Electro-optic frequency comb Doppler-broadening thermometry

Area of Science:

• Atomic Physics
• Spectroscopy
• Metrology

Background:

• Doppler-broadening thermometry is crucial for precise temperature measurements.
• Conventional methods using single-frequency lasers suffer from systematic errors like transit-induced optical pumping distortion.
• Alkali atom vapor thermometry requires robust and accurate techniques.

Purpose of the Study:

• To demonstrate and validate Doppler-broadening thermometry using a chirped electro-optic frequency comb (EOFC).
• To compare the performance of direct EOFC spectroscopy against conventional Doppler spectroscopy.
• To assess the potential of EOFC thermometry for primary thermometer applications.

Main Methods:

• Direct optical frequency comb spectroscopy of 85Rb vapor using a chirped EOFC.
• Experimental comparison with conventional Doppler spectroscopy employing a single-frequency, step-scanned laser.
• Optical Bloch equation simulations to analyze atomic lineshape distortions.

Main Results:

• Direct EOFC Doppler-broadening thermometry achieved high accuracy with approximately 1K statistical uncertainty.
• EOFC spectroscopy effectively mitigated transit-induced optical pumping distortion, a key systematic error.
• Simulations confirmed that higher optical power can be used with EOFC spectroscopy to reduce noise without distortion.

Conclusions:

• Direct EOFC spectroscopy presents a significant advancement in Doppler-broadening thermometry.
• This technique overcomes major limitations of conventional alkali atom thermometry.
• EOFC Doppler-broadening thermometry is a promising candidate for a primary thermometer suitable for industrial applications.