Optical weak measurement system with common path implementation for label-free biomolecule sensing.

A reflection-type phase-sensitive weak measurement for biosensing and chemical label-free sensing is presented. The phase difference between p and s polarizations in total internal reflection caused by biomolecular recognition is measured by weak value amplification. The system with p and s polarizations in a common path is stable and robust. The sensing process occurring on the silicon dioxide surface is achieved with a resolution of 3.6×10^-6 refractive index units. The applicability is demonstrated by real-time monitoring biomolecular interaction of IgG and protein A.