IIT Kanpur

Education / Work History

  • Ph.D. Scholar, IIT Kanpur (2011-present)
  • M.Sc, IIT Kanpur (2009-2011)
  • B.Sc, Presidency College, Kolkata (2009)

Research Interest: .

Research Topic / Interest

My main interests are:

  • Femtosecond Shaped Pulse Bioimaging
  • Molecular Dynamics

Publications

These include only those published in our lab.

  1. Polarization Induced Control of Optical Trap Potentials in Binary Liquids. D. Mondal, S. Dinda, S. N. Bandyopadhyay, and D. Goswami, Scientific Reports 9(1), 700 (2019) [PDF] [BibTeX]
     BibTeX: @article{mondalPolarizationInducedControl2019,
      langid = {english},
      title = {Polarization Induced Control of Optical Trap Potentials in Binary Liquids},
      volume = {9},
      issn = {2045-2322},
      url = {http://www.nature.com/articles/s41598-018-36856-5},
      doi = {10.1038/s41598-018-36856-5},
      number = {1},
      journaltitle = {Scientific Reports},
      shortjournal = {Sci Rep},
      urldate = {2019-08-01},
      date = {2019-12},
      pages = {700},
      author = {Mondal, Dipankar and Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  2. Rapid Programmable Pulse Shaping of Femtosecond Pulses at the MHz Repetition Rate. S. Dinda, S. N. Bandyopadhyay, and D. Goswami, OSA Continuum 2(4), 1386 (2019) [Abstract] [PDF] [BibTeX]

    Abstract: We have shown experimentally the successful engineering of femtosecond pulse shaping at a 76 MHz repetition rate input pulse with an acousto-optic modulator (AOM). High repetition rate (HRR) femtosecond laser pulse shaping using an AOM in the Fourier plane was incomprehensible because of its intrinsic 100 kHz acoustic update limit. We demonstrate an effective way of pulse selection and a calibration routine (Fourier shift theorem), which enables generation of ∼10 MHz shaped output pulses from the HRR input pulse train. We have generated a temporally shifted rectangular shaped pulse profile by applying modulation on both the phase and amplitude of the ‘sinc’ RF modulation function.

     BibTeX: @article{dindaRapidProgrammablePulse2019b,
      langid = {english},
      title = {Rapid Programmable Pulse Shaping of Femtosecond Pulses at the {{MHz}} Repetition Rate},
      volume = {2},
      issn = {2578-7519},
      url = {https://my.pcloud.com/publink/show?code=XZDaxr7Z7j2h0Ej5kjfj9pVqlqwvHViq6oeX},
      doi = {10.1364/OSAC.2.001386},
      number = {4},
      journaltitle = {OSA Continuum},
      shortjournal = {OSA Continuum},
      urldate = {2019-08-01},
      date = {2019-04-15},
      pages = {1386},
      author = {Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  3. Manifesting the Effects of Thermal Nonlinearity in Optical Trapping for Rayleigh Regime. T. Gaur, S. N. Bandyopadhyay, and D. Goswami, in 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) (IEEE, 2019), pp. 1–5 [Abstract] [PDF] [BibTeX]

    Abstract: Since long the thermal effects have not been much explored in the optical trapping theory, in this paper, we are establishing the effects of optically induced thermal nonlinearity in the medium of optical trapping in the Rayleigh regime for both continuous wave and a pulsed laser. For a single beam, optical tweezers with high numerical aperture (N.A.) objectives are used as a routine. In such a tight focusing scenario, both optical nonlinearity and thermal effects may prevail in the cases of continuous wave (C.W.) and pulsed laser-mediated optical trapping events. In this paper we will introduce the effects sequentially, starting from optical nonlinearity and methods to implement this effect and subsequently introduce the thermal nonlinearity in the medium. The effects are significantly different when compared between CW and pulsed optical tweezers and will be discussed in detail in this paper.

