Optical properties of conducting polymers with Sn atoms in main chains, such as optical absorption, photoluminescence (PL), and electroluminescence, have been studied. The electronic energy structures have been determined by optical and electrochemical measurements. Strong PL with high quantum efficiency has been clarified in the films, and photopumped multimode laser emission was demonstrated from cylindrical microcavities formed by these polymers coated around optical fibers.