Tish Paper studies a few method of generating PWM pulse, Also analyse and discuss the harmonic characteristic of these modulation techniques, and provide a prof to select these method.

对产生PWM波的几种方式的谐波特性做了比较和探讨，为合理地选取控制方式提供了依据。

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The calculations show that a ultrashort pulse laser and the medium with higher ionization potential is necessary for generating higher order phase matched harmonic.

分析表明要想使高次谐波获得相位匹配，需要超短脉宽的驱动脉冲以及电离能大的气体工作介质。

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