1 / 17

Study on Dispersion Compensating Fiber

Study on Dispersion Compensating Fiber. Presented by Rajkumar Modak (2011PHS7184) Suvayan Saha (2011PHS7099). Under the Guidance of Prof. B.P. Pal Dr. R.K. Varshney. Ref: Google Images.

ashtyn
Download Presentation

Study on Dispersion Compensating Fiber

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Study on Dispersion Compensating Fiber Presented by RajkumarModak (2011PHS7184) SuvayanSaha (2011PHS7099) Under the Guidance of Prof. B.P. Pal Dr. R.K. Varshney Ref: Google Images

  2. Motivation • To compensate temporal broadening of pulses through design of a suitable dispersion compensating fiber. • To send maximum data within a pulse in a time at a particular wavelength. • To design a DCF with high negative dispersion coefficient

  3. Work Plan • To design a coaxial dual core Dispersion Compensating Fiber(DCF) . • Study Matrix method to make a computer program to calculate effective refractive index. B. Calculate Dispersion Coefficient ( D ) of a conventional single-mode step index fiber-based DCF. C. Calculate D for the coaxial dual core step index fiber to be designed . D. Calculate bend loss of the designed fiber and optimize it.

  4. Basic principle where = material dispersion coefficient = waveguide dispersion coefficient = effective index at propagating wavelength = propagating wavelength. • To achieve zero dispersion where and are the lengths of SMF & DCF. • Ref: 1. Ghatak & Thyagarajan - Introduction to fiber optics, chapter 15. • 2. A. K. Ghatak, I. C. Goyal, R. K. Varshney – “FiberOptica”, Chapter 3 .

  5. Methodology • Matrix Method : • Wave eqn. for fiber in radial coordinate – Solutions for region of refractive index for & for where & Applying boundary conditions, can be written as where Cylindrically symmetric step index fiber . Refractive-index profile of a radially symmetric optical fiber consisting of N concentric regions of homogeneous refractive indices Ref: K. Thyagarajan, SupriyaDiggavi, AnjuTaneja, and A. K. Ghatak - “Simple numerical technique for the analysis of cylindrically symmetric refractive-index profile optical fibers”, APPLIED OPTICS , Vol. 30, No. 27 , 20 September 1991.

  6. Determination of wavelength dependence of refractive index. • Wavelength variation of the refractive index for germanium doped silica is given by where = operating wavelength , are known as Sellemeier coefficients . • Concentration of germanium is related with the refractive indices as: where = refractive index of pure silica, n = refractive index at a given wavelength, are constants at particular wavelength. • The refractive index for any arbitrary concentration is given by where are constants at particular wavelength. • Ref :- A. K. Ghatak, I. C. Goyal, R. K. Varshney – “Fiber Optica”, chapter 3

  7. Fig. 6(a) Fig. 6(b) Fig. 7(a) Fig. 7(b) • Ref: 1. Ghatak & Thyagarajan-Introduction to fiber optics, chapter 15, • K. Thyagarajan, B. P. Pal, “Modelling dispersion in optical fibers: applications to dispersion tailoring and dispersion compensation”, Journal of Opt. FiberCommun. Rep. , vol. 4, 2007, pp. 1- 42

  8. Fig. 6(a) Fig. 6(b) Δ=2%, =1.4729004, =1.44402 a=1μm , D= -57.65 ps/km-nm Fig. 7(a) • Ref: 1. Ghatak & Thyagarajan-Introduction to fiber optics, chapter 15, • K. Thyagarajan, B. P. Pal, “Modelling dispersion in optical fibers: applications to dispersion tailoring and dispersion compensation”, Journal of Opt. FiberCommun. Rep. , vol. 4, 2007, pp. 1- 42

  9. Coaxial dual core DCF with =1.472617, =1.448345, =1.44402 , a=1 μm, b=15.2 μm, c=22 μm D= -4223.63 ps/km-nm at Fig. 7 • Ref: 1. Ghatak & Thyagarajan-Introduction to fiber optics, chapter 15, • 2. K. Thyagarajan, R. K. Varshney, P. Palai, A. K. Ghatak and I. C. Goyal, “A Novel Design of a Dispersion • Compensating Fiber ” , IEEE Photon. Tech. Letts. , vol. 8, no. 11, novenber 1996, pp. 1510-1512.

