Applications of silicon carbide as window materials in atomic cells and atomic devices

TL;DR

The paper addresses the limitation of silicon-based anodically bonded atomic cells, which block beams with wavelengths shorter than around 1000 nm, by evaluating silicon carbide (SiC) windows as an alternative. The authors characterize SiC's wide band gap, high optical transmission, and superior thermal and mechanical properties, and demonstrate anodic bonding of SiC windows to borosilicate glass. They show that SiC windows enable high transmission with anti-reflection coatings, dramatically improved thermal management in vapor cells, and practical utility in multipass-cavity based comagnetometers, including external-mirror configurations and spin-noise measurements. The work suggests SiC-window cells can broaden optical access and improve measurement stability in compact atomic devices, with plans to integrate into next-generation precision measurement systems.

Abstract

Atomic cells made by anodically bonding silicon and borosilicate glasses are widely used in atomic devices. One inherent problem in these cells is that the silicon material blocks beams with wavelengths shorter than 1000 nm, which limits available optical accesses when alkali metal atoms are involved. In this work, we investigate the possibility of the silicon carbide material as an alternative of silicon materials in fabricating anodically bonded cells. We demonstrate that the optical, thermal and mechanical properties of silicon carbide help to improve the performance of atomic devices in certain applications.

Figures (5)

• Figure 1: Relation between of the bonding current and time during the process of anodically bonding a SiC window with Pyrex glasses.
• Figure 2: Comparisons of light absorption spectra near Rb D1 line using SiC-window based vapor cells with and without buffer gases. All data sets are acquired with a cell temperature of 80 $^\circ$C, and a beam with a diameter of 2 mm and a power of 0.2 mW.
• Figure 3: Illustration of the SiC-window based vapor cell used in the temperature gradient test, with the presence of heaters (the bottom heater is not shown), thermal insulation materials and a container. The thermal couples are placed on the side window made of Pyrex glasses.
• Figure 4: (a) Illustration of the core optical setup in the new generation of Herriott-cavity-assisted nuclear spin comagnetometers. (b) Atomic cells made by bonding anti-reflection coated glass windows to the glass cell via Si wafers. (c) Spin-noise spectrum of Rb atoms using the setup in plot (a), with a cell temperature of 95 $^\circ$C, a probe beam power of 1 mW exiting from the cavity, and a probe beam detuning of -80 GHz from the Rb D1 line. Two cells are used: one is the buffer-gas cell without Xe gases used in Fig. \ref{['fig:absorption']}, and the other one is the comagnetometer cell filled with Xe gases mentioned in the main text.
• Figure 5: Xenon isotope precession signals probed by the in-situ Rb magnetometer.