ADOPT Winter School Merging silicon photonics and plasmonics

Transcription

1 ADOPT Winter School 2014 Merging silicon photonics and plasmonics Prof. Min Qiu Optics and Photonics, Royal Institute of Technology, Sweden and Optical Engineering, Zhejiang University, China

2 Contents Introduction to plasmonics Plasmonic waveguides Hybrid integration of plasmonic waveguides and silicon wire waveguides Optical wireless interconnect network based on plasmonic antennas Plasmonic light absorber Conclusions

3 What is plasmonics? The science of plasmonics is dealing with generation, manipulation, and detection of surface plasmon polaritons (SPPs). SPP: Quasi-particle due to coupling of light and surface plasmon (SP). SP: electron oscillation wave at metal surfaces.

4 Waveguiding with one interface Metal has a negative e.

5 Field pattern of a SPP = p /2 k x vacuum metal 2D field distribution in xz plane. The colormap denotes H y field, while the arrows indicate the E field (consisting both E x and E z ).

6 Contents Introduction to plasmonics Plasmonic waveguides Hybrid integration of plasmonic waveguides and silicon wire waveguides Optical wireless interconnect network based on plasmonic antennas Plasmonic light absorber Conclusions

7 SPP waveguides Various plasmonic waveguides with lateral confinement. (a) Strip SPP waveguide; (b) Suspended strip waveguide; (c) Slot waveguide; (d) V-channel waveguide; (e) -wedge waveguide; (f) metallic fiber waveguide. Line-shaded regions are metal; greyshaded regions are dielectric materials.

8 Channel plasmon subwavelength waveguide components V-channel Plasmon polariton guide Propagation length is only a few tens of micrometers Bozhevolnyi, S.I., et.al., Nature, 440,508,2006 M. Yan and M. Qiu, J. Opt. Soc. Am. B 24, p (2007)

9 Plasmonic gap waveguides λ=1.55μm εau= i Subwavelength confinement! Loss is a big issue! KTH 11

10 Plasmonic waveguides: Diameter: 300 nm Length: 45 μm. Experiments Leaky modes! Collaboration with LM Tong Qiang Li et al, IEEE JSTQE, 17, 1107, 2011 Logarithm of intensity (a.u) Propagation loss 1550 nm 980 nm Distance between exictation spot and wire end ( m) 980 nm: 0.41 db/µm (L 0 =10.5 µm) 1550 nm: 0.3 db/µm (L 0 =14.5 µm) 12

11 Contents Introduction to plasmonics Plasmonic waveguides Hybrid integration of plasmonic waveguides and silicon wire waveguides Optical wireless interconnect network based on plasmonic antennas Plasmonic light absorber Conclusions

12 Hybrid integration Dielectric waveguides Long Large bending radius Large mode area Low loss Easy in-coupling... Plasmonic waveguides Short Small bending radius High confinement High loss Difficult in-coupling... Miniturization Hybrid integration of plasmonics and dieletrics Only using plasmonics when it needed! 14

13 Broadband high-efficiency Plasmonic Silicon waveguide coupler Average coupling efficiency is about 4.5 db (35%). Au Si SiO2 Au 250nm Au Air Au SiO2 J. Tian et al, Broadband high-efficiency surface-plasmon-polariton coupler with siliconmetal interface, Appl. Phys. Lett. 95, (2009) 15

14 Broadband coupler Average coupling efficiency is about 4.5 db (35%). The average loss is about 2.5 db/ m (Simulation results 1.5 db/ m) Appl. Phys. Lett. 95, (2009) 16

15 Plasmonic-dielectric coupler 450nm With a 0.4μm-long HP taper, η=70%. HP-taper coupler Y. Song et al, Opt. Express. 18, 13173,

16 Coupling of Plasmonic and Photonic Nanowires for Hybrid Nanophotonic Circuits Prof. Limin Tong s group in Zhejiang U, China Q factor 520! X. Guo, M. Qiu, et al, Direct Coupling of Plasmonic and Photonic Nanowires for Hybrid Nanophotonic Components and Circuits, Nano Lett. 9 (12), pp (2009) KTH 18

