Current Optics and Photonics

Optical Society of Korea (한국광학회)
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Software-based Simple Lock-in Amplifier and Built-in Sound Card for Compact and Cost-effective Terahertz Time-domain Spectroscopy System

  • Yu-Jin Nam (Department of Physics, Dankook University) ;
  • Jisoo Kyoung (Department of Physics, Dankook University)
  • Received : 2023.06.07
  • Accepted : 2023.10.12
  • Published : 2023.12.25
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Abstract

A typical terahertz time-domain spectroscopy system requires large, expensive, and heavy hardware such as a lock-in amplifier and a function generator. In this study, we replaced the lock-in amplifier and the function generator with a single sound card built into a typical desktop computer to significantly reduce the system size, weight, and cost. The sound card serves two purposes: 1 kHz chopping signal generation and raw data acquisition. A unique software lock-in (Python coding program to eliminate noise from raw data) method was developed and successfully extracted THz time-domain signals with a signal-to-noise ratio of ~40,000 (the intensity ratio between the peak and average noise levels). The built-in sound card with the software lock-in method exhibited sufficiently good performance compared with the hardware-based method.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF 2020R1F1A1074832, NRF 2021R1F1A1058307, and NRF 2022R1A2C2006379), International Research & Development Program of the NRF funded by the Ministry of Science and ICT (Grant no. 2022K1A3A1A73080783), Nano·Material Technology Development Program through the NRF funded by the Ministry of Science, ICT and Future Planning (NRF 2009-0082580, Project number K210309005, K230208009), and Research-focused Department Promotion Project as a part of the University Innovation Support Program 2020 of Dankook University.

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