title: Real-time phase error compensation in phase sensitive scanning near-field optical microscopy.
abstract: Phase measurements are critical for investigations on the optical properties of surface plasmon polariton (SPP) nanostructures. In this paper, a real-time phase error compensation method based on a phase sensitive scanning near-field optical microscopy (SNOM) measurement system is proposed. The method adopts the common optical path configuration and CMR (common-mode rejection) principle. It can be seen that the phase error compensation is real-time and mainly relies on optical devices, therefore neither post processing nor previous knowledge of environmental effects is required. The causes of the phase drift errors are discussed. We demonstrate experimentally the effectiveness of this method by measuring a SPP focusing device. Regardless of the drift velocity, degree of linearity, or phase accuracy, the compensation method shows great improvement compared to the previous phase sensitive SNOMs. All the measured distributions are in good agreement with theoretical simulations obtained by the finite-different time-domain (FDTD) method.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Wu
authors.forename: Lin
authors.initials: L
authors.lastname: Sun
authors.forename: Jia
authors.initials: J
authors.lastname: Wang
authors.forename: Qiaofeng
authors.initials: Q
authors.lastname: Tan