The document summarizes research on manipulating the geometric and structural parameters of photonic crystal fibers to minimize dispersion and propagation loss. It discusses 4 models of photonic crystal fiber structures that were designed and analyzed using the Finite Difference Time Domain method. The models varied parameters like pitch, hole diameter, and refractive index. All 4 models achieved near-zero dispersion, with values ranging from -0.5 to 1.0 ps/nm-km. Propagation losses were also calculated. Future work is proposed to design photonic crystal fibers with zero dispersion over a wide wavelength range to enable broadband supercontinuum generation.

1. Effects of Structural Parameters of Photonic
Crystal Fiber on Propagation
Under the supervision of
Dr. Sanjeev Kumar Metya
Submitted by
Saswati Rudra Paul
Roll-MTMC/14/12
Mobile Communication & Computing
Department of CSE

2. Contents:
• Problem statement
• Literature survey
• Result & Discussion
• Conclusion & future work
• Reference

3. Problem Statement
• The main goal of this work is to minimize the dispersion of a photonic crystal fiber
by manipulating geometrical and structural parameter of the crystal.
• By minimizing the dispersion of a photonic crystal fiber almost zero level dispersion
is obtained which means that the photonic crystal fibers disperse less when light
propagating through the crystal and
• Hence it reduces the propagation loss of the light.
• Here some parameters like pitch, refractive index, diameter of the dielectric
material are manipulated to achieve low dispersion.

4. Literature survey
Photonic crystal
• Photonic crystal, a low loss periodic dielectric medium, is an optical material which
consists of material with different periodic dielectric constants, preventing light
from propagating in certain directions with specified frequencies .
• If for some frequency range, a photonic crystal prohibits the propagation of
electromagnetic waves of any polarization traveling in any direction from any
source, it can be said that the crystal has a complete photonic band gap . A crystal
with complete photonic band gap will obviously be an omnidirectional reflector.
• The periodicity of the dielectric function in photonic crystal along one, two or three
axes form one-, two- or three- dimensional photonic crystal respectively.

5. Contd…

6. Contd…
FDTD (Finite DifferenceTime Domain)
• Finite Difference Time Domain (FDTD), a universal brute-force numerical method
in optics and electromagnetism.
• As it is a time domain algorithm, it can cover a wide range of frequency, treating
nonlinearity in a natural way.
Fig.1: Structure of aYee cube.

7. Contd…
• This method is aimed to solve Maxwell’s equations by discretizing it using central
difference approximations both in space and time domain.
• Space is divided into box-shaped cells, smaller than the wavelength, where electric
fields are positioned on the edges of that small box and magnetic fields are located
on the faces of the cells. This type of arrangements of the fields is called Yee cell
shown in fig.1.
• To calculate any H-field component we require the value of that previous time step
H-field along the the surrounding two directions and newly computed values of
surrounding E-field components of other two directions is needed and,
• To obtain the E-field components similar procedure is followed using the newly
computed H- fields.

8. Contd…
• In this method leap-frog technique is used in which E and H field is shifted in time by half
a time step and in space by half a cell.
• The electric and magnetic fields are updated using leapfrog method, as shown in fig below
in which first the electric fields and after that the magnetic fields are computed at each
time step.
Fig.2: Leap frog method for updating electric and magnetic field component

9. Contd…
Photonic crystal as a fiber
• Photonic crystal can be used as a fiber, called photonic crystal fiber.
• Photonic crystal fiber is a kind of optical fiber whose operation is based on the
properties of photonic crystal.
• Photonic crystal fiber can be categorized into three primary different types
depending on the dispersion property of the crystal.These are:
 Dispersion shifted photonic crystal fiber (DSPCF)
 Dispersion flattened photonic crystal fiber (DFPCF)
 Dispersion compensation photonic crystal fiber (DCPCF)

10. Contd…
• According to the optical confinement method it can be of two types
 Guided index
 Photonic band gap
• Chromatic dispersion
= −
[ ]
• Propagation loss
= 40 . ( )/(ln 10 )

