Wiederhecker Gustavo S, Chen Long, Gondarenko Alexander, Lipson Michal
School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA.
Nature. 2009 Dec 3;462(7273):633-6. doi: 10.1038/nature08584. Epub 2009 Nov 15.
The use of optical forces to manipulate small objects is well known. Applications include the manipulation of living cells by optical tweezers and optical cooling in atomic physics. The miniaturization of optical systems (to the micro and nanoscale) has resulted in very compliant systems with masses of the order of nanograms, rendering them susceptible to optical forces. Optical forces have been exploited to demonstrate chaotic quivering of microcavities, optical cooling of mechanical modes, actuation of a tapered-fibre waveguide and excitation of the mechanical modes of silicon nano-beams. Despite recent progress in this field, it is challenging to manipulate the optical response of photonic structures using optical forces; this is because of the large forces that are required to induce appreciable changes in the geometry of the structure. Here we implement a resonant structure whose optical response can be efficiently statically controlled using relatively weak attractive and repulsive optical forces. We demonstrate a static mechanical deformation of up to 20 nanometres in a silicon nitride structure, using three milliwatts of continuous optical power. Because of the sensitivity of the optical response to this deformation, such optically induced static displacement introduces resonance shifts spanning 80 times the intrinsic resonance linewidth.
利用光力操纵微小物体已广为人知。其应用包括通过光镊操纵活细胞以及原子物理学中的光冷却。光学系统的小型化（至微米和纳米尺度）产生了质量在纳克量级的非常柔顺的系统，使它们易受光力影响。光力已被用于演示微腔的混沌颤动、机械模式的光冷却、锥形光纤波导的驱动以及硅纳米梁机械模式的激发。尽管该领域最近取得了进展，但利用光力操纵光子结构的光学响应仍具有挑战性；这是因为需要很大的力才能在结构几何形状上引起可观的变化。在此，我们实现了一种谐振结构，其光学响应可以使用相对较弱的吸引和排斥光力进行高效的静态控制。我们使用三毫瓦的连续光功率，在氮化硅结构中演示了高达20纳米的静态机械变形。由于光学响应对此变形的敏感性，这种光致静态位移引入了跨越固有共振线宽80倍的共振频率偏移。
