Glass material suitable for a waveguide of an optical amplifier

Details Glass material suitable for a waveguide of an optical amplifier Glass material suitable for a waveguide of an optical amplifier

2000-10-11

2002-07-02

Sample, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

C501S037000, C501S042000, C501S043000, C359S341430, C359S343000, C372S006000, C372S040000

Reexamination Certificate

active

06413891

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a glass; and more particularly to a glass doped with rare earth ions for use in an optical amplifier.
Description of the Prior Art
A silicate glass based on a quartz glass is dominantly used as a host glass of a gain medium fiber in optical amplifiers for optical communication. It has excellent properties on facilities of fiber fabrication, chemical stability and optical transparency. However, the fluorescence of silicate glass suffers from its high phonon energy in many cases. The transition with energy gap less than 4,500 cm
−1
is not capable of effectively performing laser oscillation or optical amplification in the silicate glass.
In order to overcome the above problems, a special glass, e.g., a fluoride or a chalcogenide glass, having low phonon energy has been proposed. However, the special glass still has some problems such as thermal stability, chemical durability, resistance to humidity.
Recently, there has been considerable attention paid to a tellurite glass which has phonon energy (600~800 cm
−1
) higher than those of the fluoride (400~500 cm
−1
) and the chalcogenide (300~400 cm
−1
) glasses, but lower than that of the silicate glass (1,100 cm
−1
). Therefore, the tellurite glass can suppress non-radiative transition through multi-phonon relaxation in the transition with energy gap of 3,500 cm
−1
or more. The tellurite glass has larger absorption and emission cross-sections than those of the silicate glass and the fluoride glass, thereby obtaining relatively strong fluorescence. Further, the tellurite glass has higher thermal stability, chemical durability and resistance to humidity than those of the fluoride and the chalcogenide glasses, thereby being expected to have relatively higher reliability when used in optical communication system.
U.S. Pat. No. 5,251,062 discloses a tellurite glass with a composition of: 58~84 mole % of TeO
2
, 0~24 mole % of Na
2
O and 10~30 mole % of ZnO. The tellurite glass may be applicable to an optical amplifier or a solid laser oscillator utilizing an optical fiber or other optical waveguide structures. The tellurite glass has several advantages as follows: it easily give a different refractive index to a core and a cladding; and to draw a preform made of the tellurite glass into an optical fiber with ease, while TeO
2
—ZnO—Li
2
O glasses proposed in the prior patent document (U.S. Pat. No. 3,836,871) are of compositions inapplicable to the optical fiber. U.S. Pat. No. 5,798,306 discloses rare-earth ion doped oxyhalide glass for laser, which comprises the substitution of fluorine for oxygen in the glass having a representative composition of 50 mole % of SiO
2
, 25 mole % of CaO and 25 mole % of Al
2
O
3
. When Er
2
O
3
can be doped with amounts of 0.01 mole % to 1.2 mole % (500 ppm ~5.68% by weight) into this glass. There is not concentration quenching in fluorescence. The fluorescence lifetime is longer in the fluorine-substituted glass than that of the pure oxide glass when same amounts of Er
2
O
3
are doped into both glasses.
U.S. Pat. No. 4,652,536 discloses glasses, which comprise 60~85 mole % of TeO
2
, 0~25 mole % of Li
2
O, 0~35 mole % of Na
2
O, 0~25 mole % of K
2
O, 0~25 mole % of Rb
2
O, 0~15 mole % of Cs
2
O, 0~10 mole % of MgO, 0~5 mole % of CaO, 0~5 mole % of SrO, 1~30 mole % of BaO, 0~30 mole % of ZnO, 0~30 mole % of PbO, and 0~5 mole % of La
2
O
3
+ZrO
2
+TiO
2
+Nb
2
O
5
+Ta
2
O
5
+WO
3
, wherein the amount of K
2
O+Rb
2
O+Cs
2
O is limited to 1~25 mole %, and the amount of ZnO+PbO is limited to 1~30 mole %. These glasses have lower light path difference with temperature change and enhanced figure of merit for acoustic optical devices than those of the prior glasses. These glasses may be used in acoustic optical devices such as light modulator and light path conversion devices, and can be also used as a glass with high refractive index or a glass with low melting point.
There have been other research results for tellurite glasses (See, J. S. Wang, E. M. Vogel and E. Snitzer, “Tellurite Glass: A New Candidate for Fiber Devices”, Optical materials, 3, 187-203(1994), D. L. Sidebottom, M. A. Hruschka, B. G. Potter and R. K. Brow, “Structure and Optical Properties of Rare-Earth-Doped Zinc Oxyhalide Glasses”, J. of Non-cryst. Solids, 222, 282-289(1997), Zhengda pan and Steven H. Morgan, “Raman Spectra and Thermal Analysis of A New Lead-Tellurium-Germanate Glass System” J. of Non-Cryst. Solids, 210, 130-135(1997)).
However, the tellurite glass still has a problem of being easily crystallized when heated up to a crystallization temperature, that is, between the glass transition temperature and the melting temperature. This problem may result in cutting off the optical fiber during the fiber drawing process. It may also largely increase an optical loss due to fine crystals within the optical fiber.
Therefore, there would be needed to solve the above-mentioned problem in the crystallization of the tellurite glass and to provide the tellurite glass with enhanced optical properties for light waveguide type optical amplifiers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a glass composition applicable to a gain medium glass for rare-earth ions doped light waveguide type amplifiers.
It is also another object of the present invention to provide a tellurite glass, which is hardly crystallized or phase-separated during the fabrication of an optical fiber, thereby being stable thermally and chemically.
In accordance with one aspect of the present invention, there are provided a glass material suitable for a waveguide of an optical amplifier, comprising: 20~70 mole % of TeO
2
; 1~30 mole % of In
2
O
3
or a combination of GeO
2
and In
2
O
3
oxide; 0.001~10 mole % of a rare earth ion dopant; 5~30 mole % of MO, M being a material selected from a group consisting of Mg, Ca, Sr, Ba, Zn and Pb; and optionally 1~20 mole % of R
2
O , R being a material selected from a group consisting of Li, Na, K, Rb and Cs.
In accordance with another aspect of the present invention, there are provided a glass material suitable for optical waveguide type amplifier, comprising: 20~70 mole % of TeO
2
; a heavy metal oxide; 0.001~10 mole % of a rare earth ion dopant; 5~30 mole % of MO, M being a material selected from a group consisting of Mg, Ca, Sr, Ba, Zn and Pb; optionally 1~20 mole % of R
2
O, R being a material selected from a group consisting of Li, Na, K, Rb and Cs; and 3~18 mole % of the metal oxide of MO or/and R
2
O is substituted by metal halide(s).


