Monochromatic THz generation by beating two SG laser beams in the array of anharmonic upright CNTs present in the form of weakly coupled plasma under the influence of static magnetic and electric fields

In the present manuscript, we have presented a novel theoretical model to study the monochromatic terahertz (THz) generation by beating two spatial-Gaussian (SG) laser beams in the array of anharmonic upright carbon nanotubes (CNTs) present in the form of weakly coupled plasma under the influence of static magnetic and electric fields, well supported by numerical simulation and physical interpretation. We have chosen SG laser beams because these have steep gradients in their intensity, which results in stronger ponderomotive force. The nonlinear restoration force along with the strong ponderomotive, magnetic, and electric forces with surface plasmon resonance (SPR) condition \(\left( {\omega /\omega_{{\text{P}}} = \sqrt {0.5\left( {1 + i\upsilon /\omega } \right)\rho /\varepsilon_{{\text{g}}} + (\omega_{{\text{c}}}^{2} /\omega_{{\text{P}}}^{2} ) - \left( {\upsilon^{2} /\omega_{{\text{P}}}^{2} } \right) + 2i\upsilon \omega /\omega_{{\text{P}}}^{2} } } \right)\) $\left(\omega /{\omega }_{\text{P}}=\sqrt{0.5\left(1+i\upsilon /\omega \right)\rho /{\epsilon }_{\text{g}}+({\omega }_{\text{c}}^2/{\omega }_{\text{P}}^2)-\left({\upsilon }^2/{\omega }_{\text{P}}^2\right)+2i\upsilon \omega /{\omega }_{\text{P}}^2}\right)$ facilitates the enhancement of nonlinear current. To evaluate the SPR condition, we have assumed that all the electrons of upright CNTs in the array are oscillating in the same phase. As a result, monochromatic THz waves are expected to be emitted by the system. Most of the THz sensors and instruments are employed in the frequency range of 0.1–10 THz to use for the nondestructive evaluation technique (NDET) with the purpose of detecting structural defects in ceramics and imaging the physical structure of old heritage paintings and manuscripts. In the proposed scheme of monochromatic THz generation, we can obtain the THz radiations in a specific frequency range of 3.15–3.25 THz and hence can play a key role in NDET. The emitted monochromatic THz radiations can also be used to perform THz pump/probe experiments in biology and nanotechnology, where output THz radiation is sensitive to the phase. In addition to that, monochromatic THz radiations with symmetrical profiles have immense potential in communication services. According to the International Telecommunication Union, the monochromaticity of THz radiations plays a significant role in communication services because of higher band utilization and lower interference.