標題: | Three-Dimensional Resolvable Plasmonic Concentric Compound Lens: Approaching the Axial Resolution from Microscale to Nanoscale |
作者: | Chang, Kai-Hao Chen, Yen-Chun Chang, Wen-Hao Lee, Po-Tsung 電機學院 光電工程學系 College of Electrical and Computer Engineering Department of Photonics |
關鍵字: | plasmonic lens;subwavelength focusing;axial resolution;depth of focus;dual-wavelength |
公開日期: | 1-三月-2018 |
摘要: | We propose the design and working principle of a plasmonic concentric compound lens (CCL) comprising inner circular nanoslits and outer circular nanogrooves. Dual-wavelength operations have been achieved for 650 and 750 nm at nanoscale and microscale focal lengths along with their depth of focus (DOF). By tuning the arrangement of nanogrooves, the axial resolution can be modulated and the narrowest DOF is achieved by a design of gradually decreasing groove width. For the ultrahigh tunability of axial resolution, DOF over 400 nm for both working wavelengths is also achieved. We not only developed an approximate-perturbed-focus model for explaining the performance of DOF but also found an extraordinary way to improve the resolution. The enhanced resonance of central disk as nannoantenna in CCL also has great influence on nanofocusing with different deigns of outer nanogrooves. This work provides new sight of focusing ability governed by the general optical nanogrooves. The optimized CCL shows excellent focusing performance with a lateral resolution down to 0.32 lambda (lambda= 650 nm), which is the best resolving ability achieved thus far in the near field region with a long focal length up to 500 nm. |
URI: | http://dx.doi.org/10.1021/acsphotonics.7b01003 http://hdl.handle.net/11536/144732 |
ISSN: | 2330-4022 |
DOI: | 10.1021/acsphotonics.7b01003 |
期刊: | ACS PHOTONICS |
Volume: | 5 |
起始頁: | 834 |
結束頁: | 843 |
顯示於類別: | 期刊論文 |