Comprehensive Review Tapered Optical Fiber Configurations for Sensing Application: Trend and Challenges

Abstract

Understanding environmental information is necessary for functions correlated with human activities to improve healthcare quality and reduce ecological risk. Tapered optical fibers reduce some limitations of such devices and can be considerably more responsive to fluorescence and absorption properties changes. Data have been collected from reliable sources such as Science Direct, IEEE Xplore, Scopus, Web of Science, PubMed, and Google Scholar. In this narrative review, we have summarized and analyzed eight classes of tapered-fiber forms: fiber Bragg grating (FBG), long-period fiber grating (LPFG), Mach–Zehnder interferometer (MZI), photonic crystals fiber (PCF), surface plasmonic resonance (SPR), multi-taper devices, fiber loop ring-down technology, and optical tweezers. We evaluated many issues to make an informed judgement about the viability of employing the best of these methods in optical sensors. The analysis of performance for tapered optical fibers depends on four mean parameters: taper length, sensitivity, wavelength scale, and waist diameter. Finally, we assess the most potent strategy that has the potential for medical and environmental applications.

Bi-Functional Coated Tapered LPFG Sensor: Gas and Temperature Sensing

“…It can be heated by for example flame, arc discharge or laser radiation with high power. In addition, the taper region can be achieved by polishing and chemical etching [20]. As a result of these processes, the core of optical fiber become thinner along with the fiber itself.…”

“…The thinner region can be few of millimeters. In the current work, the MMF was heated and stretched uniformly and its parameters were controlled based on the following expression which clearly explains the exponential shape transition of the optical fiber [20].…”

“…The sensitivity reached to 255.4 pm/℃ in the range of (20-80℃) [18]. Another interesting study combined FBG with TiO2 coated LPFG for trucking organic solvents [19,20]. However, more methods of LPFG and FBG combination have been proposed.…”

A Taper-in-Taper Structured Interferometric Optical Fiber Sensor for Cu2+ ion Detection

“…Recently, tapered optical fibers have become one of the current trends among optical sensors given the rapid progress in tapered optical fibers and the great demands on optical sensors with higher sensitivity and simpler structure. Based on Mach–Zehnder interferometers (MZIs) with strong evanescent field, fiber sensors with tapered structures can realize higher sensitivity compared with common and mature fiber structures such as fiber Bragg grating sensors [ 19 , 20 ]. Among a variety of tapered fiber sensors based on MZI, RI sensors have been intensively studied because RI itself is an important parameter in physical and chemical fields that could realize the indirect measurement of many other parameters such as solution concentration and pH value [ 21 , 22 , 23 ].…”

A Review on Rhenium Disulfide: Synthesis Approaches, Optical Properties, and Applications in Pulsed Lasers

“…Numerous distinct characteristics of pulsed lasers such as greater peak intensity, broad spectrum and fast temporal resolution [1] have driven a wide-range of uses such as laser welding and drilling [2], ultrafast spectroscopy [3,4] and frequency comb metrology [5,6]. Furthermore, pulsed lasers based on intensity modulation have proven their significant efficiency within a wide variety of distributed optical fiber sensors (DOFS) [7][8][9][10][11]. These kinds of lasers could be produced either by Q-switching or mode-locking methods, which are categorized into passive or active modulation methodologies.…”