Photonic Communications: Intro To Course & To Photonics

TELCOM 2222
Photonic Communications
Intro to Course
& to Photonics
Dr. Richard A. Thompson

Telecommunications Program
University of Pittsburgh
Outline for this set of slides
• Introduction to Photonics
• Describe this course
• Intro to “Sub-course” on Optical Transport
Grand claim
Photonics technology is changing

telecommunications in the same
ways that electronics technology
has been changing computing:
by improving throughput, cost,
availability, and (thereby) human
capability by orders of magnitude.
Steel Bricks
• Technological history of building a wall
– Bricks from dried clay – “adobe”
• >5 feet tall  weight crumbles bricks at the bottom
– Mix in straw while the clay is still wet
– “cinder block” – porous & hollow areas
• Steel - Should make us re-think the architecture
– Reinforced concrete (“rebars” = steel straw)
– Make a wall from steel bricks? - No
– Build steel skeleton &
attach suspended wall segments
• Photonics:Telecom :: Steel:walls
– Photonics has scaled-up data rates,
– Just beginning to take full advantage
Course purposes
• To understand:
– Data (digital) transport over fiber
• Optical fiber
• Opto-electronic transmitters & receivers
• Systems (link budget calculations)
– Photonic switching - research/future
• Devices, paradigms, architectures
• Provide overview of:
– Physics, devices, electronics
– Transport systems
Summer schedule
3:11 per week
Course structure 2 - 5:21 with
10-min break
Hour: 0 1 2 3
Week: 1
Sub-course on
Sub-course
Fiber-Optic
on
Transport
Photonic
Switching
N Comprehensive Final Exam

Course “feel”
• Physics, electronics/devices, transport

systems, architecture - as a f(t)
architecture
transport systems
physics electronics/devices
depth week
Self-contained; not…
Depth
Phys Elect Sys Arch

1. Superficial X
2. Conversational X*
3. Professional/Collegial X X X
4. Theory & derivations  X 
5. Full understanding Phys EE Telecom
A smart person knows a lot, but
also knows enough to be aware
of what he doesn’t know.
Course pre/co-requisites
• “EC-1” (T2200) - necessary
– Ohm’s Law, transients (RC), bandwidth, PN
diodes, load lines, decibels
– Can remediate: read “Pre-Reqs” under Syllabus
• EC-2 (T2210) - slight advantage
– Characteristics of transmission lines
– But, will use time domain and direct detection
• Telephone Switching (T2225) - will review
• Physics (even HS) - slight advantage: lenses
Lecture slides
• Loaded onto CourseWeb (BlackBoard)
– Suggest you print out on paper before class
– Bring to class for note-taking
• Read using “slide show”
– I use a lot of “animation”
• Naming convention
– 1st letter: maintain alphabetical order
– 2nd letter: ‘f’ or ‘s’ to identify sub-course
– Rest: abbreviated description
• Comments from prev classes on hidden slides 
Course procedures
• Weekly HW assignments in texts
– Relevant reading from texts after class
– Lots of homework, due the following week 30%
• Exceptions in advance – see the grader
• Course assignments 30%
– Lab experiment & 2 short papers
– Project - calculate & plot {link length v bit rate} ×2
• Comprehensive final exam 40%
• Numerical grade = weighted sum {hw, p/p, fx}
– Letter grade by identifying clusters of numeric grades
The Professor
• Dr. Richard A. Thompson
– Full Professor & Chair-emeritus
– Primary research area
= photonic switching
• Fall 2004: sabbatical in Physics Dept
• Also VoIP, packet stats, & auto traffic
Which is the Prof &
– Office – 717A SIS which is the student?
• Open hrs tba (or appt via rthompso@pitt.edu)
– See me to clarify lectures & concepts I will discuss
• Grader, open hrs tba in 717 some research
results in class
– See grader to argue about HW grades
Left Brain Right Brain
Logical Intuitive
Sequential Random
My Job? Objective Subjective
Rational Holistic
Analytical Synthesizing
• To teach you information Looks at parts Looks at wholes
– that will be useful for your career in Telecom

• But, it’s more than this…
– Left-brained & Right-brained thinking
• Two categories in each type
• Most of us – excellent • The “Anti-us”

• Most of us – important • Intuition can be “shaped”
• Other 2 are bad
– Good at details
• What most of us lack & need
– But insufficient • Creativity
– Tends to be “superficial • Integration – how things fit
(steel bricks) • See the system, the big picture
Course structure
Hour: 0 1 2 3
Week: 1
Most material from Sub-course on
Palais’ book, but the Sub-course
Fiber-Optic
organization/outline on
comes from Chapter Transport
Photonic
12 of the PLCS book.
Switching
++ material from
other parts of PLCS
& other sources

