Wavelength-interrogated optical sensor for biochemical applications

A novel miniature integrated-optical sensor for versatile multichannel applications is described. Wavelength-modulation techniques using laser diodes (vertical-cavity surface-emitting lasers) are used to interrogate multiple-waveguide sensing regions on a single integrated-optical chip for accurate measurement of effective refractive-index changes at a high data rate. With the experimental miniature sensor system, a resolution of $\mathrm{\Delta }{N}_{\mathrm{PP}}={10}^{-7}$ (short term, peak to peak) of the effective refractive index was demonstrated. In terms of surface-mass coverage, this resolution corresponds to $\mathrm{\Delta }{\mathrm{\Gamma }}_{\mathrm{PP}}=130 \mathrm{fg}/{\mathrm{mm}}^2$.