Codopant polymers for efficient optical amplification

Details Codopant polymers for efficient optical amplification Codopant polymers for efficient optical amplification

2000-11-28

2003-03-25

Hellner, Mark (Department: 3663)

Optical: systems and elements

Optical amplifier

Optical fiber

C372S006000, C501S045000, C252S30140P

Reexamination Certificate

active

06538805

ABSTRACT:

DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fiber optics and fiber optic waveguides. In particular, this invention relates to rare earth polymer compositions, for use in optical fibers and optical waveguides.
2. Background of the Invention
As fiber optics are increasingly employed in long distance communications, metropolitan network and local access communications, there is an increasing need for efficient, compact optical amplification.
Optical communication systems based on glass optical fibers (GOFs) allow communication signals to be transmitted not only over long distances with low attenuation but also at extremely high data rates, or bandwidth capacity. This capability arises from the propagation of a single optical signal mode in the low-loss windows of glass located at the near-infrared wavelengths of 0.85, 1.3, and 1.55 &mgr;m. Present technology has moved to erbium doped fused silica fiber for optical amplification. Since the introduction of erbium-doped fiber amplifier (EDFA), the last decade has witnessed the emergence of single-mode GOF as the standard data transmission medium for wide area networks (WANs), especially in terrestrial and transoceanic communication backbones. In addition, the bandwidth performance of single-mode GOF has been vastly enhanced by the development of dense wavelength division multiplexing (DWDM), which can couple up to 160 channels of different wavelengths of light into a single fiber, with each channel carrying gigabits of data per second. Moreover, a signal transmission of 1 terabit (10
12
bits) per second was achieved over a single fiber on a 100-channel DWDM system. Enabled by these and other technologies, the bandwidth capacities of the communication networks are increasing at rates of as much as an order of magnitude per year.
The success of single-mode GOF in long-haul communication backbones has given rise to the new technology of optical networking. The universal objective is to integrate voice, video, and data streams over all-optical systems as communication signals make their way from WANs down to smaller local area networks (LANs), down to the curb (FTTC), home (FTTH), and finally to the end user by fiber to the desktop (FTTD). Examples are the recent explosion of the Internet and use of the World Wide Web, which are demanding higher bandwidth performance in short- and medium-distance applications. Yet as the optical network nears the end user, starting at the LAN stage the system is characterized by numerous fiber connections, splices, and couplings, especially those associated with splitting of the input signal into numerous channels. All of these introduce optical loss. To compensate for the loss penalty, current solutions rely on expensive EDFAs that are bulky at fiber lengths of about 40 m. The cost of a typical commercial EDFA can reach many tens of thousands of dollars. Thus, to complete the planned build-out for FTTC, and FTTD in the U.S. would require millions of amplifiers and hundreds of billions of dollars.
An EDFA module is made up of a number of components. One of the most critical components in the module is the erbium doped silica fiber (EDF). Present EDF is limited by low concentrations of erbium atoms (maximum is about 0.1%), clustering that leads to quenching of photoluminescence, a relatively narrow emission band, a highly wavelength dependent gain spectrum, and an inability to be fabricated in a compact, planar geometry. Efforts have been directed toward the use of other rare earth ions in both fused silica glass hosts and other glasses including fluoride, tellurite and phosphate glasses. To this point, these efforts have been limited by the fundamental materials properties of these glass media with regard to their ability to dissolve rare earth atoms, mechanical properties, thermal stability, and other key properties.
Certain embodiments of the present invention comprise rare earth fluorphosphinate polymer material that comprise the following preferred properties:
compatibility with a broad range of rare earths that enable coverage of the full 1500 to 1600 nm window (and beyond) using a common host platform;
very high concentrations of rare earth elements without associated quenching and upconversion penalties, allowing for short lengths of fiber to be used as small as centimeters and less;
low intrinsic optical loss;
capable of being drawn into single mode optical fiber; and
capable of being cast into films for planar waveguide applications.
Cost effective, compact integrated optics is a solution to this problem, but currently is non-existent. Resulting is the need for very long lengths of this fiber (tens of meters) in actual use. There is a need for an efficient, compact, broadband amplifying medium to accommodate lower power pumping, reduce packaging problems, and increase network capacity.
It would also be beneficial to provide novel optical waveguide materials that are easy to process using standard silicon VLSI (very large scale integration) fabrication methods and optical fiber drawing processes. Further, it would also be beneficial to produce a fiber amplifier and material therefore having low-loss in short and medium distance communications network systems. Additionally, it would be beneficial to produce an integrated optical component that is a low-loss splitter that combines amplification and splitting of the input signal while maintaining a high signal-to-noise ratio.
SUMMARY OF THE INVENTION
In accordance with the invention, the present invention provides for a polymer comprising at least one unit comprising a first rare earth element, a second rare earth element, at least one of the elements of Group VIA, at least one of the elements of Group V
A
, a first fully halogenated organic group, a second fully halogenated organic group.
In another embodiment of the present invention there is a method of manufacturing a polymer comprising providing a sodium salt of a fully halogenated substituted acid in a first solvent, for example acetone, the sodium salt comprising a general composition and comprising at least one of the elements of Group VI
A
, at least one of the elements of Group V
A
, a first fully halogenated organic group, a second fully halogenated organic group, providing a first rare earth chloride in a second solvent, for example, dry acetone, providing a second rare earth chloride in a third solvent, for example dry acetone, combining the sodium salt in the first solvent, the first rare earth chloride in the second solvent, and the second rare earth chloride in the third solvent together to form a mixture, stirring the mixture in an atmosphere, for example under nitrogen, for a predetermined period of time at a predetermined temperature, adding a dilutent, for example distilled water to the mixture, boiling the aqueous solution, filtering the aqueous solution, washing the aqueous solution with a rinsing agent for example, boiling water, forming a washed product, and drying the washed product.
While a first and second rare earth are stated, it is contemplated that the first and second rare earth elements can be the same or different rare earth elements. Additionally, as a first and second fully halogenated organic group are stated, it is contemplated that the first and second fully halogenated organic groups are the same or different fully halogenated organic group.
In certain embodiments of the present invention there is an optical amplifying fiber assembly provided comprising a fiber formed from a first polymer and comprising a first diameter and a first refractive index, having a cladding disposed about an outer perimeter of the fiber, the cladding comprising a second diameter and a second refractive index less than the first refractive index.
In certain embodiments of the present invention there is an optical waveguide provided comprising a substrate, a first cladding layer on the substrate, the first cladding layer comprising a first refractive index. The optical waveguide also comprising a first polymer on the first claddi

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