Development of a high-performance 16-to-4 electro-optical encoder using photonic crystal resonant cavities

• The proposed 16-to-4 electro-optical encoder features tunability for flexible operation. • It achieves a high modulation depth of 96.4 %, ensuring strong signal modulation. • The device experiences notable crosstalk at −13.52 dB. • The entire encoder is integrated into a compact footprint of just 200 µm 2 . This paper presents a novel 16-input, 4-output electro-optical encoder utilizing tunable resonant cavities. Light transmission through a silicon waveguide is modulated by a nearby photonic crystal cavity comprising 20 air holes. These air holes form a resonant cavity, filtering out unwanted wavelengths. A graphene-aluminum oxide stack within the cavity controls the filter’s properties by adjusting the graphene’s chemical potential. This configuration creates an electro-optical switch, with seven such switches directing light from input bias ports to four output ports. The device’s area and the contrast ratio are 200 µm 2 and 10.61 dB, respectively. The modulation depth of 96.4 % and the crosstalk of −13.52 dB are additional advantages of the designed encoder. The tunability of the transmission efficiency for the designed switches as the basis block is an interesting feature of the designed encoder. Moreover, the design is scalable, allowing for expansion to larger systems, a crucial requirement for advanced optical circuits and networks.