Amit Nag

09 March 2026

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Education / Work History

• Assistant Professor, BITS Pilani, Hyderabad Campus, India (2012–present)
• Post-doctoral researcher, LMU, Munich, Germany (2011 - 2012)
• Post-doctoral researcher, University of California, Irvine, CA, USA (2009-2011)
• Post-doctoral researcher, Princeton University, Princeton, NJ, USA (Fall 2009)
• Ph.D., Scholar, IIT Kanpur (2009)
• M.Sc., Jadavpur University, Kolkata, W.B., India (2003)
• B.Sc., Burdwan Raj College,University of Burdwan, Burdwan, W.B., India (2001)

Thesis Abstract

Accurate Quantification and Control of Two-Photon Processes

The main theme of the thesis is to understand the two-photon process, its accurate quantification and control using femtosecond pulsed lasers. This effort culminated in identifying control parameters. The thesis has been organized into seven chapters. The introductory Chapter 1 starts with the brief history of the two-photon absorption (TPA) process, basic concepts and its significant applications in different areas of science. A general importance of the TPA related studies and a brief review of these studies performed by other research groups have been presented. In Chapter 2, the principles, technical details of different experimental setups to measure the TPA process and different pulse characterization techniques are described in detail. Chapter 3 of the thesis describes sensitive measurements of large TPA cross-section (TPCS) values of different chromophores starting from modified porphyrin to simple co-ordination metal complexes using open aperture z-scan method with high repetition rate (HRR) MHz lasers. Very small nonlinearities of neat solvent molecules are also described. The pulse pileup problems and cumulative thermal effects are the major difficulties to apprehend in the experiments using HRR lasers. In Chapter 4, it has been shown that an optical chopper can be optimized to sufficiently minimize the thermal contributions of HRR lasers by periodic blanking of the laser pulses to the system under study. This particular study also unifies the TPCS measurements from z-scan and two-photon fluorescence (TPF) techniques. In Chapter 5, experimental observations are presented on how solvents can vary the TPA and TPF properties of fluorescent dyes. Chapter 6 presents an interesting study of modulation of TPF through variation of the incident laser polarization for different fluorescent dyes. In Chapter 7, the design of a folded geometry acousto-optic modulator based pulse shaper is discussed, which is capable of shaping individual pulses from a kHz amplified laser. Once the pulse shaping scheme is established and characterized, we experimentally study the variation of TPA and TPF for several chromophores in solutions by simple phase ordering a femtosecond laser pulse.

Research Topic / Interest

Contact me to know my current interests.

Publications

These include only those published in our lab.

1. Control of Femtosecond Laser Driven Retro-Diels-Alder-like Reaction of Dicyclopentadiene. D. K. Das, T. Goswami, and D. Goswami, in Photonics 2010: Tenth International Conference on Fiber Optics and Photonics (International Society for Optics and Photonics, 2011), 8173, p. 81730O [BibTeX]

    BibTeX: @inproceedings{dasControlFemtosecondLaser2011,
     title = {Control of Femtosecond Laser Driven Retro-{{Diels-Alder-like}} Reaction of Dicyclopentadiene},
     booktitle = {Photonics 2010: {{Tenth International Conference}} on {{Fiber Optics}} and {{Photonics}}},
     author = {Das, Dipak Kumar and Goswami, Tapas and Goswami, Debabrata},
     year = {2011},
     month = aug,
     volume = {8173},
     pages = {81730O},
     publisher = {{International Society for Optics and Photonics}},
     doi = {10/dsc8s7},
     urldate = {2019-08-13},
     annotation = {GSCC: 0000000 \\
     0 citations (Crossref) [2024-05-28]}
   }
   

2. Direct Observation of Coherent Oscillations in Solution Due to Microheterogeneous Environment. D. K. Das, K. Makhal, S. N. Bandyopadhyay, and D. Goswami, Scientific Reports 4, 6097 (2014) [BibTeX]

