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Spatial-energy characteristics of focused modes of a metal terahertz laser resonator

heading: 
MICROWAVE AND TERAHERTZ TECHNOLOGY
Vlasenko, SA, Degtyarev, AV, Dubinin, MM, Maslov, VA
Organization: 

V. N. Karazin Kharkiv National University
4 Svobody Sq., Kharkiv, 61022, Ukraine
E-mail: a.v.degtyarev@karazin.ua
https://doi.org/10.15407/rej2019.02.068
Language: russian
Abstract: 

Subject and ppurpose. In this paper, the spatial-energy characteristics of laser beams with inhomogeneous spatial polarization with their moderate and sharp focusing are theoretically investigated. In the numerical simulation of focusing of wave laser beams in the terahertz range, laser resonator modes based on a circular metal waveguide were used as the radiation under study. These modes coincide with the proper types of oscillations of such a waveguide. For the calculation, we selected symmetric and asymmetric modes with azimuthal, radial, and complex spatial polarization of the field.

Methods and methodology. In the study of the propagation of the components of the electric field of laser radiation in free space, Rayleigh-Sommerfeld integrals were used in the nonparaxial approximation. The effect of the focusing lens on the radiation under study was taken into account using the function of amplitude-phase correction. The transverse distributions of the total field intensity and its individual components of the studied resonant modes in the region of the minimum size of the focal spot of focused radiation beams were studied.

Results. Wave beams with inhomogeneous spatial polarization of radiation are necessary for solving important fundamental and applied problems. These tasks are associated with the interaction of electromagnetic waves of the terahertz range with matter. For example, diagnostics of the surface of materials, thin films, biological objects, THz transmission systems and information processing, the achievement of subwave resolution THz tomography, terahertz communication systems, etc. The results of studies of focusing features in the terahertz range are practically absent. A theoretical study was made of the physical features of moderate and sharp focusing of laser beams of radiation excited by the modes of a resonator with a circular metal waveguide with different spatial polarization of the field. The results obtained extend knowledge of the focusing features of terahertz laser beams.

Conclusions. The physical features of the spatial-energy characteristics are established with moderate and sharp focusing in free space of radiation beams with different spatial polarization of the field. These beams were excited by laser resonator modes based on a circular metal waveguide in the terahertz range.
Keywords: focusing, metal resonator, modes, polarization, terahertz laser

Manuscript submitted 06.12.2018
Radiofiz. elektron. 2019, 24(2): 68-77
Full text  (PDF)

References: 
1. Xiaoqiang, Z., Ruishan, C., Anting, W., 2018. Focusing properties of cylindrical vector vortex beams. Opt. Commun., 414, pp. 10-15. DOI: https://doi.org/10.1016/j.optcom.2017.12.076
 
2. Khonina, S.N., Ustinov, A.V., 2018. Focusing properties of cylindrical vector vortex beams. Opt. Commun., 426, pp. 359-365. DOI: https://doi.org/10.1016/j.optcom.2018.05.070
 
3. Fu, J., Yu, X., Wang, Y., Chen, P., 2018. Generation of pure longitudinal magnetization needle with tunable longitudinal depth by focusing azimuthally polarized beams. Applied Physics B, 124(1), 11(4 pp.). DOI: https://doi.org/10.1007/s00340-017-6886-5
 
4. Kozawa, Y., Sato, S., 2007. Sharper focal spot formed by higher-order radially polarized laser beams. JOSA A, 24(6), pp. 1793-1798. DOI: https://doi.org/10.1364/JOSAA.24.001793
 
5. Zhan, Q., Leger, J., 2002. Focus shaping using cylindrical vector beams. Opt. Express, 10(7), pp. 324-331. DOI: https://doi.org/10.1364/OE.10.000324
 
6. Chen, Z., Hua, L., Pu, J., 2012. Tight focusing of light beams: effect of polarization, phase, and coherence. Prog. Optics, 57, pp. 219-260. DOI: https://doi.org/10.1016/B978-0-44-459422-8.00004-7
 
7. Zang, Z., Mao, C., Guo, X., You, G., Yang, H., Chen, L., Zhu, Y., Zhuang, S., 2018. Polarization-controlled terahertz super-focusing. Appl. Phys. Lett., 113(7), 071102(4 pp.). DOI: https://doi.org/10.1063/1.5039539
 
8. Ruan, D., Li, Z., Du, L., Zhou, X., Zhu, L., Lin, C., Yang, M., Chen, G., Yuan, W., Liang, G., Wen, Z., 2018. Realizing a terahertz far-field sub-diffraction optical needle with sub-wavelength concentric ring structure array. Appl. Opt., 57(27), pp. 7905-7909. DOI: https://doi.org/10.1364/AO.57.007905
 
9. Gurin, O.V., Degtyarev, A.V., Maslov, V.A., 2015. Propagation and focusing of modes of dielectric resonators of terahertz range lasers. Telecommunications and Radio Engineering, 74(7), pp. 629-640. DOI: https://doi.org/10.1615/TelecomRadEng.v74.i7.60
 
10. Gurin, O.V., Degtyarev, A.V., Maslov, V.A. Senyuta, V.S., Svich, V.S., Topkov, A.N., 2014. Propagation and focusing of modes of the dielectric resonator of terahertz laser. In: 2014 Int. Conf. «Laser Optics». St. Petersburg, Russia, 30 June - 4 July 2014 . DOI: https://doi.org/10.1109/LO.2014.6886325
 
11. Kotlyar, V.V., Kovalev, A.A., 2010. Nonparaxial propagation of a Gaussian optical vortex with initial radial polarization. J. Opt. Soc., 27(3), pp. 372-380. DOI: https://doi.org/10.1364/JOSAA.27.000372
 
12. Volodenko, A.V., Gurin, O.V., Degtyarev, A.V., Maslov, V.A., Senyuta, V.S., Svich, V.S., Topkov, A.N., 2013. Radiation characteristics of the metal waveguide resonator with a inclined mirror. Telecommunications and Radio Engineering, 72(14), pp. 3149-1359. DOI: https://doi.org/10.1615/TelecomRadEng.v72.i14.70
 
13. Gurin, O.V., Degtyarev, A.V., Dubinin, M.M., Maslov, V.A., Muntean, K.I., Ryabykh, V.N., 2018. Focusing of Modes for Metallic Resonator of a Terahertz Laser with Nonuniform Spatial Polarization. In: IEEE 22nd Int. Conf. «Mathematical Methods in Electromagnetic Theory» (MMET-2018). Kyiv, Ukraine, 2-5 July 2018. DOI: https://doi.org/10.1109/MMET.2018.8460368