Near-Visible Fiber Sensing Tandem Exploiting Single-Pulse Modulated Harmonic Bragg Gratings

Near-visible fiber Bragg grating finds myriad of applications such as quantum sensing, biomedical detection, and portable fiber probe. However, handling the requirements of flexibility, efficiency, and repeatability at the same time remains a challenge for the state-of-the-art near-visible grating inscription techniques. This work proposes a highly efficient and repeatable approach for fabricating near-visible fiber Bragg grating through harnessing the fourth harmonic order of Bragg resonance mediated by the common C-band phase mask. Even the single-pulse UV exposure can guarantee the effective reflection signal at 800 nm- waveband, allowing the grating tandem writing within a short time. After investigating the sensing characteristics of the near-visible fiber Bragg grating, the
in-situ
temperature sensing is demonstrated by utilizing the proof-of-the-concept grating tandem, enabling the spatial-temperature monitoring capability. This proposed proof-of-concept has shown tremendous promise in constituting the near-visible fiber sensing network and advancing portable sensors.