Robust asynchronous optical sampling terahertz spectroscopy using commercially available free-running lasers

TL;DR

This paper demonstrates a robust, broadband terahertz spectroscopy technique using commercially available free-running lasers, employing a novel postprocessing algorithm to correct jitter and enable long-term stable measurements.

Contribution

It introduces a jitter correction method for ASOPS terahertz spectroscopy with free-running lasers, eliminating the need for stabilization and enabling reliable long-term operation.

Findings

Achieved broadband (2.5 THz) spectroscopy with high spectral resolution (82 MHz).

Demonstrated stable operation over 60 hours under varying temperature conditions.

Validated the robustness of the jitter correction method in practical settings.

Abstract

This study presents asynchronous optical sampling (ASOPS) terahertz spectroscopy using commercially available Ti:Sapphire lasers without stabilizing repetition frequency. Our postprocessing algorithm using the multiplied repetition frequency difference as the calibration signal successfully corrected the jitter, thereby allowing broadband (2.5 THz) spectroscopy with a high spectral resolution (82 MHz). The robustness of the jitter correction based on the free-running laser setup and broadband electric circuits was rigorously examined under varying temperatures, thereby demonstrating reliable long-term operations over 60 h. This study expands the applicability of the ASOPS terahertz time-domain spectroscopy.