We present high-reflectivity mechanical resonators fabricated from AlGaAs heterostructures for use in free-space optical cavities operating in the telecom wavelength regime. The mechanical resonators are fabricated in slabs of GaAs and patterned with a photonic crystal to increase their out-of-plane reflectivity. Characterization of the mechanical modes reveals residual tensile stress in the GaAs device layer. This stress results in higher mechanical frequencies than in unstressed GaAs and can be used for strain engineering of mechanical dissipation. Simultaneously, we find that the finite waist of the incident optical beam leads to a dip in the reflectance spectrum. This feature originates from coupling to a guided resonance of the photonic crystal, an effect that must be taken into account when designing slabs of finite size. The single- and sub-$\upmu$m-spaced double-layer slabs demonstrated here can be directly fabricated on top of a distributed Bragg reflector mirror in the same material platform. Such a platform opens a route for realizing integrated multi-element cavity optomechanical devices and optomechanical microcavities on chip.

中文翻译：

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用于集成多元件光机械的 AlGaAs 异质结构中的悬浮光子晶体膜

我们提出了由 AlGaAs 异质结构制成的高反射率机械谐振器，用于在电信波长范围内工作的自由空间光腔。机械谐振器由 GaAs 板制成，并用光子晶体进行图案化，以增加其面外反射率。机械模式的表征揭示了 GaAs 器件层中的残余拉伸应力。这种应力导致比无应力 GaAs 更高的机械频率，可用于机械耗散的应变工程。同时，我们发现入射光束的有限腰导致反射光谱的下降。这个特征源于耦合到光子晶体的引导共振，在设计有限尺寸的平板时必须考虑到这一效应。这里展示的单层和亚 $\upmu$m 间隔的双层板可以直接制造在同一材料平台的分布式布拉格反射镜的顶部。这样的平台为在芯片上实现集成的多元件腔体光机器件和光机微腔开辟了道路。