Title of Invention

OPTICAL FIBER, TRANSMISSION SYSTEM AND MULTIPLE WAVELENGTH TRANSMISSION SYSTEM

Abstract An optical fiber (1) is provided with a core (2, 3) at the center and a clad (4) on the outer circumference of the core (2, 3). The core (2, 3) is provided with at least one layer of codoped layer (2) composed of a quarts glass wherein germanium and fluorine are added, and at least one layer of low concentration codoped layer (3) composed of a quartz glass wherein germanium is added or a quartz glass wherein germanium and fluorine of a smaller quantity than that added in the codoped layer (2) are added.
Full Text DESCRIPTION
TECHNICAL FIELD
The present invention relates to an optical fiber that suppresses the occurrence of
Simulated Brillouin Scattering (hereinafter referred to as SBS) to allow transmission with
higher-power signals. The present invention also relates to a transmission system and a
wavelength division multiplexing system using this optical fiber.
Priority is claimed on Japanese Patent Application No. 2004-308359 filed on
October 22, 2004, Japanese Patent Application No. 2005-55669 filed on March 1, 2005,
and Japanese Patent Application No. 2005-208687 filed on July 19,2005, the contents of
which are incorporated herein by reference.
BACKGROUND ART
Nowadays, a fiber to the home (hereinafter referred to as FTTH) service is
available in which optical fibers are extended to individual homes to be used for
exchange of various information.
As one form of FTTH that transmits various information, there is a system in
which a broadcast signal and another communication signal are simultaneously
transmitted in different systems by means of a single optical fiber (ITU-T
Recommendation G.652). Generally in this system, the broadcast signal is often an
analog signal or a baseband signal.
The characteristics of the system having an optical fiber as a transmission
medium are as follows:

- FTTH is typically a double-star type PON (Passive Optical Network), and has a large
distribution loss (typically, up to 32 branches are assumed).
- Since FTTH transmits an analog signal or a baseband signal, a CNR (Carrier Noise
Ratio) in the receiver is required to be high, and the required minimum signal light power
in the light receiving portion is larger compared with the case of digital transmission used
for communication.
From the viewpoint described above , in this system, the signal light power in
the signal input portion needs to be large.. Especially in consideration of attenuation and
distribution loss during transmission of a signal light, higher power is required in a line
with a longer distance or more branches. If a signal can be transmitted as far as possible
and distributed to many subscribers at a time, it is more advantageous from various
points of view (construction costs, maintainability, system design, etc.).
However, in an optical transmission using an optical fiber, even if light with
more than a certain power is intended to be injected into an optical fiber, SBS, which is
one type of non-linear phenomenon, allows the entrance of light with a certain amount of
power(hereinafter, referred to as SBS threshold power) or less and the rejected light is
returned to the entrance light side as backscattered light. This phenomenon sometimes
puts restrictions on signal light power in the input portion, thus posing a problem (for
example, see Non-Patent Document 1).
Conventionally, as methods for achieving SBS suppression, techniques for
modifying optical characteristics in the longitudinal direction, the dopant concentrations,
and the residual stress have been reported (see, for example, Patent Document 1 and
Non-Patent Document 2).
Non-Patent Document 1: A. R. Charaplyvy, J. Lightwave Technol., vol. 8, pp. 1548-1557
(1990)

Patent Document 1: United States Patent No. 5,267, 339
Non-Patent Document 2: K. Shiraki, et al., J. Lightwave Technol, vol. 14, pp. 50-57
(1996)
DISCLOSURE OF THE INVENTION
PROBLEM TO BE SOLVED BY THE INVENTION
However, the SBS suppression methods described in Patent Document 1 and
Non-Patent Document 2 inevitably modify optical characteristics in the longitudinal
direction of optical fibers, which makes the methods undesirable in practice.
The present invention has been achieved in view of the above circumstances,
and has an object to provide an optical fiber that can enhance the SBS threshold power
compared to conventional optical fibers, and to provide a transmission system and
wavelength division multiplexing system using the same.
MEANS FOR SOLVING THE PROBLEM
To achieve the above-mentioned object, the present invention provides an
optical fiber comprising a center core and a cladding located at an outer periphery of the
core, wherein the core comprises at least one codoped layer made from silica glass doped
with germanium and fluorine, and at least one lower-concentration codoped layer made
from silica glass doped with germaniµm, or silica glass that is doped with germanium
and fluorine wherein a dope amount of the fluorine is smaller than a dope amount of the
fluorine in the codoped layer.
In the optical fiber according to the present invention, preferably, the core
comprises an inner core located in the vicinity of the center and an outer core provided at
an outer periphery of the inner core, the inner core comprises a codoped layer made from

silica glass doped with germanium and fluorine, and the outer core comprises a
lower-concentration codoped layer made from silica glass doped with germaniµm, or
silica glass that is doped with germanium and fluorine wherein a dope amount of the
fluorine is smaller than a dope amount of the fluorine in the inner core.
In the optical fiber according to the present invention, preferably, the cladding is
made from non-doped silica glass.
Preferably, in the optical fiber of the present invention, fluorine is doped into a
part of the cladding.
Preferably, in the optical fiber of the present invention, the cladding comprises
an inner cladding provided at an outer periphery of the core and an outer cladding
provided at an outer periphery of the inner cladding, and the relationship: ncl supposing that a refractive index of the inner cladding is ncl and a refractive index of the
outer cladding is nc2.
Preferably, in the optical fiber of the present invention, the cladding comprises
an inner cladding provided at an outer periphery of the core, a trench layer provided at an
outer periphery of the inner cladding, and an outer cladding provided at an outside of the
trench layer, and the relationships:nc2 index of the inner cladding is nc1, a refractive index of the trench layer is nC2, and a
refractive index of the outer cladding is nc3.
Preferably, in the optical fiber of the present invention, a concentration of the
germanium is in a range between 4% and 15% by mass in terms of germanium oxide, and
a concentration of the fluorine is in a range between 0.2% and 5% by mass, in the inner
core.
Preferably, in the optical fiber of the present invention, a ratio of an inner core
diameter and an outer core diameter is in a range between 0.10 and 0.85.

