Description:

This course is designed for advanced undergraduate and graduate students having some previous exposure electromagnetism and/or physical optics, and wishing to become knowledgeable in the basic principles that govern light-matter interaction, including how the presence of matter enables multiphoton effects. Examples are two photons merging with each other to create a new one at twice the energy, or one photon splitting into two photons whose total energy is the same as the original photon. In a classical picture, these effects are due to a nonlinear response (mainly of the second order and of the third order) to the optical electric field.

The course is essentially an introduction to the basic building blocks of photonics, specifically the area collectively known as nonlinear optics.

After this course you will be able to understand and analyze the interaction of laser beams with transparent materials, and all its consequences in terms of multiphoton effects of different orders, or both established and new areas of technology. If faced with a new phenomenon or effect, you should be able to analyze it with the tools developed in this course, and understand its origins and implications, with an easier entry point to the literature.

Detailed topics are below, but maybe the best description of the intention behind this course is one comment from a previous student, cited verbatim:

As an aside, I've been wanting to mention for some time that, as I've had time to reflect, I consider your NLO course to be one of the more valuable physics courses I took at Lehigh. It provides a beautiful basic introduction to the constraints that symmetry places on tensors, it hints at a lot of topics that are useful in applied optics, and NLO processes themselves are so ubiquitous that it's basically mandatory for any experimentalist working with optics to understand them at least schematically. There have been numerous moments where things I've learned there helped me solve problems in my current work. I'm glad I took it.

Topics:

A very quick, practical introduction to light waves, laser beams, and how do describe them.

A basic treatment of photonics and nonlinear optics that will include the origin, symmetry, and definitions of the nonlinear optical susceptibilities. Experiments and applications that will be discussed are: Measurement of nonlinear optical properties and the pitfalls of inconsistent definitions found in the literature; Molecular hyperpolarizabilities and macroscopic nonlinearities; Second and third order effects; Wave interaction in anisotropic crystals; Frequency conversion; Parametric Down Conversion; Optical Kerr effect; Optical switching; Four-wave mixing.

Several current topics related to the material in the course may be discussed and presented depending on class interest. In fundamental research, lasers and nonlinear optical techniques can deliver information on the symmetry of materials and interfaces, on the excited states of matter, and on the dynamics of a multitude of material excitations. In technology, nonlinear optical effects are used to change the color of laser beams, to create short laser pulses, and are critical for the understanding and optimization of information-transmission in optical fibers and elsewhere.