Planar Chiral Metamaterials their application to optoelectronics devices

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

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

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

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

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

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

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= 300~400 nm Presenting Author : Wen Zhang

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

Planar chiral structure Plane of incidence Diffracted beam Polarization state Incident Beam Polarization state Presenting Author : Wen Zhang

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

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

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 Polarization sensitive modulators n Polarization sensitive filters n Polarization sensitive photodetectors n Presenting Author : Wen Zhang

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

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