TY - JOUR T1 - The positive effects of applying nonlinear chirp to a three color laser field in order to generate a shorter attosecond pulse TT - تاثیرات مثبت اعمال چیرپ غیرخطی بر میدان لیزر سه رنگی به منظور تولید پالس کوتاه تر آتوثانیه JF - opsi JO - opsi VL - 23 IS - 0 UR - http://opsi.ir/article-1-1359-en.html Y1 - 2017 SP - 69 EP - 72 KW - attosecond KW - cut off KW - nonlinear chirp KW - plateau N2 - Abstract- In this paper ,in order to achieve a short attosecond pulse, the effects of nonlinear time dependent phase, "chirp", on a three color laser field has been studied. So, with the propuse of producing high order harmonics for a three color laser field, we have solved the time dependant 1D Schrodinger equation for single Helium atom . Result of simulation has shown that applying nonlinear chirp to a three color laser field has caused the extension of plateau and The cutoff frequency in the harmonic spectra and as a result we have succeed to produce a short 79 attosecond pulse. M3 ER -