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Photoacoustic
cell designed by ISP group
Another approach to the evaluation of thermal and optical properties of materials especially those of liquid sample is to use thermal lens technique. Usually we adopt a double beam thermal lens configuration to reduce noise and other spurious signals. A recently completed study using this method is related to the energy transfer in dye solutions. Thermal lens measurement appears to point out to some new mechanism for energy transfer in dye mixtures.
Nonlinear materials are also equally important in photonics research. We are interested in preparing and studying the optical properties
of some nano-structure materials. Samples containing nano particles in PMMA and PVA have been prepared and their non-linear optical properties are under investigation.
A new impetus for the study of nonlinear optics has been given by the installation of a Spectra Physics make MOPO. This new laser source is capable of giving pulsed tunable output from 400 nm - 2000 nm. The parametric amplifier section in this instrument is pumped by 800 mJ Nd:YAG laser. The group plans to undertake a number of nonlinear optical studies using the new laser source.
Investigations in the area of
fiber optic sensors
The first thesis from the International School of Photonics in the area of
fiber optic sensors entitled "Evanascent Wave Fiber Optic Sensors:Design, Fabrication and Characterisation" was submitted by Mr. Shelly John M during 2000. This thesis discusses the design and development of fibre optic sensors to determine the deposition rate of thin films, to measure glucose concentration and to detect nitrogen dioxide gas. The sensor work relating to the detection of nitrogen dioxide gas was carried out using uncladded
fiber coated with metal phthalocyanines as the sensor element. The results of these investigations were presented at the International Conference on Fiber Optics & Photonics held at Calcutta during Dec 18-20, 2000. Another interesting work in this area was the development of a
fiber optic pH sensor with dye-doped multi-layer sol-gel coatings. This work was also presented at the same conference.
Design and development of fiber optic sensors to detect ammonia, dissolved oxygen and common water contaminants were also initiated during this period. Sensors based on hollow-core
fiber and fiber bragg gratings will be taken up in the near future.
Presently there are 3 research students working in the area of Fiber Optic Sensors. A project with a funding to the tune of Rs. 10 lakhs was sanctioned by AICTE to Dr. P Radhakrishnan of this School for the development of FO sensors to measure contaminants in water and to detect air pollutants.
Synchronisation of semiconductor lasers
Synchronisation
of two directly modulated semiconductor lasers with
bidirectional coupling was numerically studied for various
coupling strengths C. The synchronisation depends on the
strengths of the coupling. Numerical results indicate that as
C is increased the coupled system achieves synchronisation as
well as stability together with an increase in the output
power. The effectiveness of the synchronisation depends on the
strength of C. For lower values of C the system does not
regain synchronisation after it is perturbed from the
synchronised state. However, for higher values of C, the
synchronisation is quite stable.
Time series analysis, Neural network and Chaos
Another field of work undertaken by the research group of ISP, is the application of nonlinear time series analysis for real physiological data like electroencephalogram (EEG). The studies model neural system with special reference to various pathological conditions of brain by introducing a parameter called coherence index. Theoretical model of complex systems is being worked out by introducing multi-path coupling between a number of nonlinear systems. One PhD thesis entitled "Nonlinear signal processing of EEG: Application in the study of Neurodynamics" by Mr P Indic has already been submitted to
CUSAT.
New additions to the ISP labs
Awards
& Recognitions
- Prof. C P Girijavallabhan has been elected as the Vice President of Indian Laser Association for the second time.
- The paper entitled "Dynamics of the Ambient Molecules During Laser Ablation of a Solid Target" by Pramod
Gopinath, Binoy Paul, K P Unnikrishnan, V.P.N.Nampoori and
C.P.G. Vallabhan, presented by Pramod Gopinath fetched the 2 nd best paper award in the PLASMA-2000, 15th National Symposium on Plasma Science and Technology, Saha Institute of Nuclear Physics, Calcutta held during Dec 5-8, 2000.
Seminars by visitors
1.
Dr. Pramod
Pratap,
North Carolina State
University, USA
Thermodynamics of Na-K Pump
20th July , 2000.
2.
Prof. R
Unnikrishnan, Head, Dept. of Electrical Engineering,
Rochester Institute of
Technology, New York.
Distance education in the IT Age
30th August, 2000.
3.
Dr. S S
Harilal,
Ruhr Universitaat, Bochum, Germany
Soft X-ray Diagnostics of Colliding Laser Produced Plasmas
25th October, 2000.
4.
Dr. P S
Anilkumar,
University of Twente, Netherlands
Spin Valve Transistors
23rd November, 2000.
5.
Dr. Riju C
Issac,
University of Strathchlyde,
United Kingdom
Intense Laser/Solid Interaction & X-ray Generations
4th January, 2001.
