A Review of Antiresonant Hollow-Core Fiber-Assisted Spectroscopy of Gases.

Piotr Jaworski

doi:10.3390/s21165640

Abstract

Antiresonant Hollow-Core Fibers (ARHCFs), thanks to the excellent capability of guiding light in an air core with low loss over a very broad spectral range, have attracted significant attention of researchers worldwide who especially focus their work on laser-based spectroscopy of gaseous substances. It was shown that the ARHCFs can be used as low-volume, non-complex, and versatile gas absorption cells forming the sensing path length in the sensor, thus serving as a promising alternative to commonly used bulk optics-based configurations. The ARHCF-aided sensors proved to deliver high sensitivity and long-term stability, which justifies their suitability for this particular application. In this review, the recent progress in laser-based gas sensors aided with ARHCFs combined with various laser-based spectroscopy techniques is discussed and summarized.

Highlights

The end of the previous century has brought a new type of optical fiber, the socalled hollow-core fiber (HCF), which due to its unique structure and ability to guide light in the air via the photonic bandgap effect, rather than via the conventional total internal reflection phenomenon, revolutionized the development and application areas of optical fiber technology [1]
Benefiting from an empty core, which can be filled with the target gas, HCFs can be utilized as low-volume absorption gas cells, forming versatile light-gas molecules interaction paths with the desired length within a sensor setup [8]
The multipass cells based on the use of optical mirrors (e.g., Herriot- or White-type) mounted in e.g., metal optomechanical housings are sensitive to temperature changes due to thermal expansion of the material, which affects the stability of the gas sensor

Summary

Introduction

The end of the previous century has brought a new type of optical fiber, the socalled hollow-core fiber (HCF), which due to its unique structure and ability to guide light in the air via the photonic bandgap effect, rather than via the conventional total internal reflection phenomenon, revolutionized the development and application areas of optical fiber technology [1]. The multipass cells based on the use of optical mirrors (e.g., Herriot- or White-type) mounted in e.g., metal optomechanical housings are sensitive to temperature changes due to thermal expansion of the material, which affects the stability of the gas sensor. This can be minimized by using materials with lower thermal expansion coefficient, e.g., invar, at cost of a significant increase in the sensor’s price, especially when multipass cells delivering several tens of meters long paths lengths are used in the setup.

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Conclusion