IIT Kanpur

Education / Work History

  • Scientist-D, DRDO, Bangalore (2009–present)
  • M.Tech, Center for Lasers and Photonics (CELP), IIT Kanpur (2007-2009)

Research Topic / Interest

Contact me to know my current interests.

Publications

These include only those published in our lab.

  1. Probing the Ultrafast Solution Dynamics of a Cyanine Dye in an Organic Solvent Interfaced with Water. T. Goswami, S. K. K. Kumar, A. Dutta, and D. Goswami, J. Phys. Chem. B 113(51), 16332–16336 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Dependence of ultrafast dynamics on the excited state evolution and ground state recovery of a cyanine dye (IR125) in dichloromethane (DCM) solvent interfaced with neat water is presented. We use degenerate pump−probe transient absorption spectroscopy to show that the excited-state dynamics of the dye molecule is strongly dependent on the position of the measurements from bulk DCM solution to the solution near the water layer. The decay component of the transient corresponding to the excited state lifetime increases from bulk DCM solution to its interface with water. Such results show that the effect of the presence of water layer over the dye solution in DCM extends several micrometers, indicating the surfactant nature of the IR125 molecules, and provides us a measure of the penetration of water into the DCM layer. The initial ultrafast decay component (coherent spike) directly correlates to the pulse-width of our near-transform limited pulses used in these experiments. This approach of measuring the excited state decay of a dye across an immiscible liquid interface can provide important characteristics of microtransport across such interfaces.

     BibTeX: @article{goswamiProbingUltrafastSolution2009,
      title = {Probing the {{Ultrafast Solution Dynamics}} of a {{Cyanine Dye}} in an {{Organic Solvent Interfaced}} with {{Water}}},
      volume = {113},
      issn = {1520-6106},
      url = {https://doi.org/10.1021/jp903753u},
      doi = {10/dc3b67},
      number = {51},
      journaltitle = {J. Phys. Chem. B},
      urldate = {2019-08-14},
      date = {2009-12-24},
      pages = {16332-16336},
      author = {Goswami, Tapas and Kumar, S. K. Karthick and Dutta, Aveek and Goswami, Debabrata}
    }
    
  2. Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination. A. K. De, D. Roy, A. Dutta, and D. Goswami, Appl. Opt., AO 48(31), G33–G37 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Here we report how ultrafast pulsed illumination at low average power results in a stable three-dimensional (3D) optical trap holding latex nanoparticles which is otherwise not possible with continuous wave lasers at the same power level. The gigantic peak power of a femtosecond pulse exerts a huge instantaneous gradient force that has been predicted theoretically earlier and implemented for microsecond pulses in a different context by others. In addition, the resulting two-photon fluorescence allows direct observation of trapping events by providing intrinsic 3D resolution.

     BibTeX: @article{deStableOpticalTrapping2009,
      langid = {english},
      title = {Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination},
      volume = {48},
      issn = {2155-3165},
      url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-48-31-G33},
      doi = {10/b9sxj4},
      number = {31},
      journaltitle = {Appl. Opt., AO},
      urldate = {2019-08-14},
      date = {2009-11-01},
      pages = {G33-G37},
      author = {De, Arijit Kumar and Roy, Debjit and Dutta, Aveek and Goswami, Debabrata}
    }
    
  3. Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses. T. Goswami, S. K. Karthick Kumar, A. Dutta, and D. Goswami, Chemical Physics 360(1), 47–52 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: We present the effect of chirping a femtosecond laser pulse on the fragmentation of n-propyl benzene. An enhancement of an order of magnitude for the relative yields of C3H3+ and C5H5+ in the case of negatively chirped pulses and C6H5+ in the case of positively chirped pulses with respect to the transform-limited pulse indicates that in some fragmentation channel, coherence of the laser field plays an important role. For the relative yield of all other heavier fragment ions, resulting from the interaction of the intense laser field with the molecule, there is no such enhancement effect with the sign of chirp, within experimental errors. The importance of the laser phase is further reinforced through a direct comparison of the fragmentation results with the second harmonic of the chirped laser pulse with identical bandwidth.

