Optical Circuit

1. Sayantani Roy
MTCT 2nd Year
Jadavpur University

2. Optical Networks
 Optical networking is a means of communication that uses
signals encoded onto light to transmit information among
various nodes of a telecommunications network.
 They operate from the limited range of a local-area
network (LAN) or over a wide-area network (WAN)
 It is a form of optical communication that relies on optical
amplifiers, lasers or LEDs and wave division multiplexing
(WDM) to transmit large quantities of data, generally
across fiber-optic cables.
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3. History
 First generation Optical Network
 SONET (Synchronous Optical Network)
 SDH (Synchronous Digital Hierarchy)
 Second generation Optical Network
 OTDM (Optical Time Division Multiplexing)
 WDM (Wavelength Division Multiplexing)
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4. History
 First generation Optical Network
 Point-to-point optical links used simply as a
transmission medium
 Fiber connected by Electronic routers/switches with
O-E-O conversion
 Regenerators used for long haul
E-O
Switch
O-E-O
Switch
O-E
Switch
Regenerators
Electronic data
as the signal
Signal received
as electronic
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Figure1: First Generation Optical Network

5. History
 Second generation Optical Network
 Static paths in the core of the network
 All-Optical Switches (may not be intelligent)
 Circuit-switched
 Configurable (but in the order of minutes/hours)
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6. Benefits
 Higher Bandwidth Capacity
 Lower Bit Error rates
 Restoration Capability
 Wavelength Services
 Reduced Cost
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7. Bandwidth
 Usable band in a fiber
 1.30m - 1.65m  40 THz
  spaced at 100 GHz  400 s per fiber
 Link Speeds upto 40 Gbps per 
 OC-3  155Mbps
 OC-768  40Gbps becoming available
 Total link capacity
 400  * 40Gbps = 16 Tbps!
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8. Other advantages
 Transparent to bit rates and modulation
schemes
 Low bit error rates
 10-9 as compared to 10-5 for copper wires
 High speed transmission
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9. Optical Network path
* All-optical Switch with wavelength converters and optical buffers
All-Optical
Switch*
All-Optical
Switch*
All-Optical
Switch*
Optical
Amplifier
Lasers generate the signal Optical receivers
Figure2: Optical Network Path
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10. Components
 Optical Amplifier
 Narrowband Lasers
 Fiber Bragg Gratings
 Thin Film Substrates
 Optical Network Devices
 Wave length Add/Drop Multiplexers
 Wavelength Switches
 Wavelength Converters
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11. Components
 Fiber
 Larger transmission band
 Reduced dispersion, non linearity and attenuation
loss
 Lasers
 Upto 40Gbps
 Tunability emerging
 Reduced noise (both phase and intensity)
 Made from semiconductor or fiber
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12. Optical Fiber
 Working Principle
Figure3: Optical Fiber
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13. Components
 Optical Amplifiers
As opposed to regenerators
 Make possible long distance transmissions
 Transparent to bit rate and signal format
 Have large gain bandwidths (useful in WDM systems)
Then:
Regenerators
Now:
Optical Amps
Figure4: Regenerators vs Optical Amplifier
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14. Components
 Optical Add-Drop Multiplexer (OADM )
 Allows transit traffic to bypass node optically
 New traffic stream can enter without affecting
the existing streams
OADM
1
2
3
1
2
’3
’
33
Figure5: Optical Add-Drop Multiplexer
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15. Components
 Optical Cross-Connects
 Fiber switching
 Wavelength switching
 Wavelength conversion
Figure6: Optical Cross Connects
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16. Components
 Wavelength Converters
 Improve utilization of available wavelengths on
links
 All-optical WCs being developed
 Greatly reduce blocking probabilities
No  converters
1
2
New request
1 3
1
2 3
New request
1 3
With  converters
WC
Figure7: Wavelength Convertoers
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17. Components
 Optical Buffers
 Fiber delay lines are used
 To get a delay of 1 msec:
 Speed of Light = 3*108 m/sec
 Length of Fiber = 3*108 *10-3 m
= 300 km
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18. Conclusion
 End-to-end wavelength services
 Increase Network capacity
 Long-distance networks
 Technologically and economically feasible
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19.  Rajiv Ramaswami and Kumar N. Sivarjan, ”Optical
Networks, A practical Perspective,” Morgan Kaufmann.
 Gilbert Held, ” Deploying Optical Networking
Components,” McGraw-Hill.
 GOVIND E. AGRAWAL, ” Fiber-Optic Communications
Systems,” Wiley & Sons.
 "Optical Networking" by Naser Tarhuni
 "A Brief Introduction to Optical Networks" by UC Berkeley
and Gaurav Agarwal
 "Optical Networks(OPNET)" by Swagat Kumar Samantaray
 https://en.wikipedia.org/wiki/Optical_networking
References
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20. THANK YOU