Synthetic dimension band structures on a Si CMOS photonic platform

Abstract

Synthetic dimensions, which simulate spatial coordinates using nonspatial degrees of freedom, are drawing interest in topological science and other fields for modeling higher-dimensional phenomena on simple structures. We present the first realization of a synthetic frequency dimension on a silicon ring resonator integrated photonic device fabricated using a CMOS process. We confirm that its coupled modes correspond to a one-dimensional tight-binding model through acquisition of up to 280-GHz bandwidth optical frequency comb-like spectra and by measuring synthetic band structures. Furthermore, we realized two types of gauge potentials along the frequency dimension and probed their effects through the associated band structures. An electric field analog was produced via modulation detuning, whereas effective magnetic fields were induced using synchronized nearest- and second nearest–neighbor couplings. Creation of coupled mode lattices and two effective forces on a monolithic Si CMOS device represents a key step toward wider adoption of topological principles.

Nonlinear Topological Photonic Insulator in Synthetic Space

“…Possible experiments can also be considered in on‐chip platforms. [ 45,46 ] Our work could lead to potential implications in optical signal processing, and bring further attention to exploring exotic nonlinear phenomena in the synthetic space. [ 32,47,48 ]…”

Mirror-induced reflection in the frequency domain

“…Frequency synthetic dimensions in photonics has recently been experimentally investigated, including the measurement of band structure [14] and density of states of frequency crystals up to four dimensions [18], realization of two synthetic dimensions in one cavity [7], dynamical band structure measurement [15], topological windings [8] and braiding [28] in non-Hermitian bands, spectral long-range coupling [19], high-dimensional frequency conversion [21], frequency diffraction [16], and Bloch oscillations [17,29,30]. With a few exceptions [18,31], investigations of synthetic frequency dimensions on photonic chip have not been extensively studied.…”

Observation of flat-band and band transition in the synthetic space

“…22,23 The modulation applied by external voltages provides the unique advantages of breaking the constraint of fixed geometric structures after fabrication and thus provides an important possibility of achieving complicated functionalities with great experimental flexibility and reconfigurability. 4 Experimental implementations have been performed in ring resonator systems including fiber loops or on-chip microrings, [24][25][26][28][29][30][31] and physical phenomena including band structures measurements, 24,26 spectral Bloch oscillations, 29 and non-Hermitian topology 30,32 have been shown, where one ring or two identical rings have been used. On the other hand, theoretical proposals have been explored where formations of photonic lattice with different lengths of rings can enable intriguing studies of rich physics, such as the Haldane model, 7 topological quench dynamics, 33 two-dimensional Lieb lattice, 34 three-dimensional topological insulator, 35 and high-order topologies.…”