11. Contd…
d=diameter of holes
Ʌ=pitch/lattice constant
Fig.3: Holy fiber structure

12. Result & discussion
Model 1- Same pitch, different 1st ring diameter without doping
The investigated PCF structure parameter is specified in the following table
Parameter[unit] Value
Pitch Ʌ [ ] 1.62
Hole’s diameter [ ] 1.46
Normalized hole diameter /Ʌ [-] 0.9
1St
ring hole diameter [ ] 0.52-0.54
2nd
ring hole diameter [ ] 0.63
Propagating wavelength [nm] 1550
No. of rings at the cladding [-] 6
Background refractive index [-] 1.444

13. Contd…
Structural model of proposed PCF.
2D view
3D view

14. Contd…
Chromatic dispersion of the modelled PCF.

15. Contd…
Fundamental mode of propagation

16. Contd…
0.00E+00
2.00E-06
4.00E-06
6.00E-06
8.00E-06
1.00E-05
1.20E-05
5.00E-01 7.00E-01 9.00E-01 1.10E+00 1.30E+00 1.50E+00 1.70E+00 1.90E+00 2.10E+00
loss[dB/m]]
wavelength[μm]
Propagation loss curve

17. Contd…
Model 2- Same pitch (different for 1st ring, rest of the rings),
different 1st ring hole diameter & hole diameter without doping
The investigated PCF structure parameter is specified in the following table
Parameter[unit] Value
Pitch of 1st
ring Ʌ1 [ ] 2.1
Pitch of 2nd
ring Ʌ2 [ ] 2
Hole’s diameter [ ] 0.74-0.76
1St
ring hole diameter [ ] 0.54, 0.55
Propagating wavelength [nm] 1550
No. of rings at the cladding [-] 6
Background refractive index [-] 1.444

18. Contd…
Structural model of proposed PCF.
2D view
3D view

19. Contd…
Chromatic dispersion of the modelled PCF

20. Contd…
Fundamental mode of propagation

21. Contd…
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
5.00E-01 7.00E-01 9.00E-01 1.10E+00 1.30E+00 1.50E+00 1.70E+00 1.90E+00 2.10E+00
loss[dB/m]
wavelength[μm]
Propagation loss for the proposed structure

22. Contd…
Model 3- Same hole diameter with different pitch without
doping
The investigated PCF structure parameter is specified in the following table
Parameter[unit] Value
Pitch Ʌ [ ] 2.33-2.35
Hole’s diameter [ ] 0.62
Normalized hole diameter /Ʌ [-] 0.275
Propagating wavelength [nm] 1550
No. of rings at the cladding [-] 6
Background refractive index [-] 1.444
Structural parameters for the PCF

23. Contd…
Structural model of proposed PCF.
2D view
3D view

24. Contd…
Chromatic dispersion of the modelled PCF

25. Contd…
Fundamental mode of propagation

26. Contd…
0.00E+00
2.00E-04
4.00E-04
6.00E-04
8.00E-04
1.00E-03
1.20E-03
1.40E-03
1.60E-03
8.00E-01 1.00E+00 1.20E+00 1.40E+00 1.60E+00 1.80E+00 2.00E+00
loss[dB/m]
wavelength [μm]
Propagation loss for the modelled structure

27. Contd…
Model 4- Same pitch, same hole diameter with core doping
The investigated PCF structure parameter is specified in the following table
Parameter[unit] Value
Pitch Ʌ [ ] 4.4
Hole’s diameter [ ] 1.849
Normalized hole diameter /Ʌ [-] 0.43
Core diameter [ ] 2.4
Propagating wavelength [nm] 1550
No. of rings at the cladding [-] 6
Background refractive index [-] 1.444
Core refractive index [-] 1.5

28. Contd…
Structural model of proposed PCF.
2D view
3D view

29. Contd…
Chromatic dispersion of the modelled PCF

30. Contd…
Fundamental mode of propagation

31. Contd…
-1.60E-07
-1.40E-07
-1.20E-07
-1.00E-07
-8.00E-08
-6.00E-08
-4.00E-08
-2.00E-08
0.00E+00
5.00E-01 7.00E-01 9.00E-01 1.10E+00 1.30E+00 1.50E+00 1.70E+00 1.90E+00 2.10E+00
loss[dB/m]
wavelength [μm]
Propagation loss for the proposed design.

