Effect of Hot Carrier on Amplitude Modulation and Demodulation of Gaussian High Power Helicon Wave in Homogeneous Longitudinally Magnetized Strain Dependent Dielectric Material

Shivani Saxena¹, Sanjay Dixit¹, Sanjay Srivastava²

¹Department of Physics, Govt. M.V. M College, Barkatullah University, Bhopal, India.
²Department of Material Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, India.

DOI: 10.4236/oja.2015.54012                

Abstract

In the present communication, the hydrodynamic model is used to investigate the amplitude modulation as well as demodulation of an electromagnetic wave of high power helicon pump wave into another helicon wave in strain dependent dielectric material incorporating carrier heating (CH) effects. The consideration of CH in modulation and demodulation is prime importance for the adding of new dimension in analysis of amplification of acoustic helicon wave. By using the dispersion relation, threshold pump electric filed and growth rate of unstable mode from the modulation and demodulation of the high power helicon wave well above from the threshold value will be discussed in the present analysis. The numerical analysis is applied to a strain dependent dielectric material, BaTiO₃ at room temperature and irradiated with high power helicon wave of frequency 1.78 × 10¹⁴ Hz. This material is very sensitive to the pump intensities, therefore during studies, Gaussian shape of the helicon pump wave is considered during the propagation in stain dependent dielectric material and opto-acoustic wave in the form of Gaussian profile (ω₀,κ₀) is induced longitudinally along the crystallographic plane of BaTiO₃. Its variation is caused by the available magnetic field (ω_c), interaction length (z) and pulsed duration of interaction (τ). From the analysis of numerical results, the incorporation of CH effect can effectively modify the magnitude of modulation or demodulation of the amplitude of high power helicon laser wave through diffusion process. Not only the amplitude modulation and demodulation of the wave, the diffusion of the CH effectively modifies the growth rate of unstable mode of frequency in BaTiO₃. The propagation of the threshold electric field shows the sinusoidal or complete Gaussian profile, whereas this profile is found to be completely lost in growth of unstable mode. It has also been seen that the growth rate is observed to be of the order of 10⁸ - 10¹⁰ s^-1 but from diffusion of carrier heating, and that its order is enhanced from 10¹⁰ - 10¹² s^-1 with the variation of the magnetized frequency from 1 to 2.5 × 10¹⁴ Hz.

Keywords

Amplitude/Frequency Modulation, High Power Laser Wave, Hot Carrier Effect, Plasma Effect in Strain Dependent Dielectric Material

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Mamum, A.A. and Slimullah, M. (1991) Parametric Excitation of Alfven and Helicon Waves in a Magnetoactive Compensated Semiconductor by Microwave Radiation. Physical Review B, 44, 8685-8693. http://dx.doi.org/10.1103/PhysRevB.44.8685
[2]	Nimje, N., Dubey, S. and Ghosh, S. (2012) Amplitude Modulation and Demodulation of an Electrometric Wave in Magnetized Acoustio-Optic Diffusive Semiconductor Plasma: Hot Carrier Effects. Optics & Laser Technology, 44, 744-748. http://dx.doi.org/10.1016/j.optlastec.2011.11.038
[3]	Gupta, P.K. and Sen, P.K. (2001) The Role of Electrostriction on Parametric Dispersion and Amplification in Doped Piezoelectric Semiconductors. Non linear Optics, 26, 361-377.
[4]	Paiella, R., Martini, R., Capasso, F., Gmachl, C., Hwang, H.Y., Baillargeon, J.N., Sivco, D.L., Cho, A.Y., Whittaker, E.A. and Liu, H.C. (2001) High-Frequency Modulation without the Relaxation Oscillation Resonance in Quantum Cascade Lasers. Applied Physics Letters, 79, 2526.
[5]	Lashmore-Davies, C.N. (1976) Modulated Instability of a Finite Amplitude Alfven Waves. Physics of Fluids, 19, 587. http://dx.doi.org/10.1063/1.861493
[6]	Vazquez, R.A., Vachss, F.A., Neurgaonkar, R.R. and Ewbank, M.D. (1991) Large Photorefractive Coupling Coefficient in a Thin Cerium-Doped Strontium Barium Niobate Crystal. Journal of the Optical Socitey of America B, 8, 1932-1941.
[7]	Tervonen, E., Friberg, A.T. and Turunen, J. (1993) Acousto-Optic Conversion of Laser Beams into Flat-Top Beams. Journal of Modern Optics, 40, 625-641. http://dx.doi.org/10.1080/09500349314550681
[8]	Vartharajah, P., Newell, A.C., Moloney, J.V. and Aceves, A.B. (1990) Transmission, Reflection and Trapping of Collimated Light Beams in Diffusive Kerr-Like Nonlinear Media. Physical Review A, 42, 1767-1774. http://dx.doi.org/10.1103/PhysRevA.42.1767
[9]	Ghosh, S. and Rishi, M.P. (2002) Acousto-Optic Modulation in Magnetized Diffusive Semiconductor. European Physical Journal D: Atomic Molecular, Optical and Plasma Physics, 19, 223-230.
[10]	Ghosh, S. and Saxena, R.B. (1985) Amplification of Acousto-Helicon Wave Due to Modulation of a High-Power Helicon Wave in Longitudinal Magnetized Cubic Piezoelectric Semiconducting Plasmas. Acustica, 58, 91-97.
[11]	Odulov, S.G. and Sturman, B.I. (1996) Coupling of Orthogonally Polarized Waves in Barium Titanate by Parametric Scattering. JEPT, 82, 1095-1101.
[12]	Conwell, E.M. (1967) High Field Transport in Semiconductor. Academic Press, New York, 159.
[13]	Ghosh, S. and Agarwal, V.K. (1982) Exicitation of Acouto-Helicon Waves Due to Modulation of a Laser Beam in Longitudinally Magnetised Semiconductors. Physica Status Solidi (b), 110 K37-40 70 A.
[14]	Steele, M.C. and Vural, B. (1969) Wave Interactions in Solid State Plasmas. Mc-Graw Hill, New York, 154.