Sensing characteristics of structural microfiber long-period gratings.

We present a detailed investigation into the sensing characteristics of a structural microfiber long-period grating (mLPG) sensor. By spirally winding a thinner microfiber to another thicker microfiber, periodic refractive index modulation is formed while the optical signal transmitted in the thicker microfiber is resonantly coupled out to the thinner microfiber, and then a 5-period four-port mLPG can be obtained with a device length of only ∼570 µm demonstrated a strong resonant dip of 25 dB. We studied the sensitivity characteristics of the four-port mLPG with surrounding strain, force, temperature and refractive index, and the obtained sensitivities were -6.

ZIF-90-Derived Porous ZnO Coated Optical Microfiber Interferometer Sensor for Enhanced Humidity Sensing and Breath Monitoring.

Humidity plays an important role in many fields, and the realization of high sensitivity and fast response simultaneously for humidity detection is a great challenge in practical application. In this work, we demonstrated a high-performance relative humidity (RH) sensor made by supporting zeolitic imidazolate framework-90 (ZIF-90)-derived porous zinc oxide (ZnO) onto an optical microfiber Sagnac interferometer (OMSI). The ZIF-90-modified OMSI (ZIF-90-OMSI) sensor was in situ heated at different temperatures to obtain porous ZnO, and their humidity-sensing properties were investigated ranging from 25 to 80% RH.