Optimizing quasi terahertz time-domain spectroscopy signals with moderate optical feedback by varying external cavity length

Japanese Journal of Applied Physics 2026

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Authors: Linus Sison, Kristiene Joy Fernandez, Ivan Cedrick Verona, Jose Mari Sebastian Arcilla, Lourdes Nicole Dela Rosa, Horace Andrew Husay, Hannah R. Bardolaza, Hideaki Kitahara, Masahiko Tani, Caesar A. Saloma, Elmer Surat Estacio
DOI: 10.35848/1347-4065/ae38b0
Cited by: 0
References: 31

Abstract

Abstract Quasi-terahertz time-domain spectroscopy (QTDS) systems typically operate at a relatively low signal-to-noise ratio (SNR) due to the use of continuous-wave semiconductor lasers (SLs). In this work, we demonstrate experimentally that varying the SL optical feedback (OF) length on a centimeter scale can improve the operational SNR due to induced changes in the SL emission spectrum. In particular, deploying a long external cavity with a length of 70 cm under a moderate OF power level of 2.5% yielded the highest SNR improvement of ∼15 dB. Our results offer a versatile strategy for increasing the SNRs of QTDS systems.

Fields of Study & Subjects

Terahertz technology and applications Semiconductor Lasers and Optical Devices Spectroscopy and Laser Applications

Publication details

Journal / source
Japanese Journal of Applied Physics
Volume
65
Issue
2
Pages
020907–020907
Publication date
14 January 2026