Self-temperature-compensative refractometer based on singlemode–multimode–singlemode fiber structure

A Hybrid Multimode Interference Structure-Based Refractive Index and Temperature Fiber Sensor

“…Fig. 2 2, will shift to longer wavelength with the increase of RI or temperature [21]; the dip caused by SMS, namely the dip 2 in Fig. 2, will also exhibit a red shift with the increase of temperature but it isn't influenced by the ambient RI [8].…”

“…To solve the RI-temperature crosstalk problem, various methods have been proposed [16][17][18][19][20][21]. One of the most common and effective methods is to introduce an FBG [16][17][18][19], which is sensitive to temperature but not to surrounding RI.…”

“…In our previous work, we had analyzed the wavelength dependence of the RI sensitivity in SNS-based refractometer [23]. Then utilizing this characteristic, we realized the self-temperature-compensation for the SNS-based refractometer without introducing any additional structure [21]. However, in this case the actual RI-sensitivity was limited to only 23.30 nm/RIU because it was determined by the RI-sensitivity difference of two dips in transmission spectrum.…”

“…where the transmission's unit is dB; the TSNS(λ) and TSMS(λ) can be respectively calculated by [21]:…”

Highly sensitive temperature sensor using packaged optical microfiber coupler filled with liquids

“…When the temperature changes, the thermo-optic effect of the refractive index matching liquid results in a small change in its refractive index and as the refractive index of the liquid usually decreases with an increase of temperature, this leads to a red shift in the spectrum. Some of the previously reported sensors use this principle to implement temperature measurement [21,22]. Also the liquid refractive index usually increases with the increase of external pressure and the resulting spectrum is blue shifted.…”