    BibTeX: @article{dasDirectObservationCoherent2014,
     title = {Direct {{Observation}} of {{Coherent Oscillations}} in {{Solution}} Due to {{Microheterogeneous Environment}}},
     author = {Das, Dipak Kumar and Makhal, Krishnandu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata},
     year = {2014},
     month = aug,
     journal = {Scientific Reports},
     volume = {4},
     pages = {6097},
     issn = {2045-2322},
     doi = {10/gf5mth},
     urldate = {2019-08-01},
     copyright = {2014 Nature Publishing Group},
     langid = {english},
     annotation = {GSCC: 0000010 \\
     7 citations (Crossref) [2024-05-28]\\
     00006}
   }
   

3. Observing Ground State Vibrational Coherence and Excited State Relaxation Dynamics of a Cyanine Dye in Pure Solvents. D. K. Das, K. Makhal, and D. Goswami, Physical Chemistry Chemical Physics 20(19), 13400–13411 (2018) [BibTeX]

    BibTeX: @article{dasObservingGroundState2018,
     title = {Observing Ground State Vibrational Coherence and Excited State Relaxation Dynamics of a Cyanine Dye in Pure Solvents},
     author = {Das, Dipak Kumar and Makhal, Krishnandu and Goswami, Debabrata},
     year = {2018},
     journal = {Physical Chemistry Chemical Physics},
     volume = {20},
     number = {19},
     pages = {13400--13411},
     doi = {10/gf5mqz},
     urldate = {2019-08-01},
     langid = {english},
     annotation = {GSCC: 0000014 \\
     11 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

4. Solvent Effect on Multiple Emission and Ultrafast Dynamics of Higher Excited States. D. K. Das, K. Makhal, and D. Goswami, Chemical Physics Letters 706, 375–379 (2018) [BibTeX]

    BibTeX: @article{dasSolventEffectMultiple2018,
     title = {Solvent Effect on Multiple Emission and Ultrafast Dynamics of Higher Excited States},
     author = {Das, Dipak Kumar and Makhal, Krishnandu and Goswami, Debabrata},
     year = {2018},
     month = aug,
     journal = {Chemical Physics Letters},
     volume = {706},
     pages = {375--379},
     issn = {0009-2614},
     doi = {10/gd3phb},
     urldate = {2019-08-01},
     annotation = {GSCC: 0000171 \\
     14 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

5. Two Photon Spectroscopy Can Serve as a Marker of Protein Denaturation Pathway. D. K. Das, S. I. Islam, N. Samanta, Y. Yadav, D. Goswami, and R. K. Mitra, Journal of Fluorescence 28(3), 855–862 (2018) [BibTeX]

    BibTeX: @article{dasTwoPhotonSpectroscopy2018,
     title = {Two {{Photon Spectroscopy Can Serve}} as a {{Marker}} of {{Protein Denaturation Pathway}}},
     author = {Das, Dipak Kumar and Islam, Sk Imadul and Samanta, Nirnay and Yadav, Yogendra and Goswami, Debabrata and Mitra, Rajib Kumar},
     year = {2018},
     month = may,
     journal = {Journal of Fluorescence},
     volume = {28},
     number = {3},
     pages = {855--862},
     issn = {1053-0509, 1573-4994},
     doi = {10/gd2g84},
     urldate = {2019-08-01},
     langid = {english},
     annotation = {GSCC: 0000004 \\
     2 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

6. Controlling the Femtosecond Laser-Driven Transformation of Dicyclopentadiene into Cyclopentadiene. T. Goswami, D. K. Das, and D. Goswami, Chemical Physics Letters 558, 1–7 (2013) [BibTeX]

    BibTeX: @article{goswamiControllingFemtosecondLaserdriven2013,
     title = {Controlling the Femtosecond Laser-Driven Transformation of Dicyclopentadiene into Cyclopentadiene},
     author = {Goswami, Tapas and Das, Dipak K. and Goswami, Debabrata},
     year = {2013},
     month = feb,
     journal = {Chemical Physics Letters},
     volume = {558},
     pages = {1--7},
     issn = {0009-2614},
     doi = {10/f4nnb2},
     urldate = {2019-08-02},
     annotation = {GSCC: 0000011 \\
     5 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

7. Femtosecond Pump-Probe Spectroscopy for Remote Sensing of Liquid-Liquid Interface. D. Goswami, D. K. Das, and K. Makhal, Asian Journal of Physics 29(3 & 4), 313–319 (2020) [BibTeX]

