Intra-cavity second harmonic generation of a Titanium:sapphire (Ti:sa) laser system has been used to improve the conversion efficiency to the second harmonic. Over the course of several experiments performance data spanning the whole wavelength range of a Ti:sa has been collected, which may be used as a guideline for future experiments. An average output power of up to 3.7 W was achieved, resulting in a conversion efficiency of >75 % to the second harmonic. A wavelength coverage from 340-525 nm has been demonstrated. To extend the wavelength range of the solid state laser system, difference frequency mixing has been applied to the intra-cavity doubled light and the fundamental output of a second Ti:sa laser. Up to 30 mW of yellow light at the sodium D2 line at 589 nm was generated. Based on numerical calculations this output power could still be improved by a factor of ten with simple changes in the experimental setup. Laser spectroscopy and measurement of the saturation behaviour has been carried out on an atomic beam of stable sodium.