光声晶体微腔是一种同时具有光子和声子带隙局域效应的腔光机系统，基于光声晶体微腔的传感具有灵敏度高、抗干扰能力强、响应速度快、微型化、易于片上集成等显著特点，有望为下一代传感技术的研究带来突破。本论文工作对具有高机械振动频率和超小等效动质量的分离纳米臂光声晶体微腔进行了深入的理论和实验研究。 在深入研究光声晶体微腔理论的基础上，建立了光子和声子相互耦合的理论分析模型，提出了一种在传统纳米臂微腔中开槽后形成的分离臂结构，由于该结构仍是完整的光学微腔，而机械振动则分别存在于分离的两条纳米臂上，通过合理的设计，可以确保机械振动模式仍被强烈的局域在光学微腔中心，实现光波模式和机械振动模式的能量相互耦合。 研究了分离纳米臂光声晶体微腔的光学特性、机械特性、光声耦合特性以及质量传感特性，结果表明：在1550nm附近的谐振波长处，分离纳米臂光声晶体微腔的Q值可以达到1.2×105；机械振动频率大于10GHz，等效动质量小于10fg；分离纳米臂光声晶体微腔中的光子和声子的相互耦合主要由移动边界效应产生，光声耦合系数最大可达332.8kHz，光声耦合率最大可达104.4GHz/nm；质量传感的灵敏度达到22.8MHz/fg，分辨率为0.44ag，设计了片上质量传感的实验测试方案。 建立了垂直耦合型芯片的通光测试系统，完成了基于氢氧焰高温加热拉伸法拉制垂直耦合型锥形光纤的实验流程和系统的设计，对锥形光纤拉制过程中功率的变化情况进行了理论分析，摸索出了可重复性好﹑成品率高的锥形光纤拉制工艺。拉制出的锥形光纤的透射率为86%，锥形光纤功率谱的上下抖动幅度不超过2dB，为芯片的垂直耦合测试打下了坚实的基础。 制备了垂直耦合型和端面耦合型分离纳米臂光声晶体微腔芯片，前者的制备工艺流程简单，芯片上形成的“空气桥”结构不易断裂，通过对端面耦合型芯片的制备工艺流程进行改进，提高了制备成功率；实现了垂直耦合型芯片通光谱测试，实验测得与仿真结果较吻合的微腔的固有光学品质因子Qv=3600；设计了芯片声子谱和端面耦合型芯片通光谱的测试方案，完成了相关测试系统的搭建。
Optomechanical crystal cavity is a use of bandgap to confine photon and phonon optomechanical system. Sensor based on optomechanical crystal cavity have high sensitivity, anti-interference ability, fast response, miniaturization, easy to integrated on-chip, is expected to bring a breakthrough to the next generation sensor technology. This work focus on high mechanical frequency and small effective motion mass split-nanobeam optomechanical crystal cavity is studied in theoretical and experimental. Depth study of the optomechanical crystal cavity theory and the model of photon and phonon coupling, the whole split-nanobeam structure as an optical cavity and mechanical vibration on two isolated nanobeam, appropriate design can make sure the mechanical mode is strong in the center of the cavity and couple with optical mode. Study on the split-nanobeam optomechanical crystal cavity’s optical, mechanical, coupling, and sensing characteristics. Near 1550nm, optical quality factor reach to 1.2×105, mechanical frequency higher than 10GHz, effective motion mass smaller than 10fg, moving boundary effect leads to the mutual coupling, coupling coefficient and rate reach to 332.8kHz and 104.4GHz/nm; sensing sensitivity is 22.8MHz/fg, resolution is 0.44ag, designed the experiment diagram of on-chip mass sensing. Established the vertical coupling chip’s test system, designed the hydrogen flame heating and stretching taper fiber system, analysis the taper fiber’s power change in stretching process, ultimately the transmission of taper fiber reached to 86% and power spectrum fluctuation not exceed 2dB, the stretching conditions very robust, paved the way for vertical coupling experiment. Fabricated the vertical and face coupling chip, vertical coupling chip’s process is simple and the "air bridge" structure on chip hard to break, improved the face coupling chip’s process, experimentally measured a vertical coupling chip’s optical intrinsic optical quality factor reach to 3600, agree well with the simulation results; designed phonon spectrum and face coupling test diagram, set up the test systems.
