Optical: systems and elements – Optical amplifier – Optical fiber
Reexamination Certificate
1997-03-03
2001-04-10
Hellner, Mark (Department: 3662)
Optical: systems and elements
Optical amplifier
Optical fiber
C385S134000, C385S135000
Reexamination Certificate
active
06215582
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to light amplifier devices, and more particularly to a light amplifier device having an optical amplifier medium such as an optical fiber with a rare-earth element doped.
2. Description of the Related Art
FIG. 1
is a diagram of a conventional light amplifier device having an optical fiber with a rare-earth element doped. A light amplifier device
9
shown in
FIG. 1
includes an optical fiber
5
with a rare-earth element doped. For example, the optical fiber
5
is an erbium-doped optical fiber. A signal light
9
A is applied to the erbium-doped optical fiber via an optical isolator
1
a
and an optical multiplexer
2
a
, which is also called a wavelength-division multiplexing (WDM) coupler. An exciting light (pumping light)
9
C is emitted from an exciting light source
3
a
, and is forwardly applied to the erbium-doped optical fiber via the optical multiplexer
2
a
. An exciting light source
3
b
emits another exciting light
9
C, which is backwardly applied to the erbium-doped optical fiber
5
via an optical multiplexer
2
b
. The exciting lights
9
C cause an inverted distribution of energy in the erbium-doped optical fiber
5
. A control circuit
4
controls the output level and timing of the exciting lights
9
C emitted from the exciting light sources
3
a
and
3
b
.The erbium-doped optical fiber
5
amplifies the signal light
9
A due to induced emission. The amplified light signal passes through the optical multiplexer
2
b
and an optical isolator
1
b.
Generally, the above structural components of the light amplifier device
9
are module components which stand alone therein. That is, in the device there are separately provided the erbium-doped optical fiber
5
, the exciting light sources
3
a
and
3
b
, the optical multiplexers
2
a
and
2
b
and the optical isolators
1
a
and
1
b
. Hence, it is very difficult to realize down sizing of the light amplifier device
9
. The modules are optically connected together by optical fibers, which are connected to the modules by a splice method (which is a thermal fusion method in which the optical fibers are heated). It will be noted that the connecting work is very troublesome. As the number of optical components of the light amplifier device
9
increases, the yield of the production decreases and the reliability degrades.
Further, there is another problem resulting from a requirement in which the radius of curvature of the optical fibers connecting the optical components together is equal to or greater than 30 mm. This requirement makes it difficult to arrange the optical fibers in the light amplifier device
9
A (fiber homing) and prevents down sizing of the device
9
A.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a light amplifier device in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide a down-sized, highly reliable, highly producible light amplifier device.
The above objects of the present invention are achieved by a light amplifier device comprising: a module body to which an exciting source, an optical multiplexer and an optical isolator are attached; and an optical fiber having a light amplifying function, the optical fiber being wound around the module body.
The light amplifier device may further comprise a photodiode for monitoring a light in the light amplifier device, the photodiode being attached to the module body.
The light amplifier device may further comprise a filter for allowing a light component having a given wavelength to pass therethrough, the filter being attached to the module body.
The light amplifier device may further comprise a control circuit having a circuit board which controls the exciting light source, the circuit board being attached to the module body.
The light amplifier device may further comprise a distribution compensating optical fiber via in which an incoming signal light to be amplified by the light amplifier device or an amplified signal light to be output from the light amplifier device is transferred, the distribution compensating optical fiber being wound around the module body.
The light amplifier device may be configured so that the module body has a cylindrically shaped portion around which the optical fiber having the light amplifying function is wound.
The light amplifier device may further comprise a board on which the exciting source, the optical multiplexer and the optical isolator are mounted, the board being accommodated in a hollow portion of the module body.
The light amplifier device may be configured so that: the module body has a cylindrically shaped portion around which the optical fiber having the light amplifying function is wound; and the light amplifier device further comprises a board on which the exciting source, the optical multiplexer and the optical isolator are mounted, the board being accommodated in a hollow portion of the module body.
The above-mentioned objects of the present invention are achieved by a light amplifier device comprising: a module body to which an exciting source, an optical multiplexer and an optical isolator are attached; and a silica-based optical waveguide member which has a light amplifying function and is mounted on the module body.
The light amplifier device may further comprise a photodiode for monitoring a light in the light amplifier device, the photodiode being attached to the module body.
The light amplifier device may further comprise a filter for allowing a light component having a given wavelength to pass therethrough, the filter being attached to the module body.
The light amplifier device may further comprise a control circuit having a circuit board which controls the exciting light source, the circuit board being attached to the module body.
The light amplifier device may further comprise a distribution compensating optical fiber via which an incoming signal light to be amplified by the light amplifier device or an amplified signal light to be output from the light amplifier device is transferred, the distribution compensating optical fiber being wound around the module body.
The light amplifier device may be configured so that the silica-based optical waveguide member has an optical path which has the light amplifying function and has a spiral formation.
The above-mentioned objects of the present invention are also achieved by a light amplifier device comprising: a module body; a silica-based optical waveguide member which has a light amplifying function and an optical multiplexer and is mounted on the module body; and an optical isolator and an exciting light source directly attached to the silica-based optical waveguide member.
The light amplifier device may further comprise a photodiode for monitoring a light in the light amplifier device, the photodiode being attached to the silica-based optical waveguide member.
The light amplifier device may further comprise a filter for allowing a light component having a given wavelength to pass therethrough, the filter being attached to the silica-based optical waveguide member.
The light amplifier device may further comprise a control circuit having a circuit board to control controlling the exciting light source, the circuit board being attached to the silica-based optical waveguide member.
The light amplifier device may further comprise a distribution compensating optical fiber via which an incoming signal light to be amplified by the light amplifier device or an amplified signal light to be output from the light amplifier device is transferred, said distribution compensating optical fiber being wound around the module body.
The light amplifier device may be configured so that the silica-based optical waveguide member has an optical path which has the light amplifying function and has a spiral formation.
REFERENCES:
patent: 5383051 (1995-01-01), Delrosso et al.
patent: 5515200 (1996-05-01), Delrosso et al.
patent: 5642219 (1997-06-01), Ogiya et al.
patent: 5703990 (
Sudo Satoshi
Tomita Takaharu
Fujitsu Limited
Hellner Mark
Staas & Halsey
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