Guided Mid‐IR and Near‐IR Light within a Hybrid Hyperbolic‐Material/Silicon Waveguide Heterostructure

Abstract

Silicon waveguides have enabled large‐scale manipulation and processing of near‐infrared optical signals on chip. Yet, expanding the bandwidth of guided waves to other frequencies will further increase the functionality of silicon as a photonics platform. Frequency multiplexing by integrating additional architectures is one approach to the problem, but this is challenging to design and integrate within the existing form factor due to scaling with the free‐space wavelength. This paper demonstrates that a hexagonal boron nitride (hBN)/silicon hybrid waveguide can simultaneously enable dual‐band operation at both mid‐infrared (6.5–7.0 µm) and telecom (1.55 µm) frequencies, respectively. The device is realized via the lithography‐free transfer of hBN onto a silicon waveguide, maintaining near‐infrared operation. In addition, mid‐infrared waveguiding of the hyperbolic phonon polaritons (HPhPs) supported in hBN is induced by the index contrast between the silicon waveguide and the surrounding air underneath the hBN, thereby eliminating the need for deleterious etching of the hyperbolic medium. The behavior of HPhP waveguiding in both straight and curved trajectories is validated within an analytical waveguide theoretical framework. This exemplifies a generalizable approach based on integrating hyperbolic media with silicon photonics for realizing frequency multiplexing in on‐chip photonic systems.

Near-Field Excited Archimedean-like Tiling Patterns in Phonon-Polaritonic Crystals

“…They also chose dimensions for the periodic crystals that resulted in the domination of dipolar-like Bloch modes, as the dimensions of their periodic structures were comparable to the wavelengths of PhP waves in their presented bands . In addition to etching and patterning hBN flakes, the control of PhP propagations in continuous hBN has been realized by placing them onto substrates consisting of different dielectric environments. − However, a direct imaging of the near-field intensity patterns from the interaction of hBN with periodic dielectric structures remains largely unexplored.…”

Hyperbolic metamaterials: fusing artificial structures to natural 2D materials

“…Firstly, beyond the routes mentioned above, other methods to achieve natural hyperbolicity exist, including photoexcitation of electron-hole pairs in layered transition-metal dichalcogenides for broadband anisotropy [220], and materials with reduced symmetry [221,222], to name just a few. Secondly, since the hyperbolic responses in natural materials have lower loss and promise much larger momentum (meaning higher field confinement), tremendous nanotechnologies are thus possible, such as imaging [31,92,223], hyperlensing [67], biosensing [224,225], waveguide [226], on-chip electro-optic modulator [227], and many others [54,132,228]. Thirdly, we remark that those hyperbolic responses can exist in beyond 2D materials, while the bulk media can also hold the hyperbolicity.…”

Ultrahigh-Resolution, Label-Free Hyperlens Imaging in the Mid-IR

“…While is related to either the polarizability of the launcher (nickle disk here) 23 or the momentum difference between hBN/launcher and suspended hBN 24,25 . As such, the launching efficiency either maintains a constant or slowly decreases with increasing frequnency (SI, section VIII).…”

“…′′ , an analytical model 3,[25][26][27] is employed to calculate both the real and imaginary part of the HPhP wavevectors propagating in hBN over any material:…”