Utilizing Inverse Design to Create Plasmonic Waveguide Devices

In modern communications networks, data is transmitted over long distances using optical fibers. At nodes in the network, the data is converted to an electrical signal to be processed, and then converted back into an optical signal to be sent over fiber optics. This process results in higher power consumption and adds to transmission time. However, by processing the data optically, we can begin to alleviate these issues and surpass systems which rely on electronics. One promising approach for this is plasmonic devices. Plasmonic waveguide devices have smaller footprints than silicon photonics for more compact photonic integrated circuits, although they suffer from typically having higher loss than silicon photonic devices. Inverse design software can be used to optimize the plasmonic device topology to maximize the device throughput, mitigating the inherent loss of plasmonics. Additionally, inverse design tools can help us make plasmonic devices with an even smaller footprint and higher efficiency than conventionally designed plasmonic devices. Recently, commercial inverse design tools have become available for popular photonic simulation software suites. Using these commercial inverse design tools with a compatible plasmonic architecture, we create compact, efficient, and manufacturable devices such as XOR gates, grating couplers, y-splitters, and waveguide crossings. We compare the inverse-designed devices to conventional devices to characterize the performance of the commercial inverse design tool.