Introduction to Photonics

Course overview

The aim of this course is to foster and promote knowledge on photonics and skills/competencies in the design and performance analysis of communication systems based on photonics. The course will first provide an introduction to photonics and optical communication followed by the analysis of different communication technologies and their practical applications.

What you will learn

• Differentiate, categorize, and compare different photonics and optical communication technologies.
• Identify the characteristics of optical devices and specify their functionalities.
• Propose communication solutions based on photonics technologies.
• Evaluate and compare the performance of practical optical communication solutions.

Meet your instructor

Course content

Session 1: Introduction to Photonics and Optical Communication Overview of photonics and the applications in different areas such as information technology and communications, healthcare, life sciences, optical sensing, lighting, energy and manufacturing. The evolution of light-wave systems will be discussed before the basics of optical communications systems will be introduced. Session 2: Nature of light and the production of EM radiation for photonics applications i) Wave Nature of Light Light waves in homogeneous media. Refractive index. Group velocity and group index. Magnetic field, Irradiance and Poynting vector. Snell’s law and total internal reflection. Fresnel’s equations. Multiple interference and optical resonators. Temporal and spatial coherence. Diffraction principles. Polarisation. Methods to define the characteristics of light mathematically (Stokes parameters, Jones vectors & matrices) and how to determine these characteristics. ii) Optical sources and transmitters Principles of light emission and amplification in semiconductors, light emitting diodes, semiconductor lasers (edge emitting lasers and VCSELs). Semiconductor science and light emitting diodes (LED). Semiconductor concepts and energy bands. Direct and indirect band-gap semiconductors: E-k diagrams. Pn junction principles and band diagram. LED and materials. Heterojunction high intensity LED and characteristics. Steady state semiconductor rate equation. LED for Optical fibre communications. Single frequency solid state lasers. Quantum well devices. Optical amplifiers. Session 3: Optical waveguides The propagation of light in optical waveguides.Dielectric waveguides and optical fibres. Symmetric planar dielectric slab waveguide. Modal and waveguide dispersion in the planar waveguide. Step index fibre. Numerical aperture. Dispersion in single mode fibres. Bit-rate, dispersion and optical non-linearities, Electrical and optical bandwidth. Graded index optical fibre. Attenuation in optical fibres-light absorption and scattering. Fibre manufacture. Session 4: Optical detectors and receivers The detection of light and the demodulation of light including photoconductors, photodiodes and receiver systems. Principle of the p-n junction photodiode. External photocurrent. Absorption coefficient and photodiode materials. Quantum efficiency and responsivity. The pin, avalanche and heterojunction photodiodes. Phototransistors. Photoconductive detectors and photoconductive gain. Noise in photodetectors. Generic system issues: sources of noise and signal-to-noise ratio, limitations on temporal response and effective bandwidth. Sesison 5-6: Imparting information onto EM radiation & communication techniques i) Basic modulation principles Polarisation and modulation of light. Light propagation in anisotropic media: birefringence. Birefringent optical devices. Optical activity and circular birefringence. Electro-optic effects. Integrated optical modulators. Acousto-optic modulator. Magneto-optic effects. Non-linear optics and second harmonic generation. ii) Modulation Acousto-optic and electro-optic techniques, LED switching, analogue and digital techniques using lasers, AM, FM, phase modulation techniques Session 7-8: Applications for light-wave systems A summary of important concepts of digital communication including base band and broadband digital transmission, bit error rate, bit group error rate and time division multiplexing (TDM) and wavelength division multiplexing (WDM). Trends and new directions in photonic applications i) Noise and detection Noise arising from the properties of fibres, transmitters, receivers and amplifiers as well as the determination of the bit error rate. ii) Optical MUX and DEMUX The operating principle of multiplexers and demultiplexers. Different optical devices, essential to optical networks, optical amplifiers, polarisation control devices, optical isolators, optical filters and diffraction gratings, modulators and switches. iii) Optical systems design Design process for a point-to-point optical links.

Teaching methodology

Lectures, group discussion, independent learning.

Assessment

• Midterm exam (30%) Will include combination of numerical exercises and open-ended theoretical questions.
• Exercises (20%) Written assignements throughout the course.
• Final written exam (50%) Will include combination of numerical exercises and open-ended theoretical questions.