Displacement detection of silicon nanowires by polarization-enhanced fiber-optic interferometry

We describe the displacement detection of freestanding silicon [111] nanowires by fiber-optic interferometry. We observe approximately a 50-fold enhancement in the scattered intensity for nanowires $40–60nm$ in diameter for incident light polarized parallel to the nanowire axis, as compared to perpendicular polarization. This enhancement enables us to achieve a displacement sensitivity of $0.5pm∕Hz$ for $15μW$ of light incident on the nanowire. The nanowires exhibit ultralow mechanical dissipation in the range of $(2×10−15)–(2×10−14)kg∕s$ and could be used as mechanical sensors for ultrasensitive scanning probe force measurements.