Development of fiber-optic cable in FTTH

1. FTTH development at home and abroad

The narrow-sense FTTH cable refers to the further extension of fiber to the user side, ITU believes that FTTH from the fiber-optic end of the photoelectric converter to the user no more than 200 meters, thereby eliminating the need to install an electronic access system in the metal, but not excluding photoelectric converters and desktop terminals using unlimited systems, for commercial systems can also be called Ftto (Fiber to the Office), the most extreme FTTH can also be called FTTD (Fiber to the desk), the generalized FTTH can also be called FTTP (Fiber to the premise), North America has been used this term, it includes FTTB ( Fiber to the building), FTTC (Fiber to the curb).

The United States is the world's largest broadband access market, according to statistics. The United States by 2004 has 43 states using FTTH, the total user reached 1.62 million, the current optical node distance from the end user within 800 meters; in Asia, the current use of FTTH is the most popular in Japan and Korea, in Japan, by 2007, FTTH users will reach 7.73 million households, His development experience is mainly to encourage the operators to develop FTTH in order to realize E-japan, subsidize and tax relief, and to promote FTTH development from the strategic height of national informatization. The South Korean government has launched the FTTH,2004 government policy since 2003, providing half the money to develop FTTH operators to encourage development, with household penetration expected to exceed 70% in 2010. [1] The current world-wide optical fiber and cable production capacity of excess, the price of a substantial decline, so that FTTH development has more convenient conditions, and the development of optical devices for FTTH development provides a very strong impetus. [2]

China in the national "863" High-tech projects under the impetus of "XV" during the development of Epon technology research, in 2004 with the "863" Epon project completed, the country set up a network of optical fiber to the user. At present, China Telecom in Wuhan, Hangzhou, Shanghai, Guangzhou and other sites have been a FTTH pilot, but to adopt different ways, some fiber directly to the households, some of the use of Fttx+lan.

2, FTTH optical fiber and cable development

With the rapid development of communication services, people have been making demands on the transmission and exchange ability of communication networks. From the dry network to the community, the last access network between the family, the copper wire bandwidth can reach only 1 trillion to 2 trillion, but the use of fiber, bandwidth can easily reach 100 trillion per second. In the access mode, optical access network is in accordance with the "light into copper retreat" development strategy, all-optical network can provide greater bandwidth, enhance the network data format, speed, wavelength transparency, relaxed environmental conditions and power requirements, simplified maintenance and installation.

Development of optical fiber in 2.1 FTTH

For FTTH access mode, the type of fiber used is generally G652 fiber. G652 Optical fiber appeared in the 1980s, after nearly 20 years of development, it has become the first choice for optical fiber network construction, ITU-T SG15 2003 years of advice, G652 contains g.652a/b/c/d four kinds of fiber, G652C/D and g652a/ b The biggest difference is that the elimination of the 1383nm at the water peak, so that the attenuation is less than 1310nm of fiber attenuation and also reduce the fiber PMD (polarization mode dispersion), broadening the fiber's available wavelength [3]. In 2005, optical fiber manufacturers, represented by China's long-flying and Japanese Sumitomo, introduced a new type of small curved-radius fiber (insensitive fiber). The main indicators are as follows [4]:

Parameter unit common g652d fiber small bending radius fiber

Mold field diameter μm (8.6~9.5) ±0.7 (8.6~9.5) ±0.7

Cladding diameter μm125±1125±1

Core Package Concentric degree μm0.80.5

Error

Attenuation (1310nm) db/km≤0.35≤0.35

Attenuation (1383nm) db/km≤0.33≤0.33

Attenuation (1550nm) db/km≤0.2235≤0.22

Cut-off wavelength nm1190-13301190-1330

0 dispersion Wavelength nm1300-13241300-1324

0 dispersion Slope ps/nm/km≤0.092≤0.092

Polarization mode dispersion ps/nm/km≤0.2≤0.2

Bending radius mm3015

Additional db/km0.260.03 under bending

Attenuation radius

15MM10 Circle

This kind of optical fiber bending diameter is small, especially suitable for indoor cloth, so that FTTH cable into the door after the cloth conditions have been greatly improved. At present, the most used in the market is g652d and small bending radius fiber. [5]

Development of fiber optic cable in 2.2 FTTH

FTTH Optical cables used in accordance with the conditions can be divided into FTTH use of outdoor optical cables, FTTH with access to optical cables and FTTH indoor cable.

FTTH Outdoor Optical cable, its products and technology and ordinary outdoor optical cable is fully compatible, but also convenient use of existing cable resources. [5]

FTTH access to optical cables, which refers to the optical cable branch point to the user access point between the optical cable, the role is to the backbone of the optical fiber cable into the user access point, the introduction of the environment, including pipelines, overhead, road open groove shallow buried. Its main characteristics are: laying distance is shorter, generally less than 1000m; it is required that optical fiber is easy to divide and connect, it is easy to improve the construction speed; The cable cores are smaller, generally under 12 cores, and the commonly used optical cable types include small core-frame-type fiber ribbon cables, small 8-type self-supporting optical cables, road-slotted optical cables and indoor and outdoor

FTTH use of indoor optical cables, such as the design requirements of small diameter, easy to pave, but also to consider indoor fire retardant, preferably halogen-free flame-retardant, environmental protection, to meet the requirements of high and low temperature, optical fiber cable size and structure should be able to match the requirements of fiber fast connectors, To ensure that the construction site to intercept the actual requirements of the appropriate length of optical fiber cable on-site production joints, can avoid the treatment of excess optical cable before the door to leave the problem. Ordinary indoor cable can not meet the building within the convenient laying and easy to connect, and so on, so at present, Japan Sumitomo and China Long Fly (Shanghai) as the representative of optical cable manufacturers have designed some new optical cable structure to meet the requirements of FTTH indoor optical cables. The specific structure is shown in the following illustration:

(3) (4)

The design feature of this kind of optical cable is to use LSZH (Low smoke halogen free) environment-friendly material to do outer sheath, two v slots are designed on both sides of the optical cable, making the optical cable in the construction time even without the use of tools can be very convenient stripping jacket, two of non-metallic reinforced core parallel to the sides of the fiber, Since the diameter of the non-metallic reinforced core is much larger than that of the optical fiber, when the optical cable is subjected to lateral pressure and shock, the fiber is effectively protected, so it can withstand great pressure (can reach 3000n/100mm).

3. Concluding remarks

FTTH is the final form of broadband access, it can promote the voice, data, video three-network integration, pull related industry development, reduce social output costs, improve social benefits [8]. We can learn from other countries ' development experience, with the government's guidance policy to instigate the development of domestic FTTH market, in addition, operators, equipment manufacturers and cable suppliers will be conducive to improve our FTTH popularization, accelerate the construction of China's information society.