Optothermal control of the Raman gain enhanced ringing in microresonators

The cavity ringing phenomenon is vital in both fundamental research and applications such as in the rapid detection and transient sensing. Here we report a novel method - the combination of the optothermal scanning method and Raman gain to achieve and control the ringing effect in a silica optical microsphere. Comparing to the usual method requiring laser sweeping, this method does not require sweeping the probe laser, which makes it easier and more stable in applications. The ringing strength can be easily controlled by adjusting the frequency detuning of the probe laser and changing the scanning speed of the pump laser. In particular, our dynamic models can fit well with the experimental results. This letter shows that the optothermal control of ringing is robust to external fluctuations, which can enhance the performance and stability of the transient microcavity sensors.