Contents for this Presentation SDH/DWDM based Multi-Service Transport Platform by Khurram Shahzad ad
Brief Contents Description for this of Presentation the Project Development of a Unified Transport Platform facilitating multiple services like POTS, PDH, SDH, ATM, IP, CATV, HDTV, B-ISDN, Ethernet and Giga-bit Ethernet to Residential Areas, Business Groups, Enterprise Groups and Internet Services Centers etc.
Contents for for this this Presentation Lecture Optical Communications and DWDM Systems Why Move to DWDM? Optical Transmission System a. Advantages and Limits a. b. Overview Fiber Characteristics b. c. Application Fiber Propagation Modes Modes c. d. Laser Optical Modulation Transmitters Modes (LEDs, Lasers) d. e. DWDM Optical Components Receivers (Photodiodes, d Phototransistors) t t e. f. Network Optical Devices Elements (Amplifiers, (OTM, OADM, Splitters, OLA, REG) Couplers, f. System Engineering Filters and Switches) DWDM Multi-Service Transport Platform
Contents Why for Move this to Presentation DWDM The optical fiber is the best medium to be deployed at backbones of very high data rates. In order to increase the bandwidth, SDM is used by laying more and more fibers but mean while an enormous amount of bandwidth of fiber is being wasted. In order to utilize the maximum bandwidth, DWDM is the only solution.
Contents Optical Transmission for this Presentation System Optical Communication System Basic principle of light transmission on Optical Fiber
Contents Advantages for this of Optical Presentation System Weight and size less than copper cable Material cost is almost same Huge information capacity No Electrical connection No Electromagnetic Interference More distance between Regenerators Better security due to immediate failure detection
Contents Limitations for this Presentation Loss due to cable joining i (1 db/joint) Bending of fiber should not exceed the limit Optics for transmission only due to unavailability of optical amplifiers Gamma radiation can cause interference and also it cause to discolor glass that cause attenuation
Contents Fiber Propagation for this Presentation Modes Illustration of different propagation modes Typical fiber infrared absorption spectrum
Hard Contents Polymer for (plastic) this Clad Presentation (silica) Fiber
Contents Optical for this Devices Presentation Optical Transmitters Optical Detectors Optical Amplifiers Optical Couplers Optical Isolators Optical Cross Connects Optical Switches
Contents Optical Transmitters for this Presentation (Sources) Light Emitting Diodes (LEDs) LASERs (Light Amplification by Stimulated Emission i of Radiations) 10G Transmitter 40G Transmitter
Contents Characteristics for this Presentation of LEDs Low Cost compared to Lasers Low Power (recently 75mW) Relatively wider spectrum produced typically 50-100 nm Incoherent Light hence not directly coupled to fiber Digital Modulation can operate at speed of up to 300 Mbps Analogue Modulation response is linear with current flow
Contents Characteristics for this Presentation of Lasers Ideally have single wavelength Can be modulated very precisely pulse length of 0.5 femto seconds Can produce relatively high power (up to kws) High %age can be transferred into fiber (50% to 80%) Disadvantages Much expensive than LEDs The wavelength produced depends on characteristics of material used Amplitude modulation is difficult
Technical Contents for Parameters this Presentation of Lasers Spectral Width (typically (yp y 6 to 8 nm) Line Width (discrete wavelengths in Spectral Width) Coherence Length and Coherence Time (typically 15 cm) Length c = c x Time c Power (with increase in bit rate power must be increased) Operating Wavelength (Laser is chosen according to design) Wavelength Stability Tuning range and Speeds Switching time and Modulation
Contents Fabry-Perot for this Presentation Laser Conceptually an LED with a pair of end mirrors. Mirrors create right conditions to lasing to occur. Wavelengths produced are related to the distance between mirrors. Cl = X/2n Cl Cavity Length - Wavelength required X - an arbitrary number N - Refractive index Principle of Fabry-Perot Laser
