Towards broadband dynamic structuring of a complex plasmonic field

The ability to tailor a coherent surface plasmon polariton (SPP) field is an important step towards a number of new opportunities for a broad range of nanophotonic applications such as sensing [1,2], nano-circuitry [3,4], optical data storage [5,6], super-resolution imaging [7,8], plasmonic tweezers [9,10] and in-plane communications [11]. Scanning a converging SPP spot or designing SPP profiles using an ensemble of spots have both been demonstrated previously [12-14]. SPPs, however, are normally excited by intense, coherent light sources-lasers. Hence, interference between adjacent spots is inevitable and will affect the overall SPP field distributions. Here we report a reconfigurable and wavelength-independent platform for generating a tailored 2D SPP field distribution by considering the coherent field as a whole rather than individual spots. The new perspective also enables us to reveal the inherent constraints implied in a 2D coherent field distribution. Our generic design methodology works not only for SPP waves but also for other two-dimensional wave systems like surface acoustic waves [15].