    BibTeX: @article{goswamiFemtosecondPumpprobeSpectroscopy2020,
     title = {Femtosecond Pump-Probe Spectroscopy for Remote Sensing of Liquid-Liquid Interface},
     author = {Goswami, Debabrata and Das, Dipak K. and Makhal, Krishnandu},
     year = {2020},
     journal = {Asian Journal of Physics},
     volume = {29},
     number = {3\&4},
     pages = {313--319},
     annotation = {GSCC: 0000000 \\
     00000}
   }
   

8. Solvent Effect on Dual Fluorescence and the Corresponding Excited State Dynamics. D. Goswami, D. K. Das, and K. Makhal, in Reviews in Fluorescence 2017, C. D. Geddes, ed., Reviews in Fluorescence (Springer International Publishing, 2018), pp. 145–160 [BibTeX]

    BibTeX: @incollection{goswamiSolventEffectDual2018,
     title = {Solvent {{Effect}} on {{Dual Fluorescence}} and the {{Corresponding Excited State Dynamics}}},
     booktitle = {Reviews in {{Fluorescence}} 2017},
     author = {Goswami, Debabrata and Das, Dipak Kumar and Makhal, Krishnandu},
     editor = {Geddes, Chris D.},
     year = {2018},
     series = {Reviews in {{Fluorescence}}},
     pages = {145--160},
     publisher = {Springer International Publishing},
     address = {Cham},
     doi = {10.1007/978-3-030-01569-5_7},
     urldate = {2019-08-01},
     isbn = {978-3-030-01569-5},
     langid = {english},
     annotation = {GSCC: 0000113 \\
     00000}
   }
   

9. Towards Using Molecular Ions as Qubits: Femtosecond Control of Molecular Fragmentation with Multiple Knobs. T. Goswami, D. K. Das, and D. Goswami, Pramana 75(6), 1065–1069 (2010) [BibTeX]

    BibTeX: @article{goswamiUsingMolecularIons2010,
     title = {Towards Using Molecular Ions as Qubits: {{Femtosecond}} Control of Molecular Fragmentation with Multiple Knobs},
     shorttitle = {Towards Using Molecular Ions as Qubits},
     author = {Goswami, Tapas and Das, Dipak K. and Goswami, Debabrata},
     year = {2010},
     month = dec,
     journal = {Pramana},
     volume = {75},
     number = {6},
     pages = {1065--1069},
     issn = {0973-7111},
     doi = {10/cf945s},
     urldate = {2019-08-14},
     langid = {english},
     annotation = {GSCC: 0000000 \\
     0 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

10. Towards Using Molecular States as Qubits. D. Goswami, T. Goswami, S. K. K. Kumar, and D. K. Das, AIP Conference Proceedings 1384(1), 251–253 (2011) [BibTeX]

     BibTeX: @article{goswamiUsingMolecularStates2011,
      title = {Towards {{Using Molecular States}} as {{Qubits}}},
      author = {Goswami, Debabrata and Goswami, Tapas and Kumar, S. K. Karthick and Das, Dipak K.},
      year = {2011},
      month = sep,
      journal = {AIP Conference Proceedings},
      volume = {1384},
      number = {1},
      pages = {251--253},
      issn = {0094-243X},
      doi = {10/bfnp4m},
      urldate = {2019-08-02},
      annotation = {GSCC: 0000000 \\
      0 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

11. Control of Femtosecond Laser Driven Retro-Diels-Alder-like Reaction of Dicyclopentadiene. D. K. Das, T. Goswami, and D. Goswami, in Photonics 2010: Tenth International Conference on Fiber Optics and Photonics (International Society for Optics and Photonics, 2011), 8173, p. 81730O [BibTeX]

     BibTeX: @inproceedings{dasControlFemtosecondLaser2012,
      title = {Control of Femtosecond Laser Driven Retro-{{Diels-Alder-like}} Reaction of Dicyclopentadiene},
      booktitle = {Photonics 2010: {{Tenth International Conference}} on {{Fiber Optics}} and {{Photonics}}},
      author = {Das, Dipak Kumar and Goswami, Tapas and Goswami, Debabrata},
      year = {2011},
      month = aug,
      volume = {8173},
      pages = {81730O},
      publisher = {{International Society for Optics and Photonics}},
      doi = {10/dsc8s7},
      urldate = {2019-08-13},
      annotation = {GSCC: 0000000 \\
      0 citations (Crossref) [2024-05-28]}
    }
    

