Optical Switches Packet and Circuit-Based Wong King Heng

Optical Switches (Packet and Circuit-Based) Wong King Heng, Kenny Wu Ka Man, Karmen Chen Aiqin, Joanne Tam Chi Fai, Jeffrey 1

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

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 3

4

OEO vs OOO vs OEO-O-OEO Pros OEO OOO Cons - Known and mature technology - 3 R 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 - Optical Scalability - Bit-rate transparency - service/protocol transparency - Emerging Technology - not capable of bandwidth grooming, bit error rate monitoring and statistical multiplexing - Combines scalability of optics with 3 R regeneration and wavelength OEO-O- translation of electronics OEO - 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 5

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) 6

Wave Division Multiplexing (WDM) • CWDM – ITU has standardized a 20 nanometer channel spacing grid • DWDM – closer spacing of the wavelengths – 1530 nm and 1560 nm – wavelengths between 1310 nm ~ 1610 nm 7

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 8

Optical MEMS • Tiny arrays of tilting mirrors • Adjust the angle to transmit to desired output port • Eliminate OEO conversion – costly – Save space and power Optical MEMS Mirror Used in an Optical Switch 9

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 • => 2 D MEMS 10

2 D MEMS • single level mirrors • adjusted only in 2 D • A x A in size • 32 x 32 are already available • Rotating mirror as a 2*2 switch. 11

3 D MEMS • Mirror on multiple planes • Controls of thousands of mirrors 12

3 D 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 13

MPLS • Multiprotocol Label Switching (MPLS) is a data-carrying mechanism which emulates some properties of a circuitswitched network over a packet-switched network 14

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 15

GMPLS applications with MEMS • Lower capital expenses • Lower cost of ownership • Reduce space & power consumption • Local equipment connected to OEO switch 16

MEMS Products • MEMS Products: While MEMS is an amazing technology, there 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 17

Some MEMS Images A truly amazing Complex MEMS device. It is a Ratchet sophisticated MEMS Mechanism Thermal Actuator 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 18 microns across.

MEMS Adaptive Optics MEMS Chip (Pixels are 600 microns flat-to-flat) MEMX Packaged 93 Pixel AO Array (Package is 2 Inches Across) 19

MEMS Optical Cross Connect • MEMS mirrors • optics module • MEMS optical cross connect chip 20

Optical Switching Technologies • • • Optical MEMS-Based Switch Thermal Optical Switch Electro-Optical Switch Opto-Optical Switch Acousto-Optical Switch 21

• Optical MEMS-Based Switch Optical MEMS are miniature devices with optical, electrical, and mechanical functionalities at the same time, fabricated using batch process techniques derived from microelectronic fabrication. Optical MEMS provide intrinsic characteristics for very low crosstalk, wavelength insensitivity, polarization insensitivity, and scalability. Optical MEMS-based switches are distinguished in being based on mirrors , membranes, and planar moving waveguides. 22

• 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. 23

• 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 24

Commercial Products • In this section, we will discuss our survey in State-of-the-art Commercial Products about Optical Switches 25

http: //newsroom. cisco. com/dlls/2006/prod_060206 c. html 26

Mobi. Com Deploys State-of-the. Art Optical Network with Cisco • June 2, 2006 • Mobi. Com, 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 27

28

National Lambda. Rail 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. 29

30

IP over DWDM IP IP ATM SONET/SDH Optical/WDM IP IP SONET/SDH Optical/WDM 31

IP over DWDM • ATM – Strong Qo. S – 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 32

IP NGN • Multiple Transport Layer – Router-Terminated Traffic • Layer 3 (IP) lookup – Pass-Through Traffic – (~70 -80%) • SONET • SDH • DWDM 33

ROADM • Cisco combine the transponder in the optical switch to reduce costly OEO transformation • Reconfigurable optical ADM (ROADM) 34

35

36

Multi-Service Provisioning Platform • 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 (E 1, E 3, and DS 3), Ethernet (10/100 -Mbps and Gigabit Ethernet), optical interfaces (STM-1, STM-4, STM-16, and STM-64), and DWDM. 37

Multi-Service Provisioning Platform 38

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 39

Journal on Feb 2006 Integrated Array of 1 × N Optical Switches for Wavelength -Independent and WDM Applications 40

Journal on Feb 2006 ARRAYED OPTICAL SWITCH DESIGN (AOSD) • The optical configuration allows effective arrangement of optical switches as an integrated array Design • A two-dimensional (2 -D) N ×M fiber array (with attached N ×M microlens 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. 41

Journal on Feb 2006 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 42

Journal on Feb 2006 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 43

Journal on Feb 2006 Also • Useful when a large number of 1 × N optical switches is required at the same network node. • uniform performance and a mean fiber-to-fiber insertion loss of 2. 75 d. B • Switching times are better than 10 ms Ref: JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 24, NO. 2, FEBRUARY 2006 44

Latching Micromagnetic Optical Switch • a new type of latching micromagnetic optical switch • a cantilever made of soft magnetic material with a reflective surface serving as a mirror. 45

Latching Micromagnetic Optical Switch 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 46

Latching Micromagnetic Optical Switch 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 of the prototype 3. 2 ms. (fast) • optical insertion loss 4 d. B • the energy consumption 44 m. J for each switching event 47

Latching Micromagnetic Optical Switch Problem • Large insertion loss (the best result after the test is still 4 d. B) – the mirror surface was not perfectly flat – Vibration is observed for the mirror at its UP position Suggestion Try to add some vibration absorbing material Ref: JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 1, FEBRUARY 20 48

• Thank you !!! • Q & A 49