Tushar Gaur

09 March 2026

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Education / Work History

• Ph.D., IISc Bangalore
• M.Tech, Center for Lasers and Photonics (CELP), IIT Kanpur (2017-2019)
• B.Tech, Rajasthan Technical University (2009-2013)

Thesis Abstract

Discerning the Effects of Thermal Nonlinearity in Optical Trapping

The field of Optical Trapping is almost in the end of its fifth decade, importance of thermal effects have been addressed but no significant work was done in calculating the thermal effects on force and potential of the trapped particle. With the advent of using ultra short pulses in trapping it became important to describe the thermal effects on optical trapping to differentiate and articulate the advantages of pulsed lasers over CW laser based trapping. A proper theoretical comparison for the rise in temperature for both CW laser and Pulsed laser was done but the model worked only uptil pulse width of a few nanoseconds as we move to the subpico second pulses theoretical model cannot be used to predict the temperature due to computational limitations. As predicting the temperature in water medium for the case of femtosecond pulses was not approachable computationally, some other technique needed to be developed. To narrow down the gap between theoretical model and experiments it is important that the technique to be used includes all the thermal effects in optical trapping so, thermal nonlinearity of medium was included in the force equations of trapped particle. For this to happen Z-scan technique was used to measure the thermal nonlinear coefficients of various solution with both pulsed laser and CW laser which were then incorporated in optical trapping force equations through a newly generated MATLAB code to find out the effects of thermal nonlinearity which is directly related to rise in temperature of medium for studying the thermal effects on optical trapping. Results clearly show significant effects on forces and potential for trapped particle on adding thermal nonlinearity, a comparison was made to establish the difference in trapping when we use a pulsed laser and CW laser for two different regimes Rayleigh and GLMT.

Research Topic / Interest

Contact me to know my current interests.

Publications

These include only those published in our lab.

1. Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Pulsed Lasers. S. N. Bandyopadhyay, T. Gaur, and D. Goswami, arXiv:2002.00227 [physics] (2020) [BibTeX]

    BibTeX: @article{bandyopadhyayComparativeStudyRealtime2020,
     title = {Comparative Study of the Real-Time Optical Trapping in the {{Rayleigh}} Regime for Continuous and Pulsed Lasers},
     author = {Bandyopadhyay, Soumendra Nath and Gaur, Tushar and Goswami, Debabrata},
     year = {2020},
     month = feb,
     journal = {arXiv:2002.00227 [physics]},
     eprint = {2002.00227},
     primaryclass = {physics},
     urldate = {2020-02-06},
     archiveprefix = {arXiv},
     annotation = {GSCC: 0000007}
   }
   

2. Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Femtosecond Pulsed Lasers. S. N. Bandyopadhyay, T. Gaur, and D. Goswami, Optics & Laser Technology 136, 106770 (2021) [BibTeX]

    BibTeX: @article{bandyopadhyayComparativeStudyRealtime2021,
     title = {Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Femtosecond Pulsed Lasers},
     author = {Bandyopadhyay, Soumendra Nath and Gaur, Tushar and Goswami, Debabrata},
     year = {2021},
     month = apr,
     journal = {Optics \& Laser Technology},
     volume = {136},
     pages = {106770},
     issn = {0030-3992},
     doi = {10.1016/j.optlastec.2020.106770},
     urldate = {2025-03-19},
     langid = {english}
   }
   

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 [BibTeX]

    BibTeX: @inproceedings{gaurManifestingEffectsThermal2019,
     title = {Manifesting the {{Effects}} of {{Thermal Nonlinearity}} in {{Optical Trapping}} for {{Rayleigh Regime}}},
     booktitle = {2019 {{URSI Asia-Pacific Radio Science Conference}} ({{AP-RASC}})},
     author = {Gaur, Tushar and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata},
     year = {2019},
     month = mar,
     pages = {1--5},
     publisher = {IEEE},
     address = {New Delhi, India},
     doi = {10/gf5mqf},
     urldate = {2019-08-01},
     isbn = {978-90-825987-5-9},
     langid = {english},
     annotation = {GSCC: 0000002 \\
     1 citations (Crossref) [2024-05-28]\\
     00000}
   }
   

4. Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Pulsed Lasers. S. N. Bandyopadhyay, T. Gaur, and D. Goswami, arXiv:2002.00227 [physics] (2020) [BibTeX]

    BibTeX: @article{bandyopadhyayComparativeStudyRealtime2022,
     title = {Comparative Study of the Real-Time Optical Trapping in the {{Rayleigh}} Regime for Continuous and Pulsed Lasers},
     author = {Bandyopadhyay, Soumendra Nath and Gaur, Tushar and Goswami, Debabrata},
     year = {2020},
     month = feb,
     journal = {arXiv:2002.00227 [physics]},
     eprint = {2002.00227},
     primaryclass = {physics},
     urldate = {2020-02-06},
     archiveprefix = {arXiv},
     annotation = {GSCC: 0000007}
   }
   

5. Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Femtosecond Pulsed Lasers. S. N. Bandyopadhyay, T. Gaur, and D. Goswami, Optics & Laser Technology 136, 106770 (2021) [BibTeX]

    BibTeX: @article{bandyopadhyayComparativeStudyRealtime2023,
     title = {Comparative Study of the Real-Time Optical Trapping in the Rayleigh Regime for Continuous and Femtosecond Pulsed Lasers},
     author = {Bandyopadhyay, Soumendra Nath and Gaur, Tushar and Goswami, Debabrata},
     year = {2021},
     month = apr,
     journal = {Optics \& Laser Technology},
     volume = {136},
     pages = {106770},
     issn = {0030-3992},
     doi = {10.1016/j.optlastec.2020.106770},
     urldate = {2025-03-19},
     langid = {english}
   }
   

6. 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 [BibTeX]

    BibTeX: @inproceedings{gaurManifestingEffectsThermal2020,
     title = {Manifesting the {{Effects}} of {{Thermal Nonlinearity}} in {{Optical Trapping}} for {{Rayleigh Regime}}},
     booktitle = {2019 {{URSI Asia-Pacific Radio Science Conference}} ({{AP-RASC}})},
     author = {Gaur, Tushar and Bandyopadhyay, Soumendra Nath and Goswami, Debabrata},
     year = {2019},
     month = mar,
     pages = {1--5},
     publisher = {IEEE},
     address = {New Delhi, India},
     doi = {10/gf5mqf},
     urldate = {2019-08-01},
     isbn = {978-90-825987-5-9},
     langid = {english},
     annotation = {GSCC: 0000002 \\
     1 citations (Crossref) [2024-05-28]\\
     00000}
   }