     BibTeX: @inproceedings{gaurManifestingEffectsThermal2019,
      langid = {english},
      location = {{New Delhi, India}},
      title = {Manifesting the {{Effects}} of {{Thermal Nonlinearity}} in {{Optical Trapping}} for {{Rayleigh Regime}}},
      isbn = {978-90-825987-5-9},
      url = {https://my.pcloud.com/publink/show?code=XZqaxr7ZmnVNxAn4Y4mRbGS3d4A7FjmCWEv7},
      doi = {10/gf5mqf},
      eventtitle = {2019 {{URSI Asia}}-{{Pacific Radio Science Conference}} ({{AP}}-{{RASC}})},
      booktitle = {2019 {{URSI Asia}}-{{Pacific Radio Science Conference}} ({{AP}}-{{RASC}})},
      publisher = {{IEEE}},
      urldate = {2019-08-01},
      date = {2019-03},
      pages = {1-5},
      author = {Gaur, Tushar and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  4. On-the-Fly Calibrated Measure and Remote Control of Temperature and Viscosity at Nanoscale. D. Mondal, S. N. Bandyopadhyay, P. Mathur, and D. Goswami, ACS Omega 3(9), 12304–12311 (2018) [Abstract] [PDF] [BibTeX]

    Abstract: A novel on-the-f ly calibration method of optical tweezers is presented, which enables in situ control and measure of absolute temperature and viscosity at nanoscale dimensions. Such noncontact measurement and control at the nanoscale are challenging as the present techniques only provide off-line measurements that do not provide absolute values. Additionally, some of the present methods have a low spatial resolution. We simultaneously apply the high temporal sensitivity of position autocorrelation and equipartition theorem to precisely measure and control in situ temperature and the corresponding microrheological property around the focal volume of the trap at high spatial resolution. The femtosecond optical tweezers (FOTs) use a single-beam high repetition rate laser for optical trapping to result in finer temperature gradients in comparison to the continuous-wave laser tweezers. Such finer temperature gradients are due to the additional nonlinear optical (NLO) phenomena occurring only at the nanoscale focal plane of the FOTs. Because NLO processes are laser peak power-dependent, they promote an effective study of physical properties occurring only at the focal plane. Using FOTs at optically benign near-infrared wavelengths, we demonstrate microrheological control and measurement in water by adding a highly absorbing yet low fluorescent dye (IR780).

     BibTeX: @article{mondalOntheFlyCalibratedMeasure2018,
      langid = {english},
      title = {On-the-{{Fly Calibrated Measure}} and {{Remote Control}} of {{Temperature}} and {{Viscosity}} at {{Nanoscale}}},
      volume = {3},
      issn = {2470-1343, 2470-1343},
      url = {http://pubs.acs.org/doi/10.1021/acsomega.8b01572},
      doi = {10/gff5s6},
      number = {9},
      journaltitle = {ACS Omega},
      shortjournal = {ACS Omega},
      urldate = {2019-08-01},
      date = {2018-09-30},
      pages = {12304-12311},
      author = {Mondal, Dipankar and Bandyopadhyay, Soumendra Nath and Mathur, Paresh and Goswami, Debabrata}
    }
    
  5. Structured Interferometry Features in Femtosecond Supercontinuum: Towards Better Understanding of Supercontinuum for Bio Applications. D. Goswami, S. Dinda, and S. N. Bandyopadhyay, in Optical Biopsy XV: Toward Real-Time Spectroscopic Imaging and Diagnosis (International Society for Optics and Photonics, 2017), 10060, p. 1006019 [Abstract] [PDF] [BibTeX]

    Abstract: We report structured interferometry features in femtosecond supercontinuum generated with power near to supercontinuum generation threshold. We argue that these structures arise from the coherent superposition of supercontinuum generated from different sources of supercontinuum as pulse split into two daughter pulses. Increase in input pulse energy creates several more temporal pulse fragments and disrupts interference resulting in the typical feature of continuous broad supercontinuum. Such an understanding of supercontinuum generation process is critical to the use of supercontinuum as the light source for use in understanding the time dynamics and imaging of bio systems.

