Hollow fiber coupler sensor
Date
2018-12-12
Authors
Kuruba, Nithin Shekar
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Abstract
This thesis presents a method to fabricate a robust optical directional coupler sensor using a solid core fiber (SCF) and a hollow core fiber (HCF). Through
evanescent wave coupling mechanism, the optical power is exchanged between SCF
and HCF. The hollow core of the HCF can be filled with liquid samples to alter the
coupling ratio which imparts change in amount of light propagating through the SCF.
Thus, it gives the coupler with ability of sensing refractive index of the sample with
good sensitivity of 4.03 ± 0.50 volts per refractive index units (V/RIU) for refractive
indices ranging from 1.331 ± 0.003 to 1.403 ± 0.003 with a resolution of 3.5 × 10−3
refractive index units (RIU). The SCF-HCF coupler was also used to sense the temperature based on the concept of temperature dependence on refractive index of the
sample inside the hollow core of HCF. Further, the packaging methods are described
that protect coupler from ambient environments and improves the life span of sensor.
Description
Keywords
Optical directional coupler sensor, Solid core fiber, Refractive index