Contents Optical Receivers for this Presentation (Detectors) Parameters of Optical Detectors Detector Responsivity (Ratio of Output current to Input Optical Power) Spectral Response Range Response time Noise Characteristics 40G Optical Receiver
Contents Types of for Optical this Presentation Detector Photoconductors Photodiodes a. Schottky-Barrier Photodiodes b. Avalanche Photodiodes Practical Photoconductor Detector Phototransistors Sh Schottky-Barrier Photodiode d Bipolar Junction Transistor as Phototansistor Avalanche Photodiode
Contents Optical for this Amplifiers Presentation Advantages More reliable (no need of electrical regeneration) Flexibility (Independence of code format, Speed increment permissible) For WDM, electrical regenerators are not suitable (indeed Optical Amplifiers made WDM implementation possible) Cost factor (due to simplicity cost is lesser)
Contents Optical for this Amplifiers Presentation EDFA (Erbium-doped Optical Fiber Amplifier) Praseodymium (Pr) Doped Fiber Amplifier Neodymium (Nd) Doped Fiber Amplifier Plastic Fiber Amplifier Semiconductor Optical/Laser Amplifier (SOA/SLA) Raman Effect Amplifier
Erbium-Doped Contents for Fiber this Amplifier Presentation (EDFA) Typical Internal Light path of EDFA
Contents Advantages for this of Presentation EDFA High Gain Large Output Power Wide Operating Optical Bandwidth Polarization Independence Low Noise Factor Gain Independence to System Bit Rate and Format
Contents Characteristics for this Presentation of EDFA Gain (ratio of output t power over input power) Gain Coefficient (small signal gain/pump power) Bandwidth (over which h Amplifier will operate) Gain Saturation (point where an increase in input power ceases to result in increase in output power) Very little sensitivity to Polarization states (polarization sensitivity is difference in gain of an input signal in one polarization to the orthogonal polarization) Adds Noise to signal Noise = SNR (i) /SNR (o) db
Contents Gain Characteristics for this Presentation of EDFA Gain curve of Typical EDFA Response of cascade EDFA
Contents Optical for this Couplers Presentation Y Coupler Planar Star Coupler Fused Fiber Star Coupler
Contents Optical for this Isolators Presentation A Simple Isolator Operation
Contents Optical Cross for this Connect Presentation (OXC) Optical Cross Connect OXC using tunable laser technology OXC Outline Architecture t
Contents Optical for this Switches Presentation MEMS Optical Switch Technology A Typical Optical Switch being Implemented
Contents Optical for this Filters Presentation Peak wavelength (wavelength at which the filter attenuation is least ) Nominal Wavelength (Intended by manufacturer) Bandwidth (Distances between edges db) Center Wavelength (Mean wavelength between two edges)
Contents Coupling for of this Light Presentation to a Fiber
Wavelength Contents for Division this Presentation Multiplexing Multiplexing with larger channel spacing (even in different windows of optical fibers) typically around 50nm WDM functions schematics
DWDM Contents Dense for Wavelength this Presentation Division Multiplexing Network Termin nals Wavelength Division Multiplexing in the same window with smaller channel Spacing (typically less than 1nm) NT NT NT NT 1 2 n-1 n Mult tiplexer Monitor Points ultiplexe er Dem 1 2 n-1 n NT NT NT NT Wavelength Converter Wavelength Converter
Contents Advantages for this of Presentation DWDM Ultra Large Capacity Data rate transparency Protection of existing investment during system upgrade Flexibility, economy and reliability of networking Compatibility with all optical switching
Optical Contents Spectrum for this of Presentation DWDM Signal
Contents Application for Modes this Presentation of DWDM Open DWDM No special requirements for multiplex terminal optical interfaces (ITU-T G.957) Adopts wavelength conversion technology Integrated t DWDM Requires optical signal wavelengths to meet DWDM System specifications