     BibTeX: @inproceedings{goswamiStructuredInterferometryFeatures2017,
      title = {Structured Interferometry Features in Femtosecond Supercontinuum: Towards Better Understanding of Supercontinuum for Bio Applications},
      volume = {10060},
      url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10060/1006019/Structured-interferometry-features-in-femtosecond-supercontinuum--towards-better-understanding/10.1117/12.2253561.short},
      doi = {10/gf5mrd},
      shorttitle = {Structured Interferometry Features in Femtosecond Supercontinuum},
      eventtitle = {Optical {{Biopsy XV}}: {{Toward Real}}-{{Time Spectroscopic Imaging}} and {{Diagnosis}}},
      booktitle = {Optical {{Biopsy XV}}: {{Toward Real}}-{{Time Spectroscopic Imaging}} and {{Diagnosis}}},
      publisher = {{International Society for Optics and Photonics}},
      urldate = {2019-08-01},
      date = {2017-02-17},
      pages = {1006019},
      author = {Goswami, Debabrata and Dinda, Sirshendu and Bandyopadhyay, Soumendra N.}
    }
    
  6. On the Interferometric Coherent Structures in Femtosecond Supercontinuum Generation. S. Dinda, S. N. Bandyopadhyay, and D. Goswami, Applied Physics B 122(5), 148 (2016) [Abstract] [PDF] [BibTeX]

    Abstract: We report structured interferometric features in femtosecond supercontinuum generation (FSG) with incident laser powers that are near threshold for FSG. We argue that near threshold, these structures arise from the coherent superposition of pulses that are split initially into two daughter pulses during FSG process. Increase in the input pulse energy generates multiple daughter fragments in the temporal domain to an extent that correlated interference structures are not measurable.

     BibTeX: @article{dindaInterferometricCoherentStructures2016,
      langid = {english},
      title = {On the Interferometric Coherent Structures in Femtosecond Supercontinuum Generation},
      volume = {122},
      issn = {1432-0649},
      url = {https://my.pcloud.com/publink/show?code=XZfaxr7ZhXTWojTzmcfBOA16JDESUyR5fRWV},
      doi = {10/gf5mr5},
      number = {5},
      journaltitle = {Applied Physics B},
      shortjournal = {Appl. Phys. B},
      urldate = {2019-08-01},
      date = {2016-05-11},
      pages = {148},
      author = {Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  7. Resolution Enhancement through Microscopic Spatiotemporal Control. D. Goswami, D. Das, and S. N. Bandyopadhyay, Faraday Discussions 177(0), 203–212 (2015) [Abstract] [PDF] [BibTeX]

    Abstract: Operating at biologically benign conditions, multi-photon fluorescence imaging microscopy has benefitted immensely from recent developments in microscopic resolution enhancement. Fluorescence microscopy continues to be the best choice for experiments on live specimens, however, multi-photon fluorescence imaging often suffers from overlapping fluorescence of typical dyes used in microscopy, limiting its scope. This limitation has been the focus of our research where we show that by making simple modifications to the laser pulse structure, it is possible to resolve these overlapping fluorescence complications. Specifically, by using pairs of femtosecond pulses with variable delay in place of single pulse excitation, we show controlled fluorescence excitation or suppression of one of the fluorophores over the other through wave-packet interferometry. Such an effect prevails even after the fluorophore coherence timescale, which effectively results in a higher spatial resolution. Here we extend the effect of our pulse-pair technique to microscopic axial resolution experiments and show that such pairs of pulses can also ‘enhance’ axial resolution.

     BibTeX: @article{goswamiResolutionEnhancementMicroscopic2015,
      langid = {english},
      title = {Resolution Enhancement through Microscopic Spatiotemporal Control},
      volume = {177},
      issn = {1364-5498},
      url = {https://my.pcloud.com/publink/show?code=XZzvxr7Z0vbvki6gLSQhR76QzRco87Moa8Fy},
      doi = {10/gf5msv},
      number = {0},
      journaltitle = {Faraday Discussions},
      shortjournal = {Faraday Discuss.},
      urldate = {2019-08-01},
      date = {2015-04-14},
      pages = {203-212},
      author = {Goswami, Debabrata and Das, Dhiman and Bandyopadhyay, Soumendra Nath}
    }
    
  8. 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) [Abstract] [PDF] [BibTeX]

