Controlling evanescent waves using silicon photonic all-dielectric metamaterials for dense integration

Abstract

Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves. We experimentally show the reduction of cross-talk by greater than 30 times and the bending loss by greater than 3 times in densely integrated, ultra-compact photonic circuit blocks. Our prototype all-dielectric metamaterial-waveguide achieves a low propagation loss of approximately 3.7±1.0 dB/cm, comparable to those of silicon strip waveguides. Our approach marks a departure from interference-based confinement as in photonic crystals or slot waveguides, which utilize nanoscale field enhancement. Its ability to suppress evanescent waves without substantially increasing the propagation loss shall pave the way for all-dielectric metamaterial-based dense integration.

Total phase shift of terahertz wave in a rectangular waveguide with zero-refractive index metamaterial

“…The benefits to PICs can be mentioned as package density, interconnections, improved functionality and of course cost reduction [1][2][3][4][5]. It is so important to have optical dense components in the applications such as optical communication [2,4,6], imaging [2,3,7], sensing [2,4], optical signal processing [1,2,6,7], optical computers [1,6], etc. It is worth mentioning that making these devices is compatible with current planar fabrication technologies [8].…”

Ultra‐Sharp Multimode Waveguide Bends with Subwavelength Gratings

“…For example, for multi‐core SDM systems, it is important to develop dense optical waveguide arrays, as demonstrated in refs. []. For MDM systems utilizing multiple channels of guided modes, it is important to effectively manipulate the fundamental mode as well as the higher‐order modes with low excess losses and low inter‐mode crosstalks.…”

Tilted subwavelength gratings: controlling anisotropy in metamaterial nanophotonic waveguides

“…By approximating the SWG as an isotropic homogeneous material, a wide range of high-performance integrated devices has been demonstrated, including fiber-to-chip grating couplers [10][11][12][13], edge couplers [7,14,15], waveguide couplers [16,17], bragg filters [18,19], and evanescent field waveguide sensors [20,21]. Simple anisotropic models have enabled further applications of SWG waveguides, such as ultra-broadband devices [22,23], polarization management [24,25], or evanescent field confinement [26,27]. However, duty cycle changes affect both polarizations [1], and can also hamper device fabrication due to aspect ratio dependent etching and proximity effects [28].…”