Vol.:(0123456789) 1 3 Applied Physics A (2020) 126:411 https://doi.org/10.1007/s00339-020-03548-9 Induced birefringence in glass: depletion and enhancement by orthogonal‑polarized femtosecond pulses Somayeh Najaf 1  · Atoosa Sadat Arabanian 1  · Reza Massudi 1  · Aliasghar Ajami 2  · Wolfgang Husinsky 3 Received: 1 January 2020 / Accepted: 13 April 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract We show spectacular and diferent efect of the sequential and simultaneous writing of two perpendicularly polarized ultra- short laser pulse trains on profle and magnitude of induced optical retardation inside fused silica glass. Clear birefringence was observed in the region exposed to linearly polarized pulse train radiation. It found out that the induced birefringence is erasable. It means that, when the sample is irradiated again with pulse train having perpendicular polarization, the induced birefringence is vanished and can be totally erased by optimizing the pulse energy. However, in a simultaneous writing approach, a contradictory result was observed. When the glass substrates were simultaneously (i.e. with an accuracy better than the pulse duration) exposed to two beams with perpendicular polarization the induced birefringence not only remained but also enhanced. Discussion and study on the results of interaction of polarized single ultrashort laser pulse and sequential laser beams (which spatially overlapped) having diferent polarizations and also change of energy ratio of simultaneously writing pulse trains helps us to analyze diferent results of the simultaneous interaction of two orthogonally polarized ultrashort laser pulse trains with transparent material. Our results provide pieces of evidence for further understanding the physical mechanism of creation of the birefringence using ultrashort laser pulses. Additionally, they provide the ability to manipulate the transient electron dynamics to control the profle and tailor of the induced birefringence. Keywords Ultrashort laser pulses · Induced birefringence · Optical retardation · Nanograting · Fused silica glass 1 Introduction Generation of volume subwavelength structures using ultra- fast laser pulses is a feld which has attracted considerable attention. In this field, generation of three-dimensional birefringence in the bulk of isotropic transparent materials such as glass has found various applications such as 5-D optical memories [1], optical wave plates [2, 3], polariza- tion converters [4], polarization-sensitive holograms [5], polarization-sensitive waveguides [6], Fresnel zone plates [7], and nanofuidics channels for lab-on-chip devices [8]. To fabricate polarization devices, the distribution and the magnitude of the induced birefringence inside the materials should be carefully adjusted and controlled. Therefore, it is essential to investigate the dependency of the induced modi- fcations on the pulse parameters of the writing laser beam. Ultrashort laser pulses with intensities above the mul- tiphoton ionization threshold can induce refractive index changes inside glass [9]. When the sample is irradiated by several hundreds of pulses the birefringence is induced inside the material in the focal region. Such birefringence was frst observed in the bulk of fused silica by Sudrie et al. [10]. In 2003, Kazansaky et al. showed that the induced bire- fringence is due to the formation of self-organized periodic nanostructures in the material volume. The produced peri- odic nanostructures are aligned perpendicular to the direc- tion of the polarization of the writing laser beam with perio- dicity determined by the laser wavelength [11]. Because of the impact of the polarization state of the laser beam on the orientation of the nanostructures, one can consider an electronic origin for this phenomenon. * Reza Massudi r-massudi@sbu.ac.ir 1 Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, Iran 2 Faculty of Physics, Semnan University, P. O. Box 35195-363, Semnan, Iran 3 Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse. 8, 1060 Vienna, Austria