Temperature-independent strain sensor design longperiod grating (LPG) and electromagnetically induced transparency

photonic crystal fibers constitute a new class of high birefringent optical fibers with strong separation of polarization modes. This advantage appear to be perfect for designing optical fiber sensors. In this paper, we purpose a temperature-independent strain sensors based on High-Birefringence fiber loop mirror with longperiod grating written in a photonic crystal fiber. The Hi-Bi PCF in FLM resonator acts as a sensor head for monitoring the strain, while the LPG written in PCF serve as convert wavelength variation to optical power change. The sensitivity of strain sensing system is high because optical power fluctuation of light source is eliminate by LPG. also, we use electromagnetically induced transparency phenomena to reduce the length of Hi- Bi FLM to below 0.8 mm, where 3-level nanocrystals are doped in Hi-Bi FLM to realize EIT conditions. other advantages this sensor is inherently insensitive to temperature due to using Hi-Bi PCF and it doesn’t needed an expansive optical spectrum analyzer.

Keywords:

EIT , Hi-Bi FLM Strain sensor , LPG , OSA , PCF