Versatile 3D-printed LPFG: Characterization, challenges and insights

This manuscript studies a method to create Long Period Fiber Gratings in optical fibers using a cost-effective 3D-printed device equipped with interchangeable masks, allowing fast reconfiguration and non-permanent modifications. We investigate diverse configurations by analyzing their transmission spectra in the range from 1520 nm to 1570 nm, and measure the dip wavelength (λDip) evolution with the force applied to the device. A force-dependent blue-shift is observed, and the refractive index modulation is estimated up to 2.84×10−3 and 2.39×10−3 for the two examined gratings masks. Analysis of the λDip and the figure of merit suggest a threshold force beyond which the spectral characteristics tendency reverse. This is likely linked to the different elasticity between the optical fiber and the mask material and the way they deform. Although the method imposes certain limitations in bandwidth, it can produce LPFGs with good applicability in scenarios such as low Technology Readiness Level or swiftly deployable cost-efficient systems for optical filtering or sensing. Considering sensing applications, we present a simple model for real-time computing of displacement, strain, or pressure through spectrum monitoring. The model aligns with the observed experimental results, underlining its practicality for potential applications.