The document discusses fiber optic connectors and losses that occur in fiber-to-fiber connections. It proposes investigating the use of antireflection coatings to reduce losses. Specifically, it will: 1) Analyze fiber losses and various connector types. 2) Analyze materials for antireflection coatings like MgF2. 3) Measure reflectance losses using an optical reflectometer and calculate transmittance/reflectance with and without coatings. The expected outcome is that using MgF2 as a coating can significantly reduce attenuation within the operating wavelength range. Adding more coating layers may further reduce losses in fiber optic communication systems.

1. A Prethesis Presentation On

2. Introduction
For information to be conveyed over any distance, an
optical fiber communication system is required.

3. Introduction cont….
A fiber optic connector is a demountable device that
permit the coupling of optical power b/w two optical
fibers. Fiber optic connector can reduce system
performance by introducing modal & reflection noise.
Modal noise is eliminated by using single mode fiber
with laser source. Reflection noise is reduced by
index matching material, physical contact polishes or
antireflection coating.

4. Introduction cont….
Losses in Fiber-to-Fiber Connectors
 Lateral Misalignment
 Angular Misalignment
 End Separation

5. Literature Search
 Mitsuru Kihara et al in [8] described the influence of wavelength and
temperature changes on optical performance of fiber joints with small gap.
The author investigated that when an air gap occurs at the contact point of a
fiber joint, the insertion loss and return loss vary depending on wavelength.
The return losses of fiber-end joints using index matching material depend
on temperature. In this article, PC type connectors are discussed(2006).
 Dalip Singh Mehta et al in [7] suggested the method for improving the
light out-coupling efficiency of organic light-emitting devices by
antireflection coating technique. Here single layer MgF2 material is used as
an antireflection coating to improve the external efficiency of light emitting
devices(2007)
 Kazuya Ogata et al in [11] discussed a comparison between fusion splice
and mechanical splice. In this article, various connectors are discussed
such as SC,ST and LC which are used in data comm. Systems(2007).

6. Literaure Search
 Yoshiteru Abe et al in [2] demonstrated many optical fiber connection devices such
as fusion splice, mechanical splice & optical connector. A mechanical splice
requires refractive index matching material to reduce the Fresnel reflection induced
by the air gap between the fiber end faces(2009)
 G.D. Shen et al in [6] described the propagation of lights through multi layer optical
coatings was analyzed by transfer matrix method. It could improve the light
extraction efficiency of LED with the antireflection coating. SiON was used as an
antireflection coating(2009).
 Mitsuru Kihara et al in [1] discussed optical fiber connector & mechanical splices
used in optical network such as fiber to the home (FTTH) system. Optical
performances of fiber joints with a mixture of refractive index matching material
and air gap are extremely unstable and vary over a wide range of wavelength.
Losses increases as the length of gap increases. Physical Contact Type connectors
without index matching material are widely used for intra-office use where frequent
reconnections are required(2009).

7. Inferences Drawn Out Of Literature
Search
Connector losses occur due to core misalignment
and
end separation.
Splicing is permanent joint of two fibers,
demounting is not possible.
Fiber joints design with mechanical splice require
careful cleaning and precision cleaving.

8. Inferences cont…..
 Refractive index of index matching material vary with
temperature, effect system performance.
 ARC enhance the efficiency of optical source(LED).
 Physical Contact Type connector using polishing
method require better cleaving of fiber ends, otherwise
exhibit more losses(5db).

9. Scope of the work
 Anti-reflective coatings used for a wide variety of
applications where light passes through an optical
surface, and low loss or low reflection is desired.
 Modal noise and reflection can be reduced by
antireflection coatings.
 Optical source efficiency can be improved using
antireflection coatings.
 Optical detector sensitivity can be enhanced using
antireflection coatings.

10. Scope of the work
Fiber to fiber losses can be reduced up to
considerable amount.
Optical transmission capacity can be improved
by reducing losses occuring at source to fiber
interface, fiber to fiber interface and fiber to
detector interface.

11. Proposed Work
The work proposed by author is as follows:
 Analysis of Fiber losses.
 Analysis of various optical connectors.
 Analysis of Materials for Antireflection coating.
 Measurement of reflectance losses at fiber ends by
Optical Continuous-wave Reflectometer /optical time-
domain reflectometer.
 Calculation of Transmittance and Reflectance for
sequence of layer i.e. without coating, single layer
coating, two layer coating etc.