    Abstract: We report, for the first time, direct observation of coherent oscillations in the ground-state of IR775 dye due to microheterogeneous environment. Using ultrafast near-infrared degenerate pump-probe technique centered at 800 nm, we present the dynamics of IR775 in a binary mixture of methanol and chloroform at ultra-short time resolution of 30 fs. The dynamics of the dye in binary mixtures, in a time-scale of a few fs to ~740 ps, strongly varies as a function of solvent composition (volume fraction). Multi-oscillation behavior of the coherent vibration was observed, which increased with decreasing percentage of methanol in the dye mixture. Maximum number of damped oscillations were observed in 20% methanol. The observed vibrational wavepacket motion in the ground-state is periodic in nature. We needed two cosine functions to fit the coherent oscillation data as two different solvents were used. Dynamics of the dye molecule in binary mixtures can be explained by wavepacket motion in the ground potential energy surface. More is the confinement of the dye molecule in binary mixtures, more is the number of damped oscillations. The vibrational cooling time, τ2, increases with increase in the confinement of the system. The observed wavepacket oscillations in ground-state dynamics continued until 1.6 ps.

     BibTeX: @article{dasDirectObservationCoherent2014,
      langid = {english},
      title = {Direct {{Observation}} of {{Coherent Oscillations}} in {{Solution}} Due to {{Microheterogeneous Environment}}},
      volume = {4},
      issn = {2045-2322},
      url = {https://www.nature.com/articles/srep06097},
      doi = {10/gf5mth},
      journaltitle = {Scientific Reports},
      urldate = {2019-08-01},
      date = {2014-08-18},
      pages = {6097},
      author = {Das, Dipak Kumar and Makhal, Krishnandu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  9. On-the-Fly Calibrated Measure and Remote Control of Temperature and Viscosity at Nanoscale. D. Mondal, S. N. Bandyopadhyay, P. Mathur, and D. Goswami, ACS Omega 3(9), 12304–12311 (2018) [Abstract] [PDF] [BibTeX]

    Abstract: A novel on-the-fly calibration method of optical tweezers is presented, which enables in situ control and measure of absolute temperature and viscosity at nanoscale dimensions. Such noncontact measurement and control at the nanoscale are challenging as the present techniques only provide off-line measurements that do not provide absolute values. Additionally, some of the present methods have a low spatial resolution. We simultaneously apply the high temporal sensitivity of position autocorrelation and equipartition theorem to precisely measure and control in situ temperature and the corresponding microrheological property around the focal volume of the trap at high spatial resolution. The femtosecond optical tweezers (FOTs) use a single-beam high repetition rate laser for optical trapping to result in finer temperature gradients in comparison to the continuous-wave laser tweezers. Such finer temperature gradients are due to the additional nonlinear optical (NLO) phenomena occurring only at the nanoscale focal plane of the FOTs. Because NLO processes are laser peak power-dependent, they promote an effective study of physical properties occurring only at the focal plane. Using FOTs at optically benign near-infrared wavelengths, we demonstrate microrheological control and measurement in water by adding a highly absorbing yet low fluorescent dye (IR780).

     BibTeX: @article{mondalOntheFlyCalibratedMeasure2018a,
      title = {On-the-{{Fly Calibrated Measure}} and {{Remote Control}} of {{Temperature}} and {{Viscosity}} at {{Nanoscale}}},
      volume = {3},
      issn = {2470-1343},
      url = {https://doi.org/10.1021/acsomega.8b01572},
      doi = {10/gff5s6},
      number = {9},
      journaltitle = {ACS Omega},
      shortjournal = {ACS Omega},
      urldate = {2019-10-01},
      date = {2018-09-30},
      pages = {12304-12311},
      author = {Mondal, Dipankar and Bandyopadhyay, Soumendra Nath and Mathur, Paresh and Goswami, Debabrata}
    }
    
  10. Polarization Induced Control of Optical Trap Potentials in Binary Liquids. D. Mondal, S. Dinda, S. N. Bandyopadhyay, and D. Goswami, Sci Rep 9(1), 700 (2019) [PDF] [BibTeX]
     BibTeX: @article{mondalPolarizationInducedControl2020,
      langid = {english},
      title = {Polarization Induced Control of Optical Trap Potentials in Binary Liquids},
      volume = {9},
      issn = {2045-2322},
      url = {http://www.nature.com/articles/s41598-018-36856-5},
      doi = {10.1038/s41598-018-36856-5},
      number = {1},
      journaltitle = {Sci Rep},
      urldate = {2019-08-01},
      date = {2019-12},
      pages = {700},
      author = {Mondal, Dipankar and Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  11. Rapid Programmable Pulse Shaping of Femtosecond Pulses at the MHz Repetition Rate. S. Dinda, S. N. Bandyopadhyay, and D. Goswami, OSA Continuum 2(4), 1386 (2019) [Abstract] [PDF] [BibTeX]

