• Explain the function of the main components of a laser system.
• Explain the physics of laser amplification and laser oscillation and the various pumping schemes.
• Discuss gain saturation, threshold condition, mode locking, and other methods to control the laser output.   
• Discuss how laser light differs from (filtered) spontaneous emission light sources.
• Explain the noise in laser light.
• Discuss the physics of a semiconductor diode laser.
• Explain the origin of the nonlinear polarization and how this leads to nonlinear optical processes.
• Explain the central concept of phase matching.
• Describe various examples of second- and third-order nonlinear processes.
• Distinguish between parametric and nonparametric nonlinear processes.
• Discuss the Manley-Rowe relations and provide an appropriate interpretation of these equations.

This course aims to provide a basic understanding of lasers and nonlinear optics.

In the first part of the course, we focus on the fundamental concepts of lasers. We use the classical Lorentz oscillator to revisit the origin of absorption, emission, of the refractive index and discuss spectral line broadening and its consequences for laser oscillation. We describe how to use rate equations for occupancy of atomic levels and photons to describe optical gain, the laser threshold, gain saturation, spectral and spatial hole burning, and how to achieve mode selection. To explain the generation of light pulses with ultrashort duration (e.g., in the femtosecond range), we describe mode-locking of lasers. Finally, we discuss the difference between light generated by stimulated versus spontaneous emission.

In the second part of the course, we focus on nonlinear optical processes induced by intense laser light. We extend the classical Lorentz oscillator model to illustrate the origin of the nonlinear optical response of materials and introduce the nonlinear optical polarization. We introduce the coupled wave equations for second-order nonlinear processes to discuss the central concepts of phase matching and quasi-phase matching and discuss examples like second-harmonic and sum-frequency generation. Furthermore, we show how these parametric nonlinear optical processes can be distinguished from incoherent processes emitting at the same wavelength. We discuss the Manley-Rowe relations that can be derived from the coupled wave equation and the quantum picture of such nonlinear processes. As examples of third-order nonlinear processes, we discuss the Kerr effect and stimulated Brillouin scattering and how the latter can be applied to process light.