Nippon Telegraph and Telephone Corporation

Nippon Telegraph and Telephone Public Corporation

Ntt Electronics Corporation

Terutoshi Kanamori

Yasutake Ohishi

Makoto Yamada

Shoichi Sudo

Atsushi Mori

Hirotaka Ono

Toyotaka Manabe

Seiko Mitachi

Toshiyuki Shimada

Yoshiki Nishida

Shuichi Shibata

Mitsuho Yasu

Kazuo Fujiura

Tadashi Sakamoto

Shiro Takahashi

Michiya Fujiki

Makoto Shimizu

Koichi Nakagawa

Yousuke Hiraki

An ASE light source offers high outputs even in a wavelength band of 1,490 to 1,525 nm. The ASE light source outputs spontaneous emission light generated from Tm-doped optical fibers. Then, the ASE light source outputs amplified light obtained by using Er-doped optical fibers to amplify the output from the Tm-doped optical fibers and spontaneous emission light generated from the Er-doped optical fibers so that the amplified light and the spontaneous emission light are superimposed on each other.

ASE light source, optical amplifier and laser oscillator

A tellurite glass as a glass material of optical fiber and optical waveguide has a composition of 0<Bi O &lE;20 (mole %), 0&lE;Na O&lE;35 (mole %), 0&lE;ZnO&lE;35 (mole %), and 55&lE;TeO &lE;90 (mole %). The tellurite glass allows an optical amplifier and a laser device that have broadband and low-noise characteristics. In a splicing structure of non silica-based optical fiber (as a first fiber) and a silica-based optical fiber (as a second fiber), optical axes of the first and second optical fibers are held at different angles &thgr; and &thgr; (&thgr; &ne;&thgr; ) respectively from a vertical axis of a boundary surface between their spliced ends, and a relationship between the angles &thgr; and &thgr; satisfies Snell's law represented by an equation of sin &thgr; /sin &thgr; &equals;n /n (where n is a refractive index of the first optical fiber and n is a refractive index of the second optical fiber) at the time of splicing the first and second optical fibers.

Optical fiber splicing structure

Tellurite glass, optical amplifier, and light source

An optical amplification medium doped with Er,ions is selected from the group of a fluoride glass, a chalcogenide glass, a telluride glass, a halide crystal, and a lead oxide based glass. The Er,ions are excited by light of at least one wavelength in the range of 0.96 &mgr;m to 0.98 &mgr;m. A laser or an optical amplifier includes this optical amplification medium doped with Er,ions. Furthermore, an optical amplification method performs an optical amplification using the optical amplifier having the optical amplification medium doped with Er,ions. Thus, the laser to be applied in the field of optical communication, the optical amplifier having the characteristics of low noise and high gain, and the optical amplification method can be provided.

Lasers, optical amplifiers, and amplification methods

A tellurite glass as a glass material of optical fiber and optical waveguide has a composition of 0<Bi,O,&lE;20 (mole %), 0&lE;Na,O&lE;35 (mole %), 0&lE;ZnO&lE;35 (mole %), and 55&lE;TeO,&lE;90 (mole %). The tellurite glass allows an optical amplifier and a laser device that have broadband and low-noise characteristics. In a splicing structure of non silica-based optical fiber (as a first fiber) and a silica-based optical fiber (as a second fiber), optical axes of the first and second optical fibers are held at different angles &thgr;,and &thgr;,(&thgr;,&ne;&thgr;,) respectively from a vertical axis of a boundary surface between their spliced ends, and a relationship between the angles &thgr;,and &thgr;,satisfies Snell's law represented by an equation of sin &thgr;,/sin &thgr;,&equals;n,/n,(where n,is a refractive index of the first optical fiber and n,is a refractive index of the second optical fiber) at the time of splicing the first and second optical fibers.

An optical amplifier includes an erbium doped fiber of which at least one of a core part and a clad part is doped with erbium, excitation light sources or exciting the optical fiber, optical means for inputting excitation light from the excitation light source and signal light to the Er-doped fiber, and an optical isolator. The erbium doped fiber is a 1.58 &mgr;m band optical fiber having an equivalent fiber length as a product of a fiber length (m) and an erbium doping concentration (ppm by weight), which length provides a signal gain obtained at a wavelength of the excitation light source used for excitation of the erbium doped fiber of more than a predetermined practical reference value.

Optical fiber amplifier and optical amplification method

This invention relates to fluoride glass with a specific composition having wide infrared transmission. A fluoride optical fiber using this fluoride glass can give high efficiency with a low loss. The fluoride optical fiber having a second cladding on the outer periphery of a first cladding can adjust the refractive index of the first cladding suitably.