    Abstract: We have shown experimentally the successful engineering of femtosecond pulse shaping at a 76 MHz repetition rate input pulse with an acousto-optic modulator (AOM). High repetition rate (HRR) femtosecond laser pulse shaping using an AOM in the Fourier plane was incomprehensible because of its intrinsic 100 kHz acoustic update limit. We demonstrate an effective way of pulse selection and a calibration routine (Fourier shift theorem), which enables generation of ∼10 MHz shaped output pulses from the HRR input pulse train. We have generated a temporally shifted rectangular shaped pulse profile by applying modulation on both the phase and amplitude of the ‘sinc’ RF modulation function.

     BibTeX: @article{dindaRapidProgrammablePulse2019c,
      langid = {english},
      title = {Rapid Programmable Pulse Shaping of Femtosecond Pulses at the {{MHz}} Repetition Rate},
      volume = {2},
      issn = {2578-7519},
      url = {https://my.pcloud.com/publink/show?code=XZDaxr7Z7j2h0Ej5kjfj9pVqlqwvHViq6oeX},
      doi = {10.1364/OSAC.2.001386},
      number = {4},
      journaltitle = {OSA Continuum},
      urldate = {2019-08-01},
      date = {2019-04-15},
      pages = {1386},
      author = {Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  12. Manifesting the Effects of Thermal Nonlinearity in Optical Trapping for Rayleigh Regime. T. Gaur, S. N. Bandyopadhyay, and D. Goswami, in 2019 URSI Asia-Pacific Radio Science Conference (AP-RASC) (IEEE, 2019), pp. 1–5 [Abstract] [PDF] [BibTeX]

    Abstract: Since long the thermal effects have not been much explored in the optical trapping theory, in this paper, we are establishing the effects of optically induced thermal nonlinearity in the medium of optical trapping in the Rayleigh regime for both continuous wave and a pulsed laser. For a single beam, optical tweezers with high numerical aperture (N.A.) objectives are used as a routine. In such a tight focusing scenario, both optical nonlinearity and thermal effects may prevail in the cases of continuous wave (C.W.) and pulsed laser-mediated optical trapping events. In this paper we will introduce the effects sequentially, starting from optical nonlinearity and methods to implement this effect and subsequently introduce the thermal nonlinearity in the medium. The effects are significantly different when compared between CW and pulsed optical tweezers and will be discussed in detail in this paper.

     BibTeX: @inproceedings{gaurManifestingEffectsThermal2020,
      langid = {english},
      location = {{New Delhi, India}},
      title = {Manifesting the {{Effects}} of {{Thermal Nonlinearity}} in {{Optical Trapping}} for {{Rayleigh Regime}}},
      isbn = {978-90-825987-5-9},
      url = {https://my.pcloud.com/publink/show?code=XZqaxr7ZmnVNxAn4Y4mRbGS3d4A7FjmCWEv7},
      doi = {10/gf5mqf},
      eventtitle = {2019 {{URSI Asia}}-{{Pacific Radio Science Conference}} ({{AP}}-{{RASC}})},
      booktitle = {2019 {{URSI Asia}}-{{Pacific Radio Science Conference}} ({{AP}}-{{RASC}})},
      publisher = {{IEEE}},
      urldate = {2019-08-01},
      date = {2019-03},
      pages = {1-5},
      author = {Gaur, Tushar and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  13. On-the-Fly Calibrated Measure and Remote Control of Temperature and Viscosity at Nanoscale. D. Mondal, S. N. Bandyopadhyay, P. Mathur, and D. Goswami, ACS Omega 3(9), 12304–12311 (2018) [Abstract] [PDF] [BibTeX]

