A Study on the Design of Integrated-Optic Biosensor based on the Power Coupling of Two Modes utilizing Si3N4 Rib-Optical Waveguides

We proposed an integrated-optical biosensor configuration that operates at a wavelength of 0.63 μm based on the evanescent-wave and lateral two-mode power coupling of Si
3
N
4
rib-optical waveguides formed on a Si/SiO
2
/Si
3
N
4
/SiO
2
multilayer thin films. The coupling between the two propagating modes in the sensing region produces a periodically repeated optical power exchange along the propagation. The light power was steered from one output channel to the other caused by the change of the cladding layer (bio-material) refractive index, which affect the effective refractive index (phase-shift) of two modes through evanescent-waves. The sensitivity 12~23 [au/RIU] was evaluated for the two-mode region of the width and length of 4 μm and 3841.46 μm, corresponding to the refractive index range 1.36-1.43.