Contents Fiber for Modes this for Presentation DWDM DWDM Systems only utilize single mode fiber as transmission media ITU-T Standard fibers for DWDM System G.652 (1310nm property optimal, dispersion un-shifted) G.653 (1550nm property optimal, dispersion shifted) G.654 (cut-off wavelength shifted, reduced attenuation at 1550nm) G.655 (non-zero dispersion shifted, preserves dispersion near 1550nm)
Contents Laser Modulation for this Modes Presentation for DWDM Direct Modulation (Internal Modulation) Light wave intensity is changed by controlling the injection current using Laser Diodes Indirect Modulation (External Modulation) Laser is modulated indirectly by adding an external modulator in its output path to modulate the light wave
Contents External for this Modulators Presentation Constant Light Source Optical Modulator Optical Signal Output Electric Modulation Signal Input
Direct Contents Modulation for this vs. Indirect Presentation Modulation Simple Structure Low Loss Low Cost High Modulation Chirp Complex Structure High Loss High Cost Low Modulation Chirp Transmission i Distance Transmission i Distance < 100Km > 100Km Data Rate < 2.5G Data Rate > 2.5G
Network Contents Element for this Types Presentation of DWDM Optical Terminal Multiplexer (OTM) Optical Add/Drop Multiplexer (OADM) Optical Line Amplifier (OLA) Regenerators (REG)
Network Contents Element for this Types Presentation of DWDM Source: Bookham Technologies, 2002
Contents for this Presentation OTM Signal Flow W W A A RI S P A W C R D 1 6 RO M M RI S C A SDH System S C 1 A M RM TM A W B M 1 6 W C T A RO M TO A T RO M TO
Contents OADM for Signal this Presentation Flow WCR WCT RI TO S C A A RO M W P A RM1 TM1 W B A A MR 4 M S C 2 MR 4 A M W B A TM2 RM2 W P A M A RO S C A TO RI WCT WCR
Contents Remotely for Configurable this Presentation OADMs Marconi Communications PMA32 R-OADM Photonic R-OADM Architecture
DWDM Contents Component for this Presentation Requirements Enough multiplexing channels Low insertion loss Large crosstalk attenuation Wide pass band
Contents OLA for Signal this Presentation Flow RI TO S C A RO A M W P A RM1 TM1 W B A A M S C 2 A M W B A TM2 RM2 W P A RO M A S C A TO RI
Contents Optical System for this Engineering Presentation Determining the width and spacing of wavebands Stabilizing the wavelength of wavelength sensitive components Filter alignment in cascades of filters Control of non-linear effects Control of dispersion Control of cross-talk Dynamics of optical amplifiers Control of system noise (especially ASE)
DWDM Contents Networking for this Presentation Parameters Dispersion i Limited it Distance Power Signal to Noise Ratio
Contents DWDM Protection for this Presentation Mechanism No protection available to the network at DWDM Layer Reasons for unavailability of protection Cost Optical Switches Conflict between protocols of underlying networks
Contents 4 x 2.5G/DWDM for this Presentation Ring
Multi-Service Contents for Transport this Presentation Platform Multi-rate multi-service open interfaces Flexible bandwidth allocation for PCM (Pulse Coded Modulation) digital channels ATM (Asynchronous Transfer Mode) IP (Internet Protocol)
Contents Available for Interfaces this Presentation for MSTP 10M Ethernett Gigabit Ethernet STM-1 STM-16 E1 100M Ethernet ATM STM-4 STM-64 E3 POS (Packets over SDH) PDH
Contents SDH and for IP this over Presentation DWDM Simplified Diagram Showing SDH and IP Traffic over DWDM System
Simplified Contents for Transport this Presentation Hierarchy
Technology Contents Layers for this of Transport Presentation Network
An Contents Illustration for this of Metro Presentation Networks
Contents for Conclusions this Presentation Foreseeing the ever increasing bandwidth demands of the world it is inevitable to use the fiber and specifically move up to DWDM System To have a unified platform supporting all the current available services it is unavoidable to utilize the metro solution In the near future we are aiming to have the bandwidth of 100Tbps using this DWDM technology
Contents for this Presentation