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Optical Switches (Packet and Circuit-Based)

Wong King Heng, KennyWu Ka Man, Karmen

Chen Aiqin, JoanneTam Chi Fai, Jeffrey

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Outline

– Optical Switch– OEO vs OOO vs OEO-O-OEO– WDM & DWDM– MEMS & 2D MEMS & 3D MEMS– MPLS & GMPLS– More about MEMS

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Optical Switch

• ‘Optical-to-Electronic-to-Optical' (OEO)– Most lower layer networking equipment today

is still based on electronic-signals– Core network use optical-signals– Electrical ones to be amplified, regenerated or

switched– Converted to optical signals

• Significant bottleneck in transmission

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OEO vs OOO vs OEO-O-OEOPros Cons

OEO

- Known and mature technology- 3R regeneration for free- capable of bandwidth grooming

bit error rate monitoring and

statistical multiplexing

- Optical Scalability limit- Not bit-rate transparency- Not protocol transparency- Expensive

OOO

- Optical Scalability- Bit-rate transparency- service/protocol transparency

- Emerging Technology- not capable of bandwidth grooming, bit error rate monitoring and statistical multiplexing

OEO-O-OEO

- Combines scalability of optics with

3R regeneration and wavelength translation of electronics- Allow Bit error rate visibility- can choose this as an option per-port

-increased complexity over both designs- doesn‘t allow stat muxing or grooming

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Wave Division Multiplexing(WDM)

• splits light waves into different frequencies of infrared light

• each frequency capable of transmitting data at high speeds

• Mainly divided into Dense WDM(DWDM) and Coarse WDM(CWDM)

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Wave Division Multiplexing (WDM)

• CWDM– ITU has standardized

a 20 nanometer channel spacing grid

– wavelengths between 1310 nm ~ 1610 nm

• DWDM– closer spacing of the

wavelengths

– 1530 nm and 1560 nm

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MEMS

• Micro-Electrical Mechanical Systems (MEMS)

• New photonic optical switches– Switch hundreds of wavelengths at a time– a fraction of space & power & cost of existing

equipment

• Novel materials, not semi-conductors

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Optical MEMS

Optical MEMS Mirror Used in an Optical Switch

• Tiny arrays of tilting mirrors

• Adjust the angle to transmit to desired output port

• Eliminate OEO conversion– costly– Save space and power

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MEMS Drawbacks

• Moving parts– Requires milliseconds to switch– Ok for lambda provisioning or restoration – SLOW for optical burst switching or

optical packet switching application

• Ineffective improvements– Put a lot current into the array – ONLY small improvement

• Solved by design change • => Faster MEMS design• => 2D MEMS

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2D MEMS

•Rotating mirror as a 2*2 switch.

• single level mirrors

• adjusted only in 2D

• A x A in size•32x32 are already available

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3D MEMS

• Mirror on multiple planes

• Controls of thousands of mirrors

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3D MEMS

• Adv – More flexible – More scalable

• Disadv– more complex to control thousands of mirrors

request complex software to coordinate their operations– More costly

• typically support much larger switch core sizes

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MPLS

• Multiprotocol Label Switching (MPLS) is a data-carrying mechanism which emulates some properties of a circuit-switched network over a packet-switched network

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GMPLS

• Generalized Multiprotocol Label Switching (GMPLS)

• extension of the signaling protocols of MPLS to lower-layer entities in the network

• enabled photonic switches allow– automated provisioning – and bandwidth-on-demand services– optical virtual private networks

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GMPLS applications with MEMS

• Lower capital expenses

• Lower cost of ownership

• Reduce space & power consumption

•Local equipment connected to OEO switch

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MEMS Products

• MEMS Products: While MEMS is an amazing technology, there are a

number of real products emerging • Some examples of real MEMS products include

–  Adaptive Optics for Ophthalmic Applications  –  Optical Cross Connects –  Air Bag Accelerometers –  Pressure Sensors –  Mirror Arrays for Televisions and Displays –  High Performance Steerable Micromirrors –  RF MEMS Devices –  Disposable Medical Devices –  High Force, High Displacement Electrostatic Actuators –  MEMS Devices for Secure Communications

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Some MEMS Images

A truly amazing MEMS device. It is a sophisticated MEMS Thermal Actuator

Complex MEMS Ratchet Mechanism

New Torsional Actuator.  Potentially packing a lot of umph into a VERY small space.

Incredible MEMS Clutch mechanism.  This is actually a complex device that required a working clutch mechanism.  Gears are 50 microns across.

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MEMS Adaptive Optics

Adaptive Optics MEMS Chip (Pixels are 600 microns flat-to-flat)

MEMX Packaged 93 Pixel AO Array(Package is 2 Inches Across)

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MEMS Optical Cross Connect• MEMS mirrors• optics module• MEMS optical cross connect chip

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Optical Switching Technologies

• Optical MEMS-Based Switch

• Thermal Optical Switch

• Electro-Optical Switch

• Opto-Optical Switch

• Acousto-Optical Switch

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• Optical MEMS-Based Switch

Optical MEMS are miniature devices with optical, electrical,and mechanical functionalities at the same time, fabricatedusing batch process techniques derived from microelectronicfabrication . Optical MEMS provide intrinsic characteristicsfor very low crosstalk, wavelength insensitivity, polarizationinsensitivity, and scalability . Optical MEMS-based switchesare distinguished in being based on mirrors , membranes,and planar moving waveguides.

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• Thermal Optical Switch Thermal optical switches are based on

waveguide thermooptic effect or thermal phenomena of materials.