    Abstract: A novel on-the-f ly calibration method of optical tweezers is presented, which enables in situ control and measure of absolute temperature and viscosity at nanoscale dimensions. Such noncontact measurement and control at the nanoscale are challenging as the present techniques only provide off-line measurements that do not provide absolute values. Additionally, some of the present methods have a low spatial resolution. We simultaneously apply the high temporal sensitivity of position autocorrelation and equipartition theorem to precisely measure and control in situ temperature and the corresponding microrheological property around the focal volume of the trap at high spatial resolution. The femtosecond optical tweezers (FOTs) use a single-beam high repetition rate laser for optical trapping to result in finer temperature gradients in comparison to the continuous-wave laser tweezers. Such finer temperature gradients are due to the additional nonlinear optical (NLO) phenomena occurring only at the nanoscale focal plane of the FOTs. Because NLO processes are laser peak power-dependent, they promote an effective study of physical properties occurring only at the focal plane. Using FOTs at optically benign near-infrared wavelengths, we demonstrate microrheological control and measurement in water by adding a highly absorbing yet low fluorescent dye (IR780).

     BibTeX: @article{mondalOntheFlyCalibratedMeasure2019,
      langid = {english},
      title = {On-the-{{Fly Calibrated Measure}} and {{Remote Control}} of {{Temperature}} and {{Viscosity}} at {{Nanoscale}}},
      volume = {3},
      issn = {2470-1343, 2470-1343},
      url = {http://pubs.acs.org/doi/10.1021/acsomega.8b01572},
      doi = {10/gff5s6},
      number = {9},
      journaltitle = {ACS Omega},
      urldate = {2019-08-01},
      date = {2018-09-30},
      pages = {12304-12311},
      author = {Mondal, Dipankar and Bandyopadhyay, Soumendra Nath and Mathur, Paresh and Goswami, Debabrata}
    }
    
  14. Structured Interferometry Features in Femtosecond Supercontinuum: Towards Better Understanding of Supercontinuum for Bio Applications. D. Goswami, S. Dinda, and S. N. Bandyopadhyay, in Optical Biopsy XV: Toward Real-Time Spectroscopic Imaging and Diagnosis (International Society for Optics and Photonics, 2017), 10060, p. 1006019 [Abstract] [PDF] [BibTeX]

    Abstract: We report structured interferometry features in femtosecond supercontinuum generated with power near to supercontinuum generation threshold. We argue that these structures arise from the coherent superposition of supercontinuum generated from different sources of supercontinuum as pulse split into two daughter pulses. Increase in input pulse energy creates several more temporal pulse fragments and disrupts interference resulting in the typical feature of continuous broad supercontinuum. Such an understanding of supercontinuum generation process is critical to the use of supercontinuum as the light source for use in understanding the time dynamics and imaging of bio systems.

     BibTeX: @inproceedings{goswamiStructuredInterferometryFeatures2018,
      title = {Structured Interferometry Features in Femtosecond Supercontinuum: Towards Better Understanding of Supercontinuum for Bio Applications},
      volume = {10060},
      url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10060/1006019/Structured-interferometry-features-in-femtosecond-supercontinuum--towards-better-understanding/10.1117/12.2253561.short},
      doi = {10/gf5mrd},
      shorttitle = {Structured Interferometry Features in Femtosecond Supercontinuum},
      eventtitle = {Optical {{Biopsy XV}}: {{Toward Real}}-{{Time Spectroscopic Imaging}} and {{Diagnosis}}},
      booktitle = {Optical {{Biopsy XV}}: {{Toward Real}}-{{Time Spectroscopic Imaging}} and {{Diagnosis}}},
      publisher = {{International Society for Optics and Photonics}},
      urldate = {2019-08-01},
      date = {2017-02-17},
      pages = {1006019},
      author = {Goswami, Debabrata and Dinda, Sirshendu and Bandyopadhyay, Soumendra N.}
    }
    
  15. On the Interferometric Coherent Structures in Femtosecond Supercontinuum Generation. S. Dinda, S. N. Bandyopadhyay, and D. Goswami, Appl. Phys. B 122(5), 148 (2016) [Abstract] [PDF] [BibTeX]

    Abstract: We report structured interferometric features in femtosecond supercontinuum generation (FSG) with incident laser powers that are near threshold for FSG. We argue that near threshold, these structures arise from the coherent superposition of pulses that are split initially into two daughter pulses during FSG process. Increase in the input pulse energy generates multiple daughter fragments in the temporal domain to an extent that correlated interference structures are not measurable.