Preferably, in the optical fiber of the present invention, the ratio of the inner core
diameter and the outer core diameter is in a range between 0.25 and 0.70.
In the optical fiber of the present invention, optical refractive indices of the inner
core and the outer core may be configured to be substantially the same.
Preferably, in the optical fiber of the present invention, an average of relative
refractive index differences with respect to the cladding of the inner core and the outer
core is in a range between 0.30% and 0.60%, and an outer core diameter is in a range
between 6.0 µm and 10.5 µm.
Preferably, in the optical fiber of the present invention, the core comprises a first
core located in the vicinity of the center, a second core provided at an outer periphery of
the first core, and a third core provided at an outer periphery of the second core, the first
core and the third core comprise a codoped layer made from silica glass doped with
germanium and fluorine, and the second core comprises a lower-concentration codoped
layer made from silica glass doped with germaniµm, or silica glass that is doped with
germanium and fluorine wherein a dope amount of the fluorine is smaller than a dope
amount of the fluorine in the inner core.
Preferably, in the optical fiber of the present invention, the relationships: nfl >
nf2 and nf3 > nf2 hold, supposing that a fluorine concentration of is nf1 % by mass, a
fluorine concentration of the second core is nf2 % by mass, and a fluorine concentration
of the third core is nf3 % by mass.
In the above optical fiber, nf1 and nf3 may be substantially the same.
In the above optical fiber, the relationship: nf1 In the above optical fiber, the relationship: nf1 > nf3 may hold.
Preferably, in the optical fiber of the present invention, optical characteristics
satisfy the requirements of ITU-T Recommendation G.652.

Furthermore, the present invention provides a transmission system configured to
perform an analog signal transmission or a baseband transmission using the
above-mentioned optical fiber according to the present invention described above.
Furthermore, the present invention provides a wavelength division multiplexing
system configured to perform a data transmission and/or a voice transmission, in addition
to an analog signal transmission and/or a baseband transmission using the
above-mentioned optical fiber according to the present invention described above.
ADVANTAGEOUS EFFECTS OF THE INVENTION
The present invention can provide an optical fiber that suppresses the occurrence
of SBS to allow transmission with higher power signals, and a transmission system and a
wavelength division multiplexing system that enable multi-branched, long-distance
transmission using the optical fiber.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 is a cross-sectional view showing one embodiment of the optical fiber of
the present invention.
FIG. 2 is a graph showing the relationship among the ratios of inner core
diameter/outer core diameter, the inner core Ge concentrations, and the threshold power
of the optical fibers prototyped in Examples.
FIG. 3 A is a diagram illustrating the refractive index profile of an optical fiber
of the present invention.
FIG. 3B is a diagram illustrating the refractive index profile of an optical fiber of
the present invention.
FIG. 3C is a diagram illustrating the refractive index profile of an optical fiber of

the present invention.
FIG. 3D is a diagram illustrating the refractive index profile of an optical fiber
of the present invention.
FIG. 3E is a diagram illustrating the refractive index profile of an optical fiber of
the present invention.
FIG. 3F is a diagram illustrating the refractive index profile of an optical fiber of
the present invention.
FIG. 4A is graph showing the Ge concentration profile of an optical fiber
according to conventional techniques in a second embodiment.
FIG. 4B is graph showing the F concentration profile of the optical fiber
according to the conventional techniques in the second embodiment.
FIG. 4C is graph showing the refractive index difference profile of the optical
fiber according to the conventional techniques in the second embodiment.
FIG. 5 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 4A-C.
FIG. 6A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in the second embodiment.
FIG. 6B is graph showing the refractive index profile and the F concentration
profile of the optical fiber according to the technique of the present invention in the
second embodiment.
FIG. 6C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the second embodiment.
FIG. 7 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 6A-C.
FIG. 8A is graph showing the Ge concentration profile of an optical fiber

according to conventional techniques in a third embodiment.
FIG. 8B is graph showing the F concentration profile of the optical fiber
according to the conventional techniques in the third embodiment.
FIG. 8C is graph showing the refractive index difference profile of the optical
fiber according to the conventional techniques in the third embodiment.
FIG. 9 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 8A-C.
FIG. 10A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in the third embodiment.
FIG. 10B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the third embodiment.
FIG. 10C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the third embodiment.
FIG. 11 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 10A-C.
FIG. 12A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a forth embodiment.
FIG. 12B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the forth embodiment.
FIG. 12C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the forth embodiment.
FIG. 13 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 12A-C.
FIG. 14A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a fifth embodiment.

FIG. 14B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the fifth embodiment.
FIG. 14C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the fifth embodiment.
FIG. 15 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 14A-C.
FIG. 16A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a sixth embodiment.
FIG. 16B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the sixth embodiment.
FIG. 16C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the sixth embodiment.
FIG. 17 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 16A-C.
FIG. 18A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a seventh embodiment.
FIG. 18B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the seventh embodiment.
FIG. 18C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the seventh embodiment.
FIG. 19 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 18A-C.
FIG. 20 A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in an eighth embodiment.
FIG. 20B is graph showing the F concentration profile of an optical fiber

according to the technique of the present invention in the eighth embodiment.
FIG. 20C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the eighth embodiment.
FIG. 21 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 20A-C.
FIG. 22A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a ninth embodiment.
FIG. 22B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the ninth embodiment.
FIG. 22C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the ninth embodiment.
FIG. 23 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 22A-C.
FIG. 24A is graph showing the Ge concentration profile of an optical fiber
according to the technique of the present invention in a tenth embodiment.
FIG. 24B is graph showing the F concentration profile of an optical fiber
according to the technique of the present invention in the tenth embodiment.
FIG. 24C is graph showing the refractive index difference profile of the optical
fiber according to the technique of the present invention in the tenth embodiment.
FIG. 25 is a graph showing the relative Brillouin gain spectrum of the optical
fiber shown in FIGS. 24A-C.
FIG. 26 shows a transmission system (wavelength division multiplexing system)
configured using the optical fiber of the present invention.
DESCRIPTION OF THE REFERENCE SYMBOLS

