Transmission-Type Plano-Concave Lens Using in the Range of Extreme Ultraviolet Wavelength

A one-dimensional photonic crystal consisting of the fourth-order Fibonacci multilayer films has been studied by the finite-difference time-domain method and transfer matrix method. The refractive indices for two layers of the Fibonacci multilayer films are similar with that of manganese and silicon in the extreme ultraviolet (EUV) band. The simulation result shows that there is an isotropic negative refractive index for the one-dimensional photonic crystal. Based on the character above, a kind of transmission-type plano-concave lens, which can be used in the EUV band (or soft X-ray), is designed. The distributions of the electromagnetic field for the lens and transimissivity of the Fibonacci multilayers films have also been calculated. The result demonstrates that the lens can focus the incoming EUV radiation, and its transmissivity is bigger than 5%-9% compared with that of the Fibonacci multilayers films, having the same structure with the lens. This letter has potential applications in the tansmission-type lens for EUV lithography.