12. Analysis of various types of connectors
Physical Contact (PC) type Connectors with refractive index
matching material are widely used for intra-office use. Various
connectors generally in use are:
Butt Joint Connectors
Multichannel Connectors
 ST Connectors: used in local area network(LAN).Used in
multimode networks like buildings and campuses.
 SC Connectors: used in optical subscriber loop networks.
Used in single mode systems.
 LC Connectors: used in data communication networks.
small in size and offer high port density

13. Analysis of Materials for Antireflection
Coating
Material Refractive Index(n)
MgF2 1.38
Al2O3 1.65
SiON 1.53
ZnS 2.2
CeO2 2.46

14. Working of Antireflection Coating
• Anti-reflection coatings consist of a thin layer of
dielectric material, with a specially chosen thickness so
that interference effects in the coating cause the wave
reflected from the anti-reflection coating top surface to be
out of phase with the wave reflected from the
semiconductor surfaces. These out-of-phase reflected
waves destructively interfere with one another, resulting
in zero net reflected energy. In addition to anti-reflection
coatings, interference effects are also commonly
encountered when a thin layer of oil on water produces
rainbow-like bands of colour.

15. Working cont……..

16. Measurement of reflectance losses at fiber ends
by Optical Continuous-wave Reflectometer
/optical time-domain reflectometer.
Measurement of connector reflectance with an OCWR setup

17. Methodology
• Development of an algorithm in C using Matrix
Transfer Method.
• Determination of Reflectance and Transmittance
without using any coating for given range of
wavelength using a program developed in C.
• Determination of Reflectance and Transmittance for
a given range of wavelength using single layer, two
layers coatings using a program developed in C.
• Development of a function for analysis of various
results between wavelength and attenuation using
transmission window at 850 nm and 1310 nm.

18. Start
Enter code
to select
layer
B
Three Layer Double Layer
A
(N) (K)
n1 = (n0. ns)1/2
Enter layer
thickness?
d1=l0/4n1
d1=l0/2n1
Enter range of operating
wavelength (L1) & (L2)

19. Calculate reflectance (R)
Stop
A
n1=1.38 , n2 = n1(ns / n0 )1/2
d1=l0/4n1 , d2=l0/4n2
Enter range of operating
wavelength (L1) and (L2)
Calculate Reflectance (R)
Stop
B
n1=1.38, n2=2.08,
n3= n1(ns / n0) 1/2
d1=l0/4n1 , d2=l0/2n2 , d3=l0/4n3
Enter range of operating
wavelength (L1) and ( L 2)
Calculate Reflectance ( R )
Stop

20. Expected Outcome
Using Mgf2 as an antireflection coating, the attenuation
may be reduced to a considerable amount with a given
range of wavelength. Optical fiber connectors without
any coating may exhibit more losses. Using single layer
antireflection coating, the loss or attenuation may be
considerably decreased. The author may further try to
reduce the attenuation in fiber communication system by
increasing number of antireflection layers.

21. References
[1] Mitsuru Kihara, Ryuichiro Nagano, Morikazu Uchino,“Analysis on performance
deterioration of optical fiber joints with mixture of refractive index matching material and
air filled gaps”, Optical Fiber Communication Conference, March 2009.
[2] Yoshiteru Abe, Tetsuya Hoshijima, Takashi Matsui, and Shigeru Tomita, “ Optical
Characteristics and Reliability of Mechanical Splice Utilizing Solid Refractive Index
Matching Material for Hole-Assisted Fiber Connection”, Photonics Technology Letters,
IEEE,Volume21,Issue4, pp. 194-196,February2009.
[3] Shigeo Takahashi, Koji Sumida, Daigo Saito, Kazuya Ogata, “Low Return Loss Field-
installable Optical Connector’’, Optical Fiber Communication Conference,2009.
[4] Andenet Alemu , Alex Freundlich , Nacer Badi , Chris Boney and Abdelhak Bensaoula,
“ MgF2/BN Double Layer Antireflection Coating For Photo Voltaic Application”,
Photovoltaic Specialists Conference, pp. 1-4, May2008.
[5] Donyau Chiang,Cheng Hung Chu,Hai-Pang Chiang, “ Optical Constants of Thin Films
Calculated From Reflectance and Transmittance Measurements”,Optical Data Storage
Topical Meeting,pp.101-103,2009.
[6] Y. H. Guo*, X. Guo, B. L. Guan, W. J. Jiang, G. D. Shen, “ Improvement of LED
Extraction Efficiency with Antireflection Coating”, Communication and Photo-Nics
Conference and Exhibition ,pp 1-2,November2009.
[7] Dalip Singh Mehta, Kanchan Saxena, Virendra Kumar Rai, Ritu Srivastava,
“Enhancement of Light out coupling efficiency of organic light emitting devices by
antireflection coatings”, International Workshop on Physics of Semiconductor
Devices,pp.628-629,2007.

