Integrated High Order Integrated High Order Filters in AlGaAs Filters in AlGaAs

Waveguides with up to Waveguides with up to Eight Side-Coupled Eight Side-Coupled

Racetrack MicroresonatorsRacetrack MicroresonatorsRajiv IyerRajiv Iyer‡‡,, Francesca PozziFrancesca Pozzi††, Marc Sorel, Marc Sorel††, ,

Zhenshan YangZhenshan Yang‡‡,, Philip ChakPhilip Chak‡‡, John Sipe, John Sipe‡‡, Stewart , Stewart AitchisonAitchison‡‡

‡ ‡ Department of Electrical and Computer Engineering, Department of Electrical and Computer Engineering, Department of Physics, University of Toronto, Toronto, CanadaDepartment of Physics, University of Toronto, Toronto, Canada

† † Department of Electronics & Electrical Engineering, Department of Electronics & Electrical Engineering, University of Glasgow, Glasgow, UKUniversity of Glasgow, Glasgow, UK

OverviewOverview

• Microrings and SCISSORsMicrorings and SCISSORs• SCISSOR modelingSCISSOR modeling• Design and Fabrication of 8 ring Design and Fabrication of 8 ring

AlGaAs SCISSORAlGaAs SCISSOR• Experimental ResultsExperimental Results• SummarySummary

Microresonators as Microresonators as FiltersFilters

1

0

Wavelength

Transmission Spectra

SCISSOR StructuresSCISSOR Structures

• SSide-ide-CCoupled-oupled-IIntegrated-ntegrated-SSpaced-paced-SSequence-equence-OOf-f-RResonatorsesonators

• Have been proposed for: high-order Have been proposed for: high-order filtering, optical logic, and slow lightfiltering, optical logic, and slow light

Racetrack SCISSORRacetrack SCISSOR

SCISSOR ModelingSCISSOR Modeling

E-up,rightE-up,left

E+low,left E+low,right

L

r

z

GaAsSUBSTRATE

10 nm GaAs CAP

300 nm Al70Ga30As CLADDING

500 nm Al20Ga80As CORE

Etch depth2 mm Al70Ga30As CLADDING

600 nm

Waveguide DesignWaveguide Design

Spatial modal profiles Spatial modal profiles computed using computed using Full-vectorial finite-Full-vectorial finite-difference analysisdifference analysis

nneffeff @ 1550 nm = @ 1550 nm = 2.9752.975

Straight

Curved

Experimental SetupExperimental Setup

Lens

Polarizer

Half Wave Plate

Power Meter

Data Acquisition

Tunable CW laser

Lens

Results for 8 ring Results for 8 ring SCISSORSCISSOR

1525 1530 1535 1540 1545 15500.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Y A

xis

Titl

e

X Axis Title

Measurement Theory

Wavelength (nm)

Inte

nsity

(a.

u.)

• 8 ring SCISSOR8 ring SCISSOR• 20.7 micron ring-to-ring 20.7 micron ring-to-ring

separation separation • 165 nm coupling gap165 nm coupling gap

• Loss parameter = 3.8 Loss parameter = 3.8 cmcm-1-1

• 22 = = 0.15 0.15 0.13 0.13• nneffeff = = 2.975 2.975 2.967 2.967

• TMTM00 performed performed significantly better than significantly better than TETE00

Simulation timeSimulation time

~ 2 seconds~ 2 seconds

SummarySummary• Our Hamiltonian formulation of coupled mode Our Hamiltonian formulation of coupled mode

equations is a equations is a fastfast and and usefuluseful design tool to design tool to model high-index contrast structuresmodel high-index contrast structures

• We fabricated an 8-ring SCISSOR structure in We fabricated an 8-ring SCISSOR structure in AlGaAsAlGaAs

• Next steps… Next steps… Decrease losses in the deviceDecrease losses in the deviceDemonstrate Demonstrate

slow light behavior and slow light behavior and nonlinear effectsnonlinear effects

THANK YOUTHANK YOU

Integrated High Order Integrated High Order Filters in AlGaAs Filters in AlGaAs

Waveguides with up to Waveguides with up to Eight Side-Coupled Eight Side-Coupled

Racetrack Racetrack MicroresonatorsMicroresonators

Rajiv Iyer, Francesca Pozzi, Marc Sorel, Rajiv Iyer, Francesca Pozzi, Marc Sorel, Zhenshan Yang, Philip Chak, John Sipe, Zhenshan Yang, Philip Chak, John Sipe,

