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Asymmetric plasmonic-dielectric coupler with short coupling length, high extinction ratio, and low insertion loss
KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Quantum Electronics and Quantum Optics, QEO.
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2010 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 35, no 19, 3153-3155 p.Article in journal (Refereed) Published
Abstract [en]

Asymmetric directional coupling between a hybrid plasmonic waveguide with subwavelength field confinement and a conventional dielectric waveguide is investigated. The proposed hybrid coupler features short coupling length, high coupling efficiency, high extinction ratio, and low insertion loss; it can also be integrated into a silicon-based platform. This coupler can be potentially adopted for signal routing between plasmonic waveguides and dielectric waveguides in photonic integrated circuits. Furthermore, it can be exploited to efficiently excite hybrid plasmonic modes with conventional dielectric modes.

Place, publisher, year, edition, pages
2010. Vol. 35, no 19, 3153-3155 p.
Keyword [en]
SLOT WAVE-GUIDE, SUBWAVELENGTH CONFINEMENT, SILICON
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-26293ISI: 000282374800001Scopus ID: 2-s2.0-78149245628OAI: oai:DiVA.org:kth-26293DiVA: diva2:382138
Note
QC 20101229Available from: 2010-12-29 Created: 2010-11-21 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Silicon Based Photonic Devices and Their Applications
Open this publication in new window or tab >>Silicon Based Photonic Devices and Their Applications
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The integration of modern electronic devices for information processing is rapidly ap-proaching an interconnect bottleneck. Silicon photonics can be a promising solution forcircumventing this bottleneck, as already being anticipated by many electronics manu-facturers including HP, IBM and Intel. In particular, optical interconnects can expeditedata transfer both between and within microchips. This thesis aims at two basic buildingblocks of silicon photonics: waveguides and resonators and addresses their applications inoptical signal processing and their potential integration with plasmonic devices.

Firstly, the basic theories of waveguide and resonator are introduced. For a singleresonator which acts as a basic signal processing unit, the transmission, phase shift andgroup delay exhibit unique characteristics. Mode splitting is observed in both a singleresonator and a coupled-resonator system. By tuning the configuration of the coupled-resonator system, one can obtain different transmission characteristics for more advancedsignal processing.

Secondly, the fabrication and characterization of silicon waveguides and resonatorsused in the thesis are introduced. The fabrication is carried out with e-beam lithographyfollowed by inductively coupled plasma etching. A vertical grating coupling method isadopted to characterize the transmission spectrum.

Thirdly, based on a single-ring resonator, three kinds of signal processing are ex-perimentally demonstrated: (1) 10 Gb/s format conversion from non-return-to-zero toalternate-mark-inversion signal; (2) a microwave photonic phase shifter providing a tun-able phase shift of 0–4.6 rad for a 20 GHz signal; (3) a delay line providing maximaldelay times of 80 ps, 95 ps, 110 ps and 65 ps, respectively, for signals in return-to-zero,carrier-suppressed return-to-zero, return-to-zero duobinary, and return-to-zero alternate-mark-inversion formats.

Fourthly, based on a single-ring resonator with mode-splitting, two kinds of signalprocessing are experimentally demonstrated: (1) a dense wavelength conversion using thefree carrier dispersion effect with a data rate ranging from 500 Mb/s to 5 Gb/s; (2) amaximum pulse advancement of 130 ps for a 1 ns signal pulse.

Since silicon photonic devices are limited by diffraction limit, we further look intotheir hybridization with the diffraction-limit-free plasmonic devices. Two directional cou-plers from a Si photonic waveguide to a hybrid Si-metal plasmonic waveguide and to ametal-insulator-metal plasmonic waveguide are investigated. The proposed hybrid cou-plers feature a short coupling length, a high coupling efficiency, a high extinction ratioand a low insertion loss.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. xv, 75 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-31290 (URN)
Public defence
2011-04-07, Sal / Hall C1, KTH-Electrum, Isafjordsgatan 22, Kista, 10:00 (English)
Opponent
Supervisors
Note
QC 20110315Available from: 2011-03-15 Created: 2011-03-11 Last updated: 2011-03-15Bibliographically approved
2. Plasmonic waveguides and resonators for optical communication applications
Open this publication in new window or tab >>Plasmonic waveguides and resonators for optical communication applications
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Photonic circuits can transmit data signals in a much higher speed thanconventional electronic circuits. However, miniaturization of photonic circuitsand devices is hindered by the existence of light diffraction limit. A promisingsolution to this problem is by exploiting plasmonic systems for guiding andmanipulating signals at optical frequencies. Plasmonic devices are generallycomposed of noble metals and dielectrics, whose interfaces can confine surfaceplasmon polaritons, a hybrid wave that is free of diffraction limit. Plasmonicwaveguides and devices are serious contenders for achieving next-generationphotonic integrated circuits with a density comparable to the electronic counterpart.

This thesis addresses the design issues of passive plasmonic devices whichare critical for realization of photonic integration, including plasmonic waveguides,splitters, couplers, and resonators, investigated with both the finitedifferencetime-domain method and the finite-element method. In particularwe present, firstly, a coupler which efficiently couples light between a silicondielectric waveguide and a hybrid plasmonic (HP) waveguide. A coupling efficiencyas high as 70% is realized with a HP taper as short as 0.4μm. Theexperimental result agrees well with the numerical simulation. Secondly, wenumerically investigate and optimize the performances of 1×2 and 1×3 HPmultimode interferometers (MMIs), which split light from a silicon waveguideto multiple HP waveguides. Total transmission over 75% can be achieved inboth cases. Thirdly, we study the coupling and crosstalk issues in plasmonicwaveguide systems. Several methods for crosstalk reduction are proposed.Finally, HP nanodisk micro-cavities are designed and are numerically characterized.With a radius of 1μm, a high quality factor of 819 and a highPurcell factor of 1827 can be simultaneously achieved, which can be useful forrealizing efficient nano-lasers.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. xi, 60 p.
Series
Trita-ICT/MAP AVH, ISSN 1653-7610 ; 2011:10
Keyword
Plasmonic
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-33596 (URN)978-91-7501-015-1 (ISBN)
Public defence
2011-06-07, sal C1, Electrum, Kungl Tekniska Högskolan,Isafjordsgatan 26, Kista, Stockholm, 14:13 (English)
Opponent
Supervisors
Note
QC 20110523Available from: 2011-05-23 Created: 2011-05-11 Last updated: 2011-05-23Bibliographically approved

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