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 similar to 570 mu m 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 -6.4 pm/mu epsilon, -8418.6 nm/N, 7.62 pm/degrees C and 2122 nm/RIU, respectively. With the advantages of high refractive index sensitivity and wide wavelength tunable range, the four-port mLPG has great potential in applications such as tunable filters and biochemical sensor.

Automated summary

We conducted a detailed investigation on the sensing characteristics of a structural microfiber long-period grating (mLPG) sensor. By spirally winding a thinner microfiber to another thicker microfiber, we achieved periodic refractive index modulation and resonant coupling of the optical signal. The four-port mLPG exhibited strong resonant dip and showed sensitivities to surrounding strain, force, temperature, and refractive index. With its high refractive index sensitivity and wide wavelength tunable range, this mLPG sensor holds great potential in applications such as tunable filters and biochemical sensors.