Transcript Opto Electronics (ET – 421) FALL
Opto Electronics ( ET – 421) FALL-213 Lecture# 01 Introduction “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:
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?