Teaching

Courses

PHOTONICS (9 credits)
Master Degree in Electronic Engineering - 1st year
1st semester, academic year 2015/16

Prof. Claudio Calì



 Lesson Plan



The course provides the basic knowledge and the tools essential to the study of components, devices and systems that works at optical frequencies. The course aims to prepare the student for insertion into professional activities that require a good basic knowledge of photonic devices. The knowledge of “Electromagnetic Fields” and “Electronic Devices” is required. The examination consists of an oral exam.

Main Topics
Nature of light
Electromagnetic spectrum. Speed of light and refractive index. Dispersion. Photon energy. Temporal and spatial coherence.
Geometrical optics and applications
Refraction and reflection. Total internal reflection. Optical guides. Reflective prism. Refracting prism. Lenses. Construction of the image. Classification of the lenses. Spherical mirrors. Thick lenses. Magnification. Form of Newton's equation of the lens. Relative aperture. Aberrations and their possible corrections. Human eye. Photographic camera. Projection systems. Magnifying glass. Microscope. Telescope, spatial filter and beam expander.
Beam matrix representation and application to optical resonators
Transmission matrices of optical components. Matrix of a set of optical components. Optical resonator and its matrix. Stability condition of the resonator. Stability of a two-mirrors resonator. Initial conditions and stability of the resonator. Ray propagation in media with continuous distribution of lenses.
Gaussian beams
Light beam. Equation of the Gaussian beam. Solution of the equation of the Gaussian beam. Characteristics of the fundamental mode of the Gaussian beam. Transformation of Gaussian beams. Maximum focus of a beam. Stability of the optical resonator in the presence of Gaussian beams. Collins Card. Higher-order modes of a Gaussian beam. Using the volume within a resonator.
Wave optics in dielectrics
Classical model of wave propagation in dielectrics. Brewster angle. Optically isotropic and anisotropic media. Induced anisotropy. Ellipsoid index. Polarizers. Retardant foil. Electro-optical modulator. Angle between the vectors E and D in a uniaxial crystal. Birefringence. Linear and non-linear media. Centrosymmetric and non-centrosymmetric crystals. Second harmonic generation.
Fabry-Perot resonator
Comparison of optical and microwave resonators. The Fabry-Perot resonator. Principle of operation of the Fabry-Perot resonator. Transmission. Free spectral range. Bandwidth. Finesse. Finesse of multi Fabry-Perot placed in series. Finesse as a function of the free spectral range. Resolving power. Quality factor and relationship with finesse. Physical meaning of finesse. Characteristics of the beam to be placed in a Fabry-Perot cavity. Flatness of the mirrors in relation to the finesse. Fabry-Perot with losses in the medium. Scanning Fabry-Perot. Design criteria of a Scanning Fabry-Perot able to discriminate the emission lines of a laser. Fabry-Perot with fixed mirrors and variable angle. Other applications of Fabry-Perot. Frequencies of resonance in the presence of Gaussian beams.
Dielectric Mirrors
Principle of operation of dielectric mirrors. Drawbacks of dielectric mirrors
Diffraction gratings
Principle of operation of the diffraction grating. Maximum order of diffraction. Littrow condition. Angular distribution of the diffracted field. Band of the grating. Dispersion and chromatic resolution of the grating. Design criteria of a grating suitable to select the lines of a laser. Using the diffraction grating in the optical spectrum analyzers. Types of grating. Diffraction grating generated by surface acoustic wave.
Amplification and generation of the coherent optical radiation
Spontaneous emission. Line broadening. Homogeneous line broadening. Inhomogeneous line broadening. Induced transitions. Absorption or amplification of the optical radiation. Dielectric susceptibility. Imaginary part of the dielectric susceptibility in the presence of absorption or amplification. Classical model for the determination of the relationship between the real part and imaginary part of the dielectric susceptibility. Dielectric susceptibility as a function of the frequency. Propagation factor also in the presence of passive media. Dependence of the attenuation constant on the intensity of the incident radiation. Population inversion. Three-levels system. Four-levels system. Conditions of oscillation. Mode of oscillation in systems where the homogeneous broadening is prevailing. Mode of oscillation in systems where the inhomogeneous broadening is prevailing. Stabilization of the oscillation frequency. Spatial inhomogeneities in media where the homogeneous broadening is prevailing. Population inversion in the presence of oscillations. Fluorescence critical power, emitted power and output power. Optimal transmission of the output mirror.
Optical Pulses
Phase locking of the oscillating modes. Giant pulses (Q-switching). Comparison between phase locking operation of oscillating modes and Q-switching. Control of the cavity in phase locking operation and Q-switching. Technique of pulse compression. Amplification technique of pulses of high peak power.
Description of some lasers
Considerations on laser efficiency. Pumping systems. Laser classification based on the active medium. Unit of measurement of the energy levels and frequency. Ruby laser, neodymium, erbium, ytterbium, titanium: sapphire, helium-neon, argon ions, metal vapor (helium-cadmium and copper), dye, excimers, carbon dioxide, free electrons, chemical and semiconductor diodes.
Detection of the light radiation and techniques for pulse measurement
Classification of optical detectors. Noise in optical detectors. Photomultiplier. Photoconductive detectors, junction, avalanche, "photon-drag" effect, bolometric, pyroelectric and thermopile. Techniques for pulse measurement.

Course books:
- Teaching Material provided by the lecturer
In addition to the material provided by the teacher, the following text books are recommended:
- A.Yariv, "Optical electronics", Holt, Rinehart and Winston.
- J. T. Verdeyen, "Laser Electronics" Prentice-Hall, Inc.
- D. Meschede "Optics, Light and Lasers: The Practical Approach to Modern Aspects of Photonics and Laser Physics", Wiley
- Jia-Ming Liu "Photonic Devices", Cambridge University Press
- M. Young, "Optics and Lasers", Springer-Verlag
- W.J. Smith, "Modern Optical Engineering", McGraw-Hill
- B. Rossi, "Optics", Addison-Wesley
- S. Ramo, J.R. Whinnery, T.V. Duzer, "Fields and Waves in Communication Electronics" Wiley
- N. Menn, "Practical Optics", Elsevier
- F.L. Pedrotti, L.S. Pedrotti, "Introduction to optics", Prentice-Hall
- A. Nussbaum, R.A. Phillips, "Contemporary Optics for Scientists and Engineers", Prentice Hall (1976).
- E.P. Ippen, C.V. Shank, contribution to "Ultrashort Light Pulses" (S.L.Shepiro, ed.), Springer-Verlag
- M. Csele, "Fundamentals of Light Sources and Lasers" - Wiley
- P. Das, "Lasers and Optical Engineering", Springer-Verlag

Assessment:
Oral examination.



 Teaching Material



 Class organisation (Scheda di trasparenza)



 Exam registration



Communications to the students
Course start date: Wednesday September 30th, 2015, 8 a.m.



University of Palermo  -  Department of Energy, Information engineering and Mathematical models (DEIM)
viale delle Scienze, Building 9  -  I-90128  Palermo (Italy)