A refractive index sensor based on the multimode interference in a hollow fiber

A novel optical fiber refractive index sensor is presented,which employs the multimode interference in a hollow fiber to achieve the measurement of environmental solution refractive index.The sensor is wavelength-encoded with good anti-jamming,easy to fabricate and with low cost.Experimental results show that the refractive index sensing range of the sensor is from 1.333 to 1.450,and when the solution refractive index is less than 1.40,the characteristic wavelength is nearly linear to the refractive index with a sensitivity of 88.07 nm.In addition,the output spectrum energies from different solutions with the same refractive index are different.This feature indicates that this kind of fiber-optic sensors have a potential application in the detection of materials.