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. 2025 May 6;25(9):2933.
doi: 10.3390/s25092933.

All-Fiber LITES Sensor Based on Hollow-Core Anti-Resonant Fiber and Self-Designed Low-Frequency Quartz Tuning Fork

Xiaorong Sun  1   2 , Weipeng Chen  1   2 , Ying He  1 , Haiyue Sun  1   2 , Shunda Qiao  1 , Yufei Ma  1   2
Affiliations

All-Fiber LITES Sensor Based on Hollow-Core Anti-Resonant Fiber and Self-Designed Low-Frequency Quartz Tuning Fork

Xiaorong Sun et al. Sensors (Basel). .

Abstract

In this paper, an all-fiber light-induced thermoelastic spectroscopy (LITES) sensor based on hollow-core anti-resonant fiber (HC-ARF) and self-designed low-frequency quartz tuning fork (QTF) is reported for the first time. By utilizing HC-ARF as both the transmission medium and gas chamber, the laser tail fiber was spatially coupled with the HC-ARF, and the end of the HC-ARF was directly guided onto the QTF surface, resulting in an all-fiber structure. This design eliminated the need for lens combinations, thereby enhancing system stability and reducing cost and size. Additionally, a self-designed rectangular-tip QTF with a low resonant frequency of 8.69 kHz was employed to improve the sensor's detection performance. Acetylene (C2H2), with an absorption line at 6534.37 cm-1 (1.53 μm), was chosen as the target gas. Experimental results clearly demonstrated that the detection performance of the rectangular-tip QTF system was 2.9-fold higher than that of a standard commercial QTF system. Moreover, it exhibited an outstanding linear response to varying C2H2 concentrations, indicating its high sensitivity and reliability in detecting C2H2. The Allan deviation analysis was used to assess the system's stability, and the results indicated that the system exhibits excellent long-term stability.

Keywords: all-fiber; hollow-core anti-resonant fiber (HC-ARF); light-induced thermoelastic spectroscopy (LITES); self-designed low-frequency quartz tuning fork (QTF); sensor.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Sizes of two QTFs employed in the experiment. (a) The commercial QTF. (b) The self-designed rectangular-tip QTF.
Figure 2
Figure 2
Simulation results of two QTFs. (a) Surface charge density of commercial QTF. (b) Surface charge density of self-designed rectangular-tip QTF. (c) Stress distribution of commercial QTF. (d) Stress distribution of self-designed rectangular-tip QTF.
Figure 3
Figure 3
Characteristics of two QTFs. (a) Physical images of two QTFs. (b) Frequency response curves of commercial QTF (in red) and rectangular-tip QTF (in blue).
Figure 4
Figure 4
Schematic diagram of all-fiber LITES sensor based on HC-ARF.
Figure 5
Figure 5
The relationship between current modulation depth and signal amplitude of QTF1 (in red) and QTF2 (in blue).
Figure 6
Figure 6
(a) When using QTF1, the 2f signals corresponding to different concentrations of C2H2. (b) When using QTF2, the 2f signals corresponding to different concentrations of C2H2. (c) The relationship between different concentrations of C2H2 and corresponding 2f signal peaks when using QTF1. (d) The relationship between different concentrations of C2H2 and corresponding 2f signal peaks when using QTF2.
Figure 7
Figure 7
The noise of the all-fiber LITES sensor system when QTF1 and QTF2 are used as detection elements.
Figure 8
Figure 8
Allan deviation analysis for the all-fiber LITES sensor system.
See this image and copyright information in PMC

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