12. Direct Observation of Coherent Oscillations in Solution Due to Microheterogeneous Environment. D. K. Das, K. Makhal, S. N. Bandyopadhyay, and D. Goswami, Scientific Reports 4, 6097 (2014) [BibTeX]

     BibTeX: @article{dasDirectObservationCoherent2015,
      title = {Direct {{Observation}} of {{Coherent Oscillations}} in {{Solution}} Due to {{Microheterogeneous Environment}}},
      author = {Das, Dipak Kumar and Makhal, Krishnandu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata},
      year = {2014},
      month = aug,
      journal = {Scientific Reports},
      volume = {4},
      pages = {6097},
      issn = {2045-2322},
      doi = {10/gf5mth},
      urldate = {2019-08-01},
      copyright = {2014 Nature Publishing Group},
      langid = {english},
      annotation = {GSCC: 0000010 \\
      7 citations (Crossref) [2024-05-28]\\
      00006}
    }
    

13. Observing Ground State Vibrational Coherence and Excited State Relaxation Dynamics of a Cyanine Dye in Pure Solvents. D. K. Das, K. Makhal, and D. Goswami, Physical Chemistry Chemical Physics 20(19), 13400–13411 (2018) [BibTeX]

     BibTeX: @article{dasObservingGroundState2019,
      title = {Observing Ground State Vibrational Coherence and Excited State Relaxation Dynamics of a Cyanine Dye in Pure Solvents},
      author = {Das, Dipak Kumar and Makhal, Krishnandu and Goswami, Debabrata},
      year = {2018},
      journal = {Physical Chemistry Chemical Physics},
      volume = {20},
      number = {19},
      pages = {13400--13411},
      doi = {10/gf5mqz},
      urldate = {2019-08-01},
      langid = {english},
      annotation = {GSCC: 0000014 \\
      11 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

14. Solvent Effect on Multiple Emission and Ultrafast Dynamics of Higher Excited States. D. K. Das, K. Makhal, and D. Goswami, Chemical Physics Letters 706, 375–379 (2018) [BibTeX]

     BibTeX: @article{dasSolventEffectMultiple2019,
      title = {Solvent Effect on Multiple Emission and Ultrafast Dynamics of Higher Excited States},
      author = {Das, Dipak Kumar and Makhal, Krishnandu and Goswami, Debabrata},
      year = {2018},
      month = aug,
      journal = {Chemical Physics Letters},
      volume = {706},
      pages = {375--379},
      issn = {0009-2614},
      doi = {10/gd3phb},
      urldate = {2019-08-01},
      annotation = {GSCC: 0000171 \\
      14 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

15. Two Photon Spectroscopy Can Serve as a Marker of Protein Denaturation Pathway. D. K. Das, S. I. Islam, N. Samanta, Y. Yadav, D. Goswami, and R. K. Mitra, Journal of Fluorescence 28(3), 855–862 (2018) [BibTeX]

     BibTeX: @article{dasTwoPhotonSpectroscopy2019,
      title = {Two {{Photon Spectroscopy Can Serve}} as a {{Marker}} of {{Protein Denaturation Pathway}}},
      author = {Das, Dipak Kumar and Islam, Sk Imadul and Samanta, Nirnay and Yadav, Yogendra and Goswami, Debabrata and Mitra, Rajib Kumar},
      year = {2018},
      month = may,
      journal = {Journal of Fluorescence},
      volume = {28},
      number = {3},
      pages = {855--862},
      issn = {1053-0509, 1573-4994},
      doi = {10/gd2g84},
      urldate = {2019-08-01},
      langid = {english},
      annotation = {GSCC: 0000004 \\
      2 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

16. Controlling the Femtosecond Laser-Driven Transformation of Dicyclopentadiene into Cyclopentadiene. T. Goswami, D. K. Das, and D. Goswami, Chemical Physics Letters 558, 1–7 (2013) [BibTeX]

