The designing of novel targets and their effects on X-ray lasers
抽运激光在光靶中的局域及其对X射线激光特性的影响

The novel target used in X-ray lasers is designed as a one-dimensional photonic crystals (1D PCs) with 12 bilayers of SiO 2 and TiO 2, at the center of which a defect layer made of target material is embedded. The optical thickness of the target layer and each layer of the rest are a half and a quarter of the pumping laser wavelength, respectively. The pumping laser is, therefore, the localized mode of the 1D PCs. Compared with the common slab target, the pumping laser intensity in the target layer will be enhanced by about 2 orders. This is very important to the progress of X-ray lasers towards compactness, shorter wavelength and higher conversion efficiency. Gain coefficient will increase by a factor of 5, hence the target length in saturated XRL is reduced to one fifth. X-ray laser intensity will increase by about 4 orders, and so does the conversion efficiency. The average ionization state increases with pumping laser intensity, therefore, the wavelength of the X-ray laser will be shorter.