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Optical Communications I and II

Goals

The course deals with special aspects, requirements and potentials of optical as compared to conventional communication systems. Starting point are the key components: optical fibers, photodetectors and light sources. The respective principles of operation, limitations, the present status and examples are discussed. How these components together with further waveguide devices are combined to form communication systems is reviewed. An introduction is given to the topics of optical fiber amplifiers and to soliton propagation.

• Basic optical concepts
• Optical waveguides
• Properties of silica optical fibers
• Principles and properties of sources and detectors
• Further components for fiber optic systems
• Optical amplifiers and soliton transmission
• Optical fiber communication systems

Some knowledge is expected in the fields of theoretical electrical engineering, waveguide theory and electronic components.

as a part of the

Optical Communications

Goals

Survey on Optical Communications

Contents

I. Review of optical waveguide fundamentals

• total internal reflection at plane dielectric interfaces
• slab waveguides
• rays in step-index and graded-index "multi-mode" fibers
• modes in optical fibers
• single-mode fibers
• fabrication of fibers

II. Properties of silica optical fiber relevant in communications

• attenuation by scattering and absorption
• dispersion and pulse broadening
• polarization mode dispersion

III. Passive fiber optical components

• excitation of fibers, splice/connector loss
• fiber optical directional couplers
• isolators, circulators, phased arrays, grating components

IV. Review of photodiode and LED fundamentals

• pin-photodiodes: responsivity, response time, equivalent circuit
• avalanche photodiodes
• light emitting diodes: spectra, output power, modulation

V. Noise in photodetectors

• power spectral density of a train of randomly occuring events
• shot noise and thermal noise
• photodetector equivalent circuits with noise sources
• basic receiver considerations

VI. Laserdiodes

• basic laser physics
• Fabry-Perot laser diodes
• rate equations and LD characteristics
• special laserdiodes

VII. Optical fiber amplifiers

• Erbium in silica fibers: energy levels, transitions, cross sections, amplification
• noise in optical amplifiers: spontaneous emission, ASE, noise figure, periodic amplification
• modelling of optical amplifiers
• examples and applications

VIII. Nonlinearities in optical fibers

• basic nonlinear effects
• solitons for high bit rate transmission: dispersion vs. self phase modulation

IX. Optical fiber systems

Literature:

[1] J. Gowar: "Opical Communication Systems", Prentice Hall 1993

[2] I.P. Kaminov and L. Koch (ed.): "Optical Fiber Telecomminications", volume IIIA and IIIB, Academic Press, 1997

[3] A. Yariv: "Optical Electronics", Sauders College Publishing, 1997

[4] E.G. Neumann: "Single-Mode Fibers", Springer 1988

[5] H.G. Unger: "Optische Nachrichtentechnik", volume I and II, Hüthig 1992 (in German)

[6] G. Grau and W. Freude: "Optische Nachrichtentechnik", Springer 1991 (in German)

[7] J.M. Senior: "Optical Fiber communications", Prentice Hall, 1993

Lecture Material

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