1 ... Optical fiber
2 ... Inner core
3 ... Outer core
4 ... Cladding
10 ... Optical transmission system (wavelength division multiplexing system).
BEST MODE FOR CARRYING OUT THE INVENTION
Hereunder is a description of embodiments of the present invention with
reference to the drawings.
FIG. 1 is a diagram showing one embodiment of the optical fiber according to
the present invention. An optical fiber 1 of this embodiment comprises an inner core 2
that is made from silica glass doped with germanium and fluorine, an outer core 3 that is
provided at the outer periphery of the inner core 2 and is made from silica glass doped
with germaniµm, or silica glass that is doped with germanium and fluorine wherein the
dope amount of fluorine is smaller than the dope amount of fluorine in the inner core 2,
and a cladding 4 that is provided at the outer periphery of the outer core 3. This structure
can suppress the occurrence of SBS that is problematic in transmission through optical
fibers, increase the SBS threshold power, and allow transmission with higher-power
signals.
Preferably, the concentration of germanium is in a range between 4% and 15%
by mass in terms of germanium oxide, and the concentration of fluorine is in a range
between 0.2% and 5% by mass, in the inner core 2. If the concentrations of germanium
and fluorine in the inner core 2 are greater than the above ranges, the transmission loss in
the optical fiber 1 is increased due to an increase in the Rayleigh scattering, which may
become problematic in practice. In contrast, the concentrations of germanium and

fluorine in the inner core 2 are smaller than the above ranges, the advantage of increasing
SBS threshold power may become smaller, which may hinder achieving the objects of
the present invention.
Furthermore, it is desired that the ratio of the inner core diameter and the outer
core diameter be in a range between 0.10 and 0.85. By setting the ratio of the inner core
diameter and the outer core diameter within the above range, an SBS threshold power of
about 1.5 times higher than those of typical single-mode optical fibers (hereinafter
referred to as typical SM optical fibers) can be obtained.
Furthermore, it is more preferable that the ratio of the inner core diameter and
the outer core diameter be in a range between 0.25 and 0.70. By setting the ratio of the
inner core diameter and the outer core diameter within the above range, it becomes
possible to increase the SBS threshold power about 2 times higher than those of typical
SM optical fibers.
Furthermore, it is desired that the optical refractive indices of the inner core 2
and the outer core 3 be substantially the same. If the optical refractive indices of the
inner core 2 and the outer core 3 are different, the waveguide dispersion (also known as
structure dispersion) in the optical fiber shifts to the longer-wavelength side, which may
make controlling optical characteristics within desired ranges difficult. Here, "optical
refractive indices are substantially the same" assumes that each difference of refractive
indices is about 0.07% or less in terms of relative refractive index difference (Δ).
However, since the inner core 2 and the outer core 3 may have some degree of
unevenness of the refractive indices in the radial direction caused by non-uniformity in
manufacturing. It should be noted that making comparisons among average refractive
indices of the inner core 2 and the outer core 3 is appropriate. It should be also noted
that, here, a "desired range" means a range that satisfies the requirements of ITU-T

Recommendation G.652, for example. Among the characteristics defined by G.652, at
least having the comparative chromatic dispersion characteristic is very important when
designing transmission lines. In other cases, it would be suffice that no considerable
deviation from the optical characteristics of existing optical fibers in various types is
introduced by adapting a structure according to the present invention.
Furthermore, in order to obtaining optical characteristics satisfying the
requirements of ITU-T Recommendation G.652, it is required that the average value of
the optical refractive index of the entire core region, including the inner core 2 and the
outer core 3, be in a range between 0.30% and 0.40% as a relative refractive index
difference with respect to the cladding 4, and that the outer core diameter be in a range
between 7.5 µm and 11 µm.
Optical fibers that have the above-described structure of the present invention
and exhibits optical characteristics satisfying the requirements of ITU-T
Recommendation G.652 have an advantages in that they can be used in the same manner
as conventional optical fibers since they have the same optical characteristics as those of
optical fibers constituting existing transmission paths, except for having higher SBS
threshold power.
FIGS. 3A-3F are diagrams illustrating refractive index profiles in the radial
direction of optical fibers according to the present invention. However, the present
invention is not limited to these illustrations.
An optical fiber having the refractive index profile shown in FIG. 3 A comprises
an inner core 2 that has a stepped refractive index profile and has the highest refractive
index, an outer core 3 that is provided at the outer periphery of the inner core 2 and has a
little smaller refractive index than that of the inner core 2, and a cladding 4 that is
provided at the outer periphery of the outer core 3 and is made from silica glass.

