Ultra-narrow, highly efficient power splitters and waveguides that exploit the TE₀₁ Mie-resonant bandgap

Abstract

In this paper, ultra-narrow and highly-efficient straight and Ω-shaped waveguides, and Y-shaped and T-shaped optical power splitters composed of two rows of two-dimensional germanium rods in air are designed and simulated. The position-disordering effect on the waveguides is considered. Finite-difference time-domain numerical simulation results for two rows of straight and Ω-shaped waveguides with no position disordering at the normalized frequency of a λ = 0.327 show optical transmission of 90%, and two rows of Y-shaped and T-shaped power splitters with no position disordering have transmissions >46% for each output branch at the normalized frequency of a λ = 0.327 . Also, the straight and Ω-shaped waveguides with four rows of germanium rods tolerated position disordering of η = 10%. The proposed ultra-narrow waveguides and power splitters are vital components in high-density and all-dielectric optical integrated circuits.

Mie Scattering for Photonic Devices

“…For that reason, Mie-scatterers can Each waveguide line is formed by two rows of scatterers which yields theoretical splitting efficiency of 46% per arm. [124] An important feature of the proposed design is its high tolerance to the disorder of the rod arrangement. For example, a straight waveguide with no disorder that has a transmission efficiency of 90% for a case of relatively high 10% standard deviation (normalized on the spacing between the rods) only drops down in the transmission efficiency to 75%.…”

“…The rods are positioned to strongly couple between each‐other. [ 124 ] The strong coupling creates a band‐gap in the energy spectrum of the Mie‐modes that can be used to efficiently contain the light in a designed volume. Figure shows the schematics of the proposed waveguide and a Y‐splitter.…”

“…Schematic illustration of Y-splitter based on Ge-rod Miescatterers. Each waveguide line is formed by two rows of scatterers which yields theoretical splitting efficiency of 46% per arm [124]. An important feature of the proposed design is its high tolerance to the disorder of the rod arrangement.…”

Towards Perfect Ultra-Broadband Absorbers, Ultra-Narrow Waveguides, and Ultra-Small Cavities at Optical Frequencies

“…Fabrication imperfections are categorized as position and radius disorderings. By introducing x i = x i 0 + σ p U x and y i = y i 0 + σ p U y as the position of a rod, the position disordering parameter is introduced as η p = σ p a , where (x i 0 , y i 0 ) is the origin position, σp is the strength of disordering, a is the lattice constant, and U i (i : x, y) is a random variable over an interval [−1, 1] [ [36][37][38][39]. For the radius disordering, the radius of a rod is R i = R 0 i + σ r U r , where R 0 i is the origin position of the rod, σ r is the strength of the radius disordering, and U r is a random variable over the interval [−1, 1].…”

“…Reducing the size of MPHCs for subwavelength operation (corresponding to the visible and UV spectra) brings a new challenge of fabrication imperfections [2,5,7,8,13,15,35] for optical components, such as absorbers, waveguides, and cavities. The imperfections appear as position and radius disorderings that influence the functionality of the structures [13,15,[36][37][38]. As a result, designing ultra-broadband absorbers for UV and visible light, ultra-narrow and highly efficient waveguides for visible light, and ultra-small and high-quality-factor cavities for visible light that tolerate fabrication imperfections is of great importance.…”