回音壁模式光学微腔，由于其极高的品质因子与较小的模式体积，能够极大增强光与物质相互作用强度，因此已被广泛用于基础物理与光子学应用的许多领域。在微腔的应用中，通常需要对微腔光场的频率精确调控。例如，在腔量子电动力学中，为了实现微腔光场可与任意波长的量子发射体共振；或在集成光子回路中，为了使不同的光子器件能够同时共振，都需要微腔光场具有整个自由光谱范围的调谐量。本项目提出通过将磁致伸缩材料与双盘光学微腔结合，来实现磁场对微腔光场的调谐。外界磁场通过磁致伸缩材料引起双盘微腔的形变，造成模式有效折射率的变化，从而引起模式的频率移动。这种磁场调谐的方式无需接触、速度快、功耗低、调谐量大，可实现双盘微腔整个自由光谱范围的调谐。此外，利用微腔光场对磁场的敏感性，还可实现磁场传感。利用双盘微腔较高的光力耦合强度和低频段机械响应，可实现对低频段磁场的高灵敏传感，从而为脑磁检测或潜艇探测等应用提供新的可能。

Due to their ultrahigh quality factors (Qs) and small mode volumes, whispering gallery mode microcavities can greatly enhance light-matter interactions, and therefore have important applications in both fundamental physics and photonic devices. In some of these applications, it requires the optical resonance frequency of the microcavity to be precisely controlled. For instance, in cavity quantum electrodynamics, to allow resonant coupling between a cavity mode with any quantum emitters, or in an integrated photonic circuit, to allow different photonic devices to be on resonance, it both requires the cavity modes to be tunable for a full free spectral range (FSR). Here we propose to integrate a magnetostrictive material with a high-Q double disk microcavity, to realize resonance frequency tuning using a magnetic field. This magnetic tuning method has the advantages of non-invasiveness, fast speed, low power consumption, and full FSR tunability. Furthermore, due to the sensitive response of the cavity mode to the external magnetic field, magnetic sensing can be realized. Due to the extremely large optomechanical coupling strength and low-frequency mechanical response, this double disk cavity allows high magnetic field sensitivity at low frequency, and therefore opens up possibilities for applying these double-disk cavity optomechanical magnetometers to the low-frequency magnetic sensing applications, such as magnetoencephalography and magnetic anomaly detection.