Emission properties of a distributed feedback laser cavity containing silicon nanocrystals

We report on light emission from silicon nanocrystals (Si-nc) in a laser cavity. Using modified electrochemical etching of Si wafers we prepare Si-nc with blue-shifted photoluminescence spectrum down to 580-620 nm, embedded at high-volume fractions in a SiO₂-based solid matrix. We insert this active medium into an optically pumped resonator. Since our samples are only partially homogeneous, we cannot use external mirrors in order to achieve optical feedback: we induced optically an internal distributed cavity by intense, spatially periodical excitation. Mode selection was simulated by a simplified theoretical model, based on an approach of multiple reflections. In the framework of the model we discuss the experimentally observed spectral emission changes induced by the distributed cavity.