Optics and Photonics Society of Iran

 In this paper in order to achieve the optimized attosecond pulse, we solve the time dependent 1D scherodinger equation in helium atom, and them by applying the fourier transformation to the dipole acceleration for a laser with initial parameters, the high harmonic generation spectrum have been plotted. First: the one color, two color and three color laser pulses have been compared with each other and then step by step by adding a linear chirp (-βw₀t²). First to the the main field then to the main field and first controlling field and at the end to the main field, first controlling field and second controlling field simultaneously we will find out that adding the chirp to all three fields makes the pulse shorter and prepare the optimized result.