FemtoLab: Shekhar Priyadarshi

Shekhar Priyadarshi

Education / Work History

Ph.D., Physikalisch-Technische Bundesanstalt (PTB) Division 2 Electricity (2007-2011)
M.Tech, Center for Lasers and Photonics (CELP), IIT Kanpur (2005-2007)

Thesis Abstract

Structure Property Relationship in Femtosecond 1560nm induced Nonlinearity

In this thesis three apparently disjointed pieces of work are presented, namely, (a)determination of optical nonlinearity in homologous series of alcohols, (b) study ofthermal properties of alcohols using thermal lens spectroscopy and (c) a theoreticalanalysis of a Fourier 4F-Geometry pulse shaper. All the work, however, is centered on a1560nm femtosecond laser. Study of various nonlinear dynamics and control at 1560nmis gaining prime attention in recent years due to its importance in telecommunicationapplications. Study and control of third order nonlinear optical (NLO) phenomena permitall optical switching and signal processing.In this thesis molecular NLO has been exploited for determining the lifetime of excitedstates. The popular technique of z-scan was used for measuring the nonlinear parameters.Non-radiative de-excitation of optically pumped molecules induces thermal agitation inbulk samples, which can be measured by Thermal Lens Spectroscopy (TLS).Determining the thermal excitation and relaxation of hydrocarbons also has greatimportance in petroleum industry. However, thermal lensing induces sluggish switchingbehavior and reduced quantum efficiency. Therefore, the determination of thermalrelaxation dynamics is important and we used thermal lens pump-probe experiment todetermine this.Nonlinear optical and thermal properties of alcohols with increasing carbon chain wereinvestigated at 1560nm wavelength (c-band) to understand structure propertyrelationship. We obtain absorption saturation in various alcohols at 1560nm. Such acharacterization of the thermal properties enabled us to measure the nonlinear index ofrefraction by eliminating most of the thermal effect. Comparative study of degree ofthermal excitation and thermal relaxation dynamics was also performed in variousalcohols.Further control and manipulation of the parameters reported in these experiments herewould require more fineness on the optical interaction with molecules. This can be mosteffectively achieved, independent of the character of the molecules, if we can havecomplete control over the femtosecond laser pulses at 1560nm. Pulse shaping at such ashort timescale is difficult to achieve through direct time domain approaches. We,therefore, present an alternative Fourier approach of analysis for Femtosecond pulseshaping at 1560nm.

Research Topic / Interest

Contact me to know my current interests.

Publications

These include only those published in our lab.

Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics. I. Bhattacharyya, S. Priyadarshi, and D. Goswami, Chemical Physics Letters 469(1), 104–109 (2009) [Abstract] [PDF] [BibTeX]
Abstract: We apply ultrafast single beam Z-scan technique to measure saturation absorption coefficients and nonlinear-refraction coefficients of primary alcohols at 1560nm. The nonlinear effects result from vibronic transitions and cubic nonlinear-refraction. To measure the pure total third-order nonlinear susceptibility, we removed thermal effects with a frequency optimized optical-chopper. Our measurements of thermal-relaxation dynamics of alcohols, from 1560nm thermal lens pump and 780nm probe experiments revealed faster and slower thermal-relaxation timescales, respectively, from conduction and convection. The faster timescale accurately predicts thermal-diffusivity, which decreases linearly with alcohol chain-lengths since thermal-relaxation is slower in heavier molecules. The relation between thermal-diffusivity and alcohol chain-length confirms structure-property relationship.
```
 BibTeX: @article{bhattacharyyaMolecularStructurepropertyCorrelations2009,
  title = {Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics},
  author = {Bhattacharyya, Indrajit and Priyadarshi, Shekhar and Goswami, Debabrata},
  date = {2009-02-03},
  journaltitle = {Chemical Physics Letters},
  shortjournal = {Chemical Physics Letters},
  volume = {469},
  number = {1},
  pages = {104--109},
  issn = {0009-2614},
  doi = {10/cpq233},
  url = {http://www.sciencedirect.com/science/article/pii/S0009261408017028},
  urldate = {2019-08-14}
}
```

