Widely tunable Long Period Gratings using 3D printed periodic grooved plates

In this work we present mechanically induced Long Period Gratings (LPGs) realized in different kinds of glass optical fibers by using UV-cured 3D printed periodic grooved plate. The periodic modulation of the geometry and refractive index along the length of the optical fiber is induced by pressure applied transversely to the grooved plate and leads to light coupling between the core mode and co-propagating cladding modes at specific resonance wavelengths. Using the proposed method, we realize and analyze in detail the behavior of the gratings induced in different optical fibers (i.e., SMF-28 and two different double cladding fibers), with and without acrylate coating. Results confirm that the depth of the attenuation bands in the transmission spectrum of the gratings, which were induced by gradually increasing the applied load show high tunability in the range of 1400-1650 nm with the maximum depth of 24 dB. Among the methods used for the fabrication of LPGs, the one studied here is reversible, very low cost, easy to tune, compatible with different kind of fibers and does not require a specific preparation of the fiber. The obtained devices are potentially useful for several application spanning from filters to sensors.