Abstract: The present invention relates to a method for preparing a cyclic olefin polymer by addition polymerization, and more particularly to a method for preparing a norbornene-based addition polymer, which comprises a step of contacting a norbornene-based monomer having an ester or acctyl group with a catalyst system comprising: a Group X transition metal compound; a compound comprising a neutral Group XV electron donor ligand having a cone angle of at least 160°; and a salt capable of offering an anion that can be weakly coordinated to the transition metal, in solvent. The norbornene-based addition polymer having an ester or acetyl group according to the present invention is transparent, has superior adhesivity and a low dielectric constant, and it generates no byproducts when attached to metal. Therefore, it can be used as an optical film, a retardation film, a protection film for a polarizer POFs (plastic optical fiber), PCBs (printed circuit board), or insulators of electronic devices.

Abstract: An optical receiver and an optical transmitter and a producing method thereof using a variable optical attenuator includes a base member formed in a predetermined shape; an input optical fiber emitting an optical signal toward the base member; an optical receiving means provided at one side of the base member, and receiving an optical signal; and a variable optical attenuator actuated by an electrostatic force, changing a path of laser emitted from the input optical fiber, and thus adjusting optical power made to be incident to the optical receiving means. Positions of the input optical fiber and the optical receiving means can be changed, and the variable optical attenuator can be produced by a MEMS technology so that the variable optical attenuator can be produced with a low unit price, actuated with small electric power, and can transmit an accurate optical signal.