Conferences organised by ISP during the year 2000
1. Industrial & Medical Applications of Lasers - February 2000.
2. Indo - Dutch Colloquium on Low Dimensional Structures - October 2000.
3. Workshop on new frontiers in teaching and learning methodology in science education at college/university level - August 2000.
Looking into the future
In the years to come ISP has a number of projects and programmes on anvil. R&D activities are envisaged in optical computing, optical neural network and the development of photonic devices for communication and sensor technology.
A programme involving interaction between scientists and technologists working
in India in the area of photonics is envisaged in the next year. The project which includes academic exchange programme will develop a network of interactions between ISP and various institutions like IITs, Raman Research Institute and Tata Institute of Fundamental Research.
A student-attachment programme is also planned in which selected students of UG/PG classes will be given opportunities to work in the ISP lab during summer period.
In the limelight
Prof. C P Girijavallabhan, Prof. V M Nandakumaran, Prof. V P N Nampoori and Prof. P Radhakrishnan visited
Eindhoven
University under the academic exchange programme of ISP-MHO project.
Dr. Shelly John M, former Ph.D student of ISP, has taken up position as a Post Doctoral Fellow in the
Nanyang Technological
University, Singapore.
Mr. P Indic, research scholar of ISP, who has submitted his Ph.D thesis has received Post Doctoral Fellowship to work in Biomathematical Modeling Unit,
Harvard
University, USA.
Some of the recent publications from ISP
1. Dynamics of two coupled chaotic multimode Nd:YAG lasers with intracavity frequency doubling crystal.
Thomas Kuruvilla and V M Nandakumaran,
PRAMANA-J.Phys.,54, pp393-402(2000).
2. Cortical dynamics and phase synchronization during meditation.
V P N Nampoori, P Indic, N Pradhan, R Pratap, R Sreenivasan,
Special issue of Indian National Science Academy on Non-linear Phenomenon, pp395( 2000).
3. Numerical studies on bi-directionally coupled directly modulatd semiconductor lasers.
V Bindhu and V M Nandakumaran.
Phys.Lett.A,277, pp345-351( 2000).
4. Use of photoacoustic effect for the detection of phase transitions in liquid crystal mixtures.
Nibu A George, C P G Vallabhan,V P N Nampoori and P Radhakrishnan
J.Phys.D: Appl.Phys,33, pp3228-3232(2000)
5. Photoacoustic investigations of the effect of excess lead oxide on thermal
diffusivity of PLZT ceramic.
N A George,T Paul, P Radhakrishnan, V P N Nampoori,C P G Vallabhan, and M T Sebastian.
J.Mat.Sci.Lett,19, pp499-501(2000).
6. Physical and optical properties of
phthalocyanine doped inorganic glasses.
G A Kumar,J Thomas,N A George, N V Unnikrishnan, P
Radhakrishnan,V P N Nampoori and C P G Vallabhan.
J.Mat.Sci,35, pp2539(2000).
7. Optical absorption studies of free (H2Pc) and rare earth (RePc) phthalocyanine
doped borate glasses.
G A Kumar,J Thomas, N A George, N V Unnikrishnan, P Radhakrishnan,
V P N Nampoori and C P G Vallabhan.
Phys.Chem.Glasses,41, pp89(2000).
8. Spectral studies of naphthalocyanine (Nc) and rare earth phthalocyanine(RePc)
molecules in an inorganic glassy borate matrix.
G A Kumar,J Thomas, N A George, N V Unnikrishnan, P Radhakrishnan,
V P N Nampoori and C P G Vallabhan.
Phys.Chem.Glasses,41, pp199(2000).
9. Experimental investigation of optical
limiting and thermal lensing in toluene
solutions of C-70.
C V Bindhu,S S Harilal,V P N
Nampoori and C P G Vallabhan
Appl.Phys.B, 70, pp429(2000).
10. Fading of thermoluminescence from CaS
and CaS:Ce phosphors.
James Joseph, T R Ananthakrishnan, V P N Nampoori, M K Rudrawarier
Ind.J.Pure and Appl.Phys.74 A, pp21(2000).
11. Photoacoustic evaluation of the thermal
effusivity in the isotropic phase of
certain comb-shaped polymers.
Nibu A George, C P G Vallabhan, V P N
Nampoori, A K George and P Radhakrishnan.
J.Phys.Cond.Matter,13, pp365-371(2001)
12. Open cell photoacoustic investigations of
the thermal effusivity of liquid
crystals.
N A George, C P G Vallabhan, V P N
Nampoori, A K George and PRadhakrishnan.
Optical Engineering (In press).
Photonics building nearing completion
And
the last word...
When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
Arther C Clarke
Editor: Dr. V P N Nampoori
Layout & graphics: Geetha K
Online version: B.Aneesh
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