An optical fiber having the refractive index profile shown in FIG. 3B comprises
an inner core 2 that has a stepped refractive index profile, an outer core 3 that is provided
at the outer periphery of the inner core 2 and has a little higher refractive index than that
of the inner core 2, and a cladding 4 that is provided at the outer periphery of the outer
core 3 and is made from silica glass.
An optical fiber having the refractive index profile shown in FIG. 3C comprises
an inner core 2 that has the refractive index profile in which the refractive index is
gradually increased towards the center, an outer core 3 that is provided at the outer
periphery of the inner core 2, and a cladding 4 that is provided at the outer periphery of
the outer core 3 and is made from silica glass.
An optical fiber having the refractive index profile shown in FIG. 3D comprises
an inner core 2 that has higher refractive index in the vicinity of the outer periphery than
in the center, an inner core 3 that is provided at the outer periphery of the inner core 2
and has higher refractive index in the vicinity of the outer periphery, and a cladding 4
that is provided at the outer periphery of the outer core 3 and is made from silica glass.
An optical fiber having the refractive index profile shown in FIG. 3E comprises
an inner core 2 that has an approximately indented refractive index profile in which the
refractive index is smaller in the center portion, an outer core 3 that is provided at the
outer periphery of the inner core 2 and has the refractive index profile in which the
refractive index of the outer periphery portion is gradually decreased, and a cladding 4
that is provided at the outer periphery of the outer core 3 and is made from silica glass.
An optical fiber having the refractive index profile shown in FIG. 3F comprises
an inner core 2 having a wedge-shaped low-refractive index portion at the center portion,
an outer core 3 that is provided at the outer periphery of the inner core 2 and has the
refractive index profile in which the refractive index is higher than that of the inner core

2 and is gradually decreased towards the outer periphery, and a cladding 4 that is
provided at the outer periphery of the outer core 3 and is made from silica glass.
The present invention also provides a transmission system using the optical fiber
according to the present invention described above.
An advantage of using the above-described optical fiber of the present invention
is that a signal light with higher power can be introduced. Therefore, performing an
analog transmission or baseband transmission that requires comparatively high power by
used of the optical fiber of the present invention enables a longer-distance transmission
with more branches, and thus great benefits can be obtained. Especially in a system
with a transmission distance of 15 km or longer and/or 32 branches or more, the greatest
benefits can be obtained.
Furthermore, by use of the optical fiber according to the present invention,
wavelength division multiplexing can also be performed in which another transmission
can be performed simultaneously with the above-described analog transmission or
baseband transmission. As for wavelength division multiplexing, one form of FTTH
shown in ITU-T G.983.3, CWDM, or the like can be conceived. Especially in a system
with a transmission distance of 15 km or longer and/or 32 branches or more, the greatest
benefits can be obtained.
Obviously, there is no need to limit the optical fiber of the present invention to
these applications in a transmission system. For example, it can be used not only in a
typical public data communication, but also in a digital, long-distance relay-free
transmission system, an intelligent transportation system (ITS), a sensor, a remote laser
cutting system, etc.
EXAMPLES

First Embodiment
Optical fibers according to a first embodiment of the present invention were
prototyped. Tables 1-3 show Examples Nos. 2-25 of optical fibers prototyped, together
with their structures and optical characteristics. Furthermore, a typical SM optical fiber
(compliant with ITU-T Recommendation G.652) is also shown in Table 1 in No. 1 as a
comparative example. It should be noted that, in Tables 1-3, "Ge concentration"
indicates concentrations of germanium doped into the inner core or the outer core (in
terms of germanium oxide), and "F concentration" indicates concentrations of fluorine
doped into the inner core or the outer core. Furthermore, as for the optical fiber of each
of Examples Nos. 2-25, "rel. Brillouin gain" shows relative values of the SBS light
intensity measured in the optical fiber of each Example when the value of the SBS light
intensity measured in the optical fiber of the comparative example was taken as 1.
Similarly, "threshold power" shows relative values of the SBS threshold power measured
in the optical fiber of each Example when the value of the SBS threshold power
measured in the optical fiber of the comparative example was taken as 1.






The results in Tables 1-3 indicate that the occurrence of SBS were reduced and
relatively higher SBS threshold power was obtained in the optical fibers of Examples
Nos. 2-25 compared to the typical SM optical fiber of the comparative example, which
allowed transmission with higher-power signals than in the typical SM optical fiber of
the comparative example. This is because they were configured to have an inner core
containing germanium and fluorine and an outer core containing only germanium or
germanium and a small amount of fluorine.
FIG. 2 shows the relationship among the ratios of inner core diameter/outer core
diameter, the inner core Ge concentrations, and the threshold power obtained in the
optical fibers prototyped in this embodiment.
FIG. 2 indicates that the desired threshold power was obtained when the
above-described parameter range is satisfied,
second embodiment

A second embodiment is related to an SM optical fiber that has an MFD at a
wavelength of 1310 nm of about 8.6 µm. Such optical fibers have been commercialized
as optical fibers that reduce bending loss in the range satisfying ITU-T Recommendation
G.652. The concentration profiles of dopants (Ge and F) and the relative refractive
index difference of such an optical fiber that is designed using conventional techniques
are shown in FIGS. 4A-C and Table 4.

Such a refractive index profile can provide optical fibers having optical
characteristics described below:
Fiber cut-off: 1.26 µm.
MFD at a wavelength of 1310 nm: 8.59 µm.
MFD at a wavelength of 1550 nm: 9.56 µm.
Zero-dispersion wavelength: 1305.8 nm.
Chromatic dispersion at a wavelength of 1550 nm: 17.1 ps/nm/km.
Dispersion slope at a wavelength of 1550 nm: 0.057 ps/nm2/km.
Bending loss at a bending diameter of 30 mm at a wavelength of 1310 nm: Bending loss at a bending diameter of 30 mm at a wavelength of 1550 nm: 1.89*10-2
dB/m.
The optical fiber based on the refractive index profile shown in FIGS. 4A-C
improved the bending loss by having an MFD smaller than those of the typical SM

optical fiber shown as Example 1 or the comparative example. However, reduction in
the MFD may be problematic since it may deteriorate the SBS threshold power.
FIG. 5 shows the relative Brillouin gain spectrum obtained in the refractive
index profile shown in FIGS. 4A-C. The data was standardized by assuming the
maximum value of the Brillouin gain of the optical fiber of Example 1, the comparative
example, as 1. The maximum relative Brillouin gain became 1.18, and the SBS
threshold power became 0.7 dB smaller.
FIGS. 6A-C and Table 5 show Example 26 of the optical fiber based on a
second embodiment of the present invention.

