Indium tin oxide combined with anti-reflective coatings with high transmittance for wavelengths < 400 nm

TL;DR

This paper develops optimized indium tin oxide (ITO) and anti-reflective coatings with high transmittance below 400 nm, low scattering, and low-temperature processing, suitable for quantum ion trap applications.

Contribution

The study introduces a combined ITO + AR coating system with enhanced optical properties and low-temperature fabrication for ion trap technologies.

Findings

Achieved 80% transmittance at 370 nm

Low scattering of 0.012% at 370 nm

Resistance of 115 Ω/□ for the coating system

Abstract

The transparent and conductive properties of indium tin oxide (ITO) thin films, make them an attractive coating for optically integrated ion traps. However, the relatively low transmittance for wavelengths $<$ 400 nm, high scattering and high production temperature limits the usability in trapped-ion-based quantum technologies. Here we present ITO coatings and a combined ITO + anti-reflective (AR) coating system optimized for an ion trap applied using ion beam sputtering (IBS). The coatings feature a high transmittance for wavelengths $<$ 400 nm and additional wavelengths up to 1000 nm, low scattering and low production temperature $<$ 150 $^{\circ}$C. The transmission, reflection and absorption spectra are simulated and the resistance, transmittance and scattering at 370 nm are measured for different ITO coating thicknesses and the ITO + AR coating system. For the ITO + AR coating system a resistance of 115 $\pm$ 5 $\Omega/\Box$, transmittance of 80$\%$ and scattering of 0.012 $\pm$ 0.002$\%$ at 370 nm is achieved.