Mode Divisionㅁ Multiplexing Silicon Photonics for High Channel Capacity On-chip Optical Interconnect

Abstract

Mode-division multiplexing (MDM) is being considered as a promising technique to further enhance the capacity of optical transmission systems. MDM appears particularly attractive for future networks-on-chip interconnect. This thesis explores devices on silicon photonic chips for the use of MDM, especially for reconfigurable optical add-drop multiplexer (ROADM) to solve the problem of highly dense networks. The use of silicon photonics can make such devices compact, reliable, cost saving and capable of being integrated with other silicon photonic devices. Silicon photonic components which were utilized in mode division multiplexing system for high channel capacity optical interconnect were designed, simulated, fabricated and experimentally demonstrated. Propagation losses for three types of waveguides (strip waveguide, 110 nm-etched rib waveguide, and 60 nm-etched rib waveguide) with different widths or multimode propagation were experimentally demonstrated. Silicon photonic 3-dB power splitter with enhanced coupling of shallow-etched rib waveguides was reported. This device was designed to have low excess loss and broad operating wavelength range. Three-mode dual-core adiabatic (de)multiplexers were also experimentally measured. Silicon photonic mode-division reconfigurable optical add/drop multiplexers with mode-selective integrated MEMS switches was reported as well. The ROADM was designed based on effective index analysis and mode overlap calculation method. With this ROADM device, data carried by any mode-channels can be rerouted or switched at an MDM network node, i.e., any mode could be added/dropped to/from the multimode bus waveguide flexibly and selectively.