Optical tunable differentiator based on microring resonator assisted by low-loss superlattice phase change material

This paper presents a novel microring resonator (MRR)-based all-optical tunable temporal differentiator. By modulating the crystallinity of the ZnS-SiO₂/Ge₂Sb₂Te₅ (GST-SL) phase change material (PCM), the coupling regime of the MRR can be precisely adjusted, achieving a differentiation order (α) range of 0.7–1.3. Experimental validation with non-return-to-zero (NRZ) and return-to-zero (RZ) signal types demonstrates a strong alignment with theoretical models, maintaining an error margin below 7.3%, which confirms the device’s high adjustability and stability. The proposed tuning mechanism enables low-energy, high-speed optical control of MRR states, contributing to optimized chip area and power consumption. Supported by the unique characteristics of the superlattice structure, this all-optical tunable differentiator offers promising potential for large-scale AI-driven photonic integrated circuits, particularly in applications such as optical analog computing, optical image processing, and optical neural networks.