Switchable silica waveguide XOR/XNOR directed logic gate based on E₂₁-E₁₁ mode conversion

Optical directed logic gates are in high demand for artificial intelligence, and optical and quantum computing applications. A silica waveguide XOR/XNOR optical logic gate based on cascaded Mach-Zehnder thermo-optic switches and multimode interference E₂₁-E₁₁ mode converter is demonstrated. When monochromatic light is input into the device, a complementary XOR/XNOR functional output in the form of light can be obtained by controlling the electrical Boolean inputs. The proposed design is fabricated on the CMOS compatible silica planar lightwave circuit platform. The experimental results proved that the signal-to-noise ratio was greater than 10 dB over the entire C band. The proposed device with simple structure, large bandwidth, and versatility would be a promising candidate for information processing in optical wavelength division multiplexing and mode division multiplexing networks. It has good potential in arithmetic operations, parity checks, encryption, and decryption.