1. Introduction
Recently, low-water-peak fibers have been devel-oped and introduced to optical networks including access networks. The fibers are suitable for u in access network systems due to their excellent attenuation sta-bility over the entire operating wavelength range from 1260 nm to 1625 nm. On the other hand, along with the increa in FTTH subscribers, bending loss innsitive fibers have been developed to make installation and maintenance works easier. A bend innsitive fiber per-mitting 7.5 mm bend radius, UltraAccess (PureAccess-Ultra), was introduced in the SEI Technical Review No.163 (September 2003), in which the fiber design concept, bending loss characteristics at 1550 nm,splice/connection loss and so on were prented.Considering the future network flexibility such as pro-viding versatile rvices to customers by introducing full spectrum network system and/or monitoring system ud at 1650nm, it is necessary that the optical cables can be operated in a wide wavelength range from O -band to L-band. Therefore, a low-water-peak and bend innsitive fibers for applications in access network sys-tems have been developed. In this paper, the authors prent the performances of PureAccess-Ultra fiber and the cables that apply this fiber.
2. Bending loss-innsitive optical fiber
2-1 Fiber performance扇贝怎么处理
Table 1shows the performance of bend innsitive single mode fiber, PureAccess-Ultra, compared with a standard ITU G.652C/D single mode fiber having 30
mm bend radius and Sumitomo Electric’ s PureAccess single mode fiber having 15 mm bend radius. The bend-ing radius of PureAccess-Ultra is permitted to be 7.5mm in the long term, which can be achieved by the opti-mization of MFD and high screening strength.
2-2 Transmission property
Typical attenuation properties of PureAccess-Ultra are shown in Fig. 1. Water peak absorption at around 1383 nm has been reduced substantially and the trans-mission loss at 1383 nm after hydrogen aging is less than the value at 1310 nm. Over a wide range of wavelengths from 1310 nm to 1625 nm, attenuation is practically low and stable even after cabling.
2-3 Bending loss properties
Figure 2shows the wavelength dependance of bend-ing loss at 7.5 mm band radius. As the wavelength becomes longer, the bending loss of fiber increas.Though SM fiber show large bending loss at longer wavelength, bending loss of PureAccess-Ultra is signifi-cantly low even at a long wavelength of 1650 nm. Figure 3
INFORMATION & COMMUNICATION SYSTEMS
With the increa in FTTH network construction, easier access and less space of optical fiber/cables wiring are required. In order to meet the demands, a single mode f iber permitting 15 mm bend radius has been recently introduced and spread to access networks. The authors propod a more bend-innsitive f iber to allow bend radius of 7.5 mm in the SEI Technical Review No.163 (September 2003), in which the authors prented the fiber design concept, bending loss properties at 1550 nm, splice/connection loss and so on.
In this paper, a low-water-peak and bend-innlitive single mode fiber suitable for full spectrum access network systems is propod, and to verify the effectiveness of bend-innsitive fiber in practical u, the authors have evaluated fiber/cable handling and cable installation.
As the results the authors have obrved that no error has occurred in 10 Gbps transmission during mid-span access of the new fibers in an aerial closure and have also verified the excellent attenuation stability especially at a long wavelength of 1650 nm even in vere conditions such as drop/indoor wiring with small bend radius in subscribers’ residence.
Performance of Bend-innsitive Single Mode Fiber and its Application to Optical Access Networks
Itaru SAKABE, Hiroki ISHIKAWA, Hisashi TANJI, Yoshiaki TERASAWA, Masumi ITOU and Tomohiko UEDA
Table 1.Attribute of optical fibers
Attribute
ITU-T G652C/D
(SM)PureAccess PureAccess-Ultra Mode field
diameter at 1310 nm
8.6-9.5 µm ±0.7 µm Nom. 8.6 µm ±0.4 µm Nom. 6.3 µm ±0.4 µm –
125.0 µm ±1.0 µm
125.0 µm ±0.5 µm 125.0 µm ±0.5 µm Details
Cladding diameter
Attenuation coefficient at 1310 nm ≤0.4 dB/km ≤0.4 dB/km <0.4 dB/km Cable cut-off
wavelength
Maximum
1260 nm
1260 nm
1260 nm
Bending loss at 1550 nm
≤0.5 dB/100 turns at R30 mm ≤0.5 dB/100 turns at R15 mm ≤0.5 dB/100 turns at R7.5 mm
at 1550 nm ≤0.3 dB/km ≤0.25 dB/km ≤0.25 dB/km
shows bending loss as a function of bend radius.PureAccess-Ultra shows excellent bending properties,which are less than 0.5 dB/10 turns with 7.5 mm bend radius even at 1650 nm wavelength.
2-4 Splice and connection loss
Fusion splice loss and interconnection loss of PureAccess-Ultra were measured. Table 2shows typical measurement values. T he splice and interconnection
loss between two PureAccess-Ultra fibers were low enough for u in access network due to the improve-ment in the accuracy of fiber circularity concentricity and in the arrangement technique. Splice loss and inter-connection loss between different types of fiber are a lit-tle higher than that between the same types of fiber.However, the interconnection loss between different types of fiber can be limited to only one or two in an access line. Thus it can be said that this interconnection loss are permissible.
3. Application to access networks
Examples of application of PureAccess-Ultra to access networks are shown in Fig. 4. PureAccess-Ultra having excellent bending property is effective for u in vere situations such as handling of jumper cord at net-work center, drop/indoor wiring with small bending radius, fiber handling at mid-span access, handling or hooking of cable by FT T H subscribers and so on. T o verify the effectiveness of PureAccess-Ultra fiber in prac-tical u, the authors have evaluated the fiber and cable performances in the applications.
3-1 Jumper cord and its handling evaluation under
10 Gbps transmission
In a network center, high bit rate signals transmit through jumper cords congested in termination boxes.Therefore, it is necessary to handle the cords carefully.Figure 5shows an examples of a jumper cord containing PureAccess-Ultra. In order to confirm the transmission stability of jumper cord maintenance work, the authors
0.10.20.30.40.50.60.70.8
A t t e n u a t i o n [d
B /k m ]
Wave length [nm]1310
1260
1383
1650
1625
着怎么组词1300
1200
1400
1500
1600
1700
O-band
E-band
S-band
持球突破
C-band
U-band L-band
S-band Low-water peak and bend-innsitive
PureAccess-Ultra
Fig. 1.Typical spectral attenuation of PureAccess-Ultra
0.00.51.01.5
2.02.5
3.0
1200
1300
1400
1500
1600
1550
1650
1700
B e n d i n g l o s s [d B /t u r n ]
Wavelength [nm]
7.5 mm radius
Conventional SM fiber (G.652)
PureAccess
PureAccess-Ultra Fig. 2.Bending loss properties as parameter of wavelength
Table 2.Typical splice/connection loss of PureAccess-Ultra at 1310m
*1:Splice with most suitable fusion condition
Method PureAccess-Ultra vs PureAccess-Ultra PureAccess-Ultra vs PureAccess
邮差打一字PureAccess-Ultra vs conventional SM fiber
Fusion Splice <0.0 dB 0.1 dB 0.2 dB Mechanical
splice 0.1 dB 0.4 dB 0.6 dB Connector
0.1 dB
0.5 dB
0.7 dB
1.E-03
1.E-021.E-01
1.E-001.E+011.E+020
5
10
15
双子座女生性格20
Bending radius [mm]
B e n d i n g l o s s [d B /10t u r n s ]0.5dB时人
1550nm
1650nm 1650nm
1650nm
1550nm
1550nm
PureAccess-Ultra
PureAccess Conventional SM fiber (G.652)
Fig. 3.Bending loss properties as function of bend radius
Network center
Jumper cord (PA-U)
Drop cable
(PA-U)
Optical outlet
Aerial closure
Distribution cable (PA-U/PA)Indoor cable (PA-U)Premi
MC MC
MC
MC
Cabinet
Termination cable (PA-U)
MC: Media-converter
Feeder cable (SM)
PA-U: PureAccess-Ultra PA: PureAccess
Fig. 4.Application examples of PureAccess-Ultra
evaluated the handling performance with 10Gpbs trans-mission. Table 3shows the testing methods and the test results. In the tests of shaking and 90 degrees side pull a t connector portion, a conventiona l SM fiber a nd PureAccess showed stable transmission performance. In the verer tes
t of hooking simul a tion, however,PureAccess-Ultra was the only fiber that showed the loss increa that is negligibly low enough.
3-2 Distribution cable and ribbon fiber handling in
aerial closure
In mid-span access it is indispensable to assure the tr a nsmission reli a bility of fibers in u. Applying PureAccess-Ultra to distribution cable is an appropriate solution. Figure 6shows the cross ction of a 100-fiber aerial distribution cable. This cable is compod of slot-ted rod extruded on a central strength member, 4-fiber ribbons houd in the slotted rod, wra pping ta pe a nd ja cket. Beca u of the excellent bending property of PureAccess-Ultra , 4-fiber ribbons ca n be ha ndled with sma ll bend ra dius, lea ding to a n ea sier a nd more reli-a ble mid-spa n a ccess. In order to verify the relia bility performance, the authors conducted the 4-fiber ribbon ha ndling tests simula ting a ctua l ribbon bra nching a nd
mid-span access. Photo 1shows the closure ud for the tests a nd Fig. 7shows the exa mples of mea surement results of transmission loss at 1550 nm. Careful handling is required to prevent loss increa especia lly for con-ventional SM. For example, accidental handling simula-tion of gra sping
fibers with a slightly stronger force,bending fibers a t ca ble end a nd hooking on compo-
Optical fiber
High tensile yarn Jacket
Outer diameter : 2.0 mm
Fig. 5.Structure of optical jumper cord
Aerial closure (MJC-AFT)
Sheets for storing fibers
T rays for spliced fibers
Photo 1.Aerial closure for u in fiber handling tests
123456
I n c r e a s e o f t r a n s m i s s i o n l o s s a t 1.55u m [d B ]
Conventional SM
UltraAccess-Ultra
Grasping with fingers
Bending at the edge of a cable connected to a closure
Hooking at the parts of a closure Fig. 7.Examples of measurement results for fiber handling in closure
Table 3.10Gbps transmission tests assuming cord
handling at network center
Test methods
Results [∆α1550nm(Bit error)]
PureAccess-Ultra <0.01dB
(No bit error)
[
Conventional SM 5-10dB
]
(Bit error > 1E+10)
PureAccess-Ultra <0.01dB
(No bit error)
[ Conventional SM 0.01dB
](No bit error)
PureAccess-Ultra <0.01dB
(No bit error)[
Conventional SM 0.01dB
]
(No bit error)
(1) Hooking
30˚
R 30mm
Mandrel ø10mm
W 9.8N (2) Shaking
100mm
300mm
(3) Connector portion 90˚ side pull
SC connector
W 19.6N
4-fiber ribbon
Supporting wire Central strength member
4-fiber ribbon
Slotted rod (SZ)Wrapping Jacket
Dimension 12mm 18mm
Fig. 6.Structure of 100-fiber aerial distribution cable
nents of closure caud relatively high increa in atten-uation for the fibers. On the other hand, loss increas-es obrved with PureAccess-Ultra was negligibly low.Considering the increasing opportunities of branch-ing/maintenance works at aerial closure, applying PureAccess-Ultra could be an appropriate solution to maintain stable and reliable transmission.
3-3 New drop cable permitting R7.5 mm bend
radius
The enhanced bend innsitive fiber can be applied to any optical fiber cable. In some cas, however, it is necessary to develop cables suitable for small bending to make the most of the fiber performance. One of the examples refers to drop cable. The cross ction of a drop cable with small bending radius, which has the similar structure as conventional cables except for ten-sion members, is shown in Fig. 8. The properties of the cable are shown in Table 4. As bending radius of con-ventional non-metallic drop cable is restricted to 30 mm due to the G-FRP tension rods, the authors have adopt-ed a new tension member material, which is high tensile yarn rod fixed by plastic resin, that withstands small bending of 7.5 mm radius. By using the new tension menber rods in non-metallic drop cable, cable handling has become much safer and wiring has become more compact.
3-4 Installation/handling evaluation of indoor cable An indoor cable is required to be tough and to fit to wall corner in subscribers’ residence, thus realizing
compact and safe wiring. To meet the requirements,the authors examined installation and handling of indoor cable on veral conditions such as pulling at lead-in point at subscriber residence, pulling/pushing at the corner edge of wall, cable storage in optical outlet (Photo 3), and cable hooking. Figur e 9shows a cross ction of indoor cable. Two fibers and two strength members are covered with flame-retardant jacket. The cable size is about 2 mm by 4 mm. Table 5shows the te
st methods and results. SM fiber exhibited high increa of transmission loss in most tests. On the other hand,PureAccess-Ultra showed very stable transmission prop-erties, and indoor cable using PureAccess-Ultra can be wired in compact as shown in Photo 2.