     BibTeX: @article{goswamiControlLaserInduced2009,
      title = {Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses},
      volume = {360},
      issn = {0301-0104},
      url = {http://www.sciencedirect.com/science/article/pii/S0301010409001219},
      doi = {10/b2h79c},
      number = {1},
      journaltitle = {Chemical Physics},
      urldate = {2019-08-14},
      date = {2009-06-12},
      pages = {47-52},
      author = {Goswami, Tapas and Karthick Kumar, S. K. and Dutta, Aveek and Goswami, Debabrata}
    }
    
  4. Decoding Coherent Information in Femtosecond Shaped Laser Pulses. I. Bhattacharyya, A. Dutta, S. Ashtekar, S. K. Maurya, and D. Goswami, CURRENT SCIENCE 99(4), 10 (2010) [Abstract] [BibTeX]

    Abstract: We report here an experimental demonstration of a pulse decoding technique from spectral analysis of femtosecond pulses. This technique is based on a single-step Fourier domain inversion algorithm and shows the impact of the spectral window function on the retrieval of the signal pulse. Using two femtosecond laser pulses at 780 and 1560 nm from a fibre laser, we have shown that even when the spectral content of the reference pulse is far from a narrow band limit (as much as a quarter of its entire spectral content for our conditions), the single-step retrieval analysis using spectral windowing in the Fourier domain works efficiently. The enhanced signal levels possible due to the wider spectral window are critical in the unambiguous description of laser pulses, which would have potential application in the retrieval of comparatively weak and complex ultra-short pulses as is often needed in pulse shaping applications and coherent optical communications.

     BibTeX: @article{bhattacharyyaDecodingCoherentInformation2010,
      langid = {english},
      title = {Decoding Coherent Information in Femtosecond Shaped Laser Pulses},
      volume = {99},
      number = {4},
      journaltitle = {CURRENT SCIENCE},
      date = {2010},
      pages = {10},
      author = {Bhattacharyya, Indrajit and Dutta, Aveek and Ashtekar, Sumit and Maurya, Sandeep Kumar and Goswami, Debabrata}
    }
    
  5. Probing the Ultrafast Solution Dynamics of a Cyanine Dye in an Organic Solvent Interfaced with Water. T. Goswami, S. K. K. Kumar, A. Dutta, and D. Goswami, J. Phys. Chem. B 113(51), 16332–16336 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Dependence of ultrafast dynamics on the excited state evolution and ground state recovery of a cyanine dye (IR125) in dichloromethane (DCM) solvent interfaced with neat water is presented. We use degenerate pump−probe transient absorption spectroscopy to show that the excited-state dynamics of the dye molecule is strongly dependent on the position of the measurements from bulk DCM solution to the solution near the water layer. The decay component of the transient corresponding to the excited state lifetime increases from bulk DCM solution to its interface with water. Such results show that the effect of the presence of water layer over the dye solution in DCM extends several micrometers, indicating the surfactant nature of the IR125 molecules, and provides us a measure of the penetration of water into the DCM layer. The initial ultrafast decay component (coherent spike) directly correlates to the pulse-width of our near-transform limited pulses used in these experiments. This approach of measuring the excited state decay of a dye across an immiscible liquid interface can provide important characteristics of microtransport across such interfaces.

     BibTeX: @article{goswamiProbingUltrafastSolution2010,
      title = {Probing the {{Ultrafast Solution Dynamics}} of a {{Cyanine Dye}} in an {{Organic Solvent Interfaced}} with {{Water}}},
      volume = {113},
      issn = {1520-6106},
      url = {https://doi.org/10.1021/jp903753u},
      doi = {10/dc3b67},
      number = {51},
      journaltitle = {J. Phys. Chem. B},
      urldate = {2019-08-14},
      date = {2009-12-24},
      pages = {16332-16336},
      author = {Goswami, Tapas and Kumar, S. K. Karthick and Dutta, Aveek and Goswami, Debabrata}
    }
    
  6. Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination. A. K. De, D. Roy, A. Dutta, and D. Goswami, Appl. Opt., AO 48(31), G33–G37 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Here we report how ultrafast pulsed illumination at low average power results in a stable three-dimensional (3D) optical trap holding latex nanoparticles which is otherwise not possible with continuous wave lasers at the same power level. The gigantic peak power of a femtosecond pulse exerts a huge instantaneous gradient force that has been predicted theoretically earlier and implemented for microsecond pulses in a different context by others. In addition, the resulting two-photon fluorescence allows direct observation of trapping events by providing intrinsic 3D resolution.

