Planar Chiral Metamaterials & their application to optoelectronics devices W. Zhang, A. Papakostas, A. Potts, D. M. Bagnall, N. I. Zheludev Microelectronic Research Group School of Electronics and Computer Science University of Southampton

Overview Introduction Device design and fabrication Experimental setup Results Applications Conclusions Presenting Author : Wen Zhang

Introduction - 3D chirality Presenting Author : Wen Zhang A chiral carbon atom and its mirror image. Asymmetrical Enantiomers

2D chirality Triangle (a) and triangle (b) cannot be superimposed by any displacement in the plane. Reflection line (a) (b) Trying to superimpose (a) and (b) Presenting Author : Wen Zhang

Aim of the project Presenting Author : Wen Zhang Polarization rotation Reciprocity 3D chirality 2D chirality Yes ?

ξ ξ α -α-α ξ – Arm length α – Bending angle 2D gammadions design Presenting Author : Wen Zhang

Samples fabrication (a) Patterned aluminium gammadion on an electrically isolating buffer layer of polymeric material (b) Patterned Ti/Au/Ti “sandwich” multilayer gammadion structures Silicon substrate 300 nm UVIII resist Silicon substrate 50 nm Al Silicon substrate (a) 20 nm Ti 100 nm Au 20 nm Ti Silicon substrate Chiral shaped grooves etched into metallic films Silicon substrate UVIII photoresist (b)

Presenting Author : Wen Zhang Enantiomeric gammadion pair with a bending angle of ± 45º Enantiomeric gammadion pair with a bending angle of ± 90º Arm length ξ= 1.4μm, line width= 300~400nm

Experimental Setup Presenting Author : Wen Zhang Polarization state characterization Intensity measurement Polarimeter head Gammadion sample Focus lens Power meter 1 st -order reflected beam Laser source Quarter wave plate Linear polarizer Circular polarized light Linear polarized light

Presenting Author : Wen Zhang   Diffracted beam Polarization state  Planar chiral structure Plane of incidence   Incident Beam Polarization state  

Optical characterization of planar chiral metamaterials Presenting Author : Wen Zhang Polarization state dependence Intensity dependence

1 st Order diffraction from aluminium metallic planar chiral grating: polarization azimuth rotation Presenting Author : Wen Zhang Pure Al

1 st Order diffraction from aluminium metallic planar chiral grating: Ellipticity Presenting Author : Wen Zhang

1 st Order diffraction from aluminium metallic planar chiral grating: Intensity Presenting Author : Wen Zhang

Future application of planar chiral metamaterials Presenting Author : Wen Zhang Polarization sensitive modulators Polarization sensitive filters Polarization sensitive photodetectors

Polarization sensitive photodetector Presenting Author : Wen Zhang P+ anode contact P+ anode contact Top view C A N+ silicon P-sub Diffused n-silicon p+ n+ Cross-section Planar chiral structures

Conclusion Presenting Author : Wen Zhang Chirality & Handedness Optoelectronics devices Planar Chiral Metamaterials Strong polarization effect Intensity dependence Handedness polarization dependence