Nippon Telegraph and Telephone Corporation

Kouji Shikano

Atsushi Mori

Shinichi Aozasa

Makoto Shimizu

Masao Kato

Takashi Kurihara

Kazuo Fujiura

Kouji Enbutsu

Kiyoshi Oikawa

Makoto Yamada

Tadashi Sakamoto

An optical fiber, which has a zero-material dispersion wavelength equal to or greater than 2 &#x3bc;m, and a high nonlinear susceptibility &#x3c7;equal to or greater than 1&#xd7;10esu, and uses tellurite glass having sufficient thermal stability for processing into a low loss fiber, employs a PCF structure or HF structure having strong confinement into a core region. This enables light to propagate at a low loss. The size and geometry of air holes formed in the core region, and the spacing between adjacent air holes make it possible to control the zero dispersion wavelength within an optical telecommunication window (1.2-1.7 &#x3bc;m), and to achieve large nonlinearity with a nonlinear coefficient &#x3b3; equal to or greater than 500 Wkm.

Optical fiber and production method thereof

A fabrication method of an optical fiber using as a core material tellurite glass. The method includes a first process of molding a tellurite glass melt into a mold, the mold having a plurality of convex portions defining an inner wall, which portions run parallel to each other in a longitudinal direction in order to make a polygon columnar glass preform, and a second process of inserting the glass preform into a cylindrical jacket tube made of tellurite glass and carrying out fiber-drawing under pressure so as to maintain or enlarge air holes which are gaps generated between the glass preform and the jacket tube.

Tellurite optical fiber and production method thereof

New fiber lasers, spontaneous emission sources, and optical fiber amplifiers are provided. Their conventional counterparts, which have a fiber doped with thulium (Tm) ions and excited by 0.67 &#x3bc;m or 0.8 &#x3bc;m pumping light, have a problem in that their characteristics are deteriorated with the elapse of time. The new fiber lasers, spontaneous emission sources, and optical fiber amplifiers use 1.2 &#x3bc;m light as pumping light. Alternatively, they use a pumping source for exciting the thulium from the lowest energy levelHtoHexcitation level. As a more preferable configuration, they improve the emission efficiency at 2.3 &#x3bc;m band by disclosing Tm-doped host glass.

Fiber laser, spontaneous emission light source and optical fiber amplifier

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Hakodate, Japan

Kouji Shikano