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Color Changing Structures Inspired by Nature

Hashemi Abrandabadi, Saeed | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 56501 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Sadighi Bonabi, Rasoul; Anvari, Abbas
  7. Abstract:
  8. Structures that change color in an adjustable way have been noticed in recent years. There are structures in nature such as the skin of chameleons and octopuses and other animals that can change color. In recent years, inspired by these structures, materials based on photonic crystals or surface plasmonics have been proposed to change color. In this research, a review is made on these structures in nature as well as recent efforts to make such materials. In fact, photonic crystals create a special color due to the interference between scattered waves. For example, the change in the distance between the nanoparticles in the photonic crystals inside the chameleon skin is the cause of its color change. While the interference effect causes the color to depend on the viewing angle, and by changing the viewing angle for photonic crystals, the color must change, while the color of the chameleon does not depend on the viewing angle. In this research, it has been proven that there must be irregularities in the photonic crystal lattice to create structural color independent of the angle. This irregularity causes Anderson localization for light. Simulation has been done for one-dimensional and two-dimensional mode. At the wavelengths where Anderson localization occurs, the reflection coefficient is minimal. Abrey-André model has been used to investigate and compare the transition between the localized and non-localized states. Also, by tracking the beam inside the structure, the reflection coefficient of the medium and its color have been simulated. The higher the refractive index of nanoparticles, the greater the reflection coefficient
  9. Keywords:
  10. Reflection Coefficient ; Anderson Localization ; Random Refractive Index ; Structural Colors ; Observation Angle ; Photonic Crystal

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