     BibTeX: @article{dindaInterferometricCoherentStructures2017,
      langid = {english},
      title = {On the Interferometric Coherent Structures in Femtosecond Supercontinuum Generation},
      volume = {122},
      issn = {1432-0649},
      url = {https://my.pcloud.com/publink/show?code=XZfaxr7ZhXTWojTzmcfBOA16JDESUyR5fRWV},
      doi = {10/gf5mr5},
      number = {5},
      journaltitle = {Appl. Phys. B},
      urldate = {2019-08-01},
      date = {2016-05-11},
      pages = {148},
      author = {Dinda, Sirshendu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }
    
  16. Resolution Enhancement through Microscopic Spatiotemporal Control. D. Goswami, D. Das, and S. N. Bandyopadhyay, Faraday Discuss. 177(0), 203–212 (2015) [Abstract] [PDF] [BibTeX]

    Abstract: Operating at biologically benign conditions, multi-photon fluorescence imaging microscopy has benefitted immensely from recent developments in microscopic resolution enhancement. Fluorescence microscopy continues to be the best choice for experiments on live specimens, however, multi-photon fluorescence imaging often suffers from overlapping fluorescence of typical dyes used in microscopy, limiting its scope. This limitation has been the focus of our research where we show that by making simple modifications to the laser pulse structure, it is possible to resolve these overlapping fluorescence complications. Specifically, by using pairs of femtosecond pulses with variable delay in place of single pulse excitation, we show controlled fluorescence excitation or suppression of one of the fluorophores over the other through wave-packet interferometry. Such an effect prevails even after the fluorophore coherence timescale, which effectively results in a higher spatial resolution. Here we extend the effect of our pulse-pair technique to microscopic axial resolution experiments and show that such pairs of pulses can also ‘enhance’ axial resolution.

     BibTeX: @article{goswamiResolutionEnhancementMicroscopic2016,
      langid = {english},
      title = {Resolution Enhancement through Microscopic Spatiotemporal Control},
      volume = {177},
      issn = {1364-5498},
      url = {https://my.pcloud.com/publink/show?code=XZzvxr7Z0vbvki6gLSQhR76QzRco87Moa8Fy},
      doi = {10/gf5msv},
      number = {0},
      journaltitle = {Faraday Discuss.},
      urldate = {2019-08-01},
      date = {2015-04-14},
      pages = {203-212},
      author = {Goswami, Debabrata and Das, Dhiman and Bandyopadhyay, Soumendra Nath}
    }
    
  17. 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) [Abstract] [PDF] [BibTeX]

    Abstract: We report, for the first time, direct observation of coherent oscillations in the ground-state of IR775 dye due to microheterogeneous environment. Using ultrafast near-infrared degenerate pump-probe technique centered at 800 nm, we present the dynamics of IR775 in a binary mixture of methanol and chloroform at ultra-short time resolution of 30 fs. The dynamics of the dye in binary mixtures, in a time-scale of a few fs to ~740 ps, strongly varies as a function of solvent composition (volume fraction). Multi-oscillation behavior of the coherent vibration was observed, which increased with decreasing percentage of methanol in the dye mixture. Maximum number of damped oscillations were observed in 20% methanol. The observed vibrational wavepacket motion in the ground-state is periodic in nature. We needed two cosine functions to fit the coherent oscillation data as two different solvents were used. Dynamics of the dye molecule in binary mixtures can be explained by wavepacket motion in the ground potential energy surface. More is the confinement of the dye molecule in binary mixtures, more is the number of damped oscillations. The vibrational cooling time, τ2, increases with increase in the confinement of the system. The observed wavepacket oscillations in ground-state dynamics continued until 1.6 ps.

     BibTeX: @article{dasDirectObservationCoherent2015,
      langid = {english},
      title = {Direct {{Observation}} of {{Coherent Oscillations}} in {{Solution}} Due to {{Microheterogeneous Environment}}},
      volume = {4},
      issn = {2045-2322},
      url = {https://www.nature.com/articles/srep06097},
      doi = {10/gf5mth},
      journaltitle = {Scientific Reports},
      urldate = {2019-08-01},
      date = {2014-08-18},
      pages = {6097},
      author = {Das, Dipak Kumar and Makhal, Krishnandu and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata}
    }