Photonics 2008
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An optical fiber is proposed with a segmented core and depressed cladding regions to reduce nonlinearity and bend loss. The segmented core decreases optical and acoustic coupling to increase the stimulated Brillouin scattering (SBS) threshold. Depressed cladding regions improve bend properties. Test results show the fiber has an SBS threshold over 12 dBm and bend losses under IEC standards, enabling its use in a single fiber for both feeder and customer segments of fiber-to-the-home networks. This simplifies deployment and reduces costs compared to using multiple fiber types.
Photonics 2008
- 1. A New Design Concept of Optical fibers to Reduce Non Linearity and Bend Loss in Optical Networks Non Linearity -Stimulated Brillouin Scattering SBS is a nonlinear phenomenon which arises due to the interaction of Acoustical and Optical modes. When the input power reaches a certain threshold Pth then forwarding propagating light is scattered in the backward direction due to this effect. Poor picture quality due to SBS effect Good picture quality in High SBS threshold 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 Class A: G.657 Attributes Attribute Detail Value MFD Wavelength 1310 nm Range of nominal values 8.6-9.5 袖m Tolerance 0.4 袖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 Measured Bend loss values 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 complexity,cost and improve overall network performance. High SBS threshold and low bend loss fiber is a solution in todays FTTH networks.The feeder fiber used at the CO/HE allows more power transmission because of its high SBS threshold and at the customers end, it can meet the stringent wiring conditions because of its better bend properties. Typical FTTH network architecture 1 2 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 Zero dispersion 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