Strong laser field interaction with materials is rich in physics and chemistry, and gives rise to variety of spectacular phenomena ranging from multiphoton/tunneling ionization to high harmonics generation. In this talk, I will present three of these intriguing phenomena that I have investigated.
First, I will explain neutral dissociation of hydrogen molecule in strong laser field through multiphoton super-excitation. I will demonstrate the experimental results of fragmentation of hydrogen molecules in a strong laser field including observation of Balmer lines from hydrogen atoms and measuring the upper limit of the lifetime of the super-excited states by an ultrafast pump and probe experiment .
The second part of the talk is dedicated to optical gain and population inversion in ions at 428 nm wavelength through high-resolution spectroscopy. I will clarify how sufficient dissimilarity of rotational distributions in the upper and lower emission levels could lead to gain without net electronic or vibronic population inversion .
Finally, at the third part of the talk, I will show the results of use of femtosecond laser pulses to melt indium semi-spherical nanostructure (r~175 nm) and shape them by high spatial frequency laser induced periodic surface structures into linear microstructures of 2 μm long in the direction of laser polarization. The understanding of the modification process, melting and moving in the nano-grating structured field, pave the way to design nanostructures of arbitrary shapes at the sub-wavelength scale .
 A. Azarm, D. Song, K. Liu et al. J. Phys. B: At. Mol. Opt. Phys. 44 (2011) 085601
 A. Azarm, P. Corkum, P. Polynkin, Phys. Rev. A Rapid Comm. 96 (2017) 051401(R)
 A. Azarm, F. Akhoundi, R. A. Norwood et al. Appl. Phys. Lett. 113 (2018) 033103