Multi-pulse induced spectrum method and device based on femtosecond plasma grating

The invention discloses a multi-pulse induced spectrum method and device based on a femtosecond plasma grating. The method comprises the following steps: firstly, exciting a sample based on a femtosecond plasma grating, after a period of time delay, additionally setting a multi-beam pulse combination for incidence relative to the plasma grating at a first-order or high-order Bragg angle, coupling with the previous femtosecond plasma grating, exciting the sample to generate a plasma group, and then carrying out spectral analysis, wherein the post pulse can be one of a picosecond pulse combination, a femtosecond filament combination or a femtosecond plasma grating. According to the method, the advantages of high power density and electron density of the femtosecond plasma grating are utilized, and the femtosecond plasma grating is coupled with post-pulse to excite a sample. Therefore, the method can effectively improve the excitation effect, improve the detection sensitivity and overcome the matrix effect, and