Optical microcavities have become an attractive platform for precision measurement with merits of ultrahigh sensitivity, miniature footprint and fast response. Despite the achievements of ultrasensitive detection, optical microcavities still face significant challenges in the measurement of biochemical and physical processes with complex dynamics, especially when multiple effects are present. Here we demonstrate operando monitoring of the transition dynamics of a phase-change material via a self-referencing optofluidic microcavity. We use a pair of cavity modes to precisely decouple the refractive index and temperature information of the analyte during the phase-transition process. Through real-time measurements, we reveal the detailed hysteresis behaviors of refractive index during the irreversible phase transitions between hydrophilic and hydrophobic states. We further extract the phase-transition threshold by analyzing the steady-state refractive index change at various power levels. Our technology could be further extended to other materials and provide great opportunities for exploring on-demand dynamic biochemical processes.

光学微腔已成为精密测量的一个有吸引力的平台，具有超高灵敏度、微型足迹和快速响应的优点。尽管在超灵敏检测方面取得了成就，但光学微腔在具有复杂动力学的生化和物理过程的测量中仍然面临着重大挑战，尤其是在存在多种效应时。在这里，我们展示了通过自参考光流控微腔对相变材料的转变动力学进行操作监测。我们使用一对腔模式在相变过程中精确地解耦分析物的折射率和温度信息。通过实时测量，我们揭示了在亲水和疏水状态之间的不可逆相变期间折射率的详细滞后行为。我们通过分析不同功率水平下的稳态折射率变化来进一步提取相变阈值。我们的技术可以进一步扩展到其他材料，并为探索按需动态生化过程提供了很好的机会。