  10. Bend Loss of a Fiber The propagating wave beam, at the beginning of the bend, is shifted to the outside of the bend, causing a decrease in phase velocity on the inner side and an increase on the outer side. After taking some assumptions the pure bend loss of a fiber can be written Where • E. G. Neumann , “ Single Mode Fibers ” , , chapter 5, Springer – Verlag , 1988.

  11. Bend Loss of a Fiber Variation of bend-loss with bending radius for SMF.28 fiberat 1.55 wavelength Variation of bend-loss with bending radius for dual-core fiber. So, we see that the bend loss is negligible at bend radious near 4 cm. So, our designed fiber has very large negative dispesion coefficient and very low bend loss which is the basic requirment for a good dispersion compensator. We may conclude that this design provides efficient dispersion compensation and low bend loss and can be used as a effective dispersion compensating fiber.

  12. Future Scope • In or project we have studied the step index dual core fiber for high negative dispersion coefficient. We can study some other profile like parabolic index fiber and we may get more high negative dispersion. • Further we can introduce an axial index dip or a triangular shaped inner core refractive index profile and study its propagation characteristics with varying its various parameters like core separation, core radius, separating region refractive index etc. • We also try to study with different combination that is wide core with relatively low refractive index and outer narrow core with relatively high refractive index profile both for step and parabolic index variations. • In our project we have studied only for LP01 mode we can also study for LP02 mode and calculate the dispersion effect.

  13. REFERENCES • Ajoy Ghatak & K. Thyagarajan – “Introduction to fiber optics” (First south asian edition 1999, reprinted 2011 ), Chapter 15 and Chapter 24. • K. Thyagarajan, R. K. Varshney, P. Palai, A. K. Ghatak and I. C. Goyal, “A Novel Design of a Dispersion Compensating Fiber ” , IEEE Photon. Tech. Letts. , vol. 8, no. 11, novenber 1996, pp. 1510-1512. • A. K. Ghatak, I. C. Goyal, R. K. Varshney – “Fiber Optica”, Chapter 3 • A. K. Ghatak, A. Sharma, R. Tewari – “Understanding Fiber Optics on PC ” , Chapter-2, 4, 8, 13. • K. Thyagarajan, B. P. Pal, “Modelling dispersion in optical fibers: applications to dispersion tailoring and dispersion compensation”, Journal of Opt. Fiber Commun. Rep. , vol. 4, 2007, pp. 1- 42 • M. R. Shenoy , K. Thyagarajan and A. K. Ghatak , “Numerical Analysis of Optical Fibers Using Matrix Approach”, Journal of Lightwave Tech. vol. 6, no. 8, Aug. 1988. • E. G. Neumann , “ Single Mode Fibers ” , , chapter 5, Springer – Verlag , 1988.

  14. THANK YOU

  15. Methodology • Matrix formulation: ; where , = , = guided wavelength The solution for j th region is, Boundary conditions at j th & j+1 gives the matrix where an arbitrary variation of is replaced by a large number of steps Ref: Ghatak & Thyagrajan – Introduction to fiber optics , chapter-25

  16. verification of matrix method For single modes at = 1 µm. Fig-2(b) n1=1.503,n2=1.500,d1=4 µm.,d2=4 µm. Fig-2(a) calculated b = 0.53184 ( result according to book=0.53177) Fig-3(a)Fig. 3(b): n1=1.503,n2=1.500,d1=12µm,d2=4µm,d3=µm calculated b = 0.5312(result according to book= 0.5312) Ref: Ghatak & Thyagrajan – Introduction to fiber optics , chapter-25

More Related