Compared to the example based on the conventional techniques, the
concentrations of Ge and F in the inner core region were higher. However, the relative
refractive index difference A remained the same, and optical characteristics, such as the
MFD and the chromatic dispersion, were the same as those of the optical fiber with the
refractive index profile shown in FIGS. 4A-C.
FIG. 7 shows the relative Brillouin gain spectrum of the optical fiber of the
refractive index profile shown in FIGS. 6A-C. Similar to FIG. 5, the optical fiber of
Example 1 or the comparative example was taken as a reference. The maximum relative
Brillouin gain became 0.55, and the SBS threshold power was 2.6 dB improved.
In addition to exhibiting optical characteristics satisfying ITU-T
Recommendation G.652, the optical fiber of this embodiment is an optical fiber with a

low bending loss and a high SBS threshold power, and has excellent characteristics as an
optical fiber for FTTH.
Third Embodiment
A third embodiment is related to optical fiber having a further improved bending
characteristic.
FIGS. 8A-C show an example of a low-bending-loss optical fiber based on the
conventional techniques. This optical fiber has the concentration profiles and refractive
index profile shown in Table 6.

Such a refractive index profile can provide optical fibers having optical
characteristics described below:
Fiber cut-off : 1.26 µm.
MFD at a wavelength of 1310 nm: 7.36 µm.
MFD at a wavelength of 1550 nm: 8.19 µm.
Zero-dispersion wavelength: 1319.2 nm.
Chromatic dispersion at a wavelength of 1550 nm: 17.4 ps/nm/km.
Dispersion slope at a wavelength of 1550 nm: 0.060 ps/nm2/km.
Bending loss at a bending diameter of 30 mm at a wavelength of 1310 nm: Bending loss at a bending diameter of 30 mm at a wavelength of 1550 nm: Bending loss at a bending diameter of 15 mm at a wavelength of 1310 nm: Bending loss at a bending diameter of 15 mm at a wavelength of 1550 nm:
Although the MFD at a wavelength of 1310 nm was 7.36 µm, which was
somewhat small, the bending loss was improved with almost no increase in loss even
when wound in a diameter of 15 mm. However, reduction in the MFD deteriorates the
SBS threshold power. FIG. 9 shows the relative Brillouin gain spectrum of optical fiber
of this example. Similar to FIG. 5, Example 1 or the comparative example was taken as
a reference. The maximum relative Brillouin gain became 1.7, and the SBS threshold
power became 2.3 dB smaller.
FIGS. 10A-C and Table 7 show Example 27 of the optical fiber based on a third
embodiment of the present invention.

Although the Ge and F concentrations were higher in the inner core than the
example based on the conventional techniques, the relative refractive index difference A
was the same and optical characteristic, such as the MFD and the chromatic dispersion,
became the same as those of the refractive index profile shown in FIGS. 8A-C.
FIG. 11 shows the relative Brillouin gain spectrum of the optical fiber of the
refractive index profile shown in FIGS. 10A-C. Similar to FIG. 5, Example 1 or the
comparative example was taken as a reference. The maximum relative Brillouin gain
became 0.67, and the SBS threshold power was 1.7 dB improved.
In addition to exhibiting optical characteristics comparative to ITU-T
Recommendation G.652, the optical fiber of this embodiment is an optical fiber with a

low bending loss and a high SBS threshold power, and has excellent characteristics as an
optical fiber for FTTH.
Fourth Embodiment
A forth embodiment is related to an optical fiber having a core comprising a first
codoped layer in the vicinity of the center (first layer), a non-codoped layer located at the
outer periphery of the first codoped layer (second layer), and a second codoped layer
located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in
FIGS. 12A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 1.66 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 5.0 % by mass. First layer F concentration (nFl):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00% by mass.
Third layer Ge concentration (1103): 5.0 % by mass. Third layer F concentration (nf3):
0.45 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences Δ all became 0.35%.
Such a refractive index profile can provide optical fibers having optical
characteristics described below:

Fiber cut-off: 1292 nm.
Cable cut-off: 1240 nm.
MFD at a wavelength of 1310 nm: 9.21 µm.
MFD at a wavelength of 1550 nm: 10.30 µm.
Zero-dispersion wavelength: 1307.2 nm.
Chromatic dispersion at a wavelength of 1550 nm: 17.38 ps/nm/km.
Dispersion slope at a wavelength of 1550 nm: 0.060 ps/nm2/km.
Bending loss at a bending diameter of 30 mm at a wavelength of 1310 nm: 0.13 dB/m.
Bending loss at a bending diameter of 30 mm at a wavelength of 1550 nm: 3.73 dB/m.
The optical fiber of this embodiment has a substantially comparative MFD to
that of the typical optical fiber shown as Example 1, the comparative example.
FIG. 13 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 12A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.46, and the
SBS threshold power became 4.3 dB smaller.
In this embodiment, there were peaks with relative gains of 0.46, 0.32, 0.20,
0.07, and 0.02 at the frequency shifts of 10760 MHz, 10840 MHz, 10950 MHz, 11060
MHz, and 11180 MHz, respectively, in ascending order.
Fifth Embodiment
A fifth embodiment is related to an optical fiber having a core comprising a first
codoped layer in the vicinity of the center (first layer), a non-codoped layer located at the
outer periphery of the first codoped layer (second layer), and a second codoped layer
located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in

