FABRICATION AND CHARACTERIZATION OF SURFACE PLASMON RESONANCE BASED FIBER OPTIC SENSORS USING HIGH INDEX DIELECTRIC/NANOCOMPOSITE LAYER
by
PRIYA BHATIA
Department of PhysicsSubmitted
in the fulfillment of the requirements of the degree of
Doctor of Philosophy t
o theINDIAN INSTITUTE OF TECHNOLOGY DELHI
MAY 2013
Dedicated to my
grandmother(my mata)
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CERTIFICATE
This is to certify that the thesis entitled “Fabrication and characterization of surface plasmon resonance based fiber optic sensors using high index dielectric/nanocomposite layer” being submitted by Priya Bhatia to Indian Institute of Technology Delhi for the award of the degree of Doctor of Philosophy is a record of bonafide research work carried out by her. She has worked under my guidance and supervision and has fulfilled the requirements, which to my knowledge have reached the requisite standard for the submission of the thesis. The results contained in this thesis have not been submitted in part or full to any other University or Institute for the award of any degree or diploma.
Prof. B. D. Gupta Department of Physics
Indian Institute of Technology Delhi Hauz Khas, New Delhi-110016 INDIA
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ACKNOWLEDGEMENTS
First of all, I would like to thank my Master and Lord Shiva by whose blessings and grace, I would have been able to achieve this academic effort. I would like to express my heartiest gratitude to my respected supervisor Prof. B. D. Gupta who made it very easy to pass this tenure of my research in no time by his praiseworthy guidance, teaching, efforts and motivation. He has shown me the right path whenever I needed during my entire period of research work. I thank to almighty for giving me the opportunity to work under his guidance.
His fruitful suggestions, discussions and untiring efforts led me towards the path of success and enlightment. Also, I would like to thank Mrs. Uma Rani Gupta from the core of my heart.
It has been a matter of great pride and privilege in being a member of the Fiber Optics Group at IIT Delhi. I would like to express my thankfulness to Prof. Anurag Sharma and Prof. D. S. Mehta for their valuable suggestions. I am also grateful to Prof. B. P. Pal, Prof.
K. Thyagarajan, Prof. Arun Kumar, Prof. Ajit Kumar, Prof. M. R. Shenoy, Dr. R. K.
Varshney, Prof. B. R. Mehta and Prof. H. C. Gupta for providing me guidance time to time.
I am also thankful to Mr. K. Rajavinayagam and Mr. Vijay Kumar for providing me a learning atmosphere in the Fiber Optics Laboratory. It has been a great pleasure to have the company of my group roommates Kanchan, Ajanta, Roli, Satyendra, Deepa, Manoj, Surajit, Jitender, Rana, Parvinder, Piyush. I also express my sincere thanks to my senior colleagues, Akhilesh, Sarika, Ruchi, Dinesh, and former members Dr. Rajan Jha, Dr.
Rajneesh Kumar Verma, Dr. Vimlesh Mishra, Dr. Saurabh mani Tripathi, Dr.
Somnath Ghosh, Dr. Debajani Bhattacharya, Dr. Prerana, Dr. Nagaraju Bezawada.
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Though it is difficult to mention the name of all colleagues and friends who contributed directly or indirectly in this achievement, I would like to thank my best friend Parul for helping me all the time and making my stay at IIT campus very peaceful, lively and pleasant. Also I would like to thank my Dearest husband Abhishek for continuous love, care, support and faith in me and for always been a source of inspiration for me.
Finally, I would like to acknowledge the most important personalities of my life, my parents and my grandmother. I put my deepest sense of regards and gratefulness to my respected father Shri Ashok Kumar Bhatia, mother Smt. Nirmal Bhatia and grandmother (late) Smt. Savitri Devi for their love, affection and true blessings. One more person I would like to acknowledge, my mamaji, Mr. Prem Kumar Arora for his appreciation, belief in my work and presence whenever required. I would also like to thank my elder sisters Jaya and Madhur for their enormous support and continuous encouragement since my childhood.
Finally, the presence of God’s abundant grace has made this endeavour a success.
New Delhi Priya
May 2013
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ABSTRACT
The present thesis reports fabrication and characterization of surface plasmon resonance (SPR) based fiber optic sensors using high index dielectric or nanocomposite layer for the enhancement of the sensitivity of the sensor. The experimental studies include various kinds of probes for the detection of various parameters and their characterization in detail. First of all, SPR based fiber optic sensor with high index dielectric layer of silicon has been studied which is found to have high sensitivity as compared to the only metal coated probe. The effect of same has been seen on the tapered probe design. Along with this the effect of doping has been seen in the silicon layer and found the higher sensitivity of n-type silicon coated probe in comparison to p-type coated probe for the same kind and thickness of the metal layer. For the calculation purposes the dispersion relations of various layers such as fiber core, metal layer and dielectric layer have been taken into account. Along with this, for biomedical applications fiber optic sensor for the detection of urea has been studied using the high index dielectric layer between the metal and the urease enzyme layer. An important result of this study is the isolation of enzyme urease with the metal layer which otherwise deactivates enzyme urease. In another important study, a fiber optic ammonia gas sensor has been presented. Detection of ammonia gas is very important because of its high toxicity even in very small concentrations. The sensitivity of the sensor for various concentrations of ammonia has been calculated. Apart from propagating surface plasmons, a combination of propagating and localized surface plasmons has been used for hydrogen peroxide sensing.
The study reveals that on increasing hydrogen peroxide concentration the sensitivity is highest in the case of combination of surface plasmons and localized surface plasmons as compared to the case of only propagating surface plasmons or localized surface plasmons.
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Contents
Certificate i
Acknowledgements iii
Abstract v
Contents vii
List of Figures xiii
List of Tables xix
1. Introduction……….. 1
1.1 Background ………... 1
1.2 Plasmons and surface plasmons ……… 2
1.2.1 History………... 2
1.2.2 Origin and explanations……… 4
1.3 Excitation of surface plasmons ………. 6
1.3.1 Excitation of surface plasmons by light ………... 6
1.3.2 Kretschmann-Raether configuration………. 8
1.4 Angular and spectral interrogation methods used in SPR………. 11
1.5 SPR sensing with fiber optic probe……… 11
1.6 Localized surface plasmons……….……….. 12
1.7 Combination of surface plasmons and localized surface plasmons………... 1.8 Organization of thesis……… 13 14 2. Surface plasmon resonance based fiber optic refractive index sensor: sensitivity enhancement………... 21
2.1 Introduction……… 21
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2.2 Equipments used for experiments………….………. 22
2.2.1 Vacuum coating unit………... 23
2.2.2 Spectrometer………... 27
2.2.3 Light source………..……….... 29
2.2.4 Abbe’s refractometer……….... 30
2.3 Experimental.………...……….. 32
2.3.1 Materials………... 32
2.3.2 Fabrication of the probe……… 32
2.3.3 Preparation of samples……….…………. 2.3.4 Experimental setup………... 33 33 2.4 Theoretical Modeling………. 2.4.1 Fiber core………. 2.4.2 Metal layer………... 2.4.3 Dielectric layer………. 2.4.4 Calculation of reflection coefficient (Rp)………. 2.4.5 Transmitted power………... 2.5 Sensitivity……….. 2.6 Results and discussion………... 2.7 Conclusions……… 34 35 35 36 36 39 40 40 46 3. Sensitivity enhancement of a surface plasmon resonance based tapered fiber optic sensor using a high index dielectric layer……… 47
3.1 Introduction……… 47
3.2 Theoretical modeling………. 48
3.2.1 Fiber core ………. 49
3.2.2 Metal layer ………... 50
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3.2.3 Dielectric layer……….. 50
3.2.4 Calculation of reflection coefficient (RP).………. 50
3.2.5 Taper profile……….………. 3.2.6 Transmitted power……… 51 52 3.3 Results and discussion………... 53
3.4 Conclusions……… 58
4. Surface plasmon resonance based fiber optic refractive index sensor utilizing silicon layer: effect of doping... 59
4.1 Introduction……… 59
4.2 Experimental……….. 60
4.2.1 Fabrication of the sensor….………. 60
4.2.2 Preparation of liquid samples………... 61
4.2.3 Experimental setup………... 61
4.3 Results and discussion ……….. 62
4.4 Conclusions……… 70
5. Fabrication and characterization of surface plasmon resonance based fiber optic urea sensor for biomedical applications………... 71
5.1 Introduction……… 71
5.2 Experimental……….. 73
5.2.1 Materials..………. 73
5.2.2 Gel entrapment technique….……… 74
5.2.3 Fabrication of the probe….………... 74
5.2.4 Experimental setup...……….... 75
5.2.5 Lock and key model of enzymes….………. 76
5.3 Results and discussion ……….. 77
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5.4 Conclusions……… 83
6. Surface plasmon resonance based fiber optic ammonia sensor utilizing bromocresol purple……….. 85
6.1 Introduction……… 85
6.2 Experimental…… ………. 87
6.2.1 Fabrication of the probe…...………. 87
6.2.2 Experimental setup………... 87
6.3 Results and discussion………... 89 6.4 Conclusions...……….
7. Surface plasmon resonance based fiber optic hydrogen peroxide sensor using polymer embedded nanoparticles………
7.1 Introduction………...
7.2 Experimental………..
7.2.1 Reagents………...……….
7.2.2 Synthesis of silver nanoparticles-polyvinyl alcohol (Ag/PVA) composites………..
7.2.3 Preparation of samples………..
7.2.4 Fabrication of the fiber optic probe………...
7.2.5 Experimental setup………
7.3 Results and discussion………...
7.4 Conclusions………
99
101 101 103 103
103 104 104 107 108 115 8. Summary and future scope….………
References Appendix A Appendix B
117 119 139 145
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Author’s Biography 147
