June 28, 2015CS Dept., LUMS, Lahore Optical Technology Dr. Salim Tariq

March 31, 2003Salim Tariq Component Perspective Early 1960s Early 1960s  Laser Invented 1970s 1970s  Low-loss Optical Fiber 1980s 1980s  Optical Amplifier 1990s 1990s  Dispersion Compensation, MEMs & Amplifier Technologies

March 31, 2003Salim Tariq System Perspective 1970s 1970s  Single channel systems at 850 nm  Low data rate, short reach 1980s 1980s  Single channel systems at 1300 nm  Higher data rate, longer reach  WDM & DWDM  Multiple channel systems at 1550 nm

March 31, 2003Salim Tariq Optical Communication Link Data Laser Fiber Photodetector Data

March 31, 2003Salim Tariq Network Perspective 1970s 1970s  Optical links for voice/data transfer 1980s 1980s  Optical layer is a high speed dumb medium 1990s 1990s  Upper layers are inefficient  Optical Layer should become INTELLIGENT

March 31, 2003Salim Tariq Fiber Characteristics & Its Impact Low-loss windows Low-loss windows BandwidthTechnology 850 nm ~ 50GHz Single Channel 1300 nm > 5,000 GHz WDM or DWDM 1550 nm > 10,000 GHz WDM or DWDM

March 31, 2003Salim Tariq Fiber Characteristics & Its Impact Dispersion Dispersion Dispersion Data Rate per Channel 850 nm HighLow 1300 nm LowestHighest 1550 nm LowHigh

March 31, 2003Salim Tariq Graphical Effect of Loss & Dispersion Loss reduces pulse amplitude Loss reduces pulse amplitude  Limited reach Dispersion increases pulse width Dispersion increases pulse width  Limited data rate Out In Fiber

March 31, 2003Salim Tariq Optical Amplifier & Dispersion Compensation Fibers Optical Amplifiers undo the effect of fiber loss Optical Amplifiers undo the effect of fiber loss DC Fibers undo the effect of dispersion to some extent DC Fibers undo the effect of dispersion to some extent Nonlinear Effects in Fiber Nonlinear Effects in Fiber  Ultimate system limitation  Optimization techniques must be used

March 31, 2003Salim Tariq Laser Technology SM lasers SM lasers  Least effected by dispersion  Suitable for WDM Tunable SM Lasers Tunable SM Lasers ~ 100 GHz GHz MM LaserSM Laser

March 31, 2003Salim Tariq Tunable SM Lasers Spectrum is instrument limited Spectrum is instrument limited

March 31, 2003Salim Tariq Capacity of Today’s Links DWDM technology DWDM technology  150 channels of 10 Gbps each in a fiber  Reach is about 1,000 to 1,500 km Roughly from Karachi to Peshawar.Roughly from Karachi to Peshawar. No O/E/O conversion needed. No O/E/O conversion needed. How to route the traffic? How to route the traffic?

March 31, 2003Salim Tariq Electro-Optical Bottleneck Bandwidth of electronics ~ 1GHz Bandwidth of electronics ~ 1GHz Bandwidth of optical channel ~25GHz Bandwidth of optical channel ~25GHz Processing speed limitation Processing speed limitation  Multi-million gate devices needed Optical Nonlinearities Optical Nonlinearities  Nonlinear response of the fiber material

March 31, 2003Salim Tariq Optical Networking Wavelength Add/Drop Wavelength Add/Drop  A fixed wavelength is dropped  The same wavelength is added Agile Network Agile Network  Remotely reconfigured wavelength add/drop Express channelsExpress channels

March 31, 2003Salim Tariq Wavelength Add/Drop Fixed wavelength is add/dropped at a predetermined location Fixed wavelength is add/dropped at a predetermined location Modification requires hardwiring Modification requires hardwiring Electro-optical devices Electro-optical devices DropAdd 1, 2, 3 3 1, 2 3 1, 2, 3

March 31, 2003Salim Tariq Agile Networks Wavelength add/drop is dynamic Wavelength add/drop is dynamic All optical or electro-opticalAll optical or electro-optical DropAdd 1, 2, 3 3 1, 2 3 1, 2, 3 3:00 am DropAdd 1, 2, 3 2, 3 1 1, 2, 3 2, 3 10:30 am

March 31, 2003Salim Tariq Wavelength Routing Wavelength dependent routing Wavelength dependent routing  All optical is desirable for less complexity 1a, 2a, 3a 1a, 2b, 3c 1b, 2b, 3b 1c, 2c, 3c 1c, 2a, 3b 1b, 2c, 3a a b c x y z

March 31, 2003Salim Tariq MEMs Technology Micro Electro-Mechanical Mirrors Micro Electro-Mechanical Mirrors  Mirror manufactured on silicon  Mechanically controlled

March 31, 2003Salim Tariq A mirror Size ~0.1 mm - 1 mm, Gold layer ~.01  m Size ~0.1 mm - 1 mm, Gold layer ~.01  m MEMS Technology for Optical Networking Applications A. Neukermans, R. Ramswami, IEEE Comm. Mag., Jan 2001

March 31, 2003Salim Tariq MEMS Cross-connect An Optical Cross-connect (1152 x 1152) MEMS Technology for Optical Networking Applications A. Neukermans, R. Ramswami, IEEE Comm. Mag., Jan 2001

March 31, 2003Salim Tariq MEMs X-Connect for Add/Drop O/E/O conversion not needed O/E/O conversion not needed Optical Cross- Connect DropAdd Electronic Control DeMux Mux

March 31, 2003Salim Tariq