FIGS. 14A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 1.11 µm.
Second layer radius (r2): 3.33 nm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 5.0 % by mass. First layer F concentration (nF1):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (nG3): 5.0 % by mass. Third layer F concentration (nF3):
0.45 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences A all became 0.35%. Thus, the optical characteristics obtained were the
same those of the fourth embodiment.
FIG. 15 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 14A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.67, and the
SBS threshold power became 2.4 dB smaller.
In this embodiment, there were peaks with relative gains of 0.45, 0.44, 0.67, and
0.02 at the frequency shifts of 10800 MHz, 10840 MHz, 11030 MHz, and 11200 MHz,
respectively, in ascending order.
Sixth Embodiment

A sixth embodiment is related to an optical fiber having a core comprising a first
codoped layer in the vicinity of the center (first layer), a non-codoped layer located at the
outer periphery of the first codoped layer (second layer), and a second codoped layer
located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in
FIGS. 16A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 2.22 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 5.0 % by mass. First layer F concentration (nF1):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (1103): 5.0 % by mass. Third layer F concentration (nF3):
0.45 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences A all became 0.35%. Thus, the optical characteristics obtained were the
same those of the fourth embodiment.
FIG. 17 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 16A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.66, and the

SBS threshold power became 2.9 dB smaller.
In this embodiment, there were peaks with relative gains of 0.62, 0.66, and 0.07
at the frequency shifts of 10740 MHz, 10830 MHz, and 11050 MHz, respectively, in
ascending order.
Seventh Embodiment
A seventh embodiment is related to an optical fiber having a core comprising a
first codoped layer in the vicinity of the center (first layer), a non-codoped layer located
at the outer periphery of the first codoped layer (second layer), and a second codoped
layer located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in
FIGS. 18A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 1.66 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 5.0 % by mass. First layer F concentration (nF1):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (nG3): 5.0 % by mass. Third layer F concentration (nF3):
0.45 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences A all became 0.35%. Thus, the optical characteristics obtained were the

Same those of the fourth embodiment.
FIG. 19 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 18 A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.44, and the
SBS threshold power became 3.9 dB smaller.
In this embodiment, there were peaks with relative gains of 0.25, 0.44, 0.26,
0.03, and 0.07 at the frequency shifts of 10670 MHz, 10760 MHz, 11950 MHz, 11000
MHz, and 11140 MHz, respectively, in ascending order.
Eighth Embodiment
An eighth embodiment is related to an optical fiber having a core comprising a
first codoped layer in the vicinity of the center (first layer), a non-codoped layer located
at the outer periphery of the first codoped layer (second layer), and a second codoped
layer located at the outer periphery of the non-codoped layer (third layer). The
refractive index profile and the dopant profiles of the optical fiber of this embodiment are
shown in FIGS. 20A-C. The diameters, optical relative refractive index difference, and
the Ge and F concentrations in each layer are shown below:
First layer radius (r1): 1.66 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 5.0 % by mass. First layer F concentration (nF1):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (1103): 5.5 % by mass. Third layer F concentration (nF3):

0.60 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences Δ all became 0.35%. Thus, the optical characteristics obtained were the
same those of the fourth embodiment.
FIG. 21 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 20A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.69, and the
SBS threshold power became 2.9 dB smaller.
In this embodiment, there were peaks with relative gains of 0.69,0.24, 0.06, and
0.04 at the frequency shifts of 10760 MHz, 10950 MHz, 11040 MHz, and 11160 MHz,
respectively, in ascending order.
Ninth Embodiment
A ninth embodiment is related to an optical fiber having a core comprising a
first codoped layer in the vicinity of the center (first layer), a non-codoped layer located
at the outer periphery of the first codoped layer (second layer), and a second codoped
layer located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in
FIGS. 22A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 1.66 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.

First layer Ge concentration (rG1): 5.0 % by mass. First layer F concentration (nF1):
0.45 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (nG3): 7.0 % by mass. Third layer F concentration (nF3):
1.05 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences Δ all became 0.35%. Thus, the optical characteristics obtained were the
same those of the fourth embodiment.
FIG. 23 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 22A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.44, and the
SBS threshold power became 4.0 dB smaller.
In this embodiment, there were peaks with relative gains of 0.44, 0.24, 0.18, and
0.13 at the frequency shifts of 10760 MHz, 10900 MHz, 10960 MHz, and 11120 MHz,
respectively, in ascending order.
Tenth Embodiment
A tenth embodiment is related to an optical fiber having a core comprising a first
codoped layer in the vicinity of the center (first layer), a non-codoped layer located at the
outer periphery of the first codoped layer (second layer), and a second codoped layer
located at the outer periphery of the non-codoped layer (third layer). The refractive
index profile and the dopant profiles of the optical fiber of this embodiment are shown in

FIGS. 24A-C. The diameters, optical relative refractive index difference, and the Ge and
F concentrations in each layer are shown below:
First layer radius (r1): 1.66 µm.
Second layer radius (r2): 3.33 µm.
Third layer radius (r3): 4.43 µm.
First layer Ge concentration (nG1): 7.0 % by mass. First layer F concentration (nF1):
1.05 % by mass.
Second layer Ge concentration (nG2): 3.5 % by mass. Second layer F concentration
(nF2): 0.00 % by mass.
Third layer Ge concentration (nG3): 7.0 % by mass. Third layer F concentration (nF3):
1.05 % by mass.
Relative refractive index difference (Δ): 0.35%.
The Ge concentrations and the F concentrations of the first layer, the second
layer, and the third layer were adjusted such that the respective relative refractive index
differences A all became 0.35%. Thus, the optical characteristics obtained were the
same those of the fourth embodiment.
FIG. 25 shows the relative Brillouin gain spectrum of the optical fiber obtained
in the refractive index profile shown in FIGS. 24A-C. The data was standardized by
assuming the maximum value of the Brillouin gain of the optical fiber of Example 1, the
comparative example, as 1. The maximum relative Brillouin gain became 0.34, and the
SBS threshold power became 4.7 dB smaller.
In this embodiment, there were peaks with relative gains of 0.34, 0.21, 0.09,
0.05, and 0.21 at the frequency shifts of 10420 MHz, 10520 MHz, 10660 MHz, 10900
MHz, and 11010 MHz, respectively, in ascending order.
FIG. 26 shows a transmission system (wavelength division multiplexing system)