Transport subcourse
• Introduction, Rays & Waves

• Transport, Fiber, Impairments
• Sources, Detectors, Modulation
• Couplers & Connectors
• Noise & Signal-to-noise ratio
• Systems (link power budget)
• Fiber nonlinearities & dense WDM
Palais’ Book
• *Optical Fiber Communications,
– by Joseph C. Palais
– 5th ed, or map reading & exercises
• Not a “rigorous” text for EE/Physics majors
– But, it’s thorough enough & very “readable”
– Gives us “enough,” especially as 60% of a course
• Not well organized  We will skip around
• Not a perfect match for us (even for its 60%)
– I will augment (especially for WDM)
– Skip any material not mentioned on a slide
– Skim some pages  Code on slides:
• “Discuss convex lenses – other types (esp, GRIN) in Palais”
• “Focal length, f = f(R1, R2, n) – eqns in Palais”
* On reserve in SIS library

Other materials for the
Fiber Transport sub-course
• *PLCS, by 4 Pitt telecom professors
– Ch 12 & 15.4 (lecture order for transport sub-course)
– Also parts of Chapters 9, 10, Appendix, et al
– Buy this book if you will take 2210 in the Fall
• *Optical Telecommunications, by Kaminow & Li
• **Elements of Photonics, by Iizuka
• **Fundamentals of Photonics, by Saleh & Teich
* On reserve in SIS library

** Borrow my personal copy
Course structure
Hour: 0 1 2 3
Week: 1
Sub-course on
Sub-course
Fiber-Optic
on
Transport
Photonic
Switching

Fiber - Introduction
• History
• Photonic communications system
– Block diagram
– Motivation & optical advantage
– Terminology
• Decibels
• Applications – on your own
History
• Optical fiber - Corning Glass - 70s
– Wavelengths for optimal transparency
– Single-mode fiber  Overhaul infrastructure (overbuilt)
• Optoelectronics - LEDs & photodetectors
– At these same wavelengths  “NE Corridor”
– Semiconductor Diode Laser - Bell Labs
• Switching - reviving research topic
• Summary
– Relatively modern
• We’re still doing too much in electronics
– Rapid deployment
Photonic Transport System
Navigating Palais’ Book
transmitted modu- optical input

info (dig) lator source coupler
10 6
# = chapter
12 8-9 channel
in Palais
1-5
7
received signal optical output
info processor detector coupler
11 Noise
Motivation
• Broad bandwidth
• Great distance Mutually
• Low noise constrained
• Security
Terminology
• Optics
– Physics of Light
• Fiber-optics or Lightwave technology
– Optical fiber
– Opto-electronics (lasers & LEDs)
• Photonics & electro-optics 
DeciBels
• Power ratio
– In dB = 10 log10 (P1/P0)
• Absolute, with respect to 1 mW
– P in dBm = 10 log10 (P1/10-3)
Optical Power
Decibel Table
Ratio dB Ratio dB
2 3 64 18
4 6 100 20
8 9 128 21
10 +10
2 +3 160 22
10 10 200 23
16 12 256 24
20 13 512 27
32 15 1000 30
1024 30 ?
40 16
Conversion Charts
Exercise with decibels
• Fiber link - 56 km long
– Three segments with 1-dB connectors
– 2-dB coupling loss on each end
– Fiber attenuation = .25 dB/km
• Total loss = .25×56 + 6 = 20 dB
• Transmit laser power = 1 mW = 0 dBm
– Power at receiver = -20 dBm = 10W
– 1% (one photon out of 100)
Example problems
• 1.7
– 44.7 Mbps / 64K bps = 698.44 channels
– Actually only 672 because of “overhead”
• 1.20
– 10B “lines” x 4 KHz = 40 THz
– Over one fiber? – not in the “optical window”
• 1.21
– 10B “lines” x 64 Kbps = 640 Tbps
Reading Assignment
• PLCS Chapter 12
– Read Intro, 12.2.5
• Other parts of PLCS
– Read Section 9.2.3-4
• Palais Chapter 1
– Read Section 1
– Skim/Read Section 2 
– Postpone 1.3 on Ray/wave nature of light
– Skim Sections 4-6
Comm’s System
Palais 1.2
• Skim Subsections 1.2.1-8
– Good for overall picture
– Will cover many topics later in greater detail
• Subsection 1.2.9
– Know the terminology (p 12-13a)
– Skim the “review” (pp 13b-14a, 15b-17a)
– ADH & SDH (sonet) material (p 14b-15a)
• Important & practical - covered in excruciating detail in 2210
• Take that course, or attend specific lectures
• Read Subsection 1.2.10 on Decibels
Problem Assignment A
• Palais Chapter 1
– Problems 3, 4, 23, 26, 27, 28
Course Assignment
• Review Technical (JLT) paper (3 pp max)
– Summary, critique, application
• Write paper about application (5 pp max)
– Describe app, discuss market & technology
– Summary or original work
• Project assigned later
• Both papers due: week before the final
– Warning: don’t postpone too long (project)

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TELCOM 2222

Dr. Richard A. Thompson

Photonics technology is changing

N Comprehensive Final Exam

• Physics, electronics/devices, transport

Phys Elect Sys Arch

– that will be useful for your career in Telecom

• Most of us – excellent • The “Anti-us”

N Comprehensive Final Exam

• Introduction, Rays & Waves

* On reserve in SIS library

* On reserve in SIS library

N Comprehensive Final Exam

transmitted modu- optical input

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