32. Conclusion & future work
Photonic crystal fiber, a new type of optical fiber is advantageous in many ways over
conventional optical fiber. Here structural parameter of the crystal fiber has been
manipulated and zero level dispersion is obtained to minimize the dispersion. The
parameters which have been used to get low dispersion are also used for the calculation
of refractive index and hence the propagation loss is calculated from the imaginary part
of the effective refractive index.
The results obtained from the different four models are as follows:
• 1st PCF structure is designed for fixed diameter 1.849 and pitch 4.4 for the
free space wavelength of 1550nm with 6 air hole ring. In this design dispersion
achieved was nearly at -0.5 to 0.5ps/nm-km within the range of wavelength about
1.35-1.55 with fixed refractive index 1.444.

33. Contd…
• 2nd model was designed for fixed pitch value 1.62 , fixed diameter value
1.46 , fixed 2nd ring diameter value 0.63 and 1st ring diameter has different
values of 0.52 , 0.53 , and 0.54 for the free space wavelength of 1550nm
with 6 air hole ring, in this design dispersion achieved nearly at -0.5 to 0.5ps/nm-
km within the range of wavelength about 1.25-1.55 with fixed refractive index
1.444.
• 3rdmodel structure parameters are as follows, 1st ring period 2.1 , 2nd ring
period 2 , hole diameter 0.74 , 0.75 , 0.76 , 1st ring diameter 0.54 ,
0.55 , for the free space wavelength of 1550nm with 6 air hole ring, in this
design dispersion achieved nearly at 1.0ps/nm-km within the range of wavelength
about 1.25-1.55 with fixed refractive index 1.444.

34. Contd…
• The last model parameters are, pitch 2.33 , 2.34 , 2.35 , fixed normalised
diameter ( /Ʌ) 0.275 and fixed hole diameter 0.62 , for the free space
wavelength of 1550nm with 6 air hole ring, in this design dispersion achieved nearly at
0.5ps/nm-km within the range of wavelength about 1.3-1.45 with fixed refractive
index 1.444.
FutureWork
Dispersion as well as nonlinear property of photonic crystal fiber helps to generate
supercontinnum to realise broadband optical sources, which is suitable for application in
dense wavelength division multiplexing optical network such as transmission and
wavelength switching. Wide supercontinnum can be generated by photonic crystal fiber that
operates at zero dispersion wavelength of the fiber owing to its high non-linearity and
flexible design of the dispersion profile. So designing of a PCF with zero dispersion over a
wide wavelength range will leads to generate supercontinnum which will open many scopes
in optical world.

35. Reference
1. John D. Joannopoulos, Steven G. Johnson, Joshua N.Winn, Robert D.Meade,
“Photonic Crystals,Molding the Flow of Light”, Princeton University Press,
Princeton And Oxford.
2. Lin-Ping Shen,Wei-Ping Huang, and Shui-Sheng Jian,“Design of photonic crystal
fiber for dispersion-related application”, Journal Of LightwaveTechnology,Vol. 21,
No. 7, July 2003.
3. Michal Lucki, “Photonic Crystal Fibers with Optimized Dispersion for
Telecommunication Systems”, Recent progress in opticle fiber research-InTech.
4. AndreiV. Lavrinenko, Jesper Lægsgaard, Niels Gregersen, Frank Schmidt,Thomas
Søndergaar,“Numerical Methods in Photonics”, CRC Press.