     BibTeX: @article{goswamiControllingFemtosecondLaserdriven2014,
      title = {Controlling the Femtosecond Laser-Driven Transformation of Dicyclopentadiene into Cyclopentadiene},
      author = {Goswami, Tapas and Das, Dipak K. and Goswami, Debabrata},
      year = {2013},
      month = feb,
      journal = {Chemical Physics Letters},
      volume = {558},
      pages = {1--7},
      issn = {0009-2614},
      doi = {10/f4nnb2},
      urldate = {2019-08-02},
      annotation = {GSCC: 0000011 \\
      5 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

17. Femtosecond Pump-Probe Spectroscopy for Remote Sensing of Liquid-Liquid Interface. D. Goswami, D. K. Das, and K. Makhal, Asian Journal of Physics 29(3 & 4), 313–319 (2020) [BibTeX]

     BibTeX: @article{goswamiFemtosecondPumpprobeSpectroscopy2021,
      title = {Femtosecond Pump-Probe Spectroscopy for Remote Sensing of Liquid-Liquid Interface},
      author = {Goswami, Debabrata and Das, Dipak K. and Makhal, Krishnandu},
      year = {2020},
      journal = {Asian Journal of Physics},
      volume = {29},
      number = {3\&4},
      pages = {313--319},
      annotation = {GSCC: 0000000 \\
      00000}
    }
    

18. Solvent Effect on Dual Fluorescence and the Corresponding Excited State Dynamics. D. Goswami, D. K. Das, and K. Makhal, in Reviews in Fluorescence 2017, C. D. Geddes, ed., Reviews in Fluorescence (Springer International Publishing, 2018), pp. 145–160 [BibTeX]

     BibTeX: @incollection{goswamiSolventEffectDual2019,
      title = {Solvent {{Effect}} on {{Dual Fluorescence}} and the {{Corresponding Excited State Dynamics}}},
      booktitle = {Reviews in {{Fluorescence}} 2017},
      author = {Goswami, Debabrata and Das, Dipak Kumar and Makhal, Krishnandu},
      editor = {Geddes, Chris D.},
      year = {2018},
      series = {Reviews in {{Fluorescence}}},
      pages = {145--160},
      publisher = {Springer International Publishing},
      address = {Cham},
      doi = {10.1007/978-3-030-01569-5_7},
      urldate = {2019-08-01},
      isbn = {978-3-030-01569-5},
      langid = {english},
      annotation = {GSCC: 0000113 \\
      00000}
    }
    

19. Towards Using Molecular Ions as Qubits: Femtosecond Control of Molecular Fragmentation with Multiple Knobs. T. Goswami, D. K. Das, and D. Goswami, Pramana 75(6), 1065–1069 (2010) [BibTeX]

     BibTeX: @article{goswamiUsingMolecularIons2011,
      title = {Towards Using Molecular Ions as Qubits: {{Femtosecond}} Control of Molecular Fragmentation with Multiple Knobs},
      shorttitle = {Towards Using Molecular Ions as Qubits},
      author = {Goswami, Tapas and Das, Dipak K. and Goswami, Debabrata},
      year = {2010},
      month = dec,
      journal = {Pramana},
      volume = {75},
      number = {6},
      pages = {1065--1069},
      issn = {0973-7111},
      doi = {10/cf945s},
      urldate = {2019-08-14},
      langid = {english},
      annotation = {GSCC: 0000000 \\
      0 citations (Crossref) [2024-05-28]\\
      00000}
    }
    

20. Towards Using Molecular States as Qubits. D. Goswami, T. Goswami, S. K. K. Kumar, and D. K. Das, AIP Conference Proceedings 1384(1), 251–253 (2011) [BibTeX]

     BibTeX: @article{goswamiUsingMolecularStates2012,
      title = {Towards {{Using Molecular States}} as {{Qubits}}},
      author = {Goswami, Debabrata and Goswami, Tapas and Kumar, S. K. Karthick and Das, Dipak K.},
      year = {2011},
      month = sep,
      journal = {AIP Conference Proceedings},
      volume = {1384},
      number = {1},
      pages = {251--253},
      issn = {0094-243X},
      doi = {10/bfnp4m},
      urldate = {2019-08-02},
      annotation = {GSCC: 0000000 \\
      0 citations (Crossref) [2024-05-28]\\
      00000}
    }