Femtosecond laser fabrication of micron and sub-micron sized S-shaped constrictions on high Tc superconducting YBCO thin films: ablation and lithography issues

Abstract

We demonstrate the fabrication of micron and sub-micron sized constrictions on high TcTc superconducting YBa2Cu3O7−x (YBCO) thin films using the femtosecond laser. The lithography process was optimized by programming the movement of the translation stage during etching with G-code (a control systems programming language), controlling the power incident on the sample to a certain degree and by bringing the laser ablation spots close to one another without clipping the constriction. S-shaped constrictions of micron and sub-micron size (smallest being ~858 nm) have been fabricated to be used as the constriction type Josephson junctions. The constrictions made have a variable width, with the width measured at the narrowest point.