Finally, the main conclusions are extracted from the obtained results of the case study.
