Investigation of Optical Coupling in ZnO Nanowires by µ-PL Measurements

Semiconductor nanowires are a keystone in the miniturization of optoelectronic devices, because they bring the potential to realize compact and low power consumption nanolasers. This is due to their good waveguiding properties, high optical gain and low power consumption.<br/>For many nanoscale applications, the evanescent coupling between two adjacent nanowires may yield interesting consequences, such as frequency selection of the Fabry-Perot modes.<br/>In recent years the optical resonances in nanowire pairs have been investigated for Silicon nanowires, GaN nanowires and CdS nanowires for various arrangements and with disparate measurement techniques.<br/>It is possible to set the nanowire spacing and angle, using nanomanipulation to precisely position ZnO nanowires. In this study, we used this to examine the effect of a varying overlap of the evanescent fields for a chosen nanowire pair. Performing µ- photo luminescence measurements with a pulsed 355nm laser offers three approaches: Emission spectra provide insights into mode selection, a Fourier back focal plane setup may reveal lasing coherence and intensity measurements could show changes in the lasing threshold.