Picometre displacement tracking of an optical beam in a silicon Schottky barrier sensor

An Ni-Si-Ni Schottky barrier sensor is used to sense 0.032 nm (0.064 nm peak-to-peak, 0.023 nm RMS) displacement of an optical beam incident on the sensor. This spatial resolution is more than two orders of magnitude better than any previously reported with a simple solid-state device and approaches interferometric levels