Robust Helical Dichroism on Microadditively Manufactured Copper Helices via Photonic Orbital Angular Momentum

Abstract

Three-dimensional chiral metallic metamaterials have already attracted extensive attention in the wide research fields of chiroptical responses. These artificial chiral micronanostructures, possessing strong chiroptical signals, show huge significance in next-generation photonic devices and chiroptical spectroscopy techniques. However, most of the existing chiral metallic metamaterials are designed for generating chiroptical signals dependent on photonic spin angular momentum (SAM). The chiral metallic metamaterials for generating strong chiroptical responses by photonic orbital angular momentum (OAM) remain unseen. In this work, we fabricate copper microhelices with opposite handedness by additively manufacturing and further examine their OAM-dominated chiroptical response: helical dichroism (HD). The chiral copper microhelices exhibit differential reflection to the opposite OAM states, resulting in a significant HD signal (∼50%). The origin of the HD can be theoretically explained by the difference in photocurrent distribution inside copper microhelices under opposite OAM states. Moreover, the additively manufactured copper microhelices possess an excellent microstructural stability under varying annealing temperatures for robust HD responses. Lower material cost and noble-metal-similar optical properties, accompanied with well thermal stability, render the copper microhelices promising metamaterials in advanced chiroptical spectroscopy and photonic OAM engineering.

Two‐Photon Polymerization Lithography for Optics and Photonics: Fundamentals, Materials, Technologies, and Applications

“…[670] The field of TPL printing related topological photonics and BIC related photonics is still newborn, but rapidly growing with cutting-edge physical concepts. [671][672][673][674] It is expected that the burgeon of topological or BIC photonics will rely more on the TPL based fabrication techniques. bound states in the continuum.…”

A salt pollution self-cleaning Al based solar desalination evaporator fabricated using a picosecond laser

“…Recently, ultra-fast laser direct writing, with good consistency and a negligible heat-affected zone, has been widely utilized to control the surface wettability and topography. [18][19][20][21][22][23] Numerous efforts have been devoted to laser processing for achieving efficient solar desalination. For example, Yin et al reported a femtosecond laser structured foam titanium used for solar desalination.…”

Observation of Magnetic Quadrupole Endowed Helical Dichroism in Artificial Propeller Meta‐Molecules

“…Light field with orbital angular momentum (OAM) is also known as vortex beam which has been well applied in optical tweezers, [12] communication, [13] manufacturing, [14] etc. [15,16] The helical wavefront also gives vortex beam a chiral degree of freedom and its handedness is determined by the sign of the OAM munber l. [17][18][19] Interestingly, recent theoretical and experimental studies have demonstrated that the interaction between vortex beam and chiral matters depends on the sign of l. [20][21][22][23][24][25][26][27][28][29][30] This suggests that photonic OAM can provide another promising approach to investigate chiral physics. The giant helical dichroism (HD) has been achieved for a single helix, [25,29] planar-chiral nanostructure, [26] twisted stereometamaterial, [27] and chiral oligomer.…”

“…[15,16] The helical wavefront also gives vortex beam a chiral degree of freedom and its handedness is determined by the sign of the OAM munber l. [17][18][19] Interestingly, recent theoretical and experimental studies have demonstrated that the interaction between vortex beam and chiral matters depends on the sign of l. [20][21][22][23][24][25][26][27][28][29][30] This suggests that photonic OAM can provide another promising approach to investigate chiral physics. The giant helical dichroism (HD) has been achieved for a single helix, [25,29] planar-chiral nanostructure, [26] twisted stereometamaterial, [27] and chiral oligomer. [28] With the virtues of HD spectroscopy, enantiomeric distinction can be performed using monochromatic linearly polarized light fields, which is completely different from circular dichroism spectroscopy methods.…”