Optical networks transmit information as light signals through fiber optic cables. They rely on components like lasers, fiber, and multiplexers. Fiber comes in single-mode and multi-mode varieties and transmits light through a core surrounded by cladding. SONET is a standard for synchronous data transmission over optical networks that defines transmission rates and provides high availability through rapid restoration. Optical networks offer advantages over metal networks like greater bandwidth, lower power loss, immunity to interference, smaller size, lighter weight, safety, security, flexibility and potentially lower long-term costs. Their disadvantages include higher initial installation costs, need for signal repeating over long distances, fragility if bent too sharply, and need for protective cabling.

1. Optical Networking
.

2. Contents
• Optical network definition
• Components of optical network
• Optical fibre
• SONET
• Advantages
• Disadvantages

3. Optical Network
• An optical Network is a communication network in
which information is transmitted as optical or
Infrared radiation transmission (IR) signals.
• It is also called Photonic Network
• 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 Fibre-optic cables.

4. Components of Optical Network System
• Fiber. Multi-mode or single-mode.
• Laser or LED light source.
• Multiplexer/demultiplexer, also called mux/demux,
filter, or prism. These can include Optical Add/Drop
Multiplexer (OADM) and Reconfigurable Optical
Add/Drop Multiplexer (ROADM).
• Optical switch, to direct light between ports without an
optical-electrical-optical conversion
• Optical splitter, to send a signal down different fiber
paths.
• Optical amplifier.

5. Optical Fiber
• An optical fiber is made of
three sections:
– The core carries the
light signals
– The cladding keeps the light
in the core
– The coating protects the glass
5
CladdingCore
Coating

6. Optical Fiber (cont.)
• Single-mode fiber
– Carries light pulses by
laser along single path
• Multimode fiber
– Many pulses of light
generated by LED
travel at different
angles
SM: core=8.3 cladding=125 µm
MM: core=50 or 62.5 cladding=125 µm

7. 7.7
Bending of light ray

8. 7.8
Propagation modes

9. Figure Modes

10. SONET
• Synchronous Optical Network (SONET)
• The ANSI standard for synchronous data transmission on
optical media.
• Provide end-to-end circuit-switched connections
• Provide efficient mechanism for multiplexing low-speed
connections into higher-speed connections
– Define a base rate of 51.84 Mbps and a set of multiples of the base rate
known as "Optical Carrier levels (OCx)"
• Provide efficient way to extract low-speed streams from a
high-speed stream at intermediate nodes
• High availability (99.99% to 99.999%)
– Rapid service restoration in the event of failures

11. 11
SONET Transmission Rates
OC-1 = 51.84 Mbps
OC-3 = 155.52 Mbps
OC-12 = 622.08 Mbps
OC-24 = 1.244 Gbps
OC-48 = 2.488 Gbps
OC-192 = 9.953 Gbps
OC-768 = 39.814 Gbps

12. 12
SONET Elements
• Terminal multiplexers (TMs): nodes at the ends of
point-to-point links, multiplex and demultiplex traffic
streams
• Add/drop multiplexers (ADMs):drop/add one or
more low-speed streams from/to a high-speed
stream, allow the remaining traffic to pass through
– Deployed in linear and ring networks
• Digital crossconnects (DCSs): large number of ports,
extract and switch lower-speed streams
(44.736Mbps and 1.544Mbps), interconnect SONET
rings

13. Advantages
• Bandwidth - Fibre optic cables have a much greater bandwidth than metal cables
• Low Power Loss - An optical fibre offers low power loss. This allows for longer
transmission distances. In comparison to copper; in a network, the longest
recommended copper distance is 100m while with fibre, it is 2000m.
• Interference - Fibre optic cables are immune to electromagnetic interference. It
can also be run in electrically noisy environments without concern as electrical
noise will not affect fibre.
• Size - In comparison to copper, a fibre optic cable has nearly 4.5 times as much
capacity as the wire cable has and a cross sectional area that is 30 times less.
• Weight - Fibre optic cables are much thinner and lighter than metal wires. They
also occupy less space with cables of the same information capacity. Lighter
weight makes fibre easier to install.
• Safety - Since the fibre is a dielectric, it does not present a spark hazard.
• Security - Optical fibres are difficult to tap.
• Flexibility - An optical fibre has greater tensile strength than copper or steel fibres
of the same diameter.
• Cost - The raw materials for glass are plentiful, unlike copper. This means glass can
be made more cheaply than copper.

14. Disadvantage
• Cost - Cables are expensive to install but last
longer than copper cables.
• Transmission - transmission on optical fibre
requires repeating at distance intervals.
• Fragile - Fibres can be broken or have
transmission loses when wrapped around curves
of only a few centimetres radius. However by
encasing fibres in a plastic sheath, it is difficult to
bend the cable into a small enough radius to
break the fibre.
• Protection - Optical fibres require more
protection around the cable compared to copper.

15. Thank You