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Birefringence is caused by both orientation of polymer chains and photoelasticity. These birefringences were compensated by random copolymerization of negative birefringent methyl methacrylate and positive birefringent benzyl methacrylate, but orientational and photoelastic zero birefringences were achieved with quite different compositions of the copolymers. Note that the birefringence of the copolymer that occurred in the process of injection molding was almost completely eliminated with a composition for orientational zero birefringence. The orientational and photoelastic zero-birefringence copolymers possessed enough transparency as optical materials that the total scattering losses were 30.4 and 19.5 dB/km, respectively, competing with the transparency of homopolymers. Key words: Zero-birefringence copolymer, orientational birefringence, photoelastic birefringence, injection molding, light scattering.

Rhodamine B (RB), Rhodamine 6G (R6G), Oxazine 4 perchlorate (O4PC), and 4-Dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl-4H-pyran)-doped graded-index (GI) polymer optical fiber amplifiers (POFA's) were successfully prepared by novel techniques to prevent degradation of organic dyes and to enhance solubility of the dyes in methyl methacrylate and in poly(methyl methacrylate) (PMMA). High-power (620 W) and high-gain (33-dB, 2070 times) amplification was achieved for RB-doped GI POFA's based on the spectral investigation of dyes in PMMA bulk. It should be noted that amplification in the low-loss region of polymer optical fibers was achieved in the R6G- and O4PC-doped GI POFA. Key words: Polymer optical fiber amplifier, Rhodamine B, Rhodamine 6G, Oxazine 4 perchlorate, 4-(Dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl-4H-pyran).

We describe graded-index polymer optical fibers with high bandwidth (5.12 GHz for 100-m transmission) and low loss in the near-infrared region (56 and 115 dB/km at wavelengths of 688 and 773 nm, respectively) that we successfully obtained with a new interfacial-gel polymerization technique using an all-deuterated methyl methacrylate monomer and a partially fluorinated acrylate monomer. The necessity for both low attenuation and high bandwidth for a polymer optical fiber is described for its use as a physical media in a high-speed multimedia network. Key words: Graded index, polymer optical fiber, high bandwidth, low absorption loss.

The optimum refractive-index distribution of the high-bandwidth graded- index polymer optical fiber (POF) was clarified for the first time by consideration of both modal and material dispersions. The ultimate bandwidth achieved by the POF is investigated by a quantitative estimation of the material dispersion as well as the modal dispersion. The results indicate that even if the refractive-index distribution is tightly controlled, the bandwidth of the graded-index POF is dominated by the material dispersion when the required bit rate becomes larger than a few gigabits per second. It is also confirmed that the material dispersion strongly depends on the matrix polymer and that the use of a fluorinated polymer whose material dispersion [-0.078 ns/(nm km)] is lower than that of poly(methyl methacrylate) [-0.305 ns/(nm km)] allows for a 10-Gb/s signal transmission. Key words: Modal dispersion, material dispersion, graded index, polymer optical fiber (POF), high bandwidth, WKB method.

A very large radial graded-index (GRIN) polymer was successfully prepared for the first time, to the best of our knowledge, by two methods: the curved mold method and the diffusion copolymerization method. Both methods gave a radial GRIN polymer with a diameter of 70 mm and a An value greater than 0.02. Ray tracing through these radial GRIN polymers was used to predict that such a GRIN polymer could be a promising candidate for thinner ophthalmic lenses with no spherical aberration or multifocusing characteristics. Key words: Graded index, plastic lens, spherical aberration, ophthalmic lens, copolymerization.

The performance of a rhodamine B-doped polymer optical fiber amplifier is evaluated through experimental and numerical analyses. The amplifier is subjected to pump and signal pulses of several nanosecond duration and subsequently analyzed by means of a mathematical model. Cross section measurements are also carried out using the computed data. Results show that the fiber amplifier is capable of performing high-power and high-gain amplification.

A gradient-index (GRIN) contact lens (CL) is proposed to decrease spherical aberration and to increase the diopter. A plastic radial GRIN rod was successfully obtained by using the vapor-phase diffusion copolymerization technique. The resulting index distribution of the GRIN rod was almost parabolic against the distance from the center axis, and the [Delta]n value was -0.030. The GRIN CL was prepared by grinding and polishing the rod. It is theoretically and experimentally concluded that using the radial GRIN material can significantly improve the optical properties of CL's. Key words: GRIN, polymer, methyl methacrylate, copolymerization, contact lens, diopter, Maxwell's ray equation.

A polymer optical fiber amplifier (POFA) of the graded-index (GI) type, with gain in the visible region, was successfully prepared for the first time, to our knowledge, with the interfacial-gel polymerization technique. An input signal of 0.85 W at 591 nm was amplified to 420 W (27-dB gain) by injection of 690 W of pump power at 532 nm into a GI POFA with a 0.5-m length. The efficiency of conversion of pump energy to signal amplification was more than 60%. Key words: Graded index, polymer optical fiber amplifier, amplification, organic dye, Rhodamine B.

We successfully obtained a high-bandwidth (1 GHz km) and low-loss (90 dB/km at 0.572 [[micro]meter] of wavelength) graded-index polymer optical fiber by using the interfacial-gel polymerization technique, in which we used an unreactive component to obtain the quadratic refractive-index distribution. This high-bandwidth graded-index polymer optical fiber makes it possible to transmit a high-speed optical signal in a short-range network, which is not possible when we use the step-index type of polymer optical fiber commercially available.

A sphere lens with a spherical gradient index (GRIN) was prepared by the modified suspension polymerization technique. GRIN spheres with quadratic- and linear-index distributions were obtained by two different methods to confirm the effect of the GRIN profile on the focusing property of the sphere lens. It was confirmed in both theory and experiment that the spherical aberration of such GRIN spheres was remarkably decreased compared with that of a homogeneous sphere.

A poly[(methyl methacrylate/2,2,2-trifluoroethyl methacrylate/benzyl methacrylate) = 52/42/6 (w/w/w)] copolymer was used to form the core of a polymer optical fiber (POF) with the purpose of fabricating a birefringence-reduced core (BRC). The fabricated POF showed almost no phase shift, regardless of the stress that was applied to the fiber. Therefore, it is possible to maintain the polarization in the POF core, which is an important factor for detection of the direction in which stress is applied to the POF. To detect the stress direction, the core of a BRC–POF was doped with dichroic dye. A doped BRC–POF that was fabricated using magenta dye showed variations in its output under operating conditions where the stress vector and the incident polarization formed different angular relationships. The results presented here are considered to be applicable to detailed structural monitoring using POFs. [ABSTRACT FROM AUTHOR]