Optical waveguides – Optical fiber waveguide with cladding – With graded index core or cladding
Reexamination Certificate
2003-08-19
2004-09-21
Kim, Robert H. (Department: 2871)
Optical waveguides
Optical fiber waveguide with cladding
With graded index core or cladding
C385S126000
Reexamination Certificate
active
06795629
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an optical fiber used in optical transmission such as wavelength division multiplexing (WDM) transmission, etc. in a wavelength band of e.g., 1.5 &mgr;m, etc., and optical communication systems using this optical fiber.
BACKGROUND OF THE INVENTION
A communication information capacity tends to be greatly increased as information society is developed. Techniques of the wavelength division multiplexing transmission (WDM transmission) and time division multiplexing (TDM) transmission are noticed as such information is increased. This wavelength division multiplexing transmission uses a system for transmitting signals of plural wavelengths by one optical fiber. Therefore, this system is an optical transmitting system suitable for high capacity and high bit-rate transmission. The wavelength division multiplexing transmission technique is vigorously studied at present.
It is considered at present that the wavelength division multiplexing transmission is performed in a wavelength band of 1.55 &mgr;m as a gain band of an erbium-doped optical fiber amplifier. The wavelength band of 1.55 &mgr;m is a wavelength band with 1550 nm in wavelength approximately as a center, e.g., as in a wavelength band from 1530 nm to 1570 nm.
However, there are problems of an increase in power of an optical signal and a non-linear phenomenon due to an interaction between signals, etc. to perform the wavelength division multiplexing transmission. Therefore, for example, it is reported in a society report document OFC' 97 TuNlb of Japan, etc. to consider that a non-linear refractive index difference (n
2
) is reduced and restrained to restrain the non-linear phenomenon.
It is also noticed to consider that an effective core area (A
eff
) of the optical fiber is increased together with this reduction in the non-linear refractive index difference. Distortion &phgr;
NL
of a signal due to the non-linear phenomenon is generally represented by the following formula (1). Therefore, when the effective core area of the optical fiber is increased, the waveform distortion of a signal due to the non-linear phenomenon can be reduced.
&phgr;
NL
=(2
&pgr;×n
2
×L
eff
×P
)/(&lgr;×
A
eff
) (1)
In the formula (1), &pgr;, n
2
, L
eff
, P and &lgr; respectively designate a ratio of the circumference of a circle to its diameter, a non-linear refractive index, an effective optical fiber length, signal power and a signal optical wavelength.
Accordingly, it is very important to enlarge the effective core area in the optical-fiber used for e.g. the wavelength multiplexing transmission, and this enlargement is very noticed as reported in society report documents OFC' 96 WK15 and OFC' 97 YuN2 of Japan.
SUMMARY OF THE INVENTION
The present invention provides an optical fiber and an optical communication system using this optical fiber.
The optical fiber of the invention comprises:
an effective core area from 40 &mgr;m
2
to 60 &mgr;m
2
in a set wavelength band of at least one portion of a wavelength band of 1.5 &mgr;m;
a dispersion value set to 4 ps
m/km or more and 10 ps
m/km or less at a wavelength of 1.55 &mgr;m;
a dispersion slope set to a positive value equal to or smaller than 0.04 ps
m
2
/km in a wavelength band of 1.55 &mgr;m; and
a zero dispersion wavelength equal to or smaller than 1.4 &mgr;m.
REFERENCES:
patent: 6169837 (2001-01-01), Kato et al.
patent: 6477306 (2002-11-01), Kato et al.
patent: 6487353 (2002-11-01), Kato et al.
patent: 6567596 (2003-05-01), Kato et al.
patent: 1201913 (1998-12-01), None
patent: 0 938 001 (1999-06-01), None
patent: 0 959 374 (1999-11-01), None
patent: 11-84159 (1999-03-01), None
Kazunori Mukasa, et al. “Dispersion-Managed Transmission Lines with Reverse-Dispersion Fiber” Furukawa Review, No. 19. 2000. pp. 5-9.
L.G. Cohen, et al., Electronics Letters, vol. 16, No. 24, XP-000543480, pp. 123-1024, “Low-Loss Quadruple-Clad Single-Mode Lightguides with Dispersion Below 2 ps/km nm Over the 1.28&mgr;m—1.65&mgr;m Wavelength Range”, Nov. 25, 1982.
H. Hatayama et al., General National Meeting of the Institute of Electronics, Information and Communication Engineers, XP-002946628, p. 225, “Dispersion Flattened Fiber with Large Effective Area”, Mar. 8, 1988.
D.W. Peckham, et al., Proceedings of the European Conference on Optical Communication, vol. 1, No. 1, XP-002115607, “Reduced Dispersion Slope, Non-Zero Dispersion Fiber”, Sep. 20, 1998
Kumano Naomi
Mukasa Kazunori
Kim Richard H
Kim Robert H.
The Furukawa Electric Co. Ltd.
LandOfFree
Optical fiber and optical communication system using this... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical fiber and optical communication system using this..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical fiber and optical communication system using this... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3222863