Rapid-scanning terahertz precision spectrometer with more than 6 THz spectral coverage

Area of Science:

• Spectroscopy
• Terahertz (THz) technology
• Optical physics

Background:

• Terahertz time-domain spectroscopy (THz-TDS) is a powerful technique for material characterization.
• Traditional THz-TDS systems often rely on mechanical delay stages, limiting scan speed and introducing potential errors.
• Achieving high spectral resolution and broad bandwidth simultaneously remains a challenge in THz-TDS.

Purpose of the Study:

• To report a novel terahertz time-domain spectrometer.
• To demonstrate a system with broad spectral coverage (>6 THz) and high resolution (1 GHz).
• To showcase operation without a mechanical delay stage, enabling high-speed measurements.

Main Methods:

• Utilizing high-speed asynchronous optical sampling (ASOPS) for THz generation and detection.
• Implementing a scan rate of 2 kHz without mechanical components.
• Validating system accuracy by measuring water vapor absorption spectra.

Main Results:

• Achieved spectral coverage exceeding 6 THz with a resolution of 1 GHz.
• Operated the spectrometer at a rapid 2 kHz scan rate.
• Demonstrated a mean frequency error of 142 MHz for 87 water vapor absorption lines compared to HITRAN data.

Conclusions:

• The developed ASOPS-based THz-TDS system offers high spectral resolution and broad bandwidth.
• The absence of mechanical delay stages enables fast, precise measurements.
• The system's accuracy is validated for spectroscopic applications, including atmospheric gas analysis.