8/12/2019 A New Design Concept of Optical Fibers to Reduce Non Linearity and Bend Loss in Optical Networks

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A New Design Concept of Optical fibers to Reduce

Non Linearity and Bend Loss in Optical Networks

Non Linearity -Stimulated Brillouin Scattering

BS is a nonlinear phenomenon which arises due to the interaction of Acoustical and

tical modes. When the input power reaches a certain threshold Pth then forwarding

opagating light is scattered in the backward direction due to this effect.

oor picture quality due to

BS effect

Good picture quality

n High SBS

hreshold fiber

SBS Threshold Measurement set up

Bend Loss

Radiative losses occur whenever an optical fiber is subjected to extrinsic

perturbations like bend of finite radius and such losses are called Bend Losses.

90 degree Cable

bent

Cable is

stapled

ClassA: G.657Attributes

Attribute Detail Value

MFD Wavelength 1310 nm

Ra ng e o f no mi nal v al ue s 8. 6- 9. 5 m

Tolerance 0.4 m

Bend loss

Radius (mm) 15 10

Number of turns 10 1

Max. at 1550 nm (dB) 0.25 0.75

Max. at 1625 nm (dB) 1.0 1.5

Profile Design

Core region is divided into three sub core regions and clad region consists of two

clad regions.

n1 > n2 > n3 > n5 > n4

t3 > t2 > t1

The segmented core reduces the optical and acoustical mode coupling and thus

increases the SBS threshold and the depressed clad regions improves the Bend

property of the fiber.

Results

MeasuredBend lossvalues of fiber

S.no

R=10 mm 1 turn R =15 mm 10 turns

Grade

1550 1625 1550 1625

Fiber1 0.237 0.688 0.023 0.126 G.657A

Fiber2 0.24 0.743 0.026 0.128 G.657A

Fiber3 0.237 0.633 0.021 0.124 G.657A

.

Conclusions

Introduction

Network operators are constantly looking for solutions which can decrease

omplexity,cost and improve overall network performance.

High SBS threshold and low bend loss fiber is a solution in todays FTTH

etworks.The feeder fiber used at the CO/HE allows more power transmission

ecause of its high SBS threshold and at the customers end, it can meet the

tringent wiring conditions because of its better bend properties.

Typical FTTH network architecture

1

3

4

5

6

An optical fiber with high SBS threshold and lower bend losses enables

network operators to install a single fiber in FTTH networks.

High SBS threshold fiber allows more power transmission which in

turn increases the number of customers in typical Passive optical

networks. It enables longer reach and higher split ratios.

In Indoor cabling, there are stringent bending requiremnts which

requires that the fiber should have better bend performance. Since the

same fiber will be used in the network, splice loss will also be reduced.

Deploying a single fiber will reduce equipment costs, as it needs far

less equipment than that required by other single-mode fibers to

provide the same amount of network coverage; additionally, it can

eliminate the need for special transmission equipment to manage SBS

REENA HARNAL and SAURAV DUTTA

E-2, Sterlite Technologies Ltd, MIDC, Aurangabad, India

reena.harnal@sterlite.com, dutta_s@sterlite.com

The fiber has an increased SBS

threshold value as compared to

conventional single mode fiber.

It also complies G.657A attributes

Optical parameters

MFD m 9.48

Cut off lambda nm 1286.0

Zerodispersion nm 1324.0

Slope @ ZDW ps/nm2-km 0.092

Attn 1310 dB/km 0.34

Attn 1550 dB/km 0.20

SBS Pth @1550 dBm 12.0