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AssigneeNP Photonics, Inc.
InventorsShibin Jiang, Karine Seneschal, Tao Luo
Estimating the term…
Phosphate glass fibers are an attractive alternative to silica fibers because they can be co-doped with much higher concentrations of Yb and Er and exhibit a higher optical gain per unit length. However, in such fibers the absorption of the pump is high and heating effects caused by the pump laser can cause a significant change in refractive index. This problem is overcome with a phosphate glass composition that exhibits a temperature coefficient of refractive index β=dn/dT close to zero. This is achieved by avoiding alkali metal oxides in the glass composition and by adjusting the concentration of the network modifiers such as BaO.
A phosphate glass composition comprising the following ingredients,
A phosphate glass composition comprising the following ingredients,
An optical fiber amplifier, comprising:
Dependencies are inferred from the claim text.
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Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering: fibre compositions or doping with active elements
The pumped medium being a fibre: side pumped fibre, whereby pump light is coupled laterally into the fibre via an optical component like a prism,…
Rare earth: erbium
Amorphous, e.g. glass: phosphate glass
Term end not estimated
1. Field of the Invention
This invention relates to alkali-metal-free phosphate glasses and more specifically to glasses that exhibit a temperature coefficient of refractive index (β=dn/dT) close to zero for use in fiber amplifiers.
2. Description of the Related Art
FIGS. 1a through 1d, as described above, are illustrations of a solid-state flashlamp pumped laser;
FIG. 2, as described above, is an illustration of a conventional fiber amplifier;
FIG. 3a is a diagram of an alkali-metal-free phosphate glass in accordance with the present invention;
Phosphate glass fibers are an attractive alternative to silica fibers because they can be co-doped with much higher concentrations of Yb and Er and exhibit a higher optical gain per unit length. The absorption of the pump is high and heating effects caused by the pump laser can cause a significant change in refractive index. This heating effect is even more important when low cost high power multimode pumping is used. Holding the pump at a setpoint temperature through active cooling may still induce a thermal gradient across the fiber sufficient to distort the fiber's mode profile.
A negative temperature coefficient of the refractive index can have an adverse effect on the waveguide mode properties of the signal. Therefore, a temperature coefficient of refractive index β=dn/dT close to zero, e.g. suitably from −2.0×10−6 to +2.0×10−6 K−1 and preferably −1.0×10−6 to +1.0×10−6 K−1, is desired in phosphate glass compositions for fiber amplifiers. This is achieved by avoiding alkali metal oxides in the glass composition and by adjusting the concentration of the network modifiers such as BaO. Alkali-metal-free glass has demonstrated improved mechanical and chemical durability. Maintaining a temperature coefficient of the optical path length is not as critical as in a laser glass since the beam in the fiber amplifier is confined by the cladding layer. Nonetheless, a fiber amplifier for telecommunication application has to pass a standard Bellcore test, where the temperature changes from −40° C. to 80° C.
Alkali-Metal-Free Phosphate Glass