Low-Loss GI Plastic Optical Fiber and Novel Optical Polymers
- PDF / 400,171 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 3 Downloads / 212 Views
LOW-LOSS GI PLASTIC OPTICAL FIBER AND NOVEL OPTICAL POLYMERS YASUHIRO KOIKE AND YASUJI OHTSUKA Faculty of Science and Technology, Keio University 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223, Japan ABSTRACT A low-loss GI plastic optical fiber in which the attenuation of transmission was about 130 dB/km at 650 nm wavelength was successfully obtained by a new interfacial-gel copolymerization technique. Novel optical functional polymer glasses, such as birefringence-free copolymers for any degree of orientation and optically active amorphous polymers which act as polarization modulators, were synthesized and characterized. INTRODUCTION Plastic optical fibers have been widely studied [1-4] as short distance waveguides such as local area network (LAN) [5], datalink etc., because of its easy processing and handling, and its large diameter such as 1 mm enabling high efficiencies of fiber coupling and beam insertion. All plastic optical fibers commercially developed [6-8] so far are of a multimode SI type. Therefore, in fast datalink and LAN where a bandwidth over hundreds MHz may be necessary in near future, such a SI fiber can not cover the whole information even in a short distance communication. On the other hand, the gradient-index (GI) plastic optical fiber [9,10] is a waveguide expected to have a much higher bandwidth than the SI fiber, while maintaining a large diameter. In this paper, a low-loss GI plastic optical fiber was successfully prepared by a new interfacial-gel copolymerization technique [11] where methyl methacrylate (MMA) and vinyl phenylacetate (VPAc) or vinyl benzoate (VB) are copolymerized to obtain the index distribution. Optical birefringence by the orientation of polymer chains causes some anisotropic defects in polymer optical components and waveguides. Birefringence-free copolymer glasses were prepared by a radical copolymerization of two monomers giving positive and negative birefringent polymers, respectively. Optically active amorphous polymethacrylate glasses which act as polarization modulators were synthesized. The application of these glasses for the rotation of linear polarization phase and for the conversion of linear polarization to circular polarization, which is quite different from the conventional principles of using inorganic crystals, is discussed. GI PLASTIC OPTICAL FIBER Formation of Gradient-Index The preform rod with a 10 mm diameter, where the refractive index gradually decreased from the center axis to the periphery was prepared by our interfacial-gel copolymerization technique [11] where two monomers, M1 and Mz, with different refractive indices and reactivities were copolymerized. In this paper, MMA was selected as M1 monomer, and VPAc and VB as M2 monomers. The refractive indices of the polymers of MMA, VPAc, and VB are 1.49, 1.57, and 1.58, respectively. These monomers were distilled under reduced pressure and filtered through a 0.2 ui m membrane filter. Benzoyl peroxide (BPO) and n-butylmercaptan (nBM) were used as the initiator and chain-transfer agent, respectively. In th
Data Loading...
