Optical waveguides – Accessories – Splice box and surplus fiber storage/trays/organizers/ carriers
Reexamination Certificate
2002-04-22
2004-12-07
Lee, John D. (Department: 2874)
Optical waveguides
Accessories
Splice box and surplus fiber storage/trays/organizers/ carriers
C385S114000, C359S341100
Reexamination Certificate
active
06829426
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an optical repeater device and, in particular, to an erbium-doped fiber amplifier that uses a flexible optical circuit to amplify an optical signal.
2. Description of Related Art
An erbium-doped fiber amplifier (EDFA) is basically an optical repeater device that functions to boost the amplitude of optical signals traveling through a fiber optic communications system. In particular, the EDFA incorporates a variety of components including a laser diode, a multiplexer and an optical fiber which is doped with the rare earth element erbium. The laser diode emits light having an infrared wavelength of 980 nm or 1480 nm that is passed through the multiplexer into the erbium-doped optical fiber. The emitted light excites the erbium atoms in the optical fiber. Then when an input optical signal having a wavelength of between 1530 nm and 1620 nm passes through the multiplexer and enters the optical fiber it stimulates the excited erbium atoms to emit photons at the same wavelength as the input optical signal. This action amplifies the input optical signal to a higher power by effectively boosting the amplitude of the input optical signal. Examples of two traditional EDFAs
100
and
200
are briefly discussed below with respect to
FIGS. 1 and 2
.
Referring to
FIG. 1
(PRIOR ART), there is a block diagram illustrating the basic components of a traditional EDFA
100
. The EDFA
100
includes a variety of components including a laser diode
102
, a multiplexer
104
and a custom-designed bobbin
106
that holds a predetermined length of erbium-doped optical fiber
108
. The optical fiber
108
which can be relatively long (e.g., ~50 m) is wrapped around the bobbin
106
before being placed in a package
110
. The package
110
contains the various components that make-up the EDFA
100
including the laser diode
102
, the multiplexer
104
and the bobbin
106
. In operation, the EDFA
100
receives an input optical signal
112
that is coupled by the multiplexer
104
along with the light from the laser diode
102
into the erbium-doped optical fiber
108
which becomes excited by the light from the laser diode
102
and outputs an amplified optical signal
114
.
Unfortunately, there are a number of disadvantages associated with using the bobbin
106
to hold the optical fiber
108
. First, the bobbin
106
needs to be custom designed so it can fit within the package
110
. Secondly, the bobbin
106
itself is bulky and restricts the overall outline of the package
110
. Thirdly, the optical fiber
108
may be stressed if the optical fiber
108
is wrapped to tight around the bobbin
106
. As such, the custom-designed bobbin
106
delays and adds complexity to the design of the EDFA
100
and can also adversely affect the operability of the EDFA
100
.
Referring to
FIG. 2
(PRIOR ART), there is a block diagram illustrating the basic components of another traditional EDFA
200
. The EDFA
200
includes a variety of components including a laser diode
202
, a multiplexer
204
and a predetermined length of erbium-doped optical fiber
206
that is held together by a fastener
208
including, for example, wire, string, tape, or glue (shown and described below as three wires/strings
208
). Prior to being inserted into the EDFA
200
, the optical fiber
206
which can be relatively long (e.g., ~50 m) is wrapped around a customed-designed fixture
210
(e.g., bobbin) (see exploded view). Once the desired length of optical fiber
206
is wrapped around the fixture
210
, then the optical fiber
206
is removed from the fixture
210
and the loose coil of optical fiber
206
is contained by the wire/string
208
(see exploded view). The optical fiber
206
that is held together by the wire/string
208
is then placed in a package
212
. The package
212
contains the various components that make-up the EDFA
200
including the laser diode
202
, the multiplexer
204
and the optical fiber
206
. In operation, the EDFA
200
receives an input optical signal
214
that is coupled by the multiplexer
204
along with the light from the laser diode
202
into the erbium-doped optical fiber
206
which becomes excited by the light from the laser diode
202
and outputs an amplified optical signal
216
.
Unfortunately, there are a number of disadvantages associated with using the fixture
210
to wrap the optical fiber
206
and for using the wire/string
208
to contain the optical fiber
206
. First, the fixture
210
needs to be custom designed such that the coil of optical fiber
208
has the desired diameter so it can fit within the package
212
. Secondly, the optical fiber
206
may be stressed if the optical fiber
206
is wrapped to tight around the fixture
210
. Thirdly, the optical fiber
206
may be stressed if the wire/string
208
is wrapped to tight around the optical fiber
206
. As such, the custom-designed fixture
210
delays and adds complexity to the design of the EDFA
200
and the use of wire/string
208
to hold the loose coil of optical fiber
206
can adversely affect the operability of the EDFA
200
. Accordingly, there is a need for a new way to wrap and support the optical fiber that is placed inside the package of an EDFA. This need and other needs are satisfied by the flexible optical circuit and the method of the present invention.
BRIEF DESCRIPTION OF THE INVENTION
The present invention includes an erbium-doped fiber amplifier, a flexible optical circuit and a method for fabricating the flexible optical circuit. Basically, the erbium-doped amplifier includes a laser diode, a multiplexer and a flexible optical circuit. The flexible optical circuit in one embodiment includes a predetermined length of optical fiber that is placed onto and secured to a partially flexible sheet of material. Several different embodiments of the flexible optical circuit are described herein. In operation, the erbium-doped amplifier receives an optical signal that is coupled by the multiplexer along with a light from the laser diode into the erbium-doped optical fiber which becomes excited by the light from the laser diode and outputs an amplified optical signal.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention may be had by reference to the following detailed description when taken in conjunction with the accompanying drawings wherein:
FIG. 1
(PRIOR ART) is a block diagram illustrating the basic components of a traditional EDFA;
FIG. 2
(PRIOR ART) is a block diagram illustrating the basic components of another traditional EDFA;
FIG. 3
is a block diagram illustrating the basic components of an EDFA in accordance with the present invention;
FIG. 4
illustrates a top view and a cross-sectional side view of a flexible optical circuit that can be used in the EDFA shown in
FIG. 3
;
FIG. 5
is a flowchart illustrating the basic steps of a preferred method for fabricating the flexible optical circuit shown in
FIG. 4
;
FIG. 6A
illustrates a top view and a cross-sectional side view of a first embodiment of the flexible optical circuit that can be used in the EDFA shown in
FIG. 3
;
FIG. 6B
is a flowchart illustrating the basic steps of a preferred method for fabricating the first embodiment of the flexible optical circuit shown in
FIG. 6A
;
FIG. 7A
illustrates a top view and a cross-sectional side view of a second embodiment of the flexible optical circuit that can be used in the EDFA shown in
FIG. 3
;
FIG. 7B
is a flowchart illustrating the basic steps of a preferred method for fabricating the second embodiment of the flexible optical circuit shown in
FIG. 7A
;
FIG. 8A
illustrates a top view and a cross-sectional side view of a third embodiment of the flexible optical circuit that can be used in the EDFA shown in
FIG. 3
;
FIG. 8B
is a flowchart illustrating the basic steps of a preferred method for fabricating the third embodiment of the flexible optical circuit shown in
FIG. 8A
;
FIG. 9A
illustrates a top view and a cross-sectional side view of a
Kobler George P.
Lanier Ford Shaver & Payne P.C.
Lee John D.
Lin Tina
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