Subwavelength focusing by engineered power-flow conformal metamirrors

It is highly desirable to break the diffraction limit on the resolution of optical devices and achieve subwavelength focusing. Here, the authors show that curved and inhomogeneous reflectors offer a practical method for achieving this goal. The surface profile of the focusing reflector is designed to be tangential to the desired power flow so that the metamirror can be described locally by lossless impedance boundaries and can be easily implemented using simple lossless meta-atoms. We envisage some practical applications of subwavelength focusing that become possible using this method.