36. Contd…
5. Krishna Mohan Gundu, Miroslav Kolesik, JeromeV. Moloney and Kyung Shik Lee
“Ultra-flattened-dispersion selectively liquid-filled photonic crystal fibers”,
Optical Society of America.
6. Rifat AhmmedAoni, Rajib Ahmed, Md. MahbubAlam and S. M.Abdur Razzak,
“Optimum Design of a Nearly Zero Ultra-flattened Dispersion with lower
Confinement loss Photonic Crystal Fibers for Communication Systems”,
International Journal of Scientific & Engineering ResearchVolume 4, Issue 1,
January-2013.
7. R. K. Sinha and Shailendra K.Varshney, “Dispersion properties of photonic crystal
fibers”, Microwave and OpticalTechnology Letters /Vol. 37, No. 2,April 20 2003.
8. Nguyen Hoang Hai, Nguyen Hoang Dai, HoangTuanViet, NguyenTheTien,“A
Nearly-Zero Ultra-Flattened Dispersion Photonic Crystal Fiber:Application to
BroadbandTransmission Platforms”, IEEE.

37. Contd…
9. N. Nozhat and N. Granpayeh,“Specialty Fibers Designed by Photonic Crystals”,
Progress In Electromagnetics Research, PIER 99, 225{244, 2009.
10. Tomasz Karpisz, Bartlomiej Salski,Anna Szumska, Mariusz Klimczak and Ryszard
Buczynski, “FDTD analysis of modal dispersive properties of nonlinear photonic
crystal fibers”, Opt Quant Electron (2015) 47:99–106 DOI 10.1007/s11082-
014-9987-y, Springer.
11. Yashar Esfahani Monfared,“Hybrid-cladding Photonic Crystal Fiber with Novel
Dispersion Properties”, IEEE.
12. Shaimaa I.Azzam, Rania Eid A. Shehata, Mohamed Farhat O. Hameed,A. M.
Heikal and S. S.A. Obayya,“Multichannel photonic crystal fiber surface plasmon
resonance based sensor”, Opt Quant Electron (2016) 48:142, Springer.

38. Contd…
13. Ahmmed A. Rifat, G.Amouzad Mahdiraji, Desmond M. Chow,Yu Gang
Shee, Rajib Ahmed and Faisal Rafiq Mahamd Adikan,”Photonic Crystal
Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte
Channels and Graphene-Silver Deposited Core”, sensors ISSN 1424-8220.
14. H.Ademgil, S. Haxha,T. Gorman, and F.AbdelMalek, “Bending Effects on
Highly Birefringent Photonic Crystal FibersWith Low Chromatic
Dispersion and Low Confinement Losses”, Journal of Lightwave
Technology,Vol. 27, No. 5, March 1, 2009.
15. Emmanuel K.Akowuah,Terry Gorman, Huseyin Ademgil, Shyqyri Haxha,
Gary K. Robinson, and JennyV. Oliver, “Numerical Analysis of a Photonic
Crystal Fiber for Biosensing Applications”, IEEE Journal of Quantum
Electronics,Vol. 48, No. 11, November 2012.
16. Vinay Kanungo, Sanjeev Kumar Metya,Vijay Janyani, Mohammad Salim,
“Segmented cladding index guiding photonic crystal fiber”, Elsevier.

39. Contd…
17. Nagesh Janrao , Sanjeev Kumar Metya andVijay Janyani,“New geometry of
photonic crystal fiber for improved dispersion compensation”,Taylor & Francis.
18. R. Otupiri, E. K.Akowuah,S. Haxha, Senior Member, H.Ademgil, F.AbdelMalek,
andA.Aggoun,“A Novel Birefrigent Photonic Crystal Fiber Surface Plasmon
Resonance Biosensor”, IEEE Photonics Journal.
19. Ahmed M. Heikal, Firas Faeq K. Hussain, Mohamed Farhat O. Hameed,“Efficient
Polarization Filter Design Based on Plasmonic Photonic Crystal Fiber”, Journal of
LightwaveTechnology,Vol. 33, No. 13, July 1, 2015.
20. M.A. Schmidt, H. Lee, H.Tyagi, P. Uebel and P. St.J. Russell,“Plasmonic Photonic
Crystal Fiber”, OSA/ CLEO 2011.
21. AllenTaflove,“Computational Electrodynamics-The Finite-DifferenceTime-
Domain Method”,Artech House, INC.

40. Thank you…