Optical humidity sensor based on air guided photonic crystal fiber

Abstract

We proposed a novel relative humidity (RH) sensor based on the air guided photonic crystal fiber (AGPCF) using the direct absorption spectroscopic method in this paper. The wavelength scanning around the water vapor absorption peak around 1368.59 nm was realized by injecting the saw-tooth modulated current to a distributed-feedback laser diode. A reference signal was used as a zero absorption baseline and to help reduce the interference from the distributed-feedback laser source and probed region. The humidity level was determined by the normalized voltage difference between the reference signal and sensor signal at the peak of water vapor absorption. We demonstrated that a length of 5-cm AGPCF with a fixed small air gap between the single mode fiber (SMF) and hollow core fiber as an opening achieved a humidity detection resolution of around 0.2% RH over the range 0 to 90% RH which did not require the use of any hygroscopic coating material.

Fabrication and characterization of multi-stopband Fabry–Pérot filter array for nanospectrometers in the VIS range using SCIL nanoimprint technology

“…It is foreseeable that the IoT system will lead us to the next generation of communication and information network due to the integrated networks of low-cost, light-weight, and smart-sensing devices (EPoSS 2008;Gong et al 2010). Among such networked sensing system, optical spectroscopy is obviously one of the most potential sensing techniques due to its high sensitivity, remarkable selectivity, and wide application fields from industry production guard (Brennan et al 2002), environment monitoring (Mohd et al 2012), agriculture (Clevers 1999;Kanke et al 2016) to medical prevention, and healthcare (Gerger et al 1997;Zhang et al 2009). Therefore, to integrate or embed spectrometers into sensors, actuators, mobile devices, i.e., any objects in our life to construct a socalled "smart personal environment" (Tubaishat and Madria 2003), the miniaturization of spectrometers becomes crucial and essential.…”

Sensitivity analysis for detecting chemicals by the optical chemical sensor based Photonic Crystal Fiber (PCF) in the Terahertz (THz) regime

“…In recent times, however, the sol-gel process for the manufacture of the PCF structure with optical sensors is most commonly used and is better suited for the manufacture of the PCF structure based on sensors [21,[30][31][32][33][34]. In addition, the selective filling technique is better suited for filling or loading chemical products into the core areas with any PCF fiber structure [35][36][37][38][39][40][41]. Thus, by applying the latest technology production process for filling, up technique fabrication process, we achieved better guiding properties like effective area, relative sensitivity, power fraction, confinement loss, and effective mode index.…”

Optical Fiber Sensors Based on Microstructured Optical Fibers to Detect Gases and Volatile Organic Compounds—A Review

“…M.Y.M. Noor et al proposed a novel MOF RH sensor based on the air guided by an HC-PCF using the direct absorption spectroscopic method [93,94]. The humidity level was determined by the optical power difference between a reference signal and a MOF sensor signal centered at the peak of water vapor absorption.…”