Mechanically formed loss-tunable long-period fiber gratings realized on the periodic arrayed metal wires

Temperature-sensitive mechanical LPFG using contractive force of heat-shrinkable tube

“…In LPFGs, the ratio of power coupled into the mth-cladding mode P m cl to the initial power contained in the guided LP 01 mode P 01 is given by [16] P m cl ðLÞ=P 01 ð0Þ ¼ sin 2 ðjLð1 þ ðd=jÞ 2 Þ 0:5 Þ=ð1 þ ðd=jÞ 2 Þ ð 2Þ…”

“…In particular, the applied pressure to the fiber increases due to the shrinkage of the tube in the radial direction [17,18], which enhances the magnitude of the periodic refractive index modulation on the fiber. The CTE of the polyethylene of which the heat-shrinkable tube is composed is two or three orders larger than that of the glass fiber, and one order larger than that of the screw made of the stainless steel [15,16,19]. Therefore, as the temperature increases, the applied pressure to the fiber decreases and the resonance loss decreases, because the heat-shrinkable tube has larger CTE than other materials used in the device.…”

Long‐period fiber gratings mechanically induced by winding a string around a fiber/grooved tube set

“…In modified versions, the fiber is pressed against a metallic plate with a radial grooved pattern [9] or against two out-of-phase arrays of graphite rods [10]. Recently in [11], mechanical gratings were also produced by pressing a fiber against an array of metal wires/flat glass being the space in between filled with a photopolymer. No loads are required after the curing of the photopolymer, and the resonances wavelengths can be tuned by dissipating heat through the wires.…”

High sensitivity temperature sensor based on a polymer filled hollow core optical fibre interferometer

“…In this report, we propose to use a polymer filled hollow core fibre (as opposed to surface coated fibre structure) to substitute the sandwiched SMF in the previous SMSMS * Qiang.wu@northumbria.ac.uk fibre structure. Since the polymer material has a much higher thermo-optic coefficient (-1.83 × 10 -4 / o C) [16] as compared to that of silica (1.06 × 10 -5 / o C), a high sensitivity for temperature should be achieved experimentally. Figure 1 shows a schematic diagram of the proposed singlemode-multimode-hollowcore-multimode-singlemode (SMHMS), interferometer basedfibre structure.…”