Dynamics of Chemical Bond: General Discussion. K. Dhoke, M. Zanni, U. Harbola, R. K. Venkatraman, E. Arunan, K.-C. Lin, A. Nenov, J. Skelton, R. J. D. Miller, J. D. Hirst, V. Aquilanti, J. R. Helliwell, S. Keshavamurthy, S. Ramesh, M. Ashfold, A. Pallipurath, P. Roy Chowdhury, S. Mukhopadhyay, J. E D, H. Medhi, D. Goswami, P. Halder, W. Junge, M. Hariharan, S. K. Singh, S. Umapathy, A. Lakshmannam, M. Meedom Nielsen, S. Aravamudhan, V. Deckert, K. Ghiggino, K. Tominaga, and A. Edwards, Faraday Discussions 177, 121–154 (2015) [PDF] [BibTeX]

 BibTeX: @article{dhokeDynamicsChemicalBond2015,
  title = {Dynamics of Chemical Bond: General Discussion},
  shorttitle = {Dynamics of Chemical Bond},
  author = {Dhoke, Kunal and Zanni, Martin and Harbola, Upendra and Venkatraman, Ravi Kumar and Arunan, Elangannan and Lin, King-Chuen and Nenov, Artur and Skelton, Jonathan and Miller, R J Dwayne and Hirst, Jonathan D. and Aquilanti, Vincenzo and Helliwell, John R. and Keshavamurthy, Srihari and Ramesh, Sai and Ashfold, Mike and Pallipurath, Anuradha and Roy Chowdhury, Priyadarshi and Mukhopadhyay, Sanghamitra and E D, Jemmis and Medhi, Himani and Goswami, Debabrata and Halder, Prasenjit and Junge, Wolfgang and Hariharan, Mahesh and Singh, Santosh Kumar and Umapathy, Siva and Lakshmannam, Adithya and Meedom Nielsen, Martin and Aravamudhan, Sankarampadi and Deckert, Volker and Ghiggino, Kenneth and Tominaga, Keisuke and Edwards, Alison},
  date = {2015},
  journaltitle = {Faraday Discussions},
  shortjournal = {Faraday Discuss.},
  volume = {177},
  pages = {121--154},
  issn = {1359-6640, 1364-5498},
  doi = {10/gf5mss},
  url = {https://my.pcloud.com/publink/show?code=XZhaxr7ZFTPN6Cuqf08xjq5XSTjI4zaNU8Sy},
  urldate = {2019-08-01}
}

Time and Space Resolved Methods: General Discussion. M. Zanni, J. E. D, S. Aravamudhan, A. Pallipurath, E. Arunan, C. Schnedermann, A. K. Mishra, M. Warren, J. D. Hirst, F. John, R. Pal, J. R. Helliwell, K. Moirangthem, S. Chakraborty, A. G. Dijkstra, P. R. Chowdhury, K. Ghiggino, R. J. D. Miller, S. Meech, H. Medhi, M. Hariharan, F. Ariese, A. Edwards, A. R. Mallia, S. Umapathy, M. M. Nielsen, N. Hunt, Z.-Y. Tian, J. Skelton, G. Sankar, and D. Goswami, Faraday Discussions 177(0), 263–292 (2015) [Abstract] [PDF] [BibTeX]

