OPTICAL NEAR-FIELD IMAGING WITH A SEMICONDUCTOR PROBE TIP

We present an optical near-field detection mechanism based on optical modulation of the image force between a semiconducting probe tip and a glass surface. The modulation stems from a phenomenon called surface photovoltage. The performance of the mechanism for near-field imaging is demonstrated by using a scanning force microscope over a standing evanescent light wave. The lateral resolution found to be 170 nm (subwavelength) and a representative minimum detectable power is 0.1 pW/square-root Hz in air. We develop a simple theoretical model and discuss some possible applications.