     BibTeX: @article{deStableOpticalTrapping2010,
      langid = {english},
      title = {Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination},
      volume = {48},
      issn = {2155-3165},
      url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-48-31-G33},
      doi = {10/b9sxj4},
      number = {31},
      journaltitle = {Appl. Opt., AO},
      urldate = {2019-08-14},
      date = {2009-11-01},
      pages = {G33-G37},
      author = {De, Arijit Kumar and Roy, Debjit and Dutta, Aveek and Goswami, Debabrata}
    }
    
  7. Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses. T. Goswami, S. K. Karthick Kumar, A. Dutta, and D. Goswami, Chemical Physics 360(1), 47–52 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: We present the effect of chirping a femtosecond laser pulse on the fragmentation of n-propyl benzene. An enhancement of an order of magnitude for the relative yields of C3H3+ and C5H5+ in the case of negatively chirped pulses and C6H5+ in the case of positively chirped pulses with respect to the transform-limited pulse indicates that in some fragmentation channel, coherence of the laser field plays an important role. For the relative yield of all other heavier fragment ions, resulting from the interaction of the intense laser field with the molecule, there is no such enhancement effect with the sign of chirp, within experimental errors. The importance of the laser phase is further reinforced through a direct comparison of the fragmentation results with the second harmonic of the chirped laser pulse with identical bandwidth.

     BibTeX: @article{goswamiControlLaserInduced2010,
      title = {Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses},
      volume = {360},
      issn = {0301-0104},
      url = {http://www.sciencedirect.com/science/article/pii/S0301010409001219},
      doi = {10/b2h79c},
      number = {1},
      journaltitle = {Chemical Physics},
      urldate = {2019-08-14},
      date = {2009-06-12},
      pages = {47-52},
      author = {Goswami, Tapas and Karthick Kumar, S. K. and Dutta, Aveek and Goswami, Debabrata}
    }
    
  8. Decoding Coherent Information in Femtosecond Shaped Laser Pulses. I. Bhattacharyya, A. Dutta, S. Ashtekar, S. K. Maurya, and D. Goswami, CURRENT SCIENCE 99(4), 10 (2010) [Abstract] [BibTeX]

    Abstract: We report here an experimental demonstration of a pulse decoding technique from spectral analysis of femtosecond pulses. This technique is based on a single-step Fourier domain inversion algorithm and shows the impact of the spectral window function on the retrieval of the signal pulse. Using two femtosecond laser pulses at 780 and 1560 nm from a fibre laser, we have shown that even when the spectral content of the reference pulse is far from a narrow band limit (as much as a quarter of its entire spectral content for our conditions), the single-step retrieval analysis using spectral windowing in the Fourier domain works efficiently. The enhanced signal levels possible due to the wider spectral window are critical in the unambiguous description of laser pulses, which would have potential application in the retrieval of comparatively weak and complex ultra-short pulses as is often needed in pulse shaping applications and coherent optical communications.

     BibTeX: @article{bhattacharyyaDecodingCoherentInformation2011,
      title = {Decoding Coherent Information in Femtosecond Shaped Laser Pulses},
      author = {Bhattacharyya, Indrajit and Dutta, Aveek and Ashtekar, Sumit and Maurya, Sandeep Kumar and Goswami, Debabrata},
      date = {2010},
      journaltitle = {CURRENT SCIENCE},
      volume = {99},
      pages = {10},
      keywords = {_tablet,⛔ No DOI found},
      langid = {english},
      number = {4}
    }
    
  9. Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination. A. K. De, D. Roy, A. Dutta, and D. Goswami, Applied Optics 48(31), G33–G37 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Here we report how ultrafast pulsed illumination at low average power results in a stable three-dimensional (3D) optical trap holding latex nanoparticles which is otherwise not possible with continuous wave lasers at the same power level. The gigantic peak power of a femtosecond pulse exerts a huge instantaneous gradient force that has been predicted theoretically earlier and implemented for microsecond pulses in a different context by others. In addition, the resulting two-photon fluorescence allows direct observation of trapping events by providing intrinsic 3D resolution.

