Laser pulse width controlling in the process of cavity flows empty with slowly Q adjusting

In some applcation fields,the square laser pulses are necessary.The conventional cavity flow empty lasers can obtain the pulse output with 10ns pulse width,but not the square laser pulses.In our theoretical analysis,the computer simulation was carried out to fine the solution of the rate equation and to get the relation of the photon number and the Q index.So we can control the photon number of the process of the cavity flow empty to obtain the square laser pulses by adjusting Q index.The experiments were carried out.We supplied a adjustable voltage on the Pockels' cell to control the Q index in the process of cavity flowing empty,and the experiment results show that square laser pulses with the width of 40～70ns can obtain.