10 with a PON configuration in which an the optical fiber 1 according to the present
invention is used. The transmission system 10 transmits a data signal at frequencies of
1.31 µm and 1.49 µm, and an image signal at a frequency of 1.55 µm in compliance with
the requirements of ITU-T G.983.3. FIG. 26 shows a digital image distribution over the
Internet or by streaming, by way of example of a data transmission. However, a voice
data transmission is available by adding an appropriate apparatus. For an image
transmission at a frequency band of 1.55 µm, a system is widely used in which a typical
broadcast wave is propagated in the form of an as-is analog signal. In such a system, a
signal can be demodulated into the signal of the original broadcast wave in a receiver
portion of the broadcast system on the subscriber side. Therefore, a conventional
television set can be used as it is.
The system of FIG. 26 transmits a data signal and an analog signal (image
signal) through the single the optical fiber 1. However, in the transmission system of
the present invention, an optical fiber for a data signal and an optical fiber for an analog
signal, separate from each other, may be used. In such a system, using the optical fiber
of the present invention offers an advantage such as an extension in transmission
distance.
While preferred embodiments of the present invention have been described
above, these should not be considered to be limitative of the invention. Addition,
omission, and replacement of the constituents, and other modifications can be made
without departing from the spirit or scope of the invention. The present invention is not
limited by the descriptions above, but is limited only by the appended claims.

WE CLAIM:
1. An optical fiber comprising a center core and a cladding located at an outer
periphery of the core,
wherein the core comprises at least one codoped layer made from silica glass
doped with germanium and fluorine, and at least one lower-concentration codoped layer
made from silica glass doped with germaniµm, or silica glass that is doped with
germanium and fluorine wherein a dope amount of the fluorine is smaller than a dope
amount of the fluorine in the codoped layer,
the difference of refractive indices between the codoped layer and the lower-
concentration codoped layer is about 0.07% or less in terms of relative refractive index
difference,
the core comprises an inner core located in the vicinity of the center and an outer
core provided at an outer periphery of the inner core,
the inner core comprises a codoped layer made from silica glass doped with
germanium and fluorine,
the outer core comprises a lower-concentration codoped layer made from silica
glass doped with germaniµm, or silica glass that is doped with germanium and fluorine
wherein a dope amount of the fluorine is smaller than a dope amount of the fluorine in
the inner core, and
a concentration of the germanium is in a range between 4% and 15% by mass in
terms of germanium oxide, and a concentration of the fluorine is in a range between 0.2%
and 5% by mass, in the inner core.

2. An optical fiber comprising a center core and a cladding located at an outer
periphery of the core,
wherein the core comprises at least one codoped layer made from silica glass
doped with germanium and fluorine, and at least one lower-concentration codoped layer
made from silica glass doped with germaniµm, or silica glass that is doped with
germanium and fluorine wherein a dope amount of the fluorine is smaller than a dope
amount of the fluorine in the codoped layer,
the difference of refractive indices between the codoped layer and the lower-
concentration codoped layer is about 0.07% or less in terms of relative refractive index
difference,
the core comprises a first core located in the vicinity of the center, a second core
provided at an outer periphery of the first core, and a third core provided at an outer
periphery of the second core,
the first core and the third core comprise a codoped layer made from silica glass
doped with germanium and fluorine,
the second core comprises a lower-concentration codoped layer made from silica
glass doped with germaniµm, or silica glass that is doped with germanium and fluorine
wherein a dope amount of the fluorine is smaller than a dope amount of the fluorine in
the first core, and
a concentration of the germanium is in a range between 4% and 15% by mass in
terms of germanium oxide, and a concentration of the fluorine is in a range between 0.2%
and 5% by mass, in the first core.

3. The optical fiber as claimed in claim 1 or 2, wherein the cladding is made from
non-doped silica glass.
4. The optical fiber as claimed in claim 1 or 2, wherein fluorine is doped into a part
of the cladding.
5. The optical fiber as claimed in claim 4, wherein the cladding comprises an inner
cladding provided at an outer periphery of the core and an outer cladding provided at an
outer periphery of the inner cladding, and the relationship: ncl that a refractive index of the inner cladding is ncl and a refractive index of the outer
cladding is nc2.
6. The optical fiber as claimed in claim 4, wherein the cladding comprises an inner
cladding provided at an outer periphery of the core, a trench layer provided at an outer
periphery of the inner cladding, and an outer cladding provided at an outside of the trench
layer, and the relationships: nc2 index of the inner cladding is ncl, a refractive index of the trench layer is nc2, and a
refractive index of the outer cladding is nc3.
7. The optical fiber as claimed in claim 1, wherein a ratio of an inner core diameter
and an outer core diameter is in a range between 0.10 and 0.85.

