Designing a Long Optical Path Direct-Injection-Integrated Cavity for Laser Absorption Spectroscopy

Trace gas measurement has a wide range of applications needed in industrial, medical, and environmental protection. With the evolution of time, the demand for real-time, sensitivity, and accuracy of gas detection has been increasingly heightened. Off-axis integrated cavity output spectroscopy (OA-IC...

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Bibliographic Details
Main Authors: Quyouyang Gao, Yuquan Zheng, Long Wang, Chengliang Li, Jialun Zhang, Hao Wu, Yanxue Han, Shuo Wang
Format: Article
Language:English
Published: MDPI AG 2023-12-01
Series:Photonics
Subjects:
Online Access:https://www.mdpi.com/2304-6732/11/1/36
Description
Summary:Trace gas measurement has a wide range of applications needed in industrial, medical, and environmental protection. With the evolution of time, the demand for real-time, sensitivity, and accuracy of gas detection has been increasingly heightened. Off-axis integrated cavity output spectroscopy (OA-ICOS) is an effective method for the high-sensitivity detection of trace gases. It uses an integrated cavity with two highly reflective mirrors to provide a long optical path, which guarantees its high sensitivity. However, as the reflectivity of the mirrors increases, the intensity of the output light decreases, and the signal-to-noise ratio decreases. This contradiction makes it difficult to achieve a long optical path and a high signal-to-noise ratio together. To combat this issue, this paper proposes a type of integrated cavity using a direct-injection method. This structure, under equivalent mirror conditions, can maintain an effective absorption optical path very close to the original off-axis integrated cavity while increasing the output light intensity hundreds of times. This enhancement increases the sensitivity of OA-ICOS.
ISSN:2304-6732