Current Science

Arijit Kumar De ¹, Debjit Roy ¹, Vivek Bansal ¹, Aditya Gupta ¹, Debabrata Goswami ¹

Affiliations
1 Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, IN

Abstract

No Abstract.

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Ajitesh Kumar ¹, S. K. Karthick Kumar ¹, Sumit Singhal ¹, Debabrata Goswami ¹

Affiliations
1 Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, IN

Abstract

Comparative study of the molecular dynamics of two xanthene dye derivatives (Rhodamine-6G and Fluorescein-548) is reported using spectrally resolved three-pulse photon echo spectroscopy. An appreciable change in the coherence and population dynamics was observed between the two xanthene derivatives due to the presence of different functional groups. Solution of Rhodamine-6G in methanol behaves in a more coherent fashion compared to that of Fluorescein-548 dye.

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Arijit K. De ¹, Debabrata Goswami ²

Affiliations
1 Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli 140 306, IN
2 Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, IN

Abstract

Although pulsed illumination is routinely used in multi-photon fluorescence microscopy, it is not quite common for its one-photon counterpart, i.e. (one-photon) confocal fluorescence microscopy. However, prolonged illumination with continuous wave (CW) light source leads to excited (singlet) state absorption (as well as absorption from triplet state) leading to photo-damage. Here, by photo-damage we mean any detrimental (irreversible) effect that leads to reduced fluorescence yield. Stroboscopic or pulsed light illumination has been recently introduced to reduce photo-bleaching as well as photo-toxicity.

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Indrajit Bhattacharyya ¹, Debabrata Goswami ¹

Affiliations
1 Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, IN

Abstract

Spatiotemporal imaging of sum-frequency generation process through second-order nonlinear optical interaction in a nonlinear crystal under femtosecond pulsed illumination is presented. Two focal points in the spatial dimension that result from use of widely separated wavelengths (780 and 1560 nm) including their appropriate intensity ratios are captured accurately, emphasizing the sensitivity and robustness of this detection scheme. Most importantly, crosscorrelation width that is used as characteristic measure from such techniques remains constant at the two focal points. However, this highlights the critical role of nonlinear crystal position along beam propagation axis during such collinear intensity cross-correlation measurements involving different wavelengths.

Keywords

Nonlinear Optics, Nonlinear Optical Signal Processing, Nonlinear Optical Materials, Ultrafast Lasers.

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