Stewart AitchisonStewart Aitchison

rajiv.iyer@utoronto.carajiv.iyer@utoronto.ca

ReferencesReferences[1] [1] V. Van, et. al, “Optical signal processing using nonlinear semiconductor V. Van, et. al, “Optical signal processing using nonlinear semiconductor

microring resonators,” IEEE Journal of Selected Topics in Quantum Electronics, Vol. microring resonators,” IEEE Journal of Selected Topics in Quantum Electronics, Vol. 8, No. 3, 705-713, (2002).8, No. 3, 705-713, (2002).

[2][2] Hryniewicz, et. al, “Higher Order Filter Response in Coupled Microring Hryniewicz, et. al, “Higher Order Filter Response in Coupled Microring Resonators,” Phot. Tech. Lett., Vol. 12, No. 3, (2000).Resonators,” Phot. Tech. Lett., Vol. 12, No. 3, (2000).

[3] [3] S. Pereira, P. Chak and J. E. Sipe, “All-optical AND gate by use of a Kerr S. Pereira, P. Chak and J. E. Sipe, “All-optical AND gate by use of a Kerr nonlinear microresonator structure”, Opt. Lett., Vol. 28, No. 6, 444-446 (2003).nonlinear microresonator structure”, Opt. Lett., Vol. 28, No. 6, 444-446 (2003).

[4] [4] J. E. Heebner, R. W. Boyd, Q-Han Park, “SCISSOR Solitons and other novel J. E. Heebner, R. W. Boyd, Q-Han Park, “SCISSOR Solitons and other novel propagation effects in microresonator-modified waveguides,” JOSA B, Vol. 19, No. propagation effects in microresonator-modified waveguides,” JOSA B, Vol. 19, No. 4, 722-731 (2002).4, 722-731 (2002).

[5] [5] R. Grover, V. Van, T.A. Ibrahim, P.P. Absil, L.C. Calhoun, F.G. Johnson, J.V. R. Grover, V. Van, T.A. Ibrahim, P.P. Absil, L.C. Calhoun, F.G. Johnson, J.V. Hryniewicz, P.-T. Ho, “Parallel-Cascaded Semiconductor Microring Resonators for Hryniewicz, P.-T. Ho, “Parallel-Cascaded Semiconductor Microring Resonators for High-Order and Wide-FSR Filters,” Jour. Light. Tech, Vol. 20, No. 5, 900-905 High-Order and Wide-FSR Filters,” Jour. Light. Tech, Vol. 20, No. 5, 900-905 (2002).(2002).

[6][6] M.F. Yanik, S. Fan, “Stopping light all optically,” Phys. Rev. Lett. 92, 083901, M.F. Yanik, S. Fan, “Stopping light all optically,” Phys. Rev. Lett. 92, 083901, (2004).(2004).

[7] [7] P. Chak, R. Iyer, J. S. Aitchison, and J. E. Sipe, “Hamiltonian formulation of P. Chak, R. Iyer, J. S. Aitchison, and J. E. Sipe, “Hamiltonian formulation of coupled-mode theory in waveguide structures,” submitted to Phys. Rev. E. (2005).coupled-mode theory in waveguide structures,” submitted to Phys. Rev. E. (2005).

[8] [8] MODE SolutionsMODE Solutions software package from software package from Lumerical Solutions IncLumerical Solutions Inc. Suite 660 . Suite 660 - 789 West Pender Street, Vancouver, British Columbia, Canada, V6C 1H2.. - 789 West Pender Street, Vancouver, British Columbia, Canada, V6C 1H2.. www.lumerical.comwww.lumerical.com..

gv k

Freq

uenc

y (

)Dispersion Curve

Ring Gap

Bragg Gap

Wave Number (k)

2

2GVD

k

• For the RING gap, For the RING gap,

the vthe vgg 0 and GVD 0 and GVD min at band min at band edgeedge

• Slowing and stopping light possibleSlowing and stopping light possible• III-V SCISSOR structures are difficult to III-V SCISSOR structures are difficult to

fabricate due to sub-micron feature sizesfabricate due to sub-micron feature sizes

GVD

Ring Gap

Bragg Gap

0

Fre

quency

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