Broad-band difference interferometer as a refractive index sensor.

Integrated Optical Broad-Band Difference Interferometer (IO BB DI) is introduced as an alternative and economical measurement method to integrated optical label-free affinity sensors. A detailed theoretical analysis of the method is presented and the effects of the waveguide layer on the operation of the system are shown. A very short operating distance of less than 0.5 mm allows miniaturization of the interferometer. The analysis was performed for Si3 N4 /SiO2 layers that can be obtained in standard microelectronics technological processes.