22. References
[8] Mitsuru Kihara, Shigeru Tomita, Tadashi Haibara, “ Influence of Wavelength and
Temperature changes on Optical Performance of Fiber Joints with small Gap”, vol.
18, pp.2120-2122,October2006.
[9] Saeed Mahmud Ullah, SeungHun Lee, Ryo Suemitsu, Kazuya Ohira and Shigehisa
Arai, “Improved Performance Of Distributed Reflector Laser With Antireflection
Coating”, Indium Phosphide and Related Materials Conference Proceedings,
pp360- 363, May 2006.
[10] E. B. Kim, C. Y. Park, and S. E. Park, “Selective Amplification of Optical
Frequency Comb Using Anti-Reflect Coated Laser”, Conference on Precision
Electromagnetic Measurements, PP.113-114, June 2010.
[11] Terutake Kobayashi, Daigo Saito, Kazuhiro Takizawa, Kazuya Ogata,“ Field
Installable LC Connector and Mechanical Splice”,Optical Fiber Communication
and National Optic Fiber Engineers Conference,pp.1-11,2007.
[12] Hiroaki Kurokawa, Soichiro Ikuno, Seiko Mitachi, “ An Analysis Of Ultra Low
Reflection Characteristics of FPC Connectors”, 2002.
[13] Etsuji Sugita, Ryo Nagase, Kazunori Kanayama and Toshihiro Shintaku, “SC-Type
Single-Mode Optical Fiber Connectors”, Journal of Lightwave Technology, vol. 7,
no.11, pp.1689-1696, November 2000.

23. References
[14] Lee, D. G. Lim, K. H. Kim, S. H. Kim, S. H. Lee*, D. W. Kim*, E. C. Choi*, D. S.
Kim*, and J. Yi, “ Efficiency Improvement of Buried Contact Solar Cells Using
MgF2/Ce02 Double Layer Antireflection Coatings”,Photovoltaic Specialists
Conference, pp.403-406, August 2000.
[15] Mitsuru Kihara, Shinji Nagasawa,Tadatoshi Tanifuji, “ Temperature Depandance
of Return Loss for Optical Fiber Connectors with Refractive Index Matching
Material”, Photonics Technology Letters, IEEE,Volume7, pp. 795-797, July1995.
[16] Jayakrishnan Chandrappan, Member, IEEE, Zhang Jing, Ramkumar Veppathur
Mohan, Philbert Oliver Gomez, “ Optical Coupling Methods for Cost-Effective
Polymer Optical Fiber Communication”, IEEE Transaction on Componenets and
Packaging Technologies, vol. 32, no. 3, pp.593-599,September 2009.
[17] Takashi Iwasaki,“ A Single-Mode Optical Fiber Attenuator for Inter comparison
of Attenuation”, IEEE Transaction On Instrumentation and Measurement, vol. 43,
no. 6, pp. 837-842, December 1994.
[18] M.E. De Rosa, V.A. Bhagavatula, Q. Wu., K. Matusick, “ High optical power
testing of physical contact connectors at 1550 nm”, Optical Fiber Communication
Conference and exhibit,vol.2,pp.TuI7-1-TuI7-3,2001.

24. References
[19] Hiroaki Kurokawa, Soichio Ikuno, Seiko Mitachi, “An Analysis of Ultra Low
Reflection Characteristics of FPC connectors”, Laser and Electro-optics Society,
vol.2, pp.738-739, 2002.