In this talk, I will give a brief review of the results obtained in several recent years. Three directions of research will be discussed:

• (i) Studies of interaction of ultrashort laser pulses with resonant two-level media;
• (ii) Theoretical description of distributed-feedback dye lasing by polarization modulation;
• (iii) Investigation of nonlinear effects in such photonic structures as photonic crystals and metamaterials, with emphasis on short-pulse propagation and localization.