Supporting wire
New non-metallic tension member
PureAccess-Ultra
Jacket
Fig. 8.New drop cable
Table 4.New drop cable properties
* The values except for initial loss show increa loss at 1625nm.
Attribute
Condition Propertie Transmission
properties Initial loss 1625um <0.25dB/km Temperature cycling
-30~70˚C <0.05dB/km Mechanical properties
Crush 1200N/25mm <0.05dB Bend R=7.5mm,±90˚ 5cycles <0.05dB Impact 3N·m <0.05dB Twist ±90˚/m <0.05dB Stroke
R250mm,700N
怎么写观察日记<0.05dB
Conventional SM (r = 30 mm)
PureAccess-Ultra (r = 7.5 mm)
班长竞选Photo 2.Example of lead-in point at subscribers residence
UTP
Optical cable
T elephone wire
Photo 3.Example of storage in optical outlet
T ension member Optical fiber
Flame retardant jacket
Fig. 9.Structure of indoor cable
3-5 New termination cable for u in subscriber’ s
residence
Connecting optical outlet and optical network unit with termination cable is a compact and flexible wiring,which allows rearrangement of room furnishings and changing of the position of optical network unit. The ter-mination cable with SC connectors on both ends should be tough and flexible becau it is wired in subscribers’residence and handled by general consumers. In order to meet to this demand, the authors prented a tough and flexible cable called PureFlex in the SEI Technical Review No.164 (April 2004). Applying PureAccess-Ultra to PureFlex improves transmission property and enables easier and safer handling of cables by urs.
4. Conclusion
A bend innsitive optical fiber “PureAccess-Ultra”has been confirmed to show excellent attenuation stabil-ity especially at the long wavelength of 1650 nm even in vere situations such as drop/indoor wiring with small bending radius, fiber handling at mid-span access, cable handling or hooking by FTTH subscribers and so on.Application of “PureAccess-Ultra” to FTTH access net-work area makes construction/maintenance works easi-er and speedier, and improves the reliability of cable handling by urs.
References
(1) Y. Terasawa et. al., ”Small Bending Radius Type Single Mode
O ptical Fibers for Access Network”, SEI technical review, 163rd,pp. 1-4 (2003).
(2) H. Ishikawa et. al, “New O ptical Access Network Solution with
Ultra-High Bending Resistant Single Mode Fiber”, 52nd IWCS,pp.68-74 (2003).
(3) N. Osada et. al., “ Development of Optical Fiber Cable for Indoor
Wiring Application in FTTH Networks”, SEI technical review,164th, pp. 77-81 (2004).
Table 5.Results of vere indoor u test
Test methods
Results [∆α1625nm]Hole of 6mm diameter
Cable
L o a d
Wall
(1) Lead-in point to room Load 20 N
PureAccess-Ultra <0.05 dB Conventional SM : 5-10 dB
Load
Wall
(2) Pushing at corner edge
Cable
Load 50 N
PureAccess-Ultra <0.05 dB Conventional SM : 1-3 dB
Load
(3) Pulling at corner edge
C a b l e
Wall
2 mm radius
Load 20 N
PureAccess-Ultra <0.05 dB Conventional SM >10 dB
(4) Storage of optical cable in optical oultet Dimension
Height: 110 mm Width: 70 mm Depth: 30 mm
T elephone wire
UTP Optical cable
PureAccess-Ultra <0.01 dB
Conventional SM : 3-10 dB
Load
(5) Hooking of cable
30˚
R=30mm
R=30mm
R=5mm Increa of transmission loss at load 50 N
PureAccess-Ultra <0.2 dB Conventional SM >10 dB
Contributors
I. SAKABE
• Assistant Manager, Access Fiber Optics R&D Department, Optical Communications R&D Laboratories H. ISHIKAWA
• Assistant Manager, Access Fiber Optics R&D Department, Optical Communications R&D Laboratories H. TANJI
• General manager, Access Fiber Optics R&D Department, Optical Communications R&D Laboratories Y. TERASAWA
• Manager, Engineering Department, Fiber and Communication Cable Division
M. ITOU
• Manager, Fiber Manufacturing Department, Fiber and Communication Cable Division
T. UEDA
• Manager, Network Products Technologies Department, Lightwave Network Products Division
