Multi-Functional All-Optical Reconfigurable Modulator Based on Ge₂Sb₂Te₅-Assisted Microfiber Knot

This study presents a reconfigurable all-optical modulator architecture through the synergistic integration of phase-change materials (PCMs) and a microfiber knot resonator (MKR). Nonvolatile modulation of optical intensity and wavelength is achieved through optical pulse regulation of the phase transition in Ge<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>Sb<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>Te<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> (GST), with experimental results demonstrating five-stable-level reconfigurability over extended periods. Notably, the significant refractive index contrast in GST enables the device to achieve an optical intensity contrast of 16 dB and a wavelength tuning range of 120 pm. The modulator exhibits multi-functional modes by reconfiguring different port schemes: a triode-like intensity modulation mode supporting 5 distinct transmission levels and a filter mode demonstrating bandwidth tunability from 53 pm to 119 pm (6.69 GHz to 15.02 GHz). The all-optical, nonvolatile control mechanism provides nanosecond-scale switching speeds with low power consumption, outperforming conventional electro-optic modulators in operational speed and energy consumption. These features collectively suggest the proposed modulator's promising applications in photonic integrated systems for dynamic signal transmission, storage, and processing. It demonstrates application potential as a multifunctional modulation unit, particularly in integrated optical interconnects, reconfigurable computing architectures, and programmable photonic circuits.