Etching Process Related Changes and Effects on Solid-Core Single-Mode Polymer Optical Fiber Grating

Abstract

Etching process related material and mechanical changes on solid-core singlemode polymer optical fiber (POF) and their influence on the characteristic properties of polymer fiber Bragg gratings (PFBGs) are studied. A poly(methyl methacrylate)-based POF is etched to different diameters, and it is experimentally demonstrated that etching can lead to a change in the Young's modulus of the fiber. It is found that etching process induced material changes of the polymer fiber can enhance the reflectivity and inherent sensitivity of PFBGs. It is demonstrated that gratings based on etched POF exhibit higher reflectivity with a shorter exposure time compared with unetched ones. Highest reflectivity of 98.54% is observed within 7 seconds of exposure for a diameter of 85 m. The stability of fabricated Bragg gratings is also studied. By tailoring the etching diameter of POF, Bragg gratings with high sensitivity and high reflectivity can be fabricated.

Dynamic mechanical characterization with respect to temperature, humidity, frequency and strain in mPOFs made of different materials

“…If there are different materials on the fiber composition, an approximation for the resulting Young Modulus can be made through Eq. (2) [43]:…”

Etched Polymer Fibre Bragg Gratings

“…Fig. 1(a) shows the measured reflectivity pattern of polymer FBG with different diameters [6]. From the figure it is observed that, a reflectivity of 79.42 % is observed within 60 seconds of exposure for an un-etched POF with a diameter of 185 μm.…”

Fabrication of Polymer Optical Fibre (POF) Gratings

“…The photosensitivity of the latter introduction can be more stable. In addition, the photosensitivity can also be enhanced by the straining during the grating inscription [61] or the etching of photosensitive POF cladding [47,70]. As shown in Table S1, the change of the refractive index by radiation is ranged from 10 −5 to 10 −3 .…”

“…Although the control of the writing time is a complicated process, the reduction of the inscription time is the development trend for the improvement of writing efficiency. Figure 2 shows the historical evolution of inscription time of POF Bragg gratings [44,46,52,64,65,68,70,81,85,86,91,92,95,99,102,106,112,115,120,121,126,127,132,140]. …”

“…Hu et al [47] and Bhowmik et al [70] have demonstrated that etching has significant enhanced reflectivity and shortened the exposure time. Meanwhile, the strain sensitivity has also been enhanced.…”