Abstract: No abstract available

 BibTeX: @article{zanniTimeSpaceResolved2015,
  title = {Time and {{Space}} Resolved {{Methods}}: General Discussion},
  shorttitle = {Time and {{Space}} Resolved {{Methods}}},
  author = {Zanni, Martin and D, Jemmis E. and Aravamudhan, Sankarampadi and Pallipurath, Anuradha and Arunan, Elangannan and Schnedermann, Christoph and Mishra, Ashok Kumar and Warren, Mark and Hirst, Jonathan D. and John, Franklin and Pal, R. and Helliwell, John R. and Moirangthem, Kiran and Chakraborty, Shamik and Dijkstra, Arend G. and Chowdhury, Priyadarshi Roy and Ghiggino, Kenneth and Miller, R. J. Dwayne and Meech, Stephen and Medhi, Himani and Hariharan, Mahesh and Ariese, Freek and Edwards, Alison and Mallia, Ajith R. and Umapathy, Siva and Nielsen, Martin Meedom and Hunt, Neil and Tian, Zhen-Yu and Skelton, Jonathan and Sankar, Gopinathan and Goswami, Debabrata},
  date = {2015-04-14},
  journaltitle = {Faraday Discussions},
  shortjournal = {Faraday Discuss.},
  volume = {177},
  number = {0},
  pages = {263--292},
  issn = {1364-5498},
  doi = {10/gf5mst},
  url = {https://pubs.rsc.org/en/content/articlelanding/2015/fd/c5fd90017d},
  urldate = {2019-08-01}
}

Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics. I. Bhattacharyya, S. Priyadarshi, and D. Goswami, Chemical Physics Letters 469(1), 104–109 (2009) [Abstract] [PDF] [BibTeX]
Abstract: We apply ultrafast single beam Z-scan technique to measure saturation absorption coefficients and nonlinear-refraction coefficients of primary alcohols at 1560nm. The nonlinear effects result from vibronic transitions and cubic nonlinear-refraction. To measure the pure total third-order nonlinear susceptibility, we removed thermal effects with a frequency optimized optical-chopper. Our measurements of thermal-relaxation dynamics of alcohols, from 1560nm thermal lens pump and 780nm probe experiments revealed faster and slower thermal-relaxation timescales, respectively, from conduction and convection. The faster timescale accurately predicts thermal-diffusivity, which decreases linearly with alcohol chain-lengths since thermal-relaxation is slower in heavier molecules. The relation between thermal-diffusivity and alcohol chain-length confirms structure-property relationship.
```
 BibTeX: @article{bhattacharyyaMolecularStructurepropertyCorrelations2010,
  title = {Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics},
  volume = {469},
  issn = {0009-2614},
  url = {http://www.sciencedirect.com/science/article/pii/S0009261408017028},
  doi = {10/cpq233},
  number = {1},
  journaltitle = {Chemical Physics Letters},
  urldate = {2019-08-14},
  date = {2009-02-03},
  pages = {104-109},
  author = {Bhattacharyya, Indrajit and Priyadarshi, Shekhar and Goswami, Debabrata}
}
```

Time and Space Resolved Methods: General Discussion. M. Zanni, J. E. D, S. Aravamudhan, A. Pallipurath, E. Arunan, C. Schnedermann, A. K. Mishra, M. Warren, J. D. Hirst, F. John, R. Pal, J. R. Helliwell, K. Moirangthem, S. Chakraborty, A. G. Dijkstra, P. R. Chowdhury, K. Ghiggino, R. J. D. Miller, S. Meech, H. Medhi, M. Hariharan, F. Ariese, A. Edwards, A. R. Mallia, S. Umapathy, M. M. Nielsen, N. Hunt, Z.-Y. Tian, J. Skelton, G. Sankar, and D. Goswami, Faraday Discuss. 177(0), 263–292 (2015) [Abstract] [PDF] [BibTeX]

Abstract: No abstract available

 BibTeX: @article{zanniTimeSpaceResolved2016,
  langid = {english},
  title = {Time and {{Space}} Resolved {{Methods}}: General Discussion},
  volume = {177},
  issn = {1364-5498},
  url = {https://pubs.rsc.org/en/content/articlelanding/2015/fd/c5fd90017d},
  doi = {10/gf5mst},
  shorttitle = {Time and {{Space}} Resolved {{Methods}}},
  number = {0},
  journaltitle = {Faraday Discuss.},
  urldate = {2019-08-01},
  date = {2015-04-14},
  pages = {263-292},
  author = {Zanni, Martin and D, Jemmis E. and Aravamudhan, Sankarampadi and Pallipurath, Anuradha and Arunan, Elangannan and Schnedermann, Christoph and Mishra, Ashok Kumar and Warren, Mark and Hirst, Jonathan D. and John, Franklin and Pal, R. and Helliwell, John R. and Moirangthem, Kiran and Chakraborty, Shamik and Dijkstra, Arend G. and Chowdhury, Priyadarshi Roy and Ghiggino, Kenneth and Miller, R. J. Dwayne and Meech, Stephen and Medhi, Himani and Hariharan, Mahesh and Ariese, Freek and Edwards, Alison and Mallia, Ajith R. and Umapathy, Siva and Nielsen, Martin Meedom and Hunt, Neil and Tian, Zhen-Yu and Skelton, Jonathan and Sankar, Gopinathan and Goswami, Debabrata}
}

