Direct laser micromachining of superconducting terahertz Josephson plasma emitters

Abstract

We demonstrate a rapid, maskless fabrication method for superconducting terahertz Josephson plasma emitters (JPEs) based on direct ultraviolet laser micromachining of Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ (Bi-2212) single crystals. Although machining debris is formed near the processed regions, uniform stacks of intrinsic Josephson junctions are preserved inside the crystal, enabling stable terahertz emission. Devices fabricated with Ag, Cu, and Cr electrodes all exhibited terahertz radiation, with Cu electrodes showing performance comparable to Ag while offering a low-cost alternative. Spectroscopic and polarization analyses indicate that the emitted radiation is elliptically polarized and dominated by the geometrical cavity resonance mode. Structural and electrical characterizations reveal that the machining width and depth are not limited by the optical spot size but are governed by the anisotropic thermal conductivity of Bi-2212, consistent with a thermally dominated laser ablation process. This direct laser micromachining approach provides a fast and versatile fabrication technique for JPEs and is broadly applicable to superconducting electronics and terahertz devices.

14 pages, 5 figures, 1 table

References in corpus (3)

• Mutually synchronized macroscopic Josephson oscillations demonstrated by polarization analysis of superconducting terahertz emitters
• Parametric amplification of electromagnetic waves produced by a flux-flow-oscillator made of YBaCuO Josephson junction arrays
• Terahertz imaging system with on-chip superconducting Josephson plasma emitters for nondestructive testing