We investigate the design, fabrication, and experimental characterization of high quality factor photonic crystal nanobeam cavities, with theoretical quality factors of 1.4 x 107 in silicon, operating at ∼ 1550 nm. By detecting the cross-polarized resonantly scattered light from a normally incident laser beam, we measure a quality factor of nearly 7.5 x 105. We show on-chip integration of the cavities using waveguides and an inverse taper geometry based mode size converters, and also demonstrate tuning of the optical resonance using thermo-optic effect.;We also study coupled cavities and show that the single nanobeam cavity modes are coupled into even and odd superposition modes. Using electrostatic force and taking advantage of the highly dispersive nature of the even mode to the nanobeam separation, we demonstrate dynamically reconfigurable optical filters tunable continuously and reversibly over a 9.5 nm wavelength range. The electrostatic force, obtained by applying bias voltages directly to the nanobeams, is