Multi-dimensional optical computing

We propose a mode-division multiplexing (MDM) approach for small-scale optical matrix multiplication and a multi-dimensional architecture for large-scale applications, supplementing wavelength-division multiplexing (WDM) with MDM to increase channel capacity for computations. We design and experimentally demonstrate key components for the MDM computing system, i.e., a multimode beam splitter, a micro-ring modulator for high-order modes, and a multimode waveguide bend. We further show a 2-by-2 matrix multiplexing system fabricated in a foundry that works for both MDM and MDM-WDM computing, which confirms that our approach successfully increases the input vector size for computing and ensures compatibility with existing WDM networks.