Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
  • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
  • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
  • H01S3/06—Construction or shape of active medium
  • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
  • H01S3/067—Fibre lasers
  • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
  • H01S3/06716—Fibre compositions or doping with active elements
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C13/00—Fibre or filament compositions
  • C03C13/04—Fibre optics, e.g. core and clad fibre compositions
  • C03C13/041—Non-oxide glass compositions
  • C03C13/043—Chalcogenide glass compositions
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating

Definitions

• This invention relates generally to glasses for use in optical fibers, and more specifically to cladding glasses which exhibit improved thermal stability and a low refractive index.
• the glass composition consists principally of Ge, As and S, ⁇ Ga and/or In, with small but necessary additions of Si.
• Other metals including Ca, Sr, Ba, Ag, Tl, Cd, Sn, Hg, Pb, Y, La and other rare-earth metals from the lanthanide series and Sb, as well as optional anionic components such as Se, Te and the halogens F, Cl, Br and I, can be added to optimize various other physical properties such as thermal expansion, viscosity, etc., but are not essential constituents.
• the addition of phosphorus to GeAs sulphide glasses can be used instead of silicon to accomplish the same objectives. Glasses of these compositions provide for a cladding glass which exhibits improved thermal stability and a lower refractive index relative to that of a GeGaAsS or GelnAsS core.
• FIG. 1 is a perspective view of a segment of an optical fiber made of a glass composition of the present invention.
• FIG. 2 is a cross sectional view of the fiber of Fig. 1 taken along line 2-2.
• FIG. 3 is a plot of the refractive index based on the concentration of Si (as expressed in terms of atomic %) in a GeAs sulfide glass.
• FIG. 4 is a plot of the thermal stability of GeAs sulfide glasses with varying concentrations of Si as expressed in atomic % .
• FIG. 5 is a plot of the refractive index based on the concentration of P as expressed in terms of atomic % in a GeAs sulfide glass.
• Fig. 1 illustrates a segment of an optical fiber 10 suitable for use in an amplifier, laser and/or upconverter device.
• the fiber comprises an inner glass core 14 which is clad with an outer glass cladding 12 which is a chemically and physically compatible glass that has a lower refractive index than core glass 14
• the present invention in one embodiment, is based on the discovery that the incorporation of Si in a GeAs sulphide glass results in a progressive decrease of the refractive index, as illustrated in Fig. 3 of the drawings.
• the data in Fig. 1 show that substitution of 2.5% At% of Si for Ge lowers the refractive index by about 0.025 for glasses with the (Ge, Si) 25 As 10 S 65 stoichiometry. Therefore, if glasses Nos. 7 and 1 were utilized as core and cladding glasses, respectively, the numerical aperture (NA) of the resultant waveguide would be about 0.35, which is sufficiently high for an efficient amplifier fibre.
• Tables 1 and 2 report a group of glass compositions expressed in terms of atomic percent (At%) , illustrating the subject inventive glasses. Because the glasses were prepared in the laboratory, the glasses were typically prepared by melting mixtures of the respective elements, although in some cases a given metal was batched as a sulfide. As can be appreciated, however, that practice is not necessary.
• the actual batch ingredients can be any materials which, upon melting together with the other batch components, are converted into the desired sulfide in the proper proportions.
• the batch constituents were weighed, loaded and sealed into silica ampoules which had been evacuated to about 10 s to 10 "6 Torr.
• the ampoules were placed into a furnace designed to impart a rocking motion to the batch during melting. After melting the batch for about 1-3 days at 850° -950° C, the melts were quenched to form homogeneous glass rods having diameters of about 7-10 mm and lengths of about 60-70 mm, which rods were annealed at about 325°-425°C.
