This subject focuses in studying the optical fiber communications components and systems. Students will learn how the light is propagated through the optical fiber and to design an optical-communication link considering the limitations that affect the transmission environment. Moreover, students will also learn to choose the fitting components taking into account their functional characteristics within an optical communication network. Finally, the principal kinds of communication networks will be studied.
Titular Professors
Professors
Physics, electromagnetism and electromagnetic propagation basis.
The course aims to help students understand the physical and technological principles that underpin optical communications, in particular the propagation of light in optical fibres and the phenomena that condition the transmission of information. Likewise, it is intended that students know and analyze the operation of the main components of an optical communications system, including fibers, optical sources and detectors, modulation and amplification techniques. In the same way, the aim is for the student to develop the ability to model and evaluate the performance of optical systems according to key parameters such as attenuation, dispersion, noise or error rate, and to apply this knowledge to the design and dimensioning of real fiber optic communication systems, consistent with current access and transport networks and with the professional profile of telecommunications engineers.
1. Introduction to Optical Communications
1.1. Evolution of optical communications technology.
1.2. Evolution of fiber-optic telecommunication systems from point-to-point systems to point-to-multipoint optical networks.
1.3. Optical communication system – Basic components.
2. Optical Fibers – Propagation
2.1. Introduction and basic concepts of propagation in optical fibers.
2.2. Analysis of propagation in optical fibers using Geometrical Optics.
2.3. Analysis of propagation in optical fibers using Electromagnetic Theory.
2.4. Types of fibers and their properties: multimode fibers and single-mode fibers.
2.5. Fiber-optic cables: types and characteristics.
2.6. Optical fiber connections: mechanical splicing, fusion splicing.
3. Optical Fibers – Transmission Limiting Phenomena
3.1. Attenuation in optical fibers. Transmission windows.
3.2. Dispersion in optical fibers: modal, chromatic, and polarization mode dispersion.
3.3. Dispersion-compensating fibers.
3.4. Fiber nonlinearities.
3.5. Other phenomena: Rayleigh scattering, Brillouin scattering, and Raman scattering.
4. Optical Sources
4.1. LED diode: basic concepts, types, and characteristic parameters.
4.2. Laser diode: basic concepts, types, and characteristic parameters.
4.3. Tunable lasers.
4.4. Lasers in telecommunication systems.
5. Optical Signal Modulation
5.1. Direct intensity modulation.
5.2. Analog and digital modulation.
5.3. External modulation of the optical carrier.
6. Optical Receivers
6.1. Opto-electronic conversion.
6.2. Types of photodetectors: PIN photodiodes and APD photodiodes.
6.3. Quantum efficiency and responsivity.
6.4. Shot noise, avalanche noise, and thermal noise.
6.5. Direct detection receiver.
6.6. Reception parameters: receiver sensitivity, BER, SNR, eye diagram.
7. Optical Amplifiers
7.1. Semiconductor optical amplifier (SOA).
7.2. Erbium-doped fiber amplifier (EDFA).
7.3. Raman fiber amplifier.
7.4. Noise in optical amplifiers. ASE noise.
7.5. Receiver with optical preamplifier.
8. Modeling and Design of Optical Communication Systems
8.1. Block diagram of the IM-DD system.
8.2. Modeling of optical communication systems.
8.3. System performance as a function of different parameters: fiber, bit rate, modulation format, receiver type, amplification.
8.4. Passive optical interconnection elements: polarizers, fiber couplers, attenuators, isolators, circulators, optical filters.
8.5. Wavelength-selective passive optical elements: AWGs.
8.6. Power calculations. Loss budget. Receiver sensitivity.
8.7. Design and dimensioning of a practical optical communication system.
9. Topics in Optical Communication System Implementation
9.1. Optical access networks and FTTH networks based on the GPON standard.
9.2. ITU-T G.984.x GPON standard.
9.3. Practical implementation of FTTH networks: OLTs, ONTs, ODN.
9.4. WDM, DWDM, and uDWDM systems.
9.5. Coherent systems in the access network.
9.6. Optical transport networks. Submarine fiber-optic cables.
In the EEES context, assessment should be based on determining whether a set of skills has been acquired and not just some knowledge. Therefore, and according to the Bologna Process, the evaluation of the course goes from focusing on the analysis of final results to evaluating competencies and carrying out it continuously. This means that instead of assessment being based only on the result of a final test or a set of partial tests, continuous and formative assessment is carried out. This will allow the state of progress of each student to be measured at all times throughout the training process, which allows for earlier detection of learning problems. This also means that the student has a minimum attendance of 50% of the subject, otherwise, it is preferable that they do not enrol in this subject.
Thus, the evaluation of this subject takes as its starting point the results obtained from the continuous assessment, followed by the object of evaluation, and the tests that, all of this, will measure the degree of acquisition and development of the competencies.
Finally, products or evidence of the training process are considered: participation in class, resolution of exercises, group work, the student's attitude in class, the positive attitude towards the subject and the proactive attitude to professional development. for quality and continuous improvement.
Each session will be made up of the following construction elements:
a) A master class, in which the teacher will present each of the contents of the topic, addressing them analytically, with the corresponding mathematical tools, promoting the critical and participatory spirit of the students, motivating interactivity with the student and their participation in the construction of knowledge based on questions, examples, questioning, criticism and constant feedback.
b) Application of the contents in industry and in the different development sectors, according to theme.
c) Design and implementation exercises.
d) Summary and Conclusions.
The student must contribute to the construction of knowledge with a minimum dedication of 7.7 hours/week (100 hours / 13 weeks), for a better use of the course. In addition to their participation in the (face-to-face) master classes, the student at home should:
- Prepare each session in advance, studying the contents of the presentations (available on the website eStudy - Virtual Campus La Salle BCN).
- Consolidate the knowledge gained with a brief review after the session
- Solve the exercises and practices of continuous evaluation
- Develop pre-reports and final reports of laboratory practices
Associative work in the form of study groups is strongly recommended.
Two control points have been planned:
- Partial Exam (Midterm)
- Final exam
One laboratory practice has been planned:
- Laboratory practice 1: Operations and measurements in fibers and passive optical devices, Optical Sources and Optical Receivers
Continuous evaluation practices have been planned, and they are:
- Development of exercises in class
- 2 exercise lists
- Design and sizing of a practical optical communications system.
- Understanding of the fundamentals of propagation in fiber optics, assessing the student's ability to explain and analyze the mechanisms of propagation, as well as the phenomena that limit transmission, such as attenuation, dispersion and nonlinearities.
- Knowledge and characterisation of optical components, assessing competence to identify and describe the operation, performance and limitations of optical fibres, sources, detectors, amplifiers and passive interconnection elements.
- Analysis and evaluation of the performance of optical systems, considering the student's ability to interpret key parameters such as receiver sensitivity, BER, SNR, eye diagrams and power balance.
- Application of modelling and sizing techniques, assessing the correct use of optical communications system models and coherence in the design of real optical links and networks.
- Ability to integrate knowledge into practical scenarios, assessing the way in which the student relates theoretical foundations to current applications such as FTTH networks, GPON systems, WDM and optical transport networks.
Agrawal, G.P. "Fiber-Optic Communication Systems". Wiley Interscience (2010)
Senior, J.M. "Optical fiber communications: principles and practice". 3 ed. New York: Prentice Hall, 2008.
Capmany, José "Fundamentos de comunicaciones ópticas". Síntesis. 2001. 8477385998
Keiser, Gerd; "Optical Fiber Communications", McGraw-Hill (2010)
Not required.