We have investigated in detail the influence of defect on the focusing of electromagnetic waves in a two-dimensional photonic-crystal flat lens by using the finite-difference time-domain method.The result shows that many focusings can be observed at the symmetrical positions when a defect is introduced into the lens.Furthermore,the wave-guides in the lens can confine the transmission wave effectively and improve the quality of the focusing.
We investigate in detail the influence of line defects on focusing of electromagnetic waves in a two-dimensional photonic-crystal flat lens.Through simulations,we find that a focusing can always be observed when a line defect in the lens is introduced along the light transmission direction and the width of the line defect is less than λ/2.However,there appear two focusings when the width of the line defect is more than λ/2.When the line defect is introduced along the direction perpendicular to the transmission,there is always one focusing.
