Quantum technologies

We will start by looking into the design and operating mode of semiconductor lasers. We will derive a formula describing their linewidth as well as discuss the dynamic properties of semiconductor lasers. This chapter will also explain what happens if we irradiate an external field into the laser cavity to investigate the possibilities for narrowing the linewidth of the laser and how to realize this. We have to study frequency selective components we want the laser to lock to and will explore how to build a servo loop to make the locking stable. We will generate the servo loop by using a technique rst proposed by Hänsch and Coulliaud in 1980. This technique is based on a polarization spectroscopy providing a dispersive error signal with a very broad capture range. To control our advance we have to find a method to measure the linewidth of the laser. This we will do with a self heterodyne scheme first proposed by Okoshi et al. in 1985 which provides a high spectral breakup. Afterwards we will describe how the setup was generated, which problems have occurred and how they have been solved. At the end this diploma thesis will provide an outlook which steps can be taken to improve this experiment further on. The setup generated in this diploma thesis supplies first promising results in order to generate a compact long term frequency stabilized diode laser system. In addition to the presented setup we studied a similar system with a plane-parallel cavity described in detail in the diploma thesis of Julia Kemp. This setup provided dissatisfactory results which led us to concentrate our efforts to the V-conguration. Beginning with a linewidth of (5.26 +-1.82) MHz it was possible to reduce it by a factor of 10 to (0.55 +-0.34) MHz. Many problems in generating the setup have been solved and described as well. The actual locking laser of the Cqed experiment has a linewidth of about 10 kHz. So this setup has to be improved to achieve comparable results.