Mechanically induced long period gratings in different silica multi-layered optical fibers

This work presents a thorough comparative investigation of mechanically induced long period gratings (MILPGs) realized in different unconventional multi-layered silica optical fibers: two double cladding fibers (DCF), with progressively three layered (PTL) and W-type structures, and a solid core photonic crystal fiber (PCF). A periodic interdigitated grooved structure, based on the stereo-lithography 3D printing technique, is developed for the grating formation in these fibers with simplicity and cost-effectiveness. Multiple grating periods are developed in the range 480–660 μm, resulting in attenuation bands with depth within 15–25 dB and wide range of tunability over the wavelength range of 1100–1700 nm. The results demonstrate effective management of transmission spectra evolution as a function of the applied weight, with minimal alteration in wavelength position when testing the fiber with or without its coating. Polarization dependent properties of these gratings are also investigated demonstrating a negligible impact. This is the first time that such a broad investigation is conducted about MILPGs in the fibers mentioned earlier with broad scouting in fabrication parameters, opening to the application of such devices for sensing and communication purposes.