Transcript Long Haul Fiber Optic Transmission Systems : Modeling and

Design and Simulation of Photonic
Devices and Circuits
Objectives
• To introduce the basic physics of photonic devices
and apply it for the design of optical transmission
systems and networks.
• To simulate the various photonic components and
also to do system level simulations.
• To study different noise processes in photonic
circuits and understand their impact on Q-factor or
BER.
• To develop engineering rules for the photonic
circuit design.
Expectations
• My expectation:
– Speak up.
– Course as interactive as possible.
• Your expectations ?
Point-to-Point Optical Transmission
System
Lasers Modulators
1
2
MUX
N
Fiber
Amp
DEMUX
Rx
Course Outline
• Modulation and transmission of light – 6 hours/3 lectures.
(Device behavior models with focus on the terminal
performance.)
– Sec. 1 Optical Modulators
– Sec. 2 Optical Fibers
• Generation, amplification and detection of light - 6 hours/
4 lectures
– Sec. 3 Semiconductor lasers and LED
– Sec. 4 Amplifiers (SOA, EDFA and Raman)
– Sec. 5 Photo-detectors
Course Outline
 Point-to-point, single wavelength transmission system (6 hours/2
lectures)
 Sec. 6 Functional Block (Tranmitter and Receiver) Design
 Sec. 7 Penalties due to fiber dispersion and amplifier noise
 Sec. 8 System design with Tx, fiber, concatenated amplifiers and Rx

 Eye Diagrams and Q-factor estimation
Wavelength division multiplexed system (2 hours/1 lecture)
 Sec. 9 Add/drop multiplexers
 Sec. 10 cross-talk in WDM system
 Linear cross-talk
 Nonlinear cross-talk due to four wave mixing
 Optical Networks (2 hours/1 lectures)
Sec. 11 - SONET/SDH, circuit, packet and cell networks
Schedule
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Jan 6 – Lecture - Introduction
Jan 13 – Lecture - Sec. 1
Jan 20 – Lecture - Sec. 2
Jan 27 - Lecture - Sec. 2
Feb. 3 - Lecture - Sec. 3
Feb 10 - Lecture Sec 3 & 4
Feb 17 - Lecture Sec 4 &5
Feb 24 - Lecture Sec 5
March 2 - Lecture Sec 6 &7
Schedule
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March 9 Lecture Sec 7&8
March 16 Lecture Sec. 9 &10
March 23 Lecture Sec. 11
March 30 Lecture Review
Assessment
• Final exam – 65%
• Project
- 35%
– Each student will be assigned a project.
– The project involves
• A good research survey.
• Simulation of a photonic device or a circuit.
• Project report.
History
•
Invention of Laser and Maser in 1960s
- In 1950s, Townes and Schawlow in the US and Basov and Prochorov in
the USSR proposed to make use of stimulated emission for the
construction of coherent optical sources.
– In 1960- Maiman demonstrated the first laser.
– In 1970, Hayashi et al demonstrated GaAs semiconductor laser operating
at room temperature.
•
Low Loss Fibers in 1970s
– Fibers available in 1960s had losses in excess of 1000dB/km.
– In 1970, Kapran, Keck and Maurer invented a low loss fiber with the loss
of 20 dB/km.
– In 1979, Miya et al reported a loss of 0.2 dB/km near 1550 nm.
•
Erbium Doped Fiber Amplifiers in 1980s.
– In 1980s, Poole et al in the UK and Desuvire in the US demonstrated light
amplification by EDFA. Now it is used in all commercial long haul fiber
optic networks.
The Evolution of Fiber Optic Systems
• First generation operated around 850 nm. Bit rate
45-140 Mb/s.
GaAs-based optical souces, multimode fibers and
silicon detectors.
• Second generation at 1300 nm. Substantial
increase in transmission distance and bit rate (622
Mb/s-2.5 Gb/s).
Both multimode and single mode fibers were
used.
The Evolution of Fiber Optic Systems
• Third generation systems operated around 1550 nm since
the fiber loss @ 1550 nm is the lowest.
But standard fibers have larger dispersion at 1550 nm than
at 1300 nm. Fiber manufacturers overcame this limitation
by inventing dispersion shifted (DS) fibers.
Transmission rates – 2.5 Gb/s to 10 Gb/s.
• Invention of (Erbium Doped Fiber Amplifier) EDFA
revolutionized light wave communication.
Wavelength Division Multiplexing (WDM) offered a
further boost in transmission capacity
Fourth generation systems operated at 1550 nm with EDFA
and WDM
The Evolution of Fiber Optic Systems
• With the advent of WDM, it was realized that DS fibers
were not suitable for long haul transmission because of
four wave mixing among different channels of WDM. So,
standard fiber (D=17 ps/nm.km) or Non-zero dispersion
shifted fiber (NZDSF) are used in current commercial
systems. Relatively large dispersion of these fibers is
compensated by means of dispersion compensating fibers.
• Large local dispersion helps to minimize four wave mixing
penalty in WDM systems.
Modulation Formats
• Traditionally non-return-to-zero (NRZ) format is used in
optical communication systems.
• Recently, quasi-linear return-to-zero (RZ), solitons, carriersuppressed RZ (CS-RZ) and differential phase shift keying
(DPSK) have drawn considerable attention.
• Soliton is a pulse that propagates without change in shape.
When the fiber dispersion is balanced by nonlinearity,
solitons are formed. Solton is a special case of RZ format.
• NRZ requires smaller signal bandwidth as compared to RZ
because on-off transitions occur fewer times.
Contact Info
• Instructor: Dr. S. Kumar
• E-mail: [email protected]
• Office hours: Monday 2:30 to 5:00.
Tuesday 4:00 to 5:00
• Office: CRL #204
• Web page of the course:
www.ece.mcmaster.ca/faculty/~kumars/Lightwave_course.
htm