A plasmonic coupling device comprising a first structure, and a second structure comprising two or more conductive nanoparticles, wherein each nanoparticle is elongate and is attached to the first structure such that it is oriented with a major axis thereof substantially perpendicular to the first structure. The absolute value of reflectivity at each pixel of the AlTiC air-bearing surface is obtained from an empirical equation relating it to modulation. The storage media interface is connected to a downstream port of the USB hub or an endpoint of a USB SIE. Such drive control effectively relieves the load of the inverter 42, while decreasing the frequency of lowering the switching frequency of the inverter 42.