 BibTeX: @article{dhokeDynamicsChemicalBond2016,
  langid = {english},
  title = {Dynamics of Chemical Bond: General Discussion},
  volume = {177},
  issn = {1359-6640, 1364-5498},
  url = {https://my.pcloud.com/publink/show?code=XZhaxr7ZFTPN6Cuqf08xjq5XSTjI4zaNU8Sy},
  doi = {10.1039/C5FD90016F},
  shorttitle = {Dynamics of Chemical Bond},
  journaltitle = {Faraday Discuss.},
  urldate = {2019-08-01},
  date = {2015},
  pages = {121-154},
  author = {Dhoke, Kunal and Zanni, Martin and Harbola, Upendra and Venkatraman, Ravi Kumar and Arunan, Elangannan and Lin, King-Chuen and Nenov, Artur and Skelton, Jonathan and Miller, R J Dwayne and Hirst, Jonathan D. and Aquilanti, Vincenzo and Helliwell, John R. and Keshavamurthy, Srihari and Ramesh, Sai and Ashfold, Mike and Pallipurath, Anuradha and Roy Chowdhury, Priyadarshi and Mukhopadhyay, Sanghamitra and E D, Jemmis and Medhi, Himani and Goswami, Debabrata and Halder, Prasenjit and Junge, Wolfgang and Hariharan, Mahesh and Singh, Santosh Kumar and Umapathy, Siva and Lakshmannam, Adithya and Meedom Nielsen, Martin and Aravamudhan, Sankarampadi and Deckert, Volker and Ghiggino, Kenneth and Tominaga, Keisuke and Edwards, Alison}
}

Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics. I. Bhattacharyya, S. Priyadarshi, and D. Goswami, Chemical Physics Letters 469(1), 104–109 (2009) [Abstract] [PDF] [BibTeX]
Abstract: We apply ultrafast single beam Z-scan technique to measure saturation absorption coefficients and nonlinear-refraction coefficients of primary alcohols at 1560nm. The nonlinear effects result from vibronic transitions and cubic nonlinear-refraction. To measure the pure total third-order nonlinear susceptibility, we removed thermal effects with a frequency optimized optical-chopper. Our measurements of thermal-relaxation dynamics of alcohols, from 1560nm thermal lens pump and 780nm probe experiments revealed faster and slower thermal-relaxation timescales, respectively, from conduction and convection. The faster timescale accurately predicts thermal-diffusivity, which decreases linearly with alcohol chain-lengths since thermal-relaxation is slower in heavier molecules. The relation between thermal-diffusivity and alcohol chain-length confirms structure-property relationship.
```
 BibTeX: @article{bhattacharyyaMolecularStructurepropertyCorrelations2011,
  title = {Molecular Structure-Property Correlations from Optical Nonlinearity and Thermal-Relaxation Dynamics},
  volume = {469},
  issn = {0009-2614},
  url = {http://www.sciencedirect.com/science/article/pii/S0009261408017028},
  doi = {10/cpq233},
  number = {1},
  journaltitle = {Chemical Physics Letters},
  urldate = {2019-08-14},
  date = {2009-02-03},
  pages = {104-109},
  author = {Bhattacharyya, Indrajit and Priyadarshi, Shekhar and Goswami, Debabrata}
}
```

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Shekhar Priyadarshi

Education / Work History

Thesis Abstract

Structure Property Relationship in Femtosecond 1560nm induced Nonlinearity

Research Topic / Interest

Publications