Fabrication of Polymer Optical Fibre (POF) Gratings

Abstract

Gratings inscribed in polymer optical fibre (POF) have attracted remarkable interest for many potential applications due to their distinctive properties. This paper overviews the current state of fabrication of POF gratings since their first demonstration in 1999. In particular we summarize and discuss POF materials, POF photosensitivity, techniques and issues of fabricating POF gratings, as well as various types of POF gratings.

Latest Achievements in Polymer Optical Fiber Gratings: Fabrication and Applications

“…Gratings are fabricated in fibers, due to the photosensitivity of polymer material under UV, which leads to the fiber refractive index change after UV absorption. Indeed, photosensitivity strongly depends on the wavelength and the inscription mechanism, as was completely detailed by Luo et al [66]. Since the Bell laboratories discovered this around 1970s [79], the absorption of 325 nm wavelength UV radiation was identified as the preferred technique for refractive index change in PMMA material.…”

“…Birefringent gratings have been employed to change the polarization state of light at different wavelengths [60,61], and laser micromachining has been used for obtaining POF gratings with different microstructures in the cladding, in order to enhance their humidity response time [62] with a high strain sensitivity [63]. A Fabry-Perot cavity based on POF gratings was fabricated by Dobb et al [64], phase-shifted (PS) FBGs in POF were obtained by uniform UV exposure of the central part of 1-cm-long gratings [64], and tilted FBGs were reported by Hu et al in 2014 [65] in step-index POFs, among others included in [66]. Finally, chirped FBGs were fabricated by using a chirped phase mask in 2017 [67].…”

“…Previous literature includes extensive reviews published by Webb [1], Luo et al [66], Canning [68], Marques et al [69,70], Broadway et al [71], Berghmans et al [72], and Nogueira et al [73], focusing on the uniform POF gratings fabrication and applications. Due to the emerging POF applications in communications and sensing, intense work has been done in recent years towards obtaining a short, flexible, and reliable fabrication process for gratings in these fibers.…”

Performance Analysis of a Lower Limb Multi Joint Angle Sensor Using CYTOP Fiber: Influence of Light Source Wavelength and Angular Velocity Compensation

“…To maintain the low cost, simpler interrogation techniques are usually used, such as the intensity variation principle. However, this technique offers precision limitations, presenting low sensitivity and systematic errors, such as nonlinearity, offset and hysteresis [15], when compared with more sophisticated measuring principles, such as nonlinear effects [16], fiber Bragg gratings (FBGs) [17] and interferometers [18].…”

“…The fabrication of POFs consists of a variety of optical polymers, including polymethyl-methacrylate (PMMA), cyclic transparent optical polymer (CYTOP produced by Chromis Fiberoptics, New Jersey, USA), cyclic olefin copolymer (COC), polystyrene (PS) and polycarbonate (PC) [8,19]. PMMA is the most common and popular material with a low cost [17]. However CYTOP has the lowest transmission loss among them [8,20], from the visible to near-infrared spectrum, which is a good option for sensing applications [9].…”