Micro-Tapered Fiber Few-Mode Interferometers Incorporated by Molecule Self-Assembly Fiber Grating for Temperature Sensing Applications

K.T.V. Grattan,B.M.A. Rahman,Haimiao Zhou,Xinhe Lu,Ya-Pei Peng,Shijie Ren,Fan Yang,Lina Suo,Nan-Kuang Chen

doi:10.3390/photonics9020096

K.T.V. Grattan, B.M.A. Rahman + Show 7 more

Open Access

https://doi.org/10.3390/photonics9020096

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Journal: Photonics	Publication Date: Feb 7, 2022
Citations: 1	License type: CC BY 4.0

Affiliation: Liaocheng University, Shenzhen Technology University

Abstract

We demonstrate fiber few-mode interferometers based on a self-assembly surface corrugated grating using charged nano-particles. Initially, an abrupt taper (AT) was first created using a micro flame. The AT was then further outwardly stretched to make an elongated uniformed taper until the tapered diameter achieved a micron scale. The high order core modes (HOCMs) were excited at the AT and the optical path difference (OPD) among the modes was enlarged through the uniformed taper to achieve the few-mode interference effects seen. However, to significantly enhance the interference effects with higher extinction ratios (ER) over such a short length of interferometer, an external assisted grating was made using charged nanoparticles to form surface corrugated grating with a period, Λ, of approximately 14 μm. This intermediate period of the fiber grating was helpful in scattering and attenuating some unwanted high-order modes to change the optical characteristics of the few-mode interferometer (FMI). This FMI with a self-assembly fiber grating (SAFG) was further used to make fiber temperature sensors, with a maximum resonant wavelength shift of 4.6 nm, over a temperature range from 20–60 °C. The temperature sensitivity achieved was 112.6 pm/°C and the coefficient of determination, R2, was as high as 0.99, which revealed the high linearity of the results.

Highlights

To investigate theDiscussion optical characteristics of the tapered fiber few-mode interferometer (FMI) incorporated in the self-assembly fiber grating (SAFG), a test sample was prepared with D =of2.73 μm
The FMI was made by elongating an abrupt taper (AT) on a standard single-mode fibers (SMF) to excite first the high order core modes (HOCMs) to achieve the desired interference effects
The positively charged molecules adhered to the tapered fiber and clustered into periodical groups, to form fiber gratings, with an intermediate period of 14.01 μm to remove the unwanted HOCMs

Summary

Introduction with regard to jurisdictional claims in

Over the past few decades, fiber interferometers have been recognized as powerful tools for precisely measuring physical, chemical, or biological parameters in many scientific and industrial applications. The vacancy of the missing electron, forming a color center absorber, induces the periodical changes of the refractive index seen along the Ge-doped fiber core [22,23] This method is not suitable for those special fibers, such as no-core fibers and phosphate glass fibers, which have a lack of photosensitivity (such as the no-core fiber or silica micro-/nano-tapered fibers) and are becoming more and more important for key applications in micro- or nano-photonics. The temperature sensitivity achieved was 112.6 pm/◦ C and the coefficient of determination, R2 , was as high as 0.99, indicating the high linearity of the device This SAFG-based approach, using charged smoking nanoparticles, is a new fabrication method for making compact periodical micro-structures on Photonics 2022, 9, 96 micro- or nano-tapered fibers and is able to give rise to spectral resonances [33] with high. FMIs are compact and, can be used as an efficient way to achieve high sensitivity interferometers for the sensing systems needed today

Experimental Set-Up and Working Principle

Measurements and

Conclusions