Radiation Due to Josephson Oscillations in Layered Superconductors

TL;DR

This paper derives the power of THz radiation emitted by Josephson oscillations in layered superconductors, showing that synchronization of oscillations in large junctions leads to high radiation efficiency.

Contribution

It introduces a model for radiation power in layered superconductors considering crystal shape and synchronization effects, advancing understanding of THz emission mechanisms.

Findings

Radiation power depends only on crystal shape in the super-radiation regime.

Synchronization of oscillations in many junctions enhances radiation power.

Optimal crystal parameters and bias current improve radiation efficiency.

Abstract

We derive the power of direct radiation into free space induced by Josephson oscillations in intrinsic Josephson junctions of highly anisotropic layered superconductors. We consider the super-radiation regime for a crystal cut in the form of a thin slice parallel to the c-axis. We find that the radiation correction to the current-voltage characteristic in this regime depends only on crystal shape. We show that at large enough number of junctions oscillations are synchronized providing high radiation power and efficiency in the THz frequency range. We discuss crystal parameters and bias current optimal for radiation power and crystal cooling.