Ultra-sensitive temperature sensor based on liquid crystal infiltrated photonic crystal fibers

Abstract

We investigated experimentally liquid crystal (LC) filled photonic crystal fiber's temperature responses at different temperature ranging from 30 to 80˚C. Experimental evidences presented that the LC's clearing point temperature was 58˚C, which is consistent with the theoretical given value. The bandgap transmission was found to have opposite temperature responses lower and higher than the LC's clearing point temperature owing to its phase transition property. A high bandgap tuning sensitivity of 105 nm/˚C was achieved around LC's clearing point temperature.

Infiltrated Photonic Crystal Fibers for Sensing Applications

“…Moreover, via molecular engineering, it is possible to shift the clearing point from room temperature to Tc>100 °C. By exploiting such physical properties, bandedge shift-based temperature LC-PCF sensors have been demonstrated with sensitivities ranging from 7 nm/°C in one of the early examples [37] to 27 nm/°C for a specially engineered LC for room temperature operation [182] and up to the extreme value of 105 nm/°C, albeit at a very narrow range near the clearing point and with a strong nonlinear response [183]. Linearity and broad temperature range can be restored, at the expense of lower sensitivities, as demonstrated in a thermally-sensitive notch filter in PBG [190].…”