Investigating Circular Dichroism in Distorted Double Gyroids

Circular dichroism (CD, the differential absorption of left and right circularly polarized light) offers significant applications in anti-counterfeit as well as molecular and protein sensing. 3D network materials, and specifically double gyroids, are of particular interest for circular dichroism as they can possess a number chiral elements (surface structure, bulk helices) that can be tuned for a particular CD response. These structures can also be readily generated via self-assembly. While many optical simulations of gyroids assume a perfect cubic structure, experimentally created gyroids often include distortions, especially Z-compression due to processing. In this work, the CD of distorted double gyroids is explored systematically with finite difference time domain (FDTD) simulations. When varied from 0-45%, the volume conserved, uniform Z-compression of (110) oriented silver double gyroids with a 0.52 volume fraction yields both enhanced CD (g-factors of 0.15) as well as the emergence and disappearance of CD peaks. Many of these optical behaviors are found only at certain surface terminations of the double gyroid unit cell. In this talk, both the surface structure and bulk features leading to these spectral features will be discussed. Overall, this talk will elucidate the impact of uniform distortions on the CD of double gyroids offering improved understanding and possible recommendations for structural design.