Published papers

ASE in laser dye doped DPOF is investigated experimentally and theoretically. Rate equations on laser intensity with the fluorescence intensity considered is developed to discuss the basic performance of the ASE in the DPOF. The model was useful to explain the experimentally obtained results. In addition, ASE-power on DPOF length dependence, pumping power dependence, pumping wavelength, output spectra, output waveform is evaluated. The maximum energy conversion efficiency obtained form the Rhodamine 6G 5-ppm doped DPOF was about 40%.

屈折率分布型ポリマー材料に、含フッ素材料を用いることにより、通常の炭素-水素結合からなるポリマーでは伝送損失の値が数100dB/km以上となる、688nmや773nmの近赤外領域の波長において、それぞれ約56dB/kmと約773dB/kmの低損失を実現した。また伝送帯域についても100mで５.12GHzを達成し、これまでのポリマー材料での値よりも約２倍程度優れた値であることを実験的にも確認した。

Recently, information service which can be represented by the Internet service have become available to the general households, and a broadband network has been demanded to deliver video services with low cost and easy handling. Under such circumstances, plastic optical fiber (POF) has been widely studied as the transmission medium of the high-speed information communication network system. The POF can be prepred with a large core diameter because of the high flexibility, which would enable easy connection and branching in the network system. Moreover, the realization of high bandwidth can be achieved by making a graded-nidex type. In this paper, we report on the process of the studies and development of POF and the present situation of POF.

The glass transition temperature (Tg) was the critical temperature for determining the excess light scattering of PMMA glasses. When PMMA glass is polymerized or heat-treated above the Tg, the excess scattering intensity disappears and the isotropic light scattering loss is reduced to the value calculated from the refractive index and the isothermal compressibility using the thermally induced fluctuation theory. The isotropic light scattering loss of the amorphous polymer can be estimated from its molecular structure by assuming a frozen model around Tg.

マルチメディア社会で必要な伝送容量をすべてカバーしうる、高速、低損失のポリマー光ファイバーが近年開発され、POFが高速ネットワークやLANの媒体として大きな注目を浴びている。本稿では、POFの特性とその背景について解説する。

ポリメンチルメタクリレートをクラッド層にコーティングすることにより,これまで作製されていた蛍光ポリマー光ファイバー型酸素センサーの感度を大幅に向上させることに成功した。

ポリマーTE-TMモード変換器の位相整合動作について述べた。

Improvement of the optical fiber sensor based on the fluorescence quenching by oxygen gas was studied. Using the newly synthesized PMtMA and its blend of the PMtMA/PMP as the cladding layer, in which sensing dye was doped, the POF O2 sensor with high sensitivity and a fast response time could be realized. In addition, this sensor didn’t receive any affect by humidity.

A novel TE-TM mode converter using optical active polymers (OAPs), which can be fabricated much more easily than the conventional ones, was proposed. To achieve its phase-matched operation, two methods for controlling birefringence in the OAP waveguides were studied and hence TE0-TM0 mode convention with a high efficiency of about 70% was obtained for the first time.

Birefringence is caused by orientation of polymer during injection molding or extrusion, and is a large obstacle to optical applications. Transparent Zero-birefringence copolymers were successfully synthesized by randomly copolymerizing two monomers having positive and negative birefringence, respectively. Since the anisotropic polymerization of the negative birefringence monomer units is compensated by the positive birefringent monomer units on the same polymer chain, the birefringence is compensated on the length scale of only several monomer units and becomes zero for any degree of orientation. MMA was used as the negative birefringent monomer, and 3FMA as the positive birefringent monomer. Poly (MMA-co-3FMA) copolymer synthesized with a composition of MMA/3FMA=45/55 (wt/wt) shows no birefringence for any draw ratio when a sample film was 65.9dB/km, which is comparable to those of homopolymers.

広伝送帯域を実現する屈折率分布型ポリマー光ファイバーの解説。

現在、マルチメディア社会を実現する上で最も大きな問題となっているドロップラインなどの近距離高速情報伝送の媒体として、屈折率分布型ポリマー光ファイバーの利用を提案し、その作製方法から光学特性までを明らかにしている。

素子作製が非常に簡単かる安価であり、加えて光アイソレータや光変調器などへの新たな展開が期待できる旋光性ポリマーの動作原理と基礎的実験結果について紹介する。

ポリマー光ファイバーの特徴を他のファイバーと比較検討し、屈折率分布型ポリマー光ファイバーが、将来のマルチメディア社会の情報伝送媒体として十分な特性を有していることを明らかにし、その作製方法や伝送損失特性などを明らかにしている。

The Optimum refractive index distribution of the high-bandwidth GI POF was clarified for the first time by consideration of both modal and material dispersion. 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 is tightly controlled, the bandwidth of the GI 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 PMMA allows for a 10Bb/s signal transmission.

We proposed highly scattering optical transmission (HSOT) polymers and applied it to a light pipe of a backlighting system for liquid crystal displays (LCDs). The HSOT polymer backlighting system having not only approximately twice the brightness but also twice the efficiency of the conventional one was realized based on analysis of multiple scattering in the HSOT polymers. The problem of color dispersion which had been believed to be the nature of scattering phenomenon was solved by optimizing the heterogeneous structures in the HSOT polymers. As a result, the HSOT polymer backlighting system with sufficient color uniformity was achieved. In addition, the HSOT polymer backlighting system is suitable for recent thin LCDs because of these advantages.

A new waveguide-type simple optical modulator, which consists of PMtMA core with an optical activity and electrically poled PVDF-PMMA polymer alloy cladding layer, has been studied. This device is based on toe TE-TM mode conversion controlled by the cladding nonlinearity. When a high voltage signal was applied to the device, a low-loss optical modulation was obtained at a wavelength of 441.6nm.

GI-PDFのモード分散の最新結果と分析の結果を基にしてデザインした屈折率分布について述べた。

高速G1型POFとして現在、PMMA系、PFポリマー系と、構成材料をベースに2種類に分類され、それぞれの光学特性、それらについて考えられる応用展開に関して解説した。