Chiral plasmonic films with gold nanohelices in polymer matrix are fabricated by templated electroless plating using self‐assembled enantiomeric polylactide‐based block copolymers (BCPs) as templates. By taking advantage of the helicity control of forming helical phase from the self‐assembly of chiral BCPs, mirror‐image signals from Cotton effect in electronic circular dichroism spectra can be clearly identified. The polymeric films with gold nanohelices show chiral plasmonic properties, as further evidenced by simulation from finite‐difference time‐domain method. This study may shed the light on fabrication of chiral plasmonic materials with adaptability in the applications for optical devices.
Bioinspired from structural coloration of butterfly wing structure, this work aims to fabricate nanoporous chitosan for UVC reflection. By taking advantage of self-assembled polystyrene-b-polydimethylsiloxane (PS-b-PDMS) with double gyroid texture followed by hydrofluoric acid etching of PDMS block, nanoporous PS with well-defined nanochannels can be fabricated, and used as a template for templated crosslinking reaction of chitosan through a multiple pore-filling process. Well-ordered nanoporous chitosan with shifting networks in nanoscale can be successfully fabricated after removal of the PS template. With the low absorption of chitosan in the ultraviolet region and the shifting networks for opening the bandgap, it is appealing to exploit the nanonetwork chitosan as high reflective materials for UVC optical devices, as evidenced by finite-difference time-domain (FDTD) simulation and optical measurements experimentally.
We study the control of spontaneous emission in a three-level V-type atom that is coupled by a static magnetic field in photonic crystals. We find that by changing the position of the upper band edge and Larmor frequency of the magnetic field, control of the steady-state behavior of spontaneous emission can be achieved. As the transition frequencies move from outside the band gap to inside, the structure of the spectral line changes from a two-peak structure to a single-peak structure, and then to a non-Lorentzian shape. With the increase of the Larmor frequency of the magnetic field, when both transition frequencies are outside the photonic band gap, the partial spectral line disappears; however, when both frequencies are inside the band gap, the non-Lorentzian shape is replaced by a Lorentzian shape. These phenomena arise from the fact that the corresponding transition frequency is pushed into or out of the band gap.
As shown in article number 2002133 by Rong‐Ming Ho and co‐workers, gold nanohelices for chiral plasmonic polymer films can be fabricated by using self‐assembled chiral block copolymers as templates for templated electroless plating. The gold nanohelix can serve as absorber and scatterer in the polymeric films for manipulating circular‐polarized light based on its chirality. This bottom‐up approach suggests a facile method for fabrication of plasmonic nanohelices.
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