Real-space distribution of cavity modes in single ZnO nanowires

In this work, we have used a near-field optical microscope to map out the evanescent fields of optically excited single-crystal ZnO NWs grown on quartz substrates by the vapour transport method using Au as catalyst. The SNOM measurements were performed at room temperature in transmission-collection mode using four different laser wavelengths (378, 514, 633 and 785 nm). They reveal a different spatial distribution of the electromagnetic fields associated to each cavity mode, which are unique properties of the NWs depending primarily on their size and the wavelength of the mode.