     BibTeX: @article{deStableOpticalTrapping2011,
      title = {Stable Optical Trapping of Latex Nanoparticles with Ultrashort Pulsed Illumination},
      author = {De, Arijit Kumar and Roy, Debjit and Dutta, Aveek and Goswami, Debabrata},
      date = {2009-11-01},
      journaltitle = {Applied Optics},
      shortjournal = {Appl. Opt., AO},
      volume = {48},
      pages = {G33-G37},
      issn = {2155-3165},
      doi = {10/b9sxj4},
      url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-48-31-G33},
      urldate = {2019-08-14},
      keywords = {_tablet,High numerical aperture optics,Laser beams,Laser scattering,Pulsed operation,Rayleigh scattering,Ultrafast lasers},
      langid = {english},
      number = {31}
    }
    
  10. Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses. T. Goswami, S. K. Karthick Kumar, A. Dutta, and D. Goswami, Chemical Physics 360(1), 47–52 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: We present the effect of chirping a femtosecond laser pulse on the fragmentation of n-propyl benzene. An enhancement of an order of magnitude for the relative yields of C3H3+ and C5H5+ in the case of negatively chirped pulses and C6H5+ in the case of positively chirped pulses with respect to the transform-limited pulse indicates that in some fragmentation channel, coherence of the laser field plays an important role. For the relative yield of all other heavier fragment ions, resulting from the interaction of the intense laser field with the molecule, there is no such enhancement effect with the sign of chirp, within experimental errors. The importance of the laser phase is further reinforced through a direct comparison of the fragmentation results with the second harmonic of the chirped laser pulse with identical bandwidth.

     BibTeX: @article{goswamiControlLaserInduced2011,
      title = {Control of Laser Induced Molecular Fragmentation of N-Propyl Benzene Using Chirped Femtosecond Laser Pulses},
      author = {Goswami, Tapas and Karthick Kumar, S. K. and Dutta, Aveek and Goswami, Debabrata},
      date = {2009-06-12},
      journaltitle = {Chemical Physics},
      shortjournal = {Chemical Physics},
      volume = {360},
      pages = {47--52},
      issn = {0301-0104},
      doi = {10/b2h79c},
      url = {http://www.sciencedirect.com/science/article/pii/S0301010409001219},
      urldate = {2019-08-14},
      keywords = {_tablet,Chirped femtosecond laser pulse,Coherent control,Fragmentation},
      number = {1}
    }
    
  11. Probing the Ultrafast Solution Dynamics of a Cyanine Dye in an Organic Solvent Interfaced with Water. T. Goswami, S. K. K. Kumar, A. Dutta, and D. Goswami, The Journal of Physical Chemistry B 113(51), 16332–16336 (2009) [Abstract] [PDF] [BibTeX]

    Abstract: Dependence of ultrafast dynamics on the excited state evolution and ground state recovery of a cyanine dye (IR125) in dichloromethane (DCM) solvent interfaced with neat water is presented. We use degenerate pump−probe transient absorption spectroscopy to show that the excited-state dynamics of the dye molecule is strongly dependent on the position of the measurements from bulk DCM solution to the solution near the water layer. The decay component of the transient corresponding to the excited state lifetime increases from bulk DCM solution to its interface with water. Such results show that the effect of the presence of water layer over the dye solution in DCM extends several micrometers, indicating the surfactant nature of the IR125 molecules, and provides us a measure of the penetration of water into the DCM layer. The initial ultrafast decay component (coherent spike) directly correlates to the pulse-width of our near-transform limited pulses used in these experiments. This approach of measuring the excited state decay of a dye across an immiscible liquid interface can provide important characteristics of microtransport across such interfaces.

     BibTeX: @article{goswamiProbingUltrafastSolution2011,
      title = {Probing the {{Ultrafast Solution Dynamics}} of a {{Cyanine Dye}} in an {{Organic Solvent Interfaced}} with {{Water}}},
      author = {Goswami, Tapas and Kumar, S. K. Karthick and Dutta, Aveek and Goswami, Debabrata},
      date = {2009-12-24},
      journaltitle = {The Journal of Physical Chemistry B},
      shortjournal = {J. Phys. Chem. B},
      volume = {113},
      pages = {16332--16336},
      issn = {1520-6106},
      doi = {10/dc3b67},
      url = {https://doi.org/10.1021/jp903753u},
      urldate = {2019-08-14},
      keywords = {_tablet},
      number = {51}
    }