Focusing a beam beyond the diffraction limit using a hyperlens-based device

• Published in: Chinese physics B Vol. 20; no. 11; pp. 506 - 511
• Main Author: 郑国兴 张瑞瑛 李松 何平安 周辉
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.11.2011
• Subjects: Beams (radiation); Computer simulation; Devices; Diffraction; Focal plane; Focusing; Plane waves; Wave propagation; 入射平面波; 双曲; 对焦; 数值孔径; 目标转换; 聚焦光束; 衍射极限; 设备组成
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/20/11/117802

A super-focusing device composed of a focusing objective and a hyperlens is proposed to focus an incident plane wave into the deep subwavelength dimension. In the device, the objective converts the incident plane wave into a convergent one. The half cylindrical hyperlens can support high wave vector k modes propagating towards its core. So the convergent wave can be focused into an ultrasmall spot beyond the diffraction limit. The layout is proposed for the super-focusing device and its characteristics are investigated theoretically. Numerical simulations verify that the focused beams are confined in a spot with a diameter of 16.3 nm in the focal plane of the focusing objective with a numerical aperture of 0.6, which corresponds to a super-resolution spot of λ0/23 （λ0 is the wavelength in vacuum）. The simulations confirm the effectiveness of the proposed device.