• Electro-Optical Switch Electro-optical switches realize optical

switching functions by using electro-optic effects, which offer relatively faster switching

speed.

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• Opto-Optical Switch Opto-optical switches realize switching

functions relying on the intensity-dependent nonlinear optic effect (which is ultrafast) in optical waveguides

• Acousto-Optical Switch Acousto-optic switches are based on the

acousto-optic effect in crystals

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Commercial Products

• In this section, we will discuss our survey in State-of-the-art Commercial Products about Optical Switches

26http://newsroom.cisco.com/dlls/2006/prod_060206c.html

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MobiCom Deploys State-of-the-Art Optical Network with Cisco

• June 2, 2006 • MobiCom, a Mongolian mobile

communications service provider • Cisco® Internet Protocol Next-Generation

Network (IP NGN) architecture • Cisco ONS 15454 SDH Multiservice

Provisioning Platform (MSPP) • Converging its mobile and Internet traffic

into a unified optical transport platform

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National LambdaRail and Cisco Systems, Inc. Extend Strategic Relationship to 2013

• The foundation of the NLR infrastructure is a dense wave division multiplexing (DWDM)-based national optical network using Cisco ONS 15808 and 15454 systems, with capacity of 40 and 32 wavelengths per fiber pair respectively. Each wavelength can support transmission at 10 billion bits (or gigabits) per second.

• Over this optical DWDM network, NLR has also deployed nationwide a very robust switched Ethernet network built on the Catalyst 6509 Series switches. Rounding out NLR's unique set of capabilities and services is the routed IP network built on the Cisco CRS-1 Carrier Routing System, the core of Cisco's Internet Protocol Next-Generation Network (IP NGN) architecture.

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IP over DWDM

ATM ATM

SONET/SDH

IP

Optical/WDMOptical/WDMOptical/WDM

IP

SONET/SDH

IP

Optical/WDM

IP

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IP over DWDM

• ATM– Strong QoS– High overhead

• SONET/SDH– Protection/restoration functionality– High equipment cost and operational costs

• Wavelength Routers (Intelligent Network)– Can be configured to provide dynamic provisioning,

reconfiguration for optimizing network resources and protection and restoration at the wavelength level

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IP NGN

• Multiple Transport Layer– Router-Terminated Traffic

• Layer 3 (IP) lookup

– Pass-Through Traffic– (~70-80%)

• SONET• SDH• DWDM

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ROADM

• Cisco combine the transponder in the optical switch to reduce costly OEO transformation

• Reconfigurable optical ADM (ROADM)

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• The ONS 15454 SDH MSPP integrates digital cross connect functionality, add-drop multiplexing, and multiple service interfaces in a single network element.

• This evolutionary platform supports a broad variety of service interfaces, including electrical (E1, E3, and DS3), Ethernet (10/100-Mbps and Gigabit Ethernet), optical interfaces (STM-1, STM-4, STM-16, and STM-64), and DWDM.

Multi-Service Provisioning Platform

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Multi-Service Provisioning Platform

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Research efforts

• In the recent years, the demand of high speed links strongly increases

• In the IEEE Xplore website

• Nearly 5000 articles are about Optical Switches

• This topic is very hot in these few years

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Journal on Feb 2006

Integrated Array of 1 × N Optical Switches for Wavelength-Independent and WDM Applications

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ARRAYED OPTICAL SWITCH DESIGN (AOSD)• The optical configuration allows effective arrangement of optical swit

ches as an integrated array

Design• A two-dimensional (2-D) N ×M fiber array (with attached N ×M micro

lens array for individual optical beam collimation• A cylindrical lens• A one-dimensional (1-D) 1 ×M MEMS mirror array positioned in the

back focal plane of the cylindrical lens.

Journal on Feb 2006

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Feature:• Independence

– a cylindrical lens focuses the light only in the horizontal plane

– the optical switching module could be functionally divided into M independent planar 1 × N optical switches (“sandwiched” design).

– Each of the fiber rows has one input fiber (central fiber) and N − 1 output fibers

Journal on Feb 2006

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What is so special?• each of the 1 × N optical switches requires only

one MEMS mirror for its switching operation• use of a cylindrical lens in the proposed AOSD

allows the compact arrangement of several planar optical switches

• potentially a very cost-effective integrated optical module

Journal on Feb 2006

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Also • Useful when a large number of 1 × N optical swit

ches is required at the same network node.• uniform performance and a mean fiber-to-fiber in

sertion loss of 2.75 dB• Switching times are better than 10 ms

Journal on Feb 2006

Ref: JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 24, NO. 2, FEBRUARY 2006

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• a new type of latching micromagnetic optical switch

• a cantilever made of soft magnetic material with a reflective surface serving as a mirror.

Latching Micromagnetic Optical Switch

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How does it work?• cantilever has two stable positions• positions are controlled by magnetic field• momentarily flowing a pulsed electrical current into the

planar coil underneath the cantilever• in DOWN position without any power consumption• input optical signal to the device is switched selectively

to one of the two output ports

Latching Micromagnetic Optical Switch

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Features• large angle deflection of the cantilever can be achieved• optical signals can be effectively manipulated• the measured mechanical switching speed between the two states o

f the prototype 3.2 ms. (fast)• optical insertion loss 4 dB• the energy consumption 44 mJ for each switching event

Latching Micromagnetic Optical Switch

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Problem• Large insertion loss (the best result after

the test is still 4 dB)– the mirror surface was not perfectly flat– Vibration is observed for the mirror at its UP

position

SuggestionTry to add some vibration absorbing material

Latching Micromagnetic Optical Switch

Ref: JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 1, FEBRUARY 20

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• Thank you !!!

• Q & A