Abstract-Longitudinal field characterization of converging terahertz vortices with linear and circular polarizations

Xinke Wang, Jing Shi, Wenfeng Sun, Shengfei Feng, Peng Han, Jiasheng Ye, and Yan Zhang

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-7-7178

Linearly and circularly polarized terahertz (THz) vortex beams are generated by adopting a THz quarter wave plate and spiral phase plates with topological charges 1 and 2. Taking advantage of a THz digital holographic imaging system, longitudinal components of THz vortices with different polarizations and topological charges are coherently measured and systemically analyzed in a focusing condition. The application potential of circularly polarized THz vortex beams in microscopy is experimentally demonstrated and the transformation between the spin angular momentums and orbital angular momentums of THz waves is also checked. Modified Richards-Wolf vector diffraction integration equations are applied to successfully simulate experimental phenomena.

© 2016 Optical Society of America

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Abstract-Emission of Circularly Polarized Terahertz Wave from Inhomogeneous Intrinsic Josephson Junctions

Hidehiro Asai,  Shiro Kawabata
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=7377043

We have theoretically demonstrated the emission of circularly-polarized terahertz (THz) waves from intrinsic Josephson junctions (IJJs) which is locally heated by an external heat source such as the laser irradiation. We focus on a mesastructured IJJ whose geometry is slightly deviate from a square and find that the local heating make it possible to emit circularlypolarized THz waves. In this mesa, the inhomogeneity of critical current density induced by the local heating excites the electromagnetic cavity modes TM (1,0) and TM (0,1), whose polarizations are orthogonal to each other. The mixture of these modes results in the generation of circularly-polarized THz waves. We also show that the circular polarization dramatically changes with the applied voltage. The emitter based on IJJs can emit circularly-polarized and continuum THz waves by the local heating, and will be useful for various technological application.