Fluoride glass fiber

An amplifying optical fiber includes a core containing Tm ions as activation ions and a clad containing at least one of Tb ions and Eu ions. Alternatively, the amplifying optical fiber includes a core composed of more than two layers. Tm is contained in more than one of the more than two layers as activation ions and at least one of Tb ions and Eu ions is contained in more than one of the more than two in which Tm is not contained.

Optical fibers for optical amplifiers

Fluoride glass-based optical fiber for an optical amplifier which contains rare earth metal ions in the core glass has a relative refractive index difference .DELTA.n between the core and the cladding of 1.4% or more. The core glass contains PbF.sub.2 in a proportion of 25 mol % or less based on the total composition of the core glass. The fluoride glass is doped with rare earth metal ions, and part of the fluorine in the glass may be substituted by at least one halogen Pr.sup.3+, Pr.sup.3+ --Yb.sup.3+, Pr.sup.3+ --Nd.sup.3+, or Pr.sup.3+ --Er.sup.3+ can be doped as the rare earth metal ions. Chlorine, bromine or iodine may be used as the halogen.

Optical fiber for optical amplifier

Fluoride glass-based optical fiber for an optical amplifier which contains rare earth metal ions in the core glass has a relative refractive index difference .DELTA..sub.n between the core and the cladding of 1.4% or more. The core glass contains PbF.sub.2 in a proportion of 25 mol % or less based on the total composition of the core glass . The fluoride glass is doped with rare earth metal ions, and part of the fluorine in the glass may be substituted by at least one halogen. Pr.sup.3+, Pr.sup.3+ --Yb.sup.3+, Pr.sup.3+ --Nd.sup.3+, or Pr.sup.3+ --Er.sup.3+ can be doped as the rare earth metal ions. Chlorine, bromine or iodine may be used as the halogen.

A method for preparing a homogenous fluoride glass containing high purity BaF.sub.2 through the CVD process using a gaseous mixture containing a barium .beta.-diketonate complex service as a first starting material and represented by the following general formula (1) of: ##STR1## where (i) R and R' are each --C(CH.sub.3).sub.3 ; or (ii) R is CH.sub.2 CH.sub.2 CH.sub.3 and R' is --C(CH.sub.3).sub.3 ; or (iii) R and R' are each CF.sub.3 ; a gaseous or vaporizable compound of the metallic element constituting said fluoride glass, the gaseous or vaporizable compound serving as a second starting material; and a fluorine-containing gas serving as fluorinating agent. Further provided is a process for preparing a perform for a fluoride optical fiber which is low in transmission loss, by depositing the fluoride glass over the interior wall of a cylindrical tube or the wall of rod-like glass substrate through the CVD process following by collapsing.

Method of making fluoride glass using barium .beta.-diketones

Provided is a process for preparing a homogeneous fluoride glass containing high purity BaF.sub.2 through the CVD process characterized in that the used gaseous mixture comprising: a barium .beta.-diketonate complex serving as a first starting material and represented by the following general formula (1) of: ##STR1## wherein R is an alkyl group having 1 to 7 carbon atoms, R' is a substituted alkyl group having fluorine atoms substituting hydrogen atoms and represented by C.sub.n F.sub.2n+1 where n is an integer of from 1 to 3; a gaseous or vaporizable compound of the metallic element constituting said fluoride glass, the gaseous or vaporizable compound serving as a second starting material; and a fluorine-containing gas serving as fluorinating agent. Further provided is a process for preparing a preform for a fluoride optical fiber which is low in transmission loss, by depositing the fluoride glass over the interior wall of a cylindrical tube or the wall of rod-like glass substrate through the CVD process followed by collapsing.

Process for the preparation of fluoride glass and process for the

An infrared ray-transmitting glass composition for optical fibers consisting essentially of 28 mol % to 38 mol % of BaF.sub.2, 2 mol % to 7 mol % of GdF.sub.3 and 58 mol % to 69 mol % of ZrF.sub.4, and optical fibers comprising said glass composition.

Glass for infrared ray-transmitting optical fibers and optical fibers

Glass for an optical fiber consists essentially of 10 to 64 mol % of at least one kind of fluoride selected from a first group consisting of CaF.sub.2, SrF.sub.2 and BaF.sub.2 ; 0.5 to 50 mol % of at least one kind of fluoride selected from a second group consisting of YF.sub.3 and fluorides of lanthanide elements; and 30 to 65 mol % of AlF.sub.3.

Growing community of inventors

Mito, Japan

Terutoshi Kanamori