| Due to the air holes in the cladding in photonic crystal fiber?PCF?have periodic and random distribution,it exhibits the superiority and singularity compared with traditional optical fiber.Filling sensitive material to the PCF can change and control its transmission characteristics,and which can get PCF sensor with different types and characteristics.It is expected to develop a new generation of fiber optic devices because of the superiority of PCF-filled,and which gradually becomes a research hotspot.Liquid crystal?liquid crystal,LC?is a special material,and it is very sensitive in the temperature field or the electromagnetic field.So it is used as a sensitive material filled into the PCF,the combination of the PCF and LC can get Photonic liquid crystal fiber?PLCF?.Firstly,the transmission characteristics of PLCF are studied from the aspects of selective filling and full filling by software simulation and experimental study.When the innermost layer of the PCF is filled with adjacent,spaced,symmetrical two-holes LC,it has a flexible zero-dispersion position and the dispersion is stable at 10-4.The PLCF with three different structures have very small limit loss,and the PLCF with symmetrical two-holes LC has the maximum birefringence.With the increase of the number of LC holes filled in the innermost layer of PCF,the light guide mechanism of PLCF changed.Full-filled is mainly in the cladding air holes of PCFs filled with three kind of different refractive index LC,and these spectrums all have bandgaps.In the electronic control tuning experiment,three different refractive index and dielectric constant of the LC in PLCF have different spectrums.The light intensity of three spectrums is degenerative,and which can produce a matting phenomenon.There is the phenomenon of redshift when the voltage improved,but the tendencies of the three spectra have no change and stable.A method of making the interferometric PLCF sensor is proposed,and the influence of different LC-filled structures and different LC-filled lengths in PCF on the interference spectrum are studied.The interference characteristics of the three structures-filled with one hole,two holes and no LC hole in PCFs are studied,the interference peaks of the two LC-filled holes in the PLCF sensor is more than the PLCF sensor with the one LC-filled hole.The temperature sensitivity is studied,the maximum temperature sensitivity of one LC-filled hole PLCF sensor reaches-1.213 nm/oC,and the spectrum has blue shift phenomenon.Then,the transmission characteristics and temperature tuning characteristics of the PLCF sensor filled with two-hole structure are studied in detail.It can be seen that the photonic bandgap of the interference spectrum becomes more and more obvious with the lengths of the LC-filled increases.The four spectra produce blue shift with the temperature increases,and the maximum and minimum temperature sensitivities can be achieved to-1.5924 nm/oC and-0.1452 nm/oC.Good temperature tuning characteristics and stable spectrum can provide a good reference to design temperature sensor. |
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