Optical Coupling of Deep-Subwavelength Semiconductor Nanowires

Systems of coupled resonators manifest a myriad of exciting fundamental physical phenomena. Analogous to the synthesis of molecules from single atoms, the construction of photonic molecules from stand-alone optical resonators represents a powerful strategy to realize novel functionalities. The coupling of high quality factor (Q) dielectric and semiconductor microresonators is by now well-understood and chipscale applications are abound. The coupling behavior of low-Q nanometallic plasmonic devices and metamaterials. Although dense arrays of semiconductor nanoparticles and nanowires (NWs) find increasing use in optoelectronic devices, their coupling has remained largely unexplored. These refractive index nano-objects can serve as low-Q optical antennas that can effectively receive and broadcast light. We demonstrate that the broad band antenna response of a pair NWs can be tuned significantly by engineering their optical coupling and develop an intuitive coupled-mode theory to explain our observations.