Surprising Scattering in Stealthy Structures
Stealthy hyperuniform materials are disordered structures that look uniform on large length scales. This property suggests that, within a certain range of wavelengths, the structures should be transparent to light, allowing it to pass through without scattering. But experimentally testing that prediction has been difficult because doing so requires large, precisely controlled samples. Now Mikael Rechtsman at Pennsylvania State University and his colleagues have overcome that challenge [1]. They have demonstrated that stealthy hyperuniform materials can scatter light within the wavelength range typically associated with transparency. The results highlight the subtle interplay between structure, disorder, and photon loss in determining how materials affect the propagation of light.
The researchers fabricated a millimeter-sized photonic-crystal slab containing millions of holes separated by half a micrometer on a square lattice. They introduced stealthy hyperuniform disorder by randomly varying each hole’s size. Instead of measuring conventional light transmission through this slab, the team determined the material’s photonic band structure, revealing how scattering depended on the wavelength and direction of light. Such experiments would not be possible in other systems: In particular, microwave and acoustic structures cannot be made large enough, and condensed-matter setups lack the needed design flexibility.
Normally, wave propagation in stealthy hyperuniform materials is modeled as a conservative process in which no power is lost. However, in photonic-crystal geometries of the type used by Rechtsman and his colleagues, light can leak out of the material. In this more realistic scenario, photons behave as though they are massive particles whose mass is a complex number with an imaginary part. The researchers showed how, and to what extent, this imaginary component of the mass increased scattering for wavelengths where transparency was expected.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK
References
- M. Barsukova et al., “Stealthy-hyperuniform wave dynamics in two-dimensional photonic crystals,” Phys. Rev. X 16, 021028 (2026).