Organic semiconductors offer promising properties for opto-electronic applications, that are already commercially used for instance,in organic light emitting diodes (OLED) for small scale displays. Yet, an even more challenging task remains - the realization of the organic laser diode. This work focuses on investigations of photophysical properties of the organic semiconductor Rubicene with the prospect of application as the optical active medium in an organic semiconductor laser. Properties of the photoluminescence emission of Rubicene in solution, thin film and as single crystals are studied. These include the luminescence quantum yield and the luminescence lifetime. Emission and absorbance spectra of Rubicene crystals under high pressure conditions are recorded in a diamond anvil cell. The work includes an attempt to build an optically pumped organic laser that employs a novel method to transfer dielectric mirrors onto Rubicene single crystals in order to build single crystal resonators. A discussion of the fundamentals of organic laser technology and the description of the original measurement setups of the present study are featured in this book.