In this work, we utilize femtosecond laser pulse shaping technology to study the role of chirp in generation and detection mechanism of Terahertz pulses with LT-GaAs photoconductive antenna. Experimental results show that the PC antenna excited with slightly up-chirped laser will generate THz pulses with higher peak amplitude, total power and broader bandwidth. In the detection process, similar behaviors have been observed. We use one dimensional Drude-Lorentz model to simulate THz generation and detection processes to analysis our experiment results. Finally, we use this coherently...