Mechanically-Induced Long-Period Fiber Gratings Using Laminated Plates

Abstract

This work presents a formation method of mechanically-induced long-period fiber gratings using laminated plates. The mechanically-induced long-period fiber grating is temporarily inscribed by compressing the optical fiber between a flat plate and the proposed laminated plate. In turn, the new laminated plate consists of a parallel assembling of single-edged utility blades. We present the experimental characterization of mechanically-induced long-period fiber gratings while employing three laminated plates with a period of 480 ± 20 µm and low duty cycles. These mechanically-induced long-period fiber gratings display a leading rejection band (>15 dB) with a couple of shallow rejection bands (<2 dB) in the range of 1100–1700 nm. This spectral behavior is due to the new mechanical fabrication process that is based on laminated plates that we have proposed, which consists of piling multiple blades with trapezoidal edges that are polished with different levels to obtain different duty-cycles. With the proposed method, we can obtain values of duty-cycles around 10%, much lower than those obtained using traditional methods. Additionally, with this new method, the required mechanical pressure to form the grating is remarkably reduced, which minimizes the probability of the optical fiber failure in the mechanically-induced long-period fiber gratings (MI-LPFGs). Moreover, the proposed mechanically-induced long-period fiber gratings with a single rejection band open the feasibility to implement coarse wavelength division multiplexing systems that are based on long-period fiber gratings.

Transverse Load and Temperature Sensing Using Multiplexed Long-Period Fiber Gratings

“…LPFGs with this number of the rejection bands and their spectral side lobes limit the wavelength-division multiplexing of LPFGs in cascade [16]. However, in the last years, it has been shown that LPFGs with a primary rejection band over a wide wavelength range using different inscription techniques is feasible [23][24][25][26][27]. Long-period fiber gratings with a primary rejection band facilitate the deployment of fiber optic distributed sensing systems based on the wavelength-division multiplexing of LPFGs.…”

“…The MI-LPFG can be achieved when the optical fiber is compressed between a flat aluminum plate and a laminated plate, see Figure 1b. The laminated plate consisted of a parallel assembling of single-edged utility blades [23]. The laminated plate had a length of approximately 30 mm, an average period of 490 ± 10 µ m, and an average duty cycle of the refractive-index modulation of 0.2.…”

“…Although these schemes require simple demodulation techniques, the wavelength-division multiplexing of LPFGs is delimited because LPFGs usually generate multiple rejection bands. However, mechanically induced long-period fiber gratings (MI-LPFGs) with a primary rejection band have recently been reported using laminated plates [23]. Such MI-LPFGs with a principal rejection band facilitate the use of the CWDM technique for LPFG sensors in cascade.…”

UV Inscription and Pressure Induced Long-Period Gratings through 3D Printed Amplitude Masks

“…[ 5 ]. LPGs have been fabricated with a variety of techniques, such as irradiation through: UV laser [ 1 ], CO 2 laser [ 6 ], and femtosecond laser [ 7 ]; electric arc discharge [ 8 , 9 ]; mechanically induced by pressing a periodically grooved plate on a fiber [ 10 , 11 , 12 ] using machined metallic or silica plates [ 10 ], v-grooves on a tube [ 13 ]; coil spring [ 14 ], and recently, pilling of blades [ 15 ], and 3D printing of amplitude masks [ 11 , 12 ]; ion implantation [ 16 ]; and periodical etching of the fiber cladding to produce a corrugated structure [ 17 ]. Among those, the CO 2 and the UV laser inscription have been one of the most used.…”

Label-Free and Reproducible Chemical Sensor Using the Vertical-Fluid-Array Induced Optical Fiber Long Period Grating (VIOLIN)

“…Among those sensors, long-period fiber grating (LPG) guides the core lightwave to outer cladding region via a longitudinal index modulation structure with a period of hundreds of microns to millimeters, allowing light to interplay further with the ambient medium. The LPG outperforms its counterparts lying in the combination of ease of fabrication, the flexibility of design, the abundance of serviceable signals, cost-effectiveness, and high sensitivity [ 15 , 16 , 17 ]. As a consequence, the LPG refractometer is soon considered as a competitive approach for label-free and in-situ assessing biological and chemical targets in which the molecular reaction events could be transduced simply by the grating resonance shift.…”