A structured target geometry for highly efficient X-ray lasers

One-dimensional photonic crystal (1D PCs) with a defect layer is proposed as target for x-ray lasers. Its structure is shown as AB...ABTBA...BA, here T represents the defect layer made of the target material for x-ray lasing, on both sides of which are N bilayers of A (silica)and B (titania). The optical thicknesses of A, B and T are a quarter, a quarter and a half of the pumping laser wavelength, respectively. Here, the pumping laser is the localized mode of the 1D PCs. When irradiating perpendicularly on the novel target, the pumping laser intensity in the target layer will be enhanced by about 2 orders of magnitude. This is very important for the development of x-ray lasers (XRL) towards compactness, shorter wavelength and higher conversion efficiency