Abstract
In this paper, a mathematical model is designed for THz generation from a nonlinear random medium. Using nonlinear optics and Maxwell’s equations a set of nonlinear wave equations are derived to give scattered electromagnetic fields from an inhomogeneous medium. First, the analysis is done with second order nonlinearity. Its scattering parameters are calculated for THz radiation. Secondly, third order nonlinearity is described in terms of the coupling of Scalar and vector field components of nonlinear wave equations. The coupling of waves results in soliton generation. Multiple nonlinear interaction in the medium also gives wide bandwidth. Speed and high bandwidth is a demand of future networks. Hence a mathematical proof is implemented for THz antennas using SHG (Second harmonic generation) and THG (Third harmonic generation) materials. These antennas are designed and simulated using GaAs as a SHG material, and Graphene with SiO2 substrate as a THG material. GaAs is used as a substrate, which radiates at 524.8 GHz giving a high bandwidth of 25 GHz. Similarly, Graphene patch antenna with SiO2 substrate radiates in THz region at 3.5THz giving very high bandwidth of 2.5THz.
Highlights
THz technology is playing an important role in the area of sensing, imaging[1] and wireless communication
When a high intensity electromagnetic wave passes through these nonlinear medium, SHG (Second harmonic generation) and THG (Third harmonic generation) waves are generated in THz region
Using Matlab the results are obtained for the susceptibility matrix of noncentrosymmetric /centrosymmetric materials defined in 1, the simulation works for the second order and third order harmonics 30 .The output is simulated for the frequency inputs 100rad/sec, rad/sec, rad/sec and 1012 rad/sec
Summary
THz technology is playing an important role in the area of sensing, imaging[1] and wireless communication. The size and geometry of the antenna will control the antenna radiation[3].Some applications such as imaging, spectroscopy, and pharmaceutical application has been elaborated by Pawar and Zhang 2,3 .THz wave has both wave nature and particle nature It has good penetration for some dielectric materials and nonpolar materials 4.Penetrability makes it a supplement for X- ray imaging and ultrasound imaging 4.THz radiation has a sufficiently small wavelength that it can discern small structures of millimeter size. When a high intensity electromagnetic wave passes through these nonlinear medium, SHG (Second harmonic generation) and THG (Third harmonic generation) waves are generated in THz region.
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