Ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference

We propose an ultra high sensitive integrated optical waveguide refractive index sensor based on multimode interference which can be integrated with other sensing elements on a single chip. The proposed sensor has ultra high sensitivity around communication wavelength (1.55 μm) varying from ∼1370 (1160) to 33,850 (26,050) nm/RIU for TM (TE) polarized input light for the refractive index changes from 1.33 to 1.44. To the best of our knowledge, this sensitivity is highest among multimode interference based sensors reported till date. A physical explanation for the ultra high sensitivity is also presented.