Wavelength interrogation of grating-based optical biosensors in the input coupler configuration

A planar optical waveguide with an input grating coupler was used as a label-free biodetection device. Nanoimprint lithography was used to integrate the grating patterns with low loss silicon oxynitride thin film waveguides. A widely tunable laser source at 1550 nm was used to characterize the device sensitivity to bulk medium changes, to thin film adsorption, and to protein binding. For each test, a comparison was performed between the sensitivity of wavelength interrogation and the more standard angular interrogation approach. The results indicate that these devices used in wavelength interrogation with a telecom laser source are perfectly suited to be integrated in compact and sensitive biodetection systems.