Page 40 - Market Analysis Report of Optical Communications Field in China & Global market 2016

Development of the Novelty G.654 Optical Fibers for
Long-haul Terrestrial Optical fiber Communication
Chen Wei, Yuan Jian, He Zuowei, Zhang Gonghui
JiangSu HengTong Optic-electric Co. Ltd, SuZhou, China, 215200
Introduction
In order to meet the rapid growth of China's
demand for data traffic, a new generation
communication network needs a great
improvement on the communication rate,
transmission capacity, transmission distance.
But thetraditional G.652 fiber could not meet
the demand of the development of a new
generation of long distance communication
networkdue to the effective area of only 80μm2.
Therefore, the researchers in the communication
fields hope thatthecut-off wavelength shift
single mode optical fiber, which is the G.654 in
ITU-T standard, could be used to thelong haul
terrestrial fiber communication network[1-5].
But due to the great differences between the
terrestrial and marine environments, submarine
cable was made of stainless steel pipe welding
and armored, and at the bottom of the ocean
the environmental temperature is constant
about -1℃to2℃. But on the land, temperature
changes larger from -45℃to 40℃,in some
special occasion, maybe the temperature varies
much larger. What’s more,the cable on the land
application will be faced complex environments,
such as the environment pressure, bending stress, of the optical fiber is firstly designed before the
mechanical impact and so on. This need the
novelty kinds of fiber could resist all kinds of
stress and have great anti-bending performance.
Traditional the cut-off wavelength shift single
mode optical fibers,including G.654.A, G.654.
B, G.654.C, G.654.D fiber, could not meet the
higher requirements for optical signal loss and
nonlinearin the next generation high data-
rate communication network[6-9]. Therefore, it
is urgent and important to study the novelty
kind optical fibers, which have the advantages
of large-effective-area and ultra-low-loss,
the ability of anti-bending, for the long haul
terrestrial fiber communication in the 400G
Figure 1 The refractive index structure diagram
40
communication system.
Through the basic theory of electromagnetic
field, using the scalar wave equation the weakly
guiding approximation,a new type of optical
fiber waveguide structure for the next generation
of optical fiber communication network was
designed.Then the large-effective-area and ultra-
low-loss,characteristics of a new type of optical
fiberwas fabricated the continuous chemical
vapor deposition (CCVD) process.
The design and fabrication of the novelty
G.654 optical fiber
The effective area of the optical fiber is
determined by the refractive index profile
of the optical fiber and the diameter of
the core layer of the fiber. It is a physical
quantity that represents the distribution of
the electromagnetic field in the optical fiber
waveguide. The key factors affecting the power
loss coefficient of the optical fiber include the
waveguide structure, the high and low refractive
index, the species and distribution of the doped
ions,the viscosity of the interface, the stress in
the fiber. As a result, the waveguide structure
preparation of the optical fiber.
Optical fiber is a circular symmetrical waveguide.
On the conditions of the weakly guiding
approximation, Ψ(R) could meet the scalar
electromagnetic wave equation[10].
(1) a low refractive index region is deposited in
(2) the optical fiber. Its refractive index is 1.45565,
(3) and the width is 6.96 microns.By simulation
Where, k0 is the vacuum wave number, R is
the radial coordinate, a is the core radius of
the fiber, R=r/a,R denotes normalized radius
of the optical fiber, N(R) represents the
Figure 2 The fiber’s effective area at different
wavelength
radial refractive index profile, Ψ(R) is the
fundamental mode of the electromagnetic
field spatial distribution function. Ψcore(R) is
the electromagnetic field distribution function
of fundamental mode fiber core area,β
representsthe axial propagation constant of the
optical fiber, Ψcl(R) represents the fundamental
modepropagation constant in the cladding.
After calculating the electromagnetic field
distribution of the fundamental mode function
Ψ(R) , then substitute Ψ(R) into formula(4)
to calculatethe effective area of the optical fiber
Aeff[10].
(4)
The refractive index profile of the new G.654
optical fiber is shown in Figure 1. The fiber core
refractive index of the optical fiber is 1.46117,
and the core diameter is 14 microns.The relative
refractive index difference between the core and
the cladding is adjusted to 0.278%. Compared
with the 0.35% relative refractive index
difference of the conventional single-mode fiber
core, the doping concentration in the optical
fiber is reduced by 20%. Therefore, the Rayleigh
scattering of light in the fiber waveguide
structure is greatly reduced.
In order to adjust the distribution of the
electromagnetic field in the optical fiber
waveguide, and to improve the bending
resistance of the long wavelength of the fiber,
analysis,the effective area of the Ultra-low-
loss and Ultra-large-effective Area (UUA) of
the new optical fiber at 1550nm wavelength is
150μm2(Fig.2) .
The optical performance index test and
environmental experiments analysis
Optical fiber preformwasfabricated by
Continuous Chemical Vapor Deposition
(CCVD) process, and then the optical fiber
preform is placed on the tower of the self-
made optical fiber wire drawing.Starting the
heating system, the high temperature of the
furnaceis controlled at 2100℃±50℃, quartz
glass preform is melted and soften. By high-
speed closed-loop self-feedback controlling
technologies, the silica preform is drawn into
optical fiber with 124.6±0.3 micron glass
cladding diameter.