Projects

Coherent light with tuneable wavelength is needed for various applications such as quantum-optical systems, bio-medical implementations and gas analysis. Lasers are known for their excellent coherence properties. Their beams can be collimated perfectly over large distances, show very narrow linewidths and their emitted frequencies are well defined. Unfortunately, the last point is connected with a disadvantage: In general, a laser is not widely tuneable, wherefore a lot of research is done in the development of monochromatic highly tuneable light sources. It is possible to realize light sources which are tuneable over many hundreds of nanometres by frequency conversion in optical nonlinear materials. This has been successfully demonstrated in huge mirror resonators. A better way to realize such optical nonlinear processes is the usage of whispering gallery resonators (WGRs). WGRs show very high Q-factors and power-enhancement. Furthermore, it is possible to set up miniaturized resonators in µm or mm range. The aim of this project is to make such miniaturized continuous wave (cw) light sources, based on frequency conversion in WGRs, become reality. To achieve this goal, WGRs out of lithium niobate with diameters in the mm-range are going to be manufactured. These resonators will be pumped by a diode-laser source. The light of the pump laser will be frequency converted by second harmonic generation (SHG) or optic parametrical oscillation (OPO). For being able to couple light into the WGRs, a micro-optical waveguide coupler is currently developed. This project is a cooperation between the Laboratory for Optical Systems and the Gisela and Erwin Sick Chair of Micro-optics.