Electro-optic frequency comb Doppler thermometry

TL;DR

This paper introduces a Doppler thermometry technique using electro-optic frequency comb spectroscopy of rubidium vapor, achieving high accuracy and mitigating systematic errors compared to traditional methods.

Contribution

It demonstrates that EOFC spectroscopy provides more accurate Doppler thermometry by reducing optical pumping distortions, with potential for practical primary temperature measurements.

Findings

Achieved temperature measurement accuracy within 1 K statistical uncertainty.

EOFC spectroscopy reduces optical pumping distortion compared to conventional methods.

Potential for high-speed, compact primary thermometry applications.

Abstract

We demonstrate a Doppler thermometer based on direct optical frequency comb spectroscopy of an $^{85}$Rb vapor with a chirped electro-optic frequency comb (EOFC). The direct EOFC Doppler thermometer is accurate to within its approximately 1 K statistical uncertainty. We experimentally compare direct EOFC spectroscopy with conventional Doppler spectroscopy using a single-frequency, step-scanned laser probe. Our results show that direct EOFC spectroscopy mitigates transit-induced optical pumping distortion of the atomic lineshape, which is the dominant systematic temperature shift in alkali atom Doppler thermometry. Optical Bloch equation simulations of conventional and direct EOFC Doppler spectroscopy confirm that EOFC spectroscopy can use higher optical power to reduce statistical noise without optical pumping distortion. Our results indicate that EOFC Doppler thermometry is a promising approach to realizing a primary thermometer with size and measurement rate sufficient for applications including pharmaceutical manufacturing and nuclear waste monitoring.