8. The optical fiber as claimed in claim 7, wherein the ratio of the inner core
diameter and the outer core diameter is in a range between 0.25 and 0.70.
9. The optical fiber as claimed in claim 1, wherein optical refractive indices of the
inner core and the outer core are substantially the same.
10. The optical fiber as claimed in claim 1, wherein an average of relative refractive
index differences with respect to the cladding of the inner core and the outer core is in a
range between 0.30% and 0.60%, and an outer core diameter is in a range between 6.0 µm and 10.5 µm.
11. The optical fiber as claimed in claim 2, wherein the relationships: nfl > nf2 and
nf3 > nf2 hold, supposing that a fluorine concentration of is nfl % by mass, a fluorine
concentration of the second core is nf2 % by mass, and a fluorine concentration of the
third core is nf3 % by mass.
12. The optical fiber as claimed in claim 11, wherein nfl and nf3 are substantially the
same.
13. The optical fiber as claimed in claim 11, wherein the relationship: nfl 14. The optical fiber as claimed in claim 11, wherein the relationship: nfl > nf3 holds.

15. The optical fiber as claimed in claim 1, wherein optical characteristics satisfy the
requirements of ITU-T Recommendation G.652.


ABSTRACT

OPTICAL FIBER, TRANSMISSION SYSTEM AND MULTIPLE
WAVELENGTH TRANSMISSION SYSTEM
An optical fiber (1) is provided with a core (2, 3) at the center and a clad (4) on
the outer circumference of the core (2, 3). The core (2, 3) is provided with at least one
layer of codoped layer (2) composed of a quarts glass wherein germanium and fluorine
are added, and at least one layer of low concentration codoped layer (3) composed of a
quartz glass wherein germanium is added or a quartz glass wherein germanium and
fluorine of a smaller quantity than that added in the codoped layer (2) are added.

Documents:

01526-kolnp-2007-abstract.pdf

01526-kolnp-2007-assignment.pdf

01526-kolnp-2007-claims.pdf

01526-kolnp-2007-correspondence others 1.1.pdf

01526-kolnp-2007-correspondence others 1.2.pdf

01526-kolnp-2007-correspondence others.pdf

01526-kolnp-2007-description complete.pdf

01526-kolnp-2007-drawings.pdf

01526-kolnp-2007-form 1.pdf

01526-kolnp-2007-form 18.pdf

01526-kolnp-2007-form 3.pdf

01526-kolnp-2007-form 5.pdf

01526-kolnp-2007-gpa.pdf

01526-kolnp-2007-international publication.pdf

01526-kolnp-2007-international search report.pdf

01526-kolnp-2007-others.pdf

01526-kolnp-2007-priority document.pdf

1526-KOLNP-2007-(01-02-2012)-EXAMINATION REPORT REPLY RECEIVED.pdf

1526-KOLNP-2007-(11-04-2012)-ABSTRACT.pdf

1526-KOLNP-2007-(11-04-2012)-AMANDED CLAIMS.pdf

1526-KOLNP-2007-(11-04-2012)-AMANDED PAGES OF SPECIFICATION.pdf

1526-KOLNP-2007-(11-04-2012)-CORRESPONDENCE.pdf

1526-KOLNP-2007-(11-04-2012)-DESCRIPTION (COMPLETE).pdf

1526-KOLNP-2007-(11-04-2012)-DRAWINGS.pdf

1526-KOLNP-2007-(11-04-2012)-FORM-1.pdf

1526-KOLNP-2007-(11-04-2012)-FORM-13.pdf

1526-KOLNP-2007-(11-04-2012)-FORM-2.pdf

1526-KOLNP-2007-(11-04-2012)-FORM-3.pdf

1526-KOLNP-2007-(11-04-2012)-OTHERS.pdf

1526-KOLNP-2007-(11-04-2012)-PETITION UNDER RULE 137.pdf

1526-KOLNP-2007-(21-08-2012)-CORRESPONDENCE.pdf

1526-KOLNP-2007-ASSIGNMENT.pdf

1526-KOLNP-2007-CORRESPONDENCE 1.1.pdf

1526-KOLNP-2007-CORRESPONDENCE.pdf

1526-KOLNP-2007-EXAMINATION REPORT.pdf

1526-KOLNP-2007-FORM 13.pdf

1526-KOLNP-2007-FORM 18.pdf

1526-KOLNP-2007-FORM 3.pdf

1526-KOLNP-2007-FORM 5.pdf

1526-KOLNP-2007-GPA.pdf

1526-KOLNP-2007-GRANTED-ABSTRACT.pdf

1526-KOLNP-2007-GRANTED-CLAIMS.pdf

1526-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

1526-KOLNP-2007-GRANTED-DRAWINGS.pdf

1526-KOLNP-2007-GRANTED-FORM 1.pdf

1526-KOLNP-2007-GRANTED-FORM 2.pdf

1526-KOLNP-2007-GRANTED-SPECIFICATION.pdf

1526-KOLNP-2007-OTHERS.pdf

1526-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

abstract-01526-kolnp-2007.jpg


Patent Number 253941
Indian Patent Application Number 1526/KOLNP/2007
PG Journal Number 36/2012
Publication Date 07-Sep-2012
Grant Date 05-Sep-2012
Date of Filing 30-Apr-2007
Name of Patentee FUJIKURA LTD.
Applicant Address 5-1, KIBA 1-CHOME, KOHTOH-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 MATSUO SHOICHIRO C/O FUJIKURA LTD., SAKURA WORKS, 1440, MUTSUZAKI, SAKURA-SHI, CHIBA-KEN
2 HIMENO KUNIHARU C/O FUJIKURA LTD., SAKURA WORKS, 1440, MUTSUZAKI, SAKURA-SHI, CHIBA-KEN
3 TANIGAWA SHOJI C/O FUJIKURA LTD., SAKURA WORKS, 1440, MUTSUZAKI, SAKURA-SHI, CHIBA-KEN
PCT International Classification Number G02B 6/036
PCT International Application Number PCT/JP2005/019493
PCT International Filing date 2005-10-24
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2005-055669 2005-03-01 Japan
2 2004-308359 2004-10-22 Japan
3 2005-208687 2005-07-19 Japan