Controlling light with light using coherent metadevices: all-optical transistor, summator and invertor
Xu Fang, Kevin F MacDonald, Nikolay I Zheludev · Light Science & Applications · 2015
Although vast amounts of information are conveyed by photons in optical fibers, the majority of data processing is performed electronically, creating the infamous ‘information bottleneck’ and consuming energy at an increasingly unsustainable rate. The potential for photonic devices to directly manipulate light remains unfulfilled due largely to a lack of materials with strong, fast optical nonlinearities. In this paper, we show that small-signal amplifier, summator and invertor functions for optical signals may be realized using a four-port device that exploits the coherent interaction of beams on a planar plasmonic metamaterial, assuming no intrinsic nonlinearity. The redistribution of energy among ports can provide nonlinear input-output signal dependencies and may be coherently controlled at very low intensity levels, with multi-THz bandwidth and without introducing signal distortion, thereby presenting powerful opportunities for novel optical data processing architectures, complexity oracles and the locally coherent networks that are becoming part of the mainstream telecommunications agenda. An all-optical device based on a planar plasmonic metamaterial is proposed that has summator, inverter and small-signal amplifier functions. Optical processing of optical data signals is strongly needed to overcome the ‘electronic bottleneck’ in current optical communication systems. Now, researchers at the University of Southampton in the UK and Nanyang Technological University in Singapore have theoretically demonstrated the feasibility of exploiting the coherent interaction of light beams in an ultrathin (substantially subwavelength) plasmonic metamaterial to achieve this. As the proposed device does not use nonlinear optical media, it should be possible to operate it at very low power levels. The energy redistribution between the four ports of the device can provide nonlinear input-output signal dependencies and may be controlled at very low intensity levels with multi-terahertz bandwidth and without distorting the signal.