Download optical switching - 123SeminarsOnly.com

OPTICAL SWITCHING
BY
SURYA ANJANI.Y.
COMMUNICATION SYSTEMS
MANIPAL UNIVERSITY-DUBAI
B.E.ECE(2008-12)
WHAT IS AN OPTICAL SWITCH?
DEFINITION: A switch that enables signals in optical fibers or integrated
optical circuits (IOCs) to be selectively switched from one circuit to another.
OPERATION:
MECHANICAL MEANS such as physically shifting an optical fiber to drive
one or more alternative fibers.
ELECTRO-OPTIC EFFECTS, MAGNETO-OPTICS, or other methods.
TYPES OF OPTICAL SWITCHES(SPEED):
Slow optical switches, such as those using moving fibers, may be used for
ALTERNATE ROUTING of an optical transmission path, e.g., routing around
a fault.
 Fast optical switches, such as those using electro-optic or magneto-optic
effects, may be used to perform logic operations.
“SYSTEMS WHICH PERFORM THE FUNCTION OF
OPTICAL SWITCHING BY PHYSICALLY SWITCHING
LIGHT ARE REFERRED TO AS PHOTONIC.”
OPTICAL NETWORKS
 A data network built on fiber-optics technology, which sends data
digitally, as light, through connected fiber strands.
 OPTICAL NETWORKS TYPES:
1)SDH/SONET SYSTEM
2)OEO(OPAQUE OPTICAL NETWORK)
3)OPTICAL NETWORKS WITH VARYING DEGREE OF TRANSPARENCY.
4)ALL-OPTICAL NETWORKS.
OPTICAL NETWORKS WITH VARYING
DEGREE OF TRANSPARENCY
 WDM(WAVELENGTH DIVISION MULTIPLEXING) AND OPTICAL SWITCHING
ARE USED.
 SWITCH AND NETWORK CONTROL IS CARRIED OUT BY ELECTRONICS.
 CLASSIFIED IN TO 3 TYPES:
i)If all nodes utilize opto-electronics conversion, the network becomes
OPAQUE(OEO).
ii)If no nodes utilize opto-electronics conversion, the network becomes
TRANSPARENT.
iii)Between both extremes is PARTIALLY TRANSPARENT.
ALL-OPTICAL NETWORKS
• NETWORKS WHERE ALL THE OPERATIONS AND
FUNCTIONS ,INCLUDING SWITCH CONTROL &
NETWORK CONTROL,WOULD BE PERFORMED
OPTICALLY.
ALL OPTICAL SWITCH





TRANSPARENCY INVOLVES THE NETWORK BEING ABLE TO TRANSFER
ANY TYPE OF INFORMATION WITHOUT REGARD TO PROTOCOL AND
CODING FORMATS,DATA RATES AND MODULATION TECHNIQUES.
ADVANTAGES:
Enables the optical network to support variety of higher layers
concurrently.
Enables network to be designed cost-effectively.
Evolve easily in future together with protocols and technologies.
MEMS BASED-ALL OPTICAL SWITCH
OPTICAL SWITCHING
OPTICAL CIRCUIT SWITCHING
OPTICAL PACKET SWITCHING
OPTICAL BURST SWITCHING
OPTICAL CIRCUIT SWITCHING
• In OCS, the network is configured to establish a circuit, from an entry to an
exit node, by adjusting the optical cross connect circuits in a manner that
the data signal can travel in an All-optical manner.
• When OCS is based on light path ,it is called as OWS(optical wavelength
switching).
OPTICAL CIRCUIT SWITCH
DISADVANTAGES
 DATA TRAFFIC.
 The circuits require time to set up and to destroy.
 When the circuit is established, there sources will not be efficiently used due
to the unpredictable nature of network traffic.
OPTICAL PACKET SWITCHING





MUST BE ALL-OPTICAL.
It requires a Packet header, header processing.
Control is fully performed in optical domain on a packet-by packet basis.
Increased bandwidth compared to optical circuit switching.
Supports bursty data traffic more efficiently than OCS by means of
statistical multiplexing.
Unlike OBS, OPS does not require burst assembly algorithms, separate
control wavelength channel, nor any offset time.
 OPS networks face challenges due to lack of optical RAM & difficulty to
execute complex computations & logical operations using only optics &
photonics without OEO conversion.
 General optical packet format consists of :
 Header
 Payload
 Additional guard bands before & after payload
OPTICAL PACKET FORMAT
OPTICAL BURST SWICTHING
• Introduced as a compromise of OCS and OPS.
• OBS is packet based and hence more bandwidth efficient than OCS.
• Technological requirements to implement OBS are relaxed as
compared to OPS.
• In OBS network, packets are assembled into larger data
bursts(DB).For every burst ,a burst header project(BHP),DB
assembly and BHP generation is created in OBS edge nodes.
• Each DB/BHP pair is routed to their destination through the nodes.
• The burst is transmitted over a data channel and BHP is sent over a
dedicated control channel to the same node.
• While data bursts switch optically,BHPS are converted to the
electrical domain for processing and converted back to optical
domain to transfer to the next node.
OPTICAL BURST SWITCH
SWITCHING TYPE
TECHNOLOGIES/OPTICAL SWITCHES
 MECHANICAL SWITCH
 Each individual fiber is manually
moved.
 optical fiber is physically moved to
drive alternate fibers.
 Physically shifting an optical fiber to
drive one or more alternative fibers.
 ELECTRO-OPTIC SWITCH
 Change in electric field that varies
slowly in comparison to the speed or
intensity of light.
 MAGNETO-OPTIC SWITCH
By use of electro-magnetic forces, the switch
can be made to transfer the data from one
fiber to the other.
 THERMO-OPTIC SWITCH
Utilizes thermo optic effect in optical
waveguides.(main materials are silica and
polymers)
 ACOUSTIC-OPTIC SWITCHING
 It employs the acousto-optic effect.
 In acousto-optic Q-switches, an ultrasonic
wave is launched into a block of transparent
optical material, usually fused silica. By
switching on the acoustic field ,a fraction of the
energy of the main beam is diffracted out of
the resonator, that prevents laser action(due to
loss).
 When acoustic field is switched off, full
transmission through the Q-switch cell is
restored and a laser pulse is created.
IMPORTANCE OF OPTICAL SWITCHING
1.LESS CROWDED NETWORK
2.REDUCED PROTOCOL ISSUES
3.INCREASED BANDWIDTH
4.INCREASED DISTANCE
5.WIDE RANGE OF USE
APPLICATIONS
COMPUTER AND NETWORKING PURPOSES.
PHONE SYSTEMS
LIGHTENING AND STORMS
OADM(OPTICAL ADD/DROP MULTIPLEXERS)
OXC(OPTICAL CROSS-CONNECTS)
PROTECTION SWITCHING
THANK YOU