Martin C. Nuss

Terahertz electromagnetic radiation from quantum wells

The observation of terahertz electromagnetic dipole radiation from quantum well structures has finally proven the existence of charge oscillations in semiconductors associated with wave packet dynamics. This article closely examines the physics behind the emission of terahertz electromagnetic radiation from excitonic charge oscillations in such quantum well structures, points out similarities and differences between the various generation schemes, and discusses the various relaxation mechanisms involved. Finally, we show how both amplitude and phase of charge oscillations and the corresponding terahertz emission can be manipulated using phase-locked optical pulses.

Dramatic Reduction of the Amplitude Noise of Colliding-Pulse-Modelocking Dye Lasers

The colliding pulse modelocking (CPM) dye laser has established itself as the work horse of femtosecond optics and spectroscopy owing to the ease of generating stable optical pulses of less than 100 fsec duration. The probably most important improvement of the CPM laser has been the addition of a four-prism sequence to adjust the intracavity group velocity dispersion [1]. Although the CPM laser has been object of extensive studies to understand the complex pulse forming mechanisms, the characterization of its amplitude noise has not received much attention. We show in this manuscript that the strong amplitude noise of the CPM laser at frequencies of several MHz can be significantly reduced by simply inserting a single frequency etalon in the cavity of the (argon-ion) pump laser.