On-chip nanophotonic topological rainbow

Abstract

The era of Big Data requires nanophotonic chips to have large information processing capacity. Multiple frequency on-chip nanophotonic devices are highly desirable for density integration, but such devices are more susceptible to structural imperfection because of their nano-scale. Topological photonics provides a robust platform for next-generation nanophotonic chips. Here we give an experimental report of an on-chip nanophotonic topological rainbow realized by employing a translational deformation freedom as a synthetic dimension. The topological rainbow can separate, slow, and trap topological photonic states of different frequencies into different positions. A homemade scattering scanning near-field optical microscope with high resolution is introduced to directly measure the topological rainbow effect of the silicon-based photonic chip. The topological rainbow based on synthetic dimension have no restrictions for optical lattice types, symmetries, materials, wavelength band, and is easy for on-chip integration. This work builds a bridge between silicon chip technologies and topological photonics.

Scalability of Large-Scale Photonic Integrated Circuits

“…The propagation of light at the topological edges establishes a highly robust path for information processing in PICs. The light in the integrated topological devices can be transmitted across the defects induced by fabrication errors and the sharp turns. , Based on the topologically protected edges, various compact functional topological devices have been demonstrated, such as topological light waveguides, , topological rainbow, topological optical interconnects, and topological routers. , Furthermore, researchers have designed various optical switches by using tunable topological photonic crystals (TPCs) with high phase-tuning efficiency or high- Q resonance. Figure shows a scanning electron microscopy (SEM) image of fabricated TPC-based optical switch; the experimental results show that the π-phase-shift power of the topological waveguide based on valley photonic crystals (VPCs) is 1.57 times lower than that of the conventional waveguide .…”

Geometric anisotropy induced higher-order topological insulators in nonsymmorphic photonic crystals

“…Let us first consider PC (m) δ,η . Notice that the displacement parameter η is periodic and can be regarded as a synthetic dimension [36][37][38]. Combined with the Bloch wave vector (k x , k y ), three-dimensional parameter space (k x , k y , η) is formed.…”

On-Chip Topological Multichannel Filtering and Routing Device Based on Synthetic Dimension

“…In the design of on-chip topological nanophotonic devices, frequency, as a basic degree of freedom of light, plays an important role as information carrier. Recently, there have been some typical frequency related topological photonic devices, such as topological filters [3,4], topological rainbow devices [5][6][7][8], and topological routers [9]. Among these devices, the topological nanophotonic filter is a frequency-selective device that allows multiple specific frequencies of incident light to pass while filtering out other frequencies.…”

“…The topological edge states can be regulated by adjusting the synthesis dimension so that the device can have various functions on the premise of simple structure. The topological photonic states based synthetic dimension provides effective method for the construction of on-chip nanophotonic topological devices [7].…”