Optical waveguides – With optical coupler – Input/output coupler
Reexamination Certificate
2002-06-05
2004-11-09
Le, Thien M. (Department: 2876)
Optical waveguides
With optical coupler
Input/output coupler
Reexamination Certificate
active
06816645
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to bi-directional fiber optic communication systems and, more particularly, to a high reflection isolation device usable with such fiber optic systems.
2. Description of Related Art
Communication service providers are experiencing significant consumer demand to accommodate additional bandwidth in optically-based communication systems, and the demand is ever-increasing. In the future, all indications are that the use of fiber optic networks will become even more prevalent as a preferred medium for transferring information as the marketplace for wide-band services matures. It is anticipated that additional services such as enhanced pay-per-view, video-on-demand, interactive television and gaming, image networking, video telephony and CATV will be depend on and be substantial users of such systems.
Because capacity is a critical parameter for system viability, bi-directional systems are desirable when the increased capacity or other attributes afforded by a dual fiber pigtail (DFP) are required. Enabling bi-directional use of installed and developing fibers in fiber optic systems will permit communication service providers to gain additional utility from limited system resources.
Lasers are employed in numerous applications, particularly within fiber optic communication networks, in which a laser emits an information-carrying light signal to an optical fiber which transmits the light signal to a device for further processing. Typically, the optical signal propagates in one direction over a single optical fiber.
In the wavelength-division multiplexing (WDM) field, a filter is adapted to filter unwanted components of an incoming light signal. Assume, for example, that an incoming light signal contains two wavelengths, &lgr;
1
and &lgr;
2
, and is carried by a first fiber of a DFP. A filter which only allows signals with wavelength &lgr;
1
to pass will block signals with wavelength &lgr;
2
, so the transmission obtains good isolation. The reflected light signal is received by a second fiber of the DFP. The second fiber will pass &lgr;
2
to another device for processing, along with any miscellaneous components of the reflected light besides &lgr;
2
. Unfortunately, the reflected signal has poor isolation, resulting in increased complexity and difficulty when processing the reflected light signal.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a device to achieve high reflection isolation in a bi-directional fiber optic communication system.
A high reflection isolation device according to the present invention, includes a metal tube, a glass tube enclosed by the metal tub; a dual fiber pigtail (DFP) having a first fiber and a second fiber, a GRIN (graded index) lens engaging with the metal tube by an adhesive, a first filter mounted on a front end of the GRIN lens, and a second filter mounted between the dual fiber pigtail and the GRIN lens.
Further objects and advantages of the present invention will become more apparent from a consideration of the drawings and the following detailed description.
REFERENCES:
patent: 6347170 (2002-02-01), Zheng
patent: 6498876 (2002-12-01), Liu et al.
patent: 2002/0118920 (2002-08-01), Francis et al.
patent: 2003/0072527 (2003-04-01), Li et al.
patent: 2003/0103725 (2003-06-01), Li
patent: 2003/0185513 (2003-10-01), Hellman et al.
Chung Wei Te
Hon Hai - Precision Ind. Co., Ltd.
Le Thien M.
Taylor April
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