• Table 1 also records the glass transition temperature (T g ), the temperature at the onset of crystallization (T x ), and the difference between those measurements (T x - T g ), which quantity is commonly used to gauge the thermal stability of a glass, as well as the refractive index at the sodium D line (n D ).
• the above-described procedures represent laboratory practice only. That is, the batches for the inventive glasses can be melted in large commercial glass melting units and the resulting melts formed into desired glass shapes utilizing commercial glass forming techniques and equipment. It is only necessary that the batch materials be heated to a sufficiently high temperature for an adequate period of time to secure a homogeneous melt, and that melt thereafter cooled and simultaneously shaped into a body of a desired configuration at a sufficiently rapid rate to avoid the development of devitrification.
• Si-containing glasses of the present invention that are useful for the purpose of cladding a core consisting of GeGaAsS or GelnAsS glass are tabulated below in Table 1 in At%, along with an example of a representative GeGaAsS core glass (Example 7).
• the thermal stability (T x -T g ) of typical cladding glasses is on the order of 230-250° C.
• the T x -T g of Si- substituted glasses can be maintained at a value in excess of 250 °C over a wide range of compositions, and in some cases can be in excess of that of the base GeAs sulphide glass, as illustrated in Fig. 2 of the drawings.
• composition of the Si containing cladding glasses comprise the following approximate ranges in terms of mole percent on the sulfide basis (see Table 2): 50-95% GeS 2 , 2-40% As 2 S 3 , 0.1-30% SiS 2 , 0-20% Ga 2 S 3 and /or In 2 S 3 , 0-10% MS X , where M is selected from Ca, Sr, Ba, Ag, Tl, Cd, Hg, Sn, Pb, Y, La and other rare-earth metals of the lanthanide series, or Sb, 0-5% of the corresponding metal selenide and/or telluride, 0-20% of the corresponding metal halide, and wherein the sulfur and/or selenium and/or tellurium content can vary between 85-125% of the stoichiometric value.
• the glasses consist principally of Ge, As and S, ⁇ Ga and/or In, with a small but necessary addition of P.
• Other metals including Ca, Sr, Ba, Ag, Tl, Cd, Hg, Sn, Pb, Y, La and other rare-earth metals from the lanthanide series and Sb, as well as optional anionic components such as Se, Te and the halogens F, Cl, Br and I, can be added to optimize various other physical properties such as thermal expansion, viscosity, etc., but are not essential constituents.
• Compositions (in atomic %) of suitable P containing glasses that are useful for the purpose of cladding a core consisting of GeGaAsS or GelnAsS glass are given below in Table 3:
• Example 8 when Example 8 is used as cladding for a core glass with the composition of Example 7, the resultant fibre is expected to have a numerical aperture of 0.32 which is more than adequate for a sulphide 1.3 ⁇ m amplifier fibre.
• compositions of these phosphorous containing cladding glasses comprise the following approximate ranges in terms of mole percent on the sulfide basis (see Table 4); 50-95% GeS 2 , 2-40% As 2 S 3 , 0.1-25% P 2 S 5 , 0-20% Ga 2 S 3 and/or In 2 S 3 , 0-10% MSx, where M is selected from Ca, Sr, Ba, Ag, Tl, Cd, Hg, Sn, Pb, Y, La and other rare-earth metals of the lanthanide series, or Sb, 0- 5% of the corresponding metal selenide and/or telluride, 0-20% of the corresponding metal halide, and wherein the sulfur and/or selenium and/or tellurium content can vary between 85-125% of the stoichiometric value.
• Fig. 5 illustrates that the substitution of 2.5 At % P for Ge lowers the refractive index by about 0.022 for glasses with the (Ge,P) 25 As 10 S 65 stoichiometry.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Electromagnetism (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Glass Compositions (AREA)
• Lasers (AREA)

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• 1998
  • 1998-10-27 EP EP98956240A patent/EP1036343A4/en not_active Withdrawn
  • 1998-10-27 WO PCT/US1998/022739 patent/WO1999023517A1/en not_active Ceased
  • 1998-10-27 CN CN 98810950 patent/CN1278927A/zh active Pending
  • 1998-10-27 CA CA002306267A patent/CA2306267A1/en not_active Abandoned
  • 1998-10-27 AU AU12811/99A patent/AU1281199A/en not_active Abandoned
  • 1998-10-27 JP JP2000519318A patent/JP2001521875A/ja active Pending

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