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Tokyo Institute of Technology○K. Kato 　 Y. Shoji 　 T. Mizumoto

Optical Add-Drop Multiplexer Integrating SiliconWaveguide Optical Circulators and Bragg Reflector

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Background

Short distance optical signal transmission

・・・

Optical interconnection

• Silica glass• III-V semiconductor• Silicon photonics

Small footprint & high functionality

Requirement• High-speed and high-capacity• Low power consumption

Optical waveguide device

5 μm

Rack to rack

Tokyo Inst. Tech.

On chip

IBM

Chip to chip

Intel

Board to board

Keio Univ.

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Silicon Waveguide Optical Circulator

Port2

Port1 Port4

Port3

Nonreciprocal optical path circulation

• Integratable with other components• Maximum isolation of 33 dB• TM mode operation

・・・

• Optical add-drop multiplexer• Dispersion compensator• Bidirectional transmission system

Optical circulator

Silicon waveguide optical circulator

T. Mizumoto, et al., Proc. SPIE, 8988, 89880C (2014).

1530 1540 1550 1560 1570

-80

-60

-40

-20

Wavelength [nm]

Tran

smitt

ance

[dB

] Port 1 → Port 2

Port 2 → Port 1

33 dB

Port1

Port4

Port2

Port3 SiSiO2

Ce:YIG

3 dB directional coupler

Non-reciprocalReciprocal phase shifter (RPS)

Magnetic field

phase shifter (NPS)

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Operation Principle of Optical CirculatorPort 1→Port 2

Port 2→Port 3

NPSRPS

-π /2+π /2

Magnetic

field

0 (Cross)

Port1

Port2

NPSRPS

Magnetic

field

+π /2+π /2+π (Bar)

Port3

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Silicon Waveguide Bragg Reflector

Optical Add Drop Multiplexer (OADM)

＋ Optical circulators

Distributed Horizontal Groove Vertical Groove

• TE and TM modes• Less fabrication

tolerant

• TE mode• Double stage etching

(depth control)

• TM mode• Single-step litho. and

etching

Reflect optical signals of a particular wavelength

Bragg reflector

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Characterization ～ Bragg Reflector ～

30 dB Bragg reflection(TM mode)

1540 1560 1580 1600 1620-70

-60

-50

-40

-30

-20

Wavelength [nm]

Tran

smitt

ance

[dB

]

Ref w/o Ce:YIG

Bragg reflector

Ref w/ Ce:YIG

Waveguide width

Waveguide height

Grating period

Groove depth

Groove length184 nm

368 nm

70 nm220 nm

550 nm

Grooves were repeated 500 times

220 nm550 nm

Si

SiO2

Ce:YIG

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Silicon Waveguide OADM

Add and drop a particular wavelength signal

OADM

l1 l2 l3 l4

Drop

Optical circulator

Bragg reflectorThrough

InputAdd

1.5 mm

Bragg reflector

Through

DropInput

Add

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Input→Through

Add→ThroughInput→Drop

Characterization ～ OADM ～

1520 1540 1560 1580 1600 1620-80

-70

-60

-50

-40

-30

Wavelength (nm)

Tran

smitt

ance

(dB

)

Input→Through

Input→Drop

Add→Through

B1 B2 B3

OADM operation - B3 band: Add/Drop - Other bands: Through

Expected characteristic

DropThrough

InputAdd

Circulator

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Summary

Successful fabrication of a silicon waveguide Bragg reflector cladded with Ce:YIG 30 dB reflection for the TM mode

Demonstration of a silicon waveguide OADM by integrating two optical circulators and a Bragg reflector