Bragg Gratings Inscription in TS-Doped PMMA POF by Using 248-nm KrF Pulses

Abstract

We demonstrate the Bragg gratings inscription in the 850 nm spectral region by using trans-4-stilbenemethanol (TS)-doped poly (methyl methacrylate) (PMMA) step-index optical fiber and a 248 nm krypton fluoride (KrF) excimer laser system. The gratings inscription only takes 0.4 second. A detailed study of the grating fabrication process using different pulse repetition rates is also reported. Additionally, temperature, humidity and strain sensitivities are measured to demonstrate the potentiality of these components for different sensing applications.

Inscription of Bragg gratings in undoped PMMA mPOF with Nd:YAG laser at 266 nm wavelength

“…However, no Bragg grating device has so far been reported in 5-rings structure mPOF using 325 nm He-Cd laser system, whereas we fabricated Bragg gratings in this fiber after 6 min by using 266 nm Nd:YAG laser. Since a 248 nm KrF pulsed laser system allowed to shorten the irradiation time, as demonstrated by Min et al [34] in doped step index POF, we tried 10 Hz frequency as the highest repetition rate of our Nd:YAG laser system using undoped two rings mPOF, and the shortest time was around 60 seconds with similar performance. In the fabricated POFBGs, the central wavelength blue-shifted after removing the fibers from the clamps of the inscription setup since the fiber was subjected to small strain during the inscription [35].…”

Latest Achievements in Polymer Optical Fiber Gratings: Fabrication and Applications

“…Since then, the research work on gratings inscription using 248 nm wavelength has been continuously growing. A typical POF FBG irradiation system is shown in Figure 1, where the pulse power and repetition rate can be optimized [97,98] in order to shorten the fabrication time, as will be shown below.…”

“…Due to the low photosensitivity of pure PMMA fiber [93], doped POFs have attracted researchers' interest [80,98,99]. Peng's group employed a step-index, multimode PMMA fiber with an organic dye doped core [100] for grating irradiation under a 325 nm UV beam, and obtained seven peaks in the reflected spectrum.…”

“…In this fiber, the cladding material is pure PMMA, while the core is PMMA doped with TS (1% w.t.) and diphenyl sulfide (DPS) (5% mole) to enhance the photosensitivity and increase the refractive index [98].…”

“…In this fiber, the cladding material is pure PMMA, while the core is PMMA doped with TS (1% w.t.) and diphenyl sulfide (DPS) (5% mole) to enhance the photosensitivity and increase the refractive index [98]. Marques et al [104] reported the inscription of gratings in POFs made of different materials (TOPAS, ZEONEX, and Polycarbonate) under 248 nm wavelength, and compared it with the same fiber irradiation under 325 nm, resulting in a reduction of the irradiation time by at least 16 times (Table 2) and better stability when 248 nm wavelength is employed.…”