Perceiving Linear-Velocity by Multiphoton Upconversion

Up to now, the rising edge of upconversion process does not receive due attention. Herein, a demonstration utilizing the feature of rising edge to practically detect linear-velocity of object is presented. Typically, upconversion processes with different numbers of participant photons would exhibit diversity in the rising edge. On this account, when the emitter is moving, the emission intensity ratio of different multiphoton processes will vary with the changing of linear-velocity, which enables accurate speed detecting through spectral analysis. To illustrate this principle, in this work, the modelling and numerical simulation were firstly performed, and then experimental demonstration was carried out, in which core-shell upconversion nanocrystals were elaborately designed and fabricated as the speed sensing probe to calibrate the speed of a home-made turnplate. It is believed that the present work will exploit a novel speed sensing method and find a new application for lanthanide-doped upconversion mate...