Role of the temporal profile of femtosecond lasers of two different colours in holography

Aix-Marseille Université, UMR 7345 CNRS, campus Saint Jérome - case 322, av. escadrille Normandie-Niemen, 13397 Marseille cedex 20, France

^(a) Permanent address: Netaji Subhas University of Technology Delhi - New Delhi-110 078, India; lohit.malik@gmail.com

Received: 24 July 2018
Accepted: 12 December 2018

Abstract

The role of the temporal profile of femtosecond lasers in obtaining the holograms is uncovered when two lasers of different colours are used to produce the fringes and recording of holograms. It was shown that the contrast of the time average interference pattern of two short light pulses (pulse duration T) of different colours is remarkably high for frequency detuning (see Odoulov S. et al., Nat. Commun., 6 (2015) 5866). However, we prove that such a continuous range of frequency detuning is not possible but null regions develop and frequency bands are observed for realizing holograms if there is a deviation of the lasers from their Gaussian profiles. The increased pulse duration leads to the generation of additional frequency bands and their narrowing along with higher modulation depth. A shifting of the null regions is noticed for the lasers having different skewness and/or pulse duration.