Emission of Circularly Polarized Terahertz Wave from Inhomogeneous Intrinsic Josephson Junctions

TL;DR

This paper theoretically demonstrates that local heating of inhomogeneous intrinsic Josephson junctions can produce circularly polarized terahertz waves, with polarization controllable by applied voltage, offering potential for technological applications.

Contribution

It introduces a novel method of generating circularly polarized THz waves using locally heated, inhomogeneous IJJs with specific cavity modes, expanding the capabilities of THz emitters.

Findings

Local heating induces inhomogeneity in critical current density.

Excitation of orthogonal cavity modes leads to circular polarization.

Circular polarization varies significantly with applied voltage.

Abstract

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 mesa-structured IJJ whose geometry is slightly deviate from a square and find that the local heating make it possible to emit circularly-polarized 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.