Published papers

The free-radical polymerization of 2,2,2-trifluoroethyl methacrylate (TEMA) was carried out in fluoroalcohols to achieve stereoregulation. The polymerization reactivity at low temperature and syndiotactic specificity were enhanced by the use of fluoroalcohol as a solvent. The polymer having triad syndiotacticity (rr) of 70% was obtained in perfluoro-t-butyl alcohol. It was noted that the stereochemistry was nearly independent of reaction temperature. The stereoeffect of fluoroalcohols seemed to be due to the hydrogen-bonding interaction between the alcohol and the monomer or growing species. The hydrogen-bonding formation was determined by FTIR. The copolymerization of TEMA with methyl methacrylate (MMA) in hexafluoroisopropanol afforded a copolymer with syndiotactic specificity. By this method, a cladding material for an optical fiber based on poly(methyl methacrylate) (PMMA) with high mechanical strength and low refractive index could be obtained.

We report a method for compensating the birefringence of optical polymers by doping them with inorganic birefringent crystals. In this method, an inorganic birefringent material is chosen that has the opposite birefringence to that of the polymer and has rod-shaped crystals that are oriented when the polymer chains are oriented. The birefringence of the polymer is thus compensated by the opposing birefringence of the crystal. Birefringence is minimized in various polymer optical devices by adjusting process conditions, because it degrades the performance of devices. This method minimizes it, independent of process conditions, which potentially improves the productivity of devices.

Polymer optical fiber (POF) is a promising transmission medium for providing broadband telecommunication services within the customer's premises. POF offers several attractive features for data transmission such as broad bandwidth and low cost for in-house, access, and LAN applications. This article presents a review on optical transmission systems using POF and their enabling technologies. A summary is given of experimental data links with record capacity over record transmission distances. Standardization activities in POF technology and transmission are reported. To conclude, we discuss trends for further development and research.

A novel coloration phenomenon in a colloidal dispersion with an amphiphilic polymer was found. The dispersion consists of tetrahydrofuran (THF), an aqueous solution of sodium thiosulfate (Na2S2O3·5H2O), and hydroxypropylcellulose (HPC). The dispersion was emulsified by HPC as an amphiphilic polymer, so that the aqueous phase was confined in droplets in the THF matrix. It typically appeared bluish violet at room temperature and turned into blue with increasing temperature. In this system, the refractive indices of the inside and outside of the droplet coincided at a certain wavelength at which the light passes through without scattering, which is called the Christiansen effect. The color observed was successfully simulated by Mie's scattering theory in combination with the Christiansen effect.

Birefringence induced by orientation of polymer main chains during an injection-molding or extrusion processing restricts the application of optical polymers to optical devices that require maintaining the polarization state of incident light. We propose the "birefringence crystal dopant method" to compensate the birefringence of polymers by homogeneous doping with an opposite birefringent needle-like crystal. Strontium carbonate was selected for this method and synthesized, with particle length of 50-200nm and aspect ratios of 2-5. Strontium carbonate was doped into poly (PMMA/BzMA=78/72(wt. /wt9) film. The film was uniaxcially drawn at 130℃ and 4mm/min. For the first time, the positive birefringence of the drawn copolymer film at a wavelength of 633nm was compensated by doping with 0.3 wt% of Strontium carbonate without losing transparency and thermostability.

We report what is to our knowledge the first observation of erbium fluorescence at the optical communication wavelength of 1.5µm in a perfluorinated medium. Using a Nd:YAG (355nm) source, we observed fluorescence of the 4I13/2-4I15/2 transition with a peak wavelength of 1.535µm and with a full width at half-maximum of 28nm. These results can lead to new active devices that use all fluorinated polymers.

ポリマー鎖が配向しても複屈折性が生じない「ゼロ複屈折性光学ポリマー」という概念とその有用性について述べ、ゼロ複屈折性光学ポリマーを実現するために新たに提案した「ランダム共重合法」と「異方性低分子ドープ法」について、詳細に紹介する。

現在ＩＴ不況と言われているが、それはソフトに対する期待と、最後の数百メートルのブロードバンド化が進まないハードとのギャップがその一因と考えられている。本セミナーでは、この最後の数百メートルを低コストで光情報化が可能な、高速プラスチック光ファイバーとそのネットワークについて紹介する。更に、それがもたらす現在のインターネットの延長でないリアルタイムの Face to Face Communication の生活と社会の在り方について述べる。

GI型POFによる高速・長距離の通信を実現するために必要な、高分子鎖中でのドーパント化合物のナノメートルオーダー分布制御技術と高速POF、高画質ディスプレイが可能にする「人にかえるギガアイランド構想」について述べる。

A scattering polarizer containing carbonate whiskers (aragonite) in a polyolefin polymer has been developed. A selective multiple scattering technique, generating transmitted linearly polarized light and backward scattered light, has been demonstrated. A refractive index match and mismatch arise from the uniaxial orientation of the host polymer and the alignment of aragonite in the drawing direction. The dependence of the transmittance on the polarization direction of the incident light has been observed. The polarization efficiency has been measured to be 60% with a 150µm thickness.

光散乱研究の支えとなった、Einstein や Debye の論文を通し、最先端の研究を進めるのには必ずしも最先端の論文が役に立つわけではなく、いかにファンダメンタルズが大切であったかをこれまでの研究成果を通してわかりやすく解説した。

情報技術の進歩により生み出されたフォトニクスポリマーによる新規デバイスを本プロジェクトにて研究中のＧＩ－ＰＯＦ、ＨＳＯＴを中心に解説する。

We have proposed the dopant-diffusion co-extrusion process for fabricating a graded-index polymer optical fiber (GI-POF), where small-size dopants can be diffused during the fabrication process. It was confirmed that the refractive index profiles were controlled to the optimized index profile by changing the temperature of the diffusion zone and screw rotation speed.

不均一構造のディメンジョン毎の相互作用および導出される光機能によって実現するフォトニクスポリマーについてその現状および将来展望について紹介した。

これまで行ってきた研究成果を光の偏波（またはフォトン）と高分子物質との係わりという視点で原子系のディメンジョンからマクロな不均質構造にわたって順に述べた。