Inverse-designed monolithic photonic logic gates: multifunctionality and combinational circuit simplification.

Area of Science:

• Photonics
• Integrated Optics
• Computer Engineering

Background:

• Photonic computing offers high-speed, low-power advantages over electronic computing.
• Existing photonic logic devices suffer from low integration density and redundant structures.
• Overcoming these limitations is crucial for advancing photonic computing.

Purpose of the Study:

• To realize multifunctional monolithic photonic logic gates using a structure-function co-optimization approach.
• To enhance on-chip functional density and reduce the spatial footprint of optical logic gates.
• To establish a scalable design paradigm for highly integrated digital photonic computing chips.

Main Methods:

• Integration of an inverse design framework with coherent light superposition.
• Structure-function co-optimization on a silicon-on-insulator (SOI) platform.
• Demonstration of complementary logic functions (NOT/BUF, AND/NAND, OR/NOR) and high-order combinational logic (half-adders, 2-to-4 decoders).

Main Results:

• Synchronous integration of complementary logic functions within a single device, achieving a 200% increase in on-chip functional density.
• Direct implementation of high-order optical combinational logic (half-adders, 2-to-4 decoders) in a monolithic structure.
• Successful realization of optical XOR and XNOR gates via two-level cascading.

Conclusions:

• The developed approach enables the creation of highly integrated photonic logic devices.
• This work overcomes critical challenges in integration density and redundancy for photonic computing.
• A scalable design paradigm for advanced digital photonic computing chips has been established.