Study on focusing of subwavelength imaging of a point source based on two-dimensional photonic crystals

A new focusing structure is proposed, consisting of periodic array air holes in silicon and based on two-dimensional (2D) photonic crystal (PC) with negative refraction and subwavelength imaging characteristics. The light radiating from a point source can form a subwavelength imaging of which the half-width reaches 0.47λ through a wedge PC. Due to the influence of the aberration and evanescent field, the symmetry plane of the image is inside the structure rather than the boundary. In addition, moving the PC by 2 μm to the left horizontally, the image moves by 3.57 μm and the half-width of each image is less than the half-wavelength in this process.