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Experimental demonstration of ultra-compact directional couplers based on silicon hybrid plasmonic waveguides
KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
Ghent Univ IMEC, Ghent, Belgium.
JORCEP, Hangzhou, Zhejiang, Peoples R China ; Zhejiang Univ, Hangzhou Zhejiang, Peoples R China .
KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
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2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 24, 241105- p.Article in journal (Refereed) Published
Abstract [en]

Hybrid plasmonic waveguides and directional couplers have been experimentally demonstrated. Using a direct measurement method, the propagation loss of a 170 nm wide waveguide is measured to be 0.08 dB/mu m at 1550 nm when the thickness of low-index region is 56 nm. Ultra-compact directional couplers based on such hybrid plasmonic waveguides are demonstrated with gaps of 140 nm, 185 nm, 235 nm, and 290 nm. The corresponding coupling lengths measured are 1.55 mu m, 2.2 mu m, 3.2 mu m, and 4.8 mu m, respectively, which are in very good agreement with the simulations. These ultra-compact devices can be potentially used in future ultra-dense photonic integrated circuits.

Place, publisher, year, edition, pages
2012. Vol. 100, no 24, 241105- p.
Keyword [en]
Propagation, Confinement, Integration
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-98937DOI: 10.1063/1.4729018ISI: 000305269200005ScopusID: 2-s2.0-84863300332OAI: diva2:540857
Swedish Research Council, VR-621-2010-4379ICT - The Next Generation

QC 20120712

Available from: 2012-07-12 Created: 2012-07-05 Last updated: 2014-04-04Bibliographically approved
In thesis
1. Design, fabrication and characterization of plasmonic components based on silicon nanowire platform
Open this publication in new window or tab >>Design, fabrication and characterization of plasmonic components based on silicon nanowire platform
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Optical interconnects based on CMOS compatible photonic integrated circuits are regarded as a promising technique to tackle the issues traditional electronics faces, such as limited bandwidth, latency, vast energy consumption and so on. In recent years, plasmonic integrated components have gained great attentions due to the properties of nano-scale confinement, which may potentially bridge the size mismatch between photonic and electronic circuits. Based on silicon nanowire platform, this thesis work studies the design, fabrication and characterization of several integrated plasmonic components, aiming to combine the benefits of Si and plasmonics.

The basic theories of surface plasmon polaritons are introduced in the beginning, where we explain the physics behind the diffraction-free confinement. Numerical methods frequently used in the thesis including finite-difference time-domain method and finite-element method are then reviewed. We summarize the device fabrication techniques such as film depositions, e-beam lithography and inductively coupled plasma etching as well as characterization methods, such as direct measurement method, butt coupling, grating coupling etc.

Fabrication results of an optically tunable silicon-on-insulator microdisk and III-V cavities in applications as light sources for future nanophotonics interconnects are briefly discussed. Afterwards we present in details the experimental demonstrations and novel design of plasmonic components.

Hybrid plasmonic waveguides and directional couplers with various splitting ratios are firstly experimentally demonstrated. The coupling length of two 170 nm wide waveguides with a separation of 140 nm is only 1.55 µm. Secondly, an ultracompact polarization beam splitter with a footprint of 2×5.1 μm2 is proposed. The device features an extinction ratio of 12 dB and an insertion loss below 1.5 dB in the entire C-band. Thirdly, we show that plasmonics offer decreased bending losses and enhanced Purcell factor for submicron bends. Novel hybrid plasmonic disk, ring and donut resonators with radii of ~ 0.5 μm and 1 μm are experimentally demonstrated for the first time. The Q-factor of disks with 0.5 μm radii are                         , corresponding to Purcell factors of . Thermal tuning is also presented. Fourthly, we propose a design of electro-optic polymer modulator based on plasmonic microring. The figure of merit characterizing modulation efficiency is 6 times better comparing with corresponding silicon slot polymer modulator. The device exhibits an insertion loss below 1 dB and a power consumption of 5 fJ/bit at 100 GHz. At last, we propose a tightly-confined waveguide and show that the radius of disk resonators based on the proposed waveguide can be shrunk below 60 nm, which may be used to pursue a strong light-matter interaction.

The presented here novel components confirm that hybrid plasmonic structures can play an important role in future inter- and intra-core computer communication systems.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xii, 76 p.
TRITA-ICT/MAP AVH, ISSN 1653-7610 ; 2014:05
Planar integrated circuit, silicon photonics, plasmonics, subwavelength, directional coupler, polarization beam splitter, disk resonator, ring resonator, finite-difference time-domain, photonic crystal, electro-optic polymer, Purcell factor.
National Category
Engineering and Technology
urn:nbn:se:kth:diva-143953 (URN)978-91-7595-060-0 (ISBN)
Public defence
2014-04-25, Sal D, Forum, Isafjordsgatan 39, Kista, 10:00 (English)
Swedish Research Council, VR-621-2010-4379

QC 20140404

Available from: 2014-04-04 Created: 2014-04-03 Last updated: 2016-03-07Bibliographically approved

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