REFERENCES:
patent: 3883357 (1975-05-01), Cooley
patent: 4652536 (1987-03-01), Nakajima et al.
patent: 5093288 (1992-03-01), Aitken et al.
patent: 5251062 (1993-10-01), Snitzer et al.
patent: 5798306 (1998-08-01), Dickinson, Jr.
patent: 6194334 (2001-02-01), Aitken et al.
patent: 858 976 (1998-08-01), None
patent: 62-288135 (1987-12-01), None
patent: 08-110535 (1996-04-01), None
patent: 11-125725 (1999-05-01), None
patent: 11-228182 (1999-08-01), None
Lewis, Sr., Hawley's Condensed Chemical Dictionary, p. 587, 1993.*
Wang et al.Optical Materials, “Tellurite glass: a new candidate for fiber devices”, 3, (Aug. 1994), pp. 187-203.
Sidebottom et al.Journal of Non-crystalline Solids, “Structure and optical properties of rate earth-doped zinc oxyhalide tellurity glasses”, 222, (1997), pp. 282-289.
Wang et al.Journal of Non-Crystalline Solids, “Raman Spectra and Thermal Analysis of a New Lead-Tellurium-Germanate Glass System”, 210, (1997) p. 130-135.

Affiliated with

Also associated with

Rating

Glass material suitable for a waveguide of an optical amplifier does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Glass material suitable for a waveguide of an optical amplifier, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Glass material suitable for a waveguide of an optical amplifier will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2880849