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Proceedings Paper

Effect of lens tilt on SCE and filamentation characteristics of femtosecond pulses in air
Author(s): S. Sreeja; T. Shuvan Prashant; Ch. Leela; V. Rakesh Kumar; Surya P. Tewari; S. Venugopal Rao; P. Prem Kiran
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Paper Abstract

We present the evolution of SCE associated with filaments due to the tilt of focusing lens under tight focusing geometries. Transform limited femtosecond (fs) pulses (800 nm, 45 fs, 1 kHz repetition rate) were focused in ambient air using three different focusing geometries f/#6, f/#7.5, and f/#12 corresponding to numerical apertures (NA) of 0.08, 0.06, and 0.04, respectively. The focusing lens was tilted from zero up to 20 degrees. The filaments decayed into two shorter parts through tilting of the lens and the separation between shorter filaments increased with increasing lens tilt, in tune with earlier reports [Kamali et al., Opt. Commun. 282, 950-954 (2009)]. The separation between the filaments matched well with the predicted distances due to astigmatism induced in loose focusing geometries. However the deviation increased as we moved to the tighter focusing geometries. The SCE spectrum demonstrated an anomalous behaviour. The SCE spectrum was suppressed at larger tilt angles of 12 - 20°. However at lower tilt angles, up to 8°, the SCE was observed to be same to that measured without any tilt of the focusing lens. This behaviour is predominant with tighter focusing geometries of f/#6 and f/#7.5, wherein the SCE was observed to be higher at 4° and 8° in comparison with that observed at an angle of 0°. Systematic study of the focusing lens tilt on anomalous SCE spectra and filament characteristics in the tight focusing geometry are presented.

Paper Details

Date Published: 10 May 2012
PDF: 6 pages
Proc. SPIE 8434, Nonlinear Optics and Applications VI, 84340T (10 May 2012); doi: 10.1117/12.921634
Show Author Affiliations
S. Sreeja, Univ. of Hyderabad (India)
Cochin Univ. of Science & Technology (India)
T. Shuvan Prashant, Univ. of Hyderabad (India)
Ch. Leela, Univ. of Hyderabad (India)
V. Rakesh Kumar, Univ. of Hyderabad (India)
Surya P. Tewari, Univ. of Hyderabad (India)
S. Venugopal Rao, Univ. of Hyderabad (India)
P. Prem Kiran, Univ. of Hyderabad (India)

Published in SPIE Proceedings Vol. 8434:
Nonlinear Optics and Applications VI
Benjamin J. Eggleton; Alexander L. Gaeta; Neil G. Broderick, Editor(s)

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