Key Multimode Silicon Photonic Devices Inspired by Geometrical Optics

Abstract

On-chip optical interconnect has been widely accepted as a promising technology to realize future large-scale multiprocessors. Mode-division multiplexing (MDM) provides a new degree of freedom for optical interconnects to dramatically increase the link capacity. For present on-chip multimode devices, although large amounts of computation and optimization are adopted to support more modes, mode-independent manipulation is still hard to be achieved due to severe mode dispersion. Here, we propose a promising solution to standardize the design of fundamental multimode building blocks, inspired by the geometrical-optics concept, adopting a waveguide width larger than the working wavelength. The proposed solution can tackle a group of modes at the same time with very simple processes, avoiding a demultiplexing procedure and ensuring compact footprint. Compared to the conventional schemes, it is scalable to larger mode channels without increasing the complexity and whole footprint. As a proof of concept, we demonstrate a set of multimode building blocks, including crossing, bend, coupler, and switches, with low loss and power consumption. Our work promotes the multimode photonics research and makes the MDM technique more practical.

On-Chip Reconfigurable and Ultracompact Silicon Waveguide Mode Converters Based on Nonvolatile Optical Phase Change Materials

“…Finally, with the features of short conversion length (2.3 μm), high conversion performance (CE > 97%, CT < −20 dB, IL~0.2 dB), reconfigurable mode conversion, and functional extensibility, we believe the proposed reconfigurable silicon waveguide mode conversion scheme and related devices could find important applications in on-chip multimode photonics and be one of the fundamental building blocks for the reconfigurable multimode PICs [ 13 , 14 ].…”

“…In comparison, MDM is best suited for the on-chip multiplexing transmission since higher-order modes could provide new multiplexing channels for the on-chip MDM transmission and reveal unique features compared with commonly used fundamental modes [ 12 ]. Multimode photonics is an emerging research field in silicon photonics, and higher-order mode generators or converters represent one of the fundamental components to generate the higher-order mode sources for on-chip multimode applications [ 13 , 14 ].…”

Ultra‐Broadband Multimode Waveguide Crossing via Subwavelength Transmitarray with Bound State

“…Wavelength division multiplexing (WDM) or mode division multiplexing (MDM) has been extensively exploited to transmit or process huge amounts of data in parallel. [1][2][3][4][5][6][7][8] As such, it has been the subject of interest to develop broadband [9][10][11][12][13][14][15] and multimode [16][17][18][19][20] functional elements, which can support a large number of wavelength or mode channels.…”

Scalable and Low Crosstalk Silicon Mode Exchanger for Mode Division Multiplexing System Enabled by Inverse Design

“…The silicon-on-insulator (SOI) has been regarded as an optimum platform for MDM photonic devices due to the large high index contrast between the silicon and the surrounding silicon dioxide. Several key components are proposed and demonstrated for realizing an on-chip MDM system on SOI, such as mode (de)multiplexers [4], [5], multimode waveguide bends [6]- [11], multimode waveguide crossings [12]- [14], multimode 3 dB splitters [15]- [19], higher order mode pass filters [20], multimode switches [21]- [25], and mode exchangers (ME) [26], [27]. Among these, ME enables exchanging data between different mode channels for an MDM link, similar to the wavelength conversion in WDM systems and polarization rotation in PDM systems.…”