Effect of subwavelength annular aperture diameter on the nondiffracting region of generated Bessel beams.
A subwavelength annular aperture (SAA) made on metallic film and deposited on a glass substrate was fabricated by electron-beam lithography (EBL) and which was followed by a metal lift-off process to generate a long propagation range Bessel beam. We propose tuning the focal length and depth of focus (DOF) by changing the diameter of the SAA. We used finite-difference time domain (FDTD) simulations to verify our experimental data. We found that the position of the Bessel Beam focus spot (i.e. focal length) will be farther away from the SAA plane as the diameter of the SAA increases. In addition, the depth of focus (DOF) which is the length of the Bessel beam non-diffracting area, also increases as the diameter of the SAA expands.
Yu
Yuh-Yan
YY
Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan.
Lin
Ding-Zheng
DZ
Huang
Long-Sun
LS
Lee
Chih-Kung
CK
D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D008027:Light; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods