II BCA Questions

Optical Communications OBJECTIVES The student will be introduced to the functionality of each of the components that comprise a fiber-optic communication system • the properties of optical fiber that affect the performance of a communication link and types of fiber materials with their properties and the losses occur in fibers. • the principles of single and multi-mode optical fibers and their characteristics • working of semiconductor lasers, and differentiate between direct modulation and external electro-optic modulation. • Analyze the operation of LEDs, laser diodes, and PIN photo detectors (spectral properties, bandwidth, and circuits) and apply in optical systems. • Analyze and design optical communication and fiber optic sensor systems. • the models of analog and digital receivers. CO1: Should be able to review the propagation of light in various fibers, operation of optical transmitter and receiver, Concepts of Fiber optic networks. CO2: Analyze the channel impairments like losses and dispersion. CO3: Illustrate the losses associated with fiber optic components. CO4: Evaluate the SNR, quantum efficiency for various sources and detectors CO5: Design a simple fiber optic link. UNIT I Overview of optical fiber communication - Historical development, The general system, advantages of optical fiber communications. Optical fiber wave guides- Introduction, Ray theory transmission, Total Internal Reflection, Acceptance angle, Numerical Aperture, Skew rays, Cylindrical fibers- Modes, V-number, Mode coupling, Step Index fibers, Graded Index fibers, Single mode fibers- Cut off wavelength, Mode Field Diameter, Effective Refractive Index, Related problems. UNIT II Fiber materials:- Glass, Halide, Active glass, Chalgenide glass, Plastic optical fibers. Signal distortion in optical fibers-Attenuation, Absorption, Scattering and Bending losses, Core and Cladding losses, Information capacity determination, Group delay, Types of Dispersion:- Material dispersion, Wave-guide dispersion, Polarization-Mode dispersion, Intermodal dispersion, Pulse broadening in Graded index fiber, Related problems. UNIT III . Optical fiber Connectors-Connector types, Single mode fiber connectors, Connector return loss, Fiber Splicing- Splicing techniques, Splicing single mode fibers, Fiber alignment and joint loss- Multimode fiber joints, single mode fiber joints. UNIT IV Optical sources- LEDs, Structures, Materials, Quantum efficiency, Power, Modulation, Power bandwidth product. Injection Laser Diodes- Modes, Threshold conditions, External quantum efficiency, Laser diode rate equations, Resonant frequencies, Reliability of LED&ILD, Optical detectors- Physical principles of PIN and APD, Detector response time, Temperature effect on Avalanche gain, Comparison of Photo detectors, Related problems. UNIT V Source to fiber power launching - Output patterns, Power coupling, Power launching, Equilibrium Numerical Aperture, Laser diode to fiber coupling, Optical receiver operation- Fundamental receiver operation, Digital signal transmission, error sources, Receiver configuration, Digital receiver performance, Probability of Error, Quantum limit, Analog receivers. UNIT VI Optical system design - Point-to- point links- Component choice and considerations, Link power budget, Rise time budget with examples, Line coding in Optical links, WDM, Necessity, Principles, Measurement of Attenuation and Dispersion, Eye pattern. TEXT BOOKS : 1. Optical Fiber Communications – Gerd Keiser, Mc Graw-Hill International edition, 3rd Edition, 2000. 2. Optical Fiber Communications – John M. Senior, PHI, 2nd Edition, 2002. RERFERENCES : 1. Fiber Optic Communications – D.K. Mynbaev , S.C. Gupta and Lowell L. Scheiner, Pearson Education,2005. 2. Text Book on Optical Fiber Communication and its Applications – S.C.Gupta, PHI, 2005. 3. Fiber Optic Communication Systems – Govind P. Agarwal , John Wiley, 3rd Ediition, 2004. 4. Fiber Optic Communications – Joseph C.Palais, 4th Edition, Pearson Education, 2004. OUTCOMES After going through this course the student will be able to • Choose necessary components required in modern optical communications systems . • Design and build optical fiber experiments in the laboratory, and learn how to calculate electromagnetic modes in waveguides, the amount of light lost going through an optical system, dispersion of optical fibers. • Use different types of photo detectors and optical test equipment to analyze optical fiber and light wave systems. • Choose the optical cables for better communication with minimum losses Design, build, and demonstrate optical fiber experiments in the laboratory.