Efficiently Detecting Spin Angular Momentum by Integrated Hybridized Spiral Groove Structure

摘要

Photon angular momentum includes spin and orbital angular momentum. This article is a research of the detection of photon spin angular momentum. We achieve this by designing and improving the structure of micro-nano spiral grooves, which requires the properties of surface plasmons as the prerequisite. The specific process is covering a silicon dioxide substrate with two mental films with the silver film overlies on the gold one; and we engrave a spiral groove on the upper film. The software COMSOL Multiphysics is used to simulate electric field intensity and calculate extinction ratios to reveal its detection capability. Based on the wavelength, the radius and the turns of the helix, we obtain various results. We also discuss the difference between left-handed and right-handed light respectively and change the design parameters to find the optimal program. Our conclusion proves the superimposed metal film has better performance comparing to the single film with the same thickness. When the radius of cross section of the spiral groove is 70nm and the spiral structure has 2 turns, the extinction ratio for the incident wave of 570nm-600nm is greater than 350; the optimal operating wavelength is 580nm, and the corresponding extinction ratio is 407.4.