Ultrawide-range refractive-index sensor based on asymmetric integrated Y-junction optical waveguide

Abstract

We present a novel ultrawide-range refractive index (RI) sensor based on an asymmetric Y-junction optical splitter.A cylindrically shaped rod with a diameter of 350 nm and a height of 1000 nm with a different RI is inserted into a junction of the asymmetric Y-junction waveguide.This rod serves as a sensing area.Our sensor is simulated using a finite-difference time-domain technique.The splitting ratio is studied for the cases of two operating wavelengths, 1480 and 1550 nm.The results show that the splitting ratio can be described as a parabolic function of the RI of the sensing area at both operating wavelengths.An approximately linear relationship between the splitting ratio and the RI occurs in a narrower RI region of 1.00-1.50,thus enabling to design an ultrawide-range RI sensor.The sensor sensitivities at the wavelengths 1480 and 1550 nm are equal respectively to 0.2653 and -0.4908 RIU -1 , with the corresponding R 2 parameters amounting to 0.9889 and 0.9777.Our device can serve as an ultrawide-range optical RI sensor for identification of micro-scale biochemical or chemical specimens.