20 research outputs found
Fabrication and characterisation of polymer optical fibers for smart sensing and optical amplification
The thesis presented the fabrication and characterisation of
polymer optical fibers in their applications as optical amplifier and smart sensors.Optical polymers such as PMMA are found to be a very good host material due
to their ability to incorporate very high concentration of optical gain media like
fluorescent dyes and rare earth compounds. High power and high gain optical
amplification in organic dye-doped polymer optical fibers is possible due to
extremely large emission cross sections of oyes. Dye doped (Rhodamine 6G)
optical fibers were fabricated by using indigenously developed polymer optical
fiber drawing tower. Loss characterization of drawn dye doped fibers was carried
out using side illumination technique. The advantage of the above technique is
that it is a nondestructive method and can also be used for studying the
uniformity in fiber diameter and doping. Sensitivity of the undoped polymer
fibers to temperature and microbending were also studied in its application in
smart sensors.Optical amplification studies using the dye doped polymer optical fibers were
carried out and found that an amplification of l8dB could be achieved using a
very short fiber of length lOcm. Studies were carried out in fibers with different
dye concentrations and diameter and it was observed that gain stability was
achieved at relatively high dye concentrations irrespective of the fiber diameter.Due to their large diameter, large numerical aperture, flexibility and geometrical
versatility of polymer optical fibers it has a wide range of applications in the field
of optical sensing. Just as in the case of conventional silica based fiber optic
sensors, sensing techniques like evanescent wave, grating and other intensity
modulation schemes can also be efficiently utilized in the case of POF based
sensors. Since polymer optical fibers have very low Young's modulus when
compared to glass fibers, it can be utilized for sensing mechanical stress and
strain efficiently in comparison with its counterpart. Fiber optic sensors have
proved themselves as efficient and reliable devices to sense various parameters
like aging, crack formation, weathering in civil structures. A similar type of study
was carried out to find the setting characteristics of cement paste used for
constructing civil structures. It was found that the measurements made by using
fiber optic sensors are far more superior than that carried out by conventional
methods. More over,POF based sensors were found to have more sensitivity as
well.International School of Photonics,
Cochin University of Science & Technolog
Synthesis and Laser induced Studies of nanosized ZnO for Photonic Applications
Over the past few years, a little word with big potential has been rapidly entering into the world's consciousness-'nano'. Nanoscience and technology is a multidisciplinary field, involving the fabrication and understanding of matter at the finest level of a few nanomters.This thesis is about the synthesis and laser induced studies of nanosized ZnO,a versatile material with a wide range of applications.After synthesizing colloids and films of nano ZnO,the samples are studied using different optical methods.Interactions of intense laser beams with nanosized particles are found to open up many interesting scenarios with possible applications in the field of photonics.International School of Photonics,
Cochin University of Science and Technolog
Photonic applications of biomaterials with special reference to biopolymers and microbes
This thesis Entitled Photonic applications of biomaterials with special reference to biopolymers and microbes. A detailed investigation will be presented in the present thesis related to direct applications of biopolymers into some selected area of photonics and how the growth kinetics of an aerial bacterial colony on solid agar media was studied using laser induced fluorescence technique.
This chapter is an overview of the spectrum of biomaterials and their application to Photonics. The chapter discusses a wide range of biomaterials based photonics applications like efficient harvesting of solar energy, lowthreshold lasing, high-density data storage, optical switching, filtering and template for nano s tructures. The most extensively investigated photonics application in biology is Laser induced fluorescence technique. The importance of fluorescence studies in different biological and related fields are also mentioned in this chapter.Cochin University of Science and TechnologyInternational School of Photonics, Cochin University of Science and Technolog
Signatures of Higher Functions of Brain Dynamics in Electroencephalogram: A Nonlinear Analysis
The brain with its highly complex structure made up of simple units,imterconnected information pathways and specialized functions has always been an object of mystery and sceintific fascination for physiologists,neuroscientists and lately to mathematicians and physicists. The stream of biophysicists are engaged in building the bridge between the biological and physical sciences guided by a conviction that natural scenarios that appear extraordinarily complex may be tackled by application of principles from the realm of physical sciences. In a similar vein, this report aims to describe how nerve cells execute transmission of signals ,how these are put together and how out of this integration higher functions emerge and get reflected in the electrical signals that are produced in the brain.Viewing the E E G Signal through the looking glass of nonlinear theory, the dynamics of the underlying complex system-the brain ,is inferred and significant implications of the findings are explored.International School of Photonics,
Cochin University of Science and Technolog
Studies on optical attenuation in sea water using dye laser and laser propagation in a turbulent medium
The central theme of the work presented in this thesis is a careful investigation of the factors influencing the attenuation of laser beam through sea water. The thesis presents a detailed report of the work done by the author on the attenuation studies in sea water and on laser propagation through a turbulent medium. The thesis contains six chapters which are more or less self-contained with separate abstracts and references. The first chapter is divided into two parts. The first part introduces the subject of laser propagation through sea water. It includes a brief
description of optical properties of sea water followed by a review of the earlier works on attenuation studies in water. The second part gives the theoretical background of the problem
of laser propagation through a turbulent medium.Cochin University of Science And TechnologyDepartment of physics, Cochin University of Science And Technolog
Investigations on Nonlinear and Radiative Properties of Certain Photonic Materials
International School of Photonics,
Cochin University of Science & Technolog