Opto Electronics(ET – 421)FALL-213

Lecture# 01Introduction “optical

communication” Engr. Tasleem Kausar

Text Books

• Gerd Keiser, “Optical Fiber Communications”, McGraw–Hill, 3/e

• G. P. Agrawal, “Fiber-Optic Communication Systems” Wiley, 3/e

• Richard S. Quimby,“Photonics and Lasers An Introduction”

Grading Policy

• Assignments, Quizzes, Attendance, Computer Simulations(10%)

• Course Project(10%)• Mid Semester Exams(20%)• End Semester Exams(60%)

Miscellaneous

► Web Page: Course management system(CMS)

► Office Hours : Monday (1:00 PM - 3:30 PM) ►Contact: tasleem.kausar@uettaxila.edu.pk

Communication???

• Channel/medium i.e guided or un-guided• Signal get distortion

Why Optical Communications

• In eight century B.C Greeks use fire to communicate

• Electrical Systems , signals are supper imposed onto the carrier(Electromagnetic waves)

• Problem ???• Data rate• Distance

Electromagnetic Spectrum

Wavelength Bands of Interest

• 50 nm (UV) – 100 μ m (IR)• 400 nm – 700 nm (visible region)• 800 nm – 1600 nm (1.55μm) range

Choice of wavelength

Choice of wavelength

• First Window(820nm-880nm)• Second Window(1200nm-1320)• Third Window(1550nm-1610nm)

Optical Communications Benefits

• Extremely wide bandwidth: High carrier frequency ( a wavelength of 1552.5 nm corresponds to a center frequency of 193.1 THz)

• Small size & light weight• Immunity to Interference: Electromagnetic

interference (high voltage transmission lines, radar systems, power electronic systems, airborne systems, ...)

• Signal Security

Optical Communications Benefits

• Lack of EMI cross talk between channels• Ruggedness and Flexibility• Low Transmission loss (0.25 to 0.3 dB/km)• System Reliability and Ease of Maintenance: high

performance• active & passive photonic components such as

tunable lasers, very sensitive photo detectors, couplers, filters,

• Low Cost systems for data rates in excess of Gbps

Practice question 01

• How carrier frequency relate with data rate and transmission range/distance

Practice question 02

• Why there is a difference between uplink and down link frequency range?