17 Hybrid coupler composed of metal-insulator-metal plasmonic waveguide and silicon dielectric waveguide Metal-insulator-metal plasmonic waveguide Output quasi-even power from the two output arms Si dielectric waveguide hybrid directional coupler quasi-odd Coupling insensitive to slot structural parameters W1=260 nm, H1=220 nm W2=150 nm, H2=200 nm S=250 nm Insertion loss 1.4 db Propagation loss 0.18 db/ m Extinction ration 16 db Coupling length 4.5 m Q. Li et al, Opt. Express. 18, 15531,

18 Hybrid coupler composed of cap plasmonic waveguide and silicon dielectric waveguide Metal cap plasmonic waveguide Si dielectric waveguide plasmonic mode dielectric mode quasi-even mode quasi-odd mode Ey profiles of TM mode Q. Li, et al Opt. Lett. 35, 3153, 2010 d=250 nm: Insertion loss 0.2 db (including the propagation loss, which is db/ m, so total propagation loss ~0.2 db) Extinction ration 18 db Coupling length 7.63 m 20

19 Contents Introduction to plasmonics Plasmonic waveguides Hybrid integration of plasmonic waveguides and silicon wire waveguides Optical wireless interconnect network based on plasmonic antennas Plasmonic light absorber Conclusions

20 Optical wireless interconnect Artists view of integrated photonics device and optical wireless interconnect node on a single chip Yuanqing Yang et al

21 Optical wireless interconnect Port to Port (P2P) Port-to-MultiPorts (P2MP) Schematic diagram of a representative optical wireless broadcast network

22 Contents Introduction to plasmonics Plasmonic waveguides Hybrid integration of plasmonic waveguides and silicon wire waveguides Optical wireless interconnect network based on plasmonic antennas Plasmonic light absorber Conclusions

23 Loss: avoiding or utlizing? Double split rings Plasmonic and metamaterial effects are all based resonances (electric or magnetic): loss associated Loss is mostly problematic for waveguiding, or other applications. Or we can use the losses (absoprtion)!

24 2D optical metamaterial absorber i =20 Fundamental Resonance a = 310 nm. Wx = 170 nm, Wy = 230 nm, t = 40 nm, d = 10 nm Many other groups are working on similar structures JM Hao et al APL 96, , 2010 In collaboration with W.J. Padilla (BC), L. Zhou (Fudan) 26

25 Physics: Effective material parameters At resonance peak (~1.58 m): e = = i JM Hao et al APL 96, , 2010 Impedance : no reflection Thick substrate: no transmission Large imaginary parts: high absoprtion

26 Lithography-free broadband visible light absorber 80nm-thick gold reflector 55nm-thick alumina layer 5nm top gold layer Fabricated in a two-stage process: 1. Electron-beam-evaporation deposition 2. Thermal annealing Large area 2.5 cm x 2.5 cm in size M Yan et al 2014 J. Opt Paper of the Week, Featured article Side view 28

27 Colorful gold Min Yan

28 Plasmonic light absorbers for nanofabrications Min Yan, Min Qiu APL , ACS Nano , Opt Express, , Nanoscale ,...

29 Metal insulator metal light absorber: a continuous structure Gold Silver FWHM ~ 2nm Q ~ 310 FWHM ~ 7nm Q ~ 90 M. Yan, J. Opt. 15, (2013) Ding Zhao et al, Submitted

30 Conclusions Plasmonic devices could provide subwavelength confinement, which could be very useful for photonic integration. However, loss is a big issue. Possible solutions for avoiding large propagation losses in plasmonic waveguides are Hybrid integration of silicon and plasmonic waveguides Wireless optical interconnect On the other hand, losses can be utilized for good: light absorption can be enhanced through plasmonic resonance. Absorption bandwidth and wavelength can be designed to almost any value in visible, infrared, and even THz. Photothermal effects due to light absorption can generate lots of interesting new applications, also understanding of new physics: thermo-optical switching controlled thermal fusion nanofabrication nanoscale-thermaldynamics

31 Acknowlegement KTH: Assoc. Prof. Min Yan, Dr. Jiaming Hao, Dr. Jing Wang, Dr. Yi Song, Xi Chen, Yiting Chen ZJU: Assoc. Prof. Qiang Li, Ding Zhao, Xingxing Chen, Hanmo Gong