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.