Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback

3 pages, 4 figures.-- OCIS codes: 140.1540, 140.5960.-- ArXiv pre-print available at: http://arxiv.org/abs/nlin/0108011The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analysed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not to be simultaneous to the dropouts, but to occur after them. The phenomenon is statistically analysed in a systematic way, and the corresponding delay is estimated.We acknowledge financial support from Ministerio de Ciencia y Tecnología (Spain), under projects PB98-0935 and BFM2000-0264, from the EU IST network OCCULT, and from the Generalitat de Catalunya, under project 1999SGR-00147.Peer reviewe