Non‐Volatile All‐Optical Switch Based on GST‐Assisted Microfiber Knot Resonator

Abstract A non‐volatile all‐optical switch is demonstrated by integrating the phase change material Ge ₂ Sb ₂ Te ₅ (GST) onto a microfiber knot resonator (MKR), designed to address the growing demands for high‐performance information processing in fiber optic systems. The resonator's enhanced light‐matter interaction amplifies the spectral modulation effects resulting from refractive index changes during GST phase transitions, while the strong evanescent field of the microfiber facilitates efficient all‐optical phase‐state switching. This synergy achieves a maximum optical contrast ratio of 15 dB with an insertion loss as low as 2.5 dB. The MKR architecture provides multi‐channel operational flexibility, and demonstrates ultrafast switching with rising/falling times of 169.6/79.8 ns, enabled by GST's sub‐nanosecond crystallization kinetics under optimized pulsed laser control. Additionally, the device supports multi‐level signal encoding through partial phase change and exhibits robust cyclic stability under multi‐sequence optical pumping. This GST‐MKR hybrid platform shows exceptional switching characteristics, positioning it as a promising candidate for advancing all‐optical networks, reconfigurable photonic circuits, and neuromorphic computing architectures.