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Laser Group of Department of Physics

Laser Group of Department of Physics. Prof. Raj K. Thareja. Prof. Asima Pradhan. Laser Plasma Interaction. Biophotonics. Fiber Optics, Photonic Band Gap Materials. Quantum Optics. Prof. HarshvardhanWanare. Prof. R. Vijaya. Department Day,

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Laser Group of Department of Physics

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  1. Laser Group of Department of Physics Prof. Raj K. Thareja Prof. Asima Pradhan Laser Plasma Interaction Biophotonics Fiber Optics, Photonic Band Gap Materials Quantum Optics Prof. HarshvardhanWanare Prof. R. Vijaya Department Day, Golden Jubilee, IIT Kanpur, March 19-20, 2010

  2. Recent publications Recent publications • R.K. Thareja, A. Mohanta, D. Yadav and A. Kushwaha, (2010) Synthesis and Characterization of • Nanoparticles and Nanocrystalline Functional Films, Materials Science Forum Vols. 636-637, 709-713. • 2 A Mohanta and R. K. Thareja, (2009) Rayleigh scattering from gaseous phase nanoparticles synthesized by pulsed laser ablation of ZnO, J. Appl. Phys. 106, 124909. • 3 Dheerendra Yadav, Varun Gupta, and Raj K Thareja (2009), Evolution and imaging of nanoparticles observed in laser ablated carbon plume, J Appl, Phys. 106, 064903. • 4 Dheerendra Yadav, Varun Gupta, and Raj K Thareja, (2009) Ground state C2 density measurement in carbon plume using Laser induced fluorescence spectroscopy, Spectra Chem ActaB 64, 986. • 5 Archana Kushwaha, Antaryami Mohanta, Raj K Thareja, (2009) C2 and CN dynamics and pulsed laser deposition of CNx films, J Appl. Phys. 105, 044902. • 6 Archana Kushwaha and R K Thareja (2008) Dynamics of laser ablated carbon plasma: formation of C2 and CN, Appl. Opt. 47, 65 • 7 A. Mohanta, V. Singh and Raj K Thareja (2008) Photoluminescence from ZnO nanoparticles in vapor phase, J. Appl. Phys. 104, 064903. • 8 Antaryami Mohanta and Raj K Thareja (2008) Photoluminescence study of ZnO nanowires grown by thermal evaporation on pulsed laser deposited ZnO buffer layer, J. Appl. Phys. 104, 044906; Virtual J. Ultrafast Sc. • 9. R. K. Thareja, A. K. Sharma, and S. Shukla (2008) Spectroscopic investigations of carious tooth decay, Med. Eng. & Phys. 30, 1143. • 10. A Mohanta and R. K. Thareja, (2008) Photoluminescence study of ZnCdO alloy, J Appl Phys, 103, 024901.

  3. Biophotonics: • Application of photonic science and technology to life sciences. • A rapidly emerging area of forefront, interdisciplinary research • Requires fundamental understanding of light-biomatter interaction Early detection of cancer : Spectroscopy and Imaging The basis of our research lies in extracting molecular (fluorescence, Raman) and subtle morphological (elastic scattering) characteristics of changes in human tissue during development of disease • For a reliable optical diagnostic tool: • Require combination of more than one technique • Fluorescence Spectroscopy and Imaging • (Sensitive Technique) • Elastic Scattering (Structural Information) • Raman Spectroscopy (Specific in nature) Developed two techniques to extract authentic biochemical information from fluorescence spectra, which are modulated by wavelength dependent optical parameters

  4. Methodology used by us for extraction of Intrinsic Fluorescence A.Polarized Fluorescence & polarized elastic scattering measurement based approach A purely experimental approach Normalization of polarized fluorescence by polarized elastic scattering spectra to remove the modulation of wavelength dependent optical transport parameters Optics Express, 2003, SPIE 2010. B. Spatially resolved fluorescence measurement Hybrid diffusion theory, Monte Carlo based analytical model for spatially resolved fluorescence Determination of optical transport parameters at the excitation & emission wavelengths (morphology) Recovery of intrinsic fluorescence(biochemical) Depth information of inhomogeneity Fiber Jig Applied Optics 2002,2006

  5. Raman Spectroscopy in Human Tissue Fluorescence Imaging in tissues with handheld probe IMueller imaging in human cervical tissues C D E F G H B 7mm 1mm 2cm S S S / / 0.22mm 40µ 40µ 2 2 = S / S S S / / 1 4mm 1 3 3 S / S S S / / 2 2 4 4 S / S 3 3 S / S 4 4 Emerging Stoke’s Emerging Stoke’s Incident vector vector Mueller Matrix Stoke’s vector Normal tissue Abnormal tissue Basal layer Basal layer Dysplastic epithelium of cervix Normal epithelium of cervix Co-polarized Polarized Raman Studies of Cervical Tissues Depolarization power images Normal (1600 – 1700 cm-1) Cancerous (1600 – 1700 cm-1) PCA & Covariance Matrix Images Dysplastic epithelium of cervix PC2 Vs PC3 (Co-polarized) for cervical tissue PC2 Vs PC3 (Un-polarized) for cervical tissue Normal epithelium of cervix Cross-polarized Polarized fluorescence spectra for normal & abnormal tissue through different fibers Average fluorescence spectra of normal & abnormal tissue Normal (1600 – 1700 cm-1) Cancerous (1600 – 1700 cm-1) Co-Cross polarized NADH band area normalized by area of corresponding normal for co-polarized spectra/elastic scattering Normal (1300 – 1400 cm-1) Cancerous (1300 – 1400 cm-1) Microscope images

  6. Recent Publications Future Plans Aim towards multimodal diagnostic tool Nano-based Imaging for contrast enhancement • JOSA A, Vol.24, #6 (2007) • Eng. Lett ( 2007) • Nanotechnology 18 (2007) • Journal of Biomedical Optics (2008) • Optics Express, Vol. 17, 1600 (2009) • Applied Optics, Vol. 48, 6099 (2009) • IEEE JSTQE, in press, (2010) Current Ph.D students: 3 Current M.Tech students: 3 Funding: MCIT (DIT), CSIR

  7. Quantum Optics, Metamaterials and Imaging in Random media All-optical bistability: double cavity, two-photon Non-linear dynamics Output Input Input Output • Negative-Positive Hysteresis • Self-pulsing • Quasi-periodic route to chaos Multicolored Coherent Population Trapping Sub-harmonic comb with modulated fields New laser cooling mechanism, optical lattices, optical metrology

  8. New paradigms of control in • metamaterials with Dispersion All superluminal pulses become subluminal at larger propagation distances

  9. Modulated Source - ω Developing statistical methods of imaging in random media with diffuse light D1 D2 0o D3 180o D4 D5 Discovered fiber-based sensor that relies on tunneling of light

  10. R. VijayaVisiting Professor, IIT Kanpur (since Aug 2009)Permanent position: Professor, Department of Physics, IIT Bombay • Sub-areas of research: • Nonlinear Fiber optics – experiment, computation, theory • Objective: To build a multi-wavelength continuous wave / short-pulse source for fiber-optic communications • Photonic band gap materials – experiment • Objective: To build advanced functionalities such as directional emission and lowered threshold for lasing in self-assembled photonic crystals • Integrated Optics - experiment • Objective: Optimization of waveguide device fabrication in newer materials • Computational Nonlinear Optics • Objective: Calculation of non-linear optical coefficients of nano-clusters by DFT • Present research funding > Rupees 1.0 Crore • Present group: 3 Ph.D students, 1 Project staff, 1 Post-doctoral scientist

  11. R Research on Nonlinear Fiber Optics at IIT Bombay Research Lab established during 1999-2003 Major facilities:high-power fiber amplifier, time-domain (up to GHz) and frequency-domain (near-IR) measurement facilities, fiber splicer, several fiber-optic components such as isolators, circulators, couplers etc. and specialty fibers (EDF, DSF, HNLF) (a) (b) (c) (a) Erbium-doped fiber ring laser tunable from 1560 to 1605 nm by intra-cavity loss (b) Broadband generation using intra-cavity four-wave mixing in a low-dispersion fiber (c) Active mode-locking at 10 GHz - economical design based on Gunn oscillator ■ Tunable fiber laser ■ Options for broadband (52 nm) and multi-wavelength (64 channels) output ■ Continuous wave and mode-lcked (15 ps and 10 GHz) output ■ Low pumping powers (< 200 mW) ■ C-band and L-band operations

  12. Research on Photonic band gap materials at IIT Bombay Research Lab established during 2004-2007 Major facilities:Thin film spin coater, film thickness measurement system, lamp - monochromator - detector for 200nm to 2000 nm, pulsed Nd:YAG laser, waveguide coupling set-up and m-line set-up. Self-assembled crystal Double stop band Directional emission Telecom band Large area crystal; Stop band at 550nm Waveguide by EBL Light guidance ■3-D photonic crystals by self-assembly ■ characterization ■ Tuning of stop band ■ Inverse crystals ■ Photonic crystal heterostructures ■ Direction-dependent emission ■ Spectral narrowing ■ Photonic crystal waveguides

  13. Future scope of studies Recent publications 1. J. Appl. Phys. 104, 053104 (2008) 2. Appl. Phys. A, 90, 559 (2008) 3. J. Non. Opt. Phys and Mater. 18, 85 (2009) 4. Applied Optics 48, G28 (2009) 5. Prog. Quant. Electr. (in press) • Nonlinear dynamical effects in fiber lasers for Secure Communications • Slow light characteristics in optical fibers • Photonic crystal antenna – design issues • Band-edge nonlinearities in Photonic crystals

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