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Surface Plasmonic Polariton

By Julie Cunningham,2014-05-27 15:44
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Surface Plasmonic Polariton

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     Surface Plasmonic Polariton Waveguide and Grating: Their Applications in Optoelectronic Devices

     Xun Li Department of Electrical and Computer Engineering McMaster University 1280 Main Street West, Hamilton, Ontario, L8S 4K1 Canada 1-905-525-9140 ext. 27698 lixun@mcmaster.ca

    http://www.ece.mcmaster.ca/faculty/li/

     Outlines

     ? ? ? ? ? Surface Plasmonic Polariton (SPP) Existing Applications SLED Built on SPP Waveguide SPP Grating SPP Waveguide Splitter Conclusion

     Understanding SPP

     H Metal S - - +++ - - -

     SPP WG

     Dielectric medium

     +++

     E

     No resonance (i.e., phase matching) condition required No standing wave exists, evanescent wave only

     Dielectric WG

     Resonance (i.e., phase matching) condition needed to form a standing wave pattern (mode)

     Existing Applications of SPP

     ? ? ? ? ? Excitation enhancement Nonlinear effect enhancement Aperture or beam control Nanoscale Microscopy Sensor Area yet to explore ?C SPP waveguide

     Excitation Enhancement

     K. Okamoto et. al., Nature Material 3, 601, 2004 K. Okamoto et. al., Applied Physics Letter 87, 071102, 2005

     Nonlinear Effect Enhancement

     Control Light Metal Ball Quantum Dot Incident Light Slow Light EIT

     K. Li, M. I. Stockman, and D. J. Bergman, Physics Review Letter 91, 227402, 2003 S. M. Sadeghi, L. Deng, X. Li, and W. -P. Huang, IOP Journal of Nanotechnology 20, 365401, 2009

     Aperture or Beam Control

     O. S. Ahmed, M. A. Swillam, M. H. Bakr, and X. Li, recent work accepted for publication by IEEE/OSA Journal of Lightwave Technology

     Aperture or Beam Control

     O. S. Ahmed, M. A. Swillam, M. H. Bakr, and X. Li, recent work accepted for publication by IEEE/OSA Journal of Lightwave Technology

     Aperture or Beam Control

     O. S. Ahmed, M. A. Swillam, M. H. Bakr, and X. Li, recent work accepted for publication by IEEE/OSA Journal of Lightwave Technology

     Nanoscale Microscopy

     Evanescent Field

     Surface Morphology

     B. Hecht, etc., Physics Review Letter 77, 1889-1893, 1996 L. Novotny, etc., Journal of Applied Physics 81, 1798-1806, 1997 T. Kalkbrenner, etc., Journal of Microscopy 202, 72-76, 2001 D. Boyer, Ph. Tamarat, A. Maali, B. Lounis, and M. Orrit, Science 297, 1160-1163, 2002

     Sensor ?Å

     ?Å ?Åm

     Resonance Condition ~ 1/( m

     As changes

     ?Å -?Å)

     J. Homola, S. S. Yee, and G. Gauglitz, Sensors and Actuators B 54, 3-15, 1999

     Typical SPP Waveguide

     Effective index and loss coefficient of bounded symmetric (sb) and bounded antisymmetric (ab) modes of a silver slab SPP waveguide Inset: the schematic of the SPP waveguide considered

     ?Å m = ?116.38 + i 11.1 Ag

     ?Å 1 = ?Å 2 = 11.2

     InGaAsP

     SLED Built on SPP Waveguide

     Understanding the working principle of SLED

     Stimulated emission gain: amplifies the spontaneously emitted photons

     ???? ????

     Spontaneous emission: <3% coupling from spherical wave to guided wave, modeled by FDTD

     SLED Performance Dependence

     Governing equation: ? Solution:

     P ( ?Ë ) = Psp ( ?Ë ) e

     dP = ?? g st P + ? g sp hv ? v dz

     p L ( ?? g st

     ?Á s )

     p ? ?? Lg st (

     ?Ë ??Ë p ?ËW

     )2

     e

     Power density at the front facet

     Stimulated emission gain amplification factor

     Spontaneous emission power density

     ?Ânsp hc 2 Psp (?Ë ) = ???Ë3

     Gaussian-shaped spectral factor

     Spectral width:

     ?Ë FWHM ?Ö

     1.67?ËW

     p L(??g st ? ?Á s )

     Problem

     It becomes quite obvious that we cannot simultaneously achieve both high power and broad spectral width in such SLED, as the former requires an optimized device length (usually quite long), whereas the latter monotonically reduces as the device length increases. ? How to raise the output power without sacrifice on the spectral width? ? Enhance the coupling of the spontaneously emitted photon to the waveguide (i.e., ?Â) seems to be a natural lead.

     Analysis

     What causes the small ?Â?

     ?C For guided wave inside a dielectric waveguide, the total internal reflection condition has to be met, which means among the decomposed plane wave components from the spherical wave, only those plane waves with their incident angle at the wave guide boundary smaller than the critical angle will possibly be captured; ?C Moreover, the resonance, or phase matching condition has to be met, which means only a discrete number of plane waves with ??right?? angles (only one in single mode waveguide) will be sustainable.

     Can we find a waveguide structure which doesn??t need the resonance condition?

     Analysis

     For a point source excitation: 1. For those rays with incident angles below the critical angle ?C excite radiation wave 2. For those rays with incident angles beyond the critical angle, and takes specific angles at which the phase matching condition is satisfied ?C guided wave 3. For those rays with incident angles beyond the critical angle, but don??t take those specific angles ?C leaky wave Radiation Wave

     Guided Wave

     Leaky Wave

     2k?Ð

     Excitation Enhancement by SPP Waveguide

     SPP WG

     ? spp

     ?Âspp(~100%) >> ?Â(~3%) ?Â

     Dielectric WG

     SLED Built on SPP Waveguide - Structure

     SPP WG

     MQW Active Region

     y

     P

     N

     x

     Substrate

     Cross-sectional Structure

     Simulated Device Performance

     Output power v.s. device length for SLEDs built on dielectric WG (left) and SPP WG (right) Different curves correspond to different modal losses

     Simulated Device Performance

     Spectral width v.s. device length for SLEDs built on dielectric WG (left) and SPP WG (right) Different curves correspond to different modal losses

     Simulated Device Performance

     Power-spectral width product v.s. device length for SLEDs built on dielectric WG (left) and SPP WG (right) Different curves correspond to different modal losses

     SPP Grating

     Deeply-etched Grating: ICP-RIE etching needed with very high aspect ratio - Very difficuly to reach

     SPP Grating: No deep-etching requried - Easy to fabricate

     SPP Grating

     1.00 0.75 |Ex| 0.50 0.25 0.00 -2

     TM

     (a)

     25 20 |Ey| 15 10 5 0

     TE

     (b)

     Unperturbed Perturbed

     Unperturbed Perturbed

     -1

     0 x(?Ìm)

     1

     2

     -6

     -4

     -2

     0 x(?Ìm)

     2

     4

     6

     SPP Grating

     1.0 0.8 Reflection TM (b)

     1.0 0.8 Reflection

     TE

     (b)

     0.6 0.4 0.2 0.0

     ?Î=0.1 ?Î=0.5

     0.6 0.4 0.2 0.0

     ?Î=0.1 ?Î=0.5

     1.50 1.52 1.54 1.56 1.58 1.60 Wavelength(?Ìm)

     1.50 1.52 1.54 1.56 1.58 1.60 Wavelength(?Ìm)

     SPP Grating

     1.0 TE 0.8 Peak reflection 0.6 0.4 0.2 0.0 0.0 Metal Deep Etched

    0.2 0.4 0.6 0.8 1.0

     Peak reflection

     (a)

     1.0 0.8 0.6 0.4 0.2 0.0

     TM

     (a)

     Metal Deep Etched

     0.2

     0.4

     0.6

     0.8

     1.0

     Duty Cycle

     Duty Cycle

     SPP Grating

     60 TE Reflection bandwidth(nm) 50 40 30 20 10 0.0 0.2 Metal Deep

    Etched 0.4 0.6 0.8 1.0 (d)

     Reflection bandwidth(nm) 45 40 35 30 25 20 15 10 0.0 0.2

     Metal Deep Etched

     TM

     (d)

     0.4

     0.6

     0.8

     1.0

     Duty Cycle

     Duty Cycle

     SPP Waveguide Splitter

     25 20 |Ey| 15 10 5 0 -6 -4 -2 0 x( ?Ì m ) 2 4 6

     U nperturbed Perturbed

     TE

     (b)

     Dielectric Waveguide Splitter Metal Nanolayer

     Normal Guided Wave ?ú SPP Wave SPP Wave ?ú Normal Guided Wave

     Drastically reduce the insertion loss or shorten the transition length

     Conclusion

     As in many other areas, SPP waves and waveguides have promising applications in optoelectronic and photonic devices ? A power-spectral width product enhancement of 2~4.5 folds can be reached for the SLED built on the SPP waveguide, as compared to the conventional SLED; moreover, the SLED with the SPP waveguide only needs ~1/3 of the conventional device length ? The SPP grating can be employed to replace the deeplyetched grating, when the latter is hard to fabricate ? The SPP waveguide splitter design can drastically reduce the insertion loss or shorten the length

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