Simple Holographic Control Of Surface Plasma

Surface plasmon polaritons are the electromagnetic waves confined to the metal surface.The energy can be localized on metal surface and propagate along metal surface.Electromagnetic wave energy will damp along the direction of propagation and the trasmission distance is limited.Surface plasmon polaritons have wide range of applications in many fields.It is needed to design devices to control surface plasmon transmission on metal surface.In this thesis,we apply holographic method to design groove structures on metal surface to couple the surface plasmon polaritons to an arbitrary point in free space,achieving the control of surface plasmon polaritons scattering to free space.In addition,we conside the control of SPPs propagation on mental surface,we designed simple holographic line structure in the metal surface to couple the SPPs to an arbitrary point on metal surface.The main work includes:1.Coupling surface plasmon polaritons into free space.Structures are designed to couple the surface plasmon polaritons(SPP)to the light wave in free space by the surface wave holography method.Interference light intensity is obtained through simulating the scalar superposition of the SPP wave beam and the target beam in free space.Groove structures are obtained by etching grooves at the maximum light intensity positions.When the SPP waves incident to the designed structures,the grooves scatter the SPP waves into free space and then the waves superpose there,producing the required light beam.Based on this principle,two structures are designed for coupling the SPP waves to focus at the specified one point or two points in free space.The finite-difference time-domain method is used to verify the principle.This coupled manner can be used as a method for solving the detection problem of the surface plasmon integrated optics.Coupling the SPPs signal into the free space and then use the common photodetectors to detect.2.Control surface plasmon polaritons propagation efficiently with only one holographic line.The designed structures are composed of an amount of nanometre grooves and distributions apper complicated.This adds the difficulties in fabricatingthe designed structures.And the efficiency is not high enough.The simple and effective structures are needed for SPP propagation controlling.In this paper,the line holography method is proposed to design a simple structure to control SPP wave propagation.The designed structure is composed of only one metal line,rather than a number of grooves in the holograms designed by the common surface electromagnetic wave holography method(SWH).The holographic line structure can control SPPs propagation effectively.Through the line holography method,two holographic line structures are designed to focus aside a plane SPP wave to one or two points.The finite-difference time-domain(FDTD)method is used to simulate the control process.Results show that the holographic line can control the SPP wave propagation with efficiency of 55%,high than that of the common SWH method.