Three-dimensional disordered hyperuniform networks with a photonic bandgap

Introduction The term “hyperuniform” refers to point patterns, whose structure factor tends to zero for short wave-vectors, meaning the absence of long-wavelength density fluctuations. Apart from crystalline and... [ view full abstract ]

Introduction

The term “hyperuniform” refers to point patterns, whose structure factor tends to zero for short wave-vectors, meaning the absence of long-wavelength density fluctuations. Apart from crystalline and quasi-crystalline patterns belonging to this class, there exist structures with no long-range order which also have this property. It has been shown that networks derived from such patterns can possess an isotropic photonic band-gap.

Methods

We have generated 3D networks from a hyperuniform disordered point pattern by performing a Delaunay tessellation and connecting the centers of resulting tetrahedra with dielectric rods. We have been able to fabricate such three-dimensional networks by means of 3D laser nanolithography in a polymer photoresist and to prove by FIB-SEM, light scattering and optical microscopy that their geometry is correct [1-2]. These polymer networks were then used as templates and replicated in silicon on two different routes of single and double inversion, involving atomic layer deposition, high-temperature chemical vapor deposition and calcination [3-4]. FTIR measurements were performed to extract spectral features of our structures. Interaction of light with the networks was simulated using the finite difference time domain technique (FDTD).

Results and discussion

We have shown that the resulting networks posses the expected spectral characteristics and specifically a dip in transmission, being a footprint of PBG. With a characteristic structural distance below 2 μm it falls in the near-infrared regime. The spectroscopic results are in good quantitative agreement with our FDTD simulations, both in terms of position of the PBG on the frequency scale as well as isotropy. 

References

[1] Opt. Ex. 21(1), 1057–1065 (2013)

[2] Phys. Rev. A 88(4) 043822-1–043822-9 (2013)

[3] Adv. Opt. Mat. 2(2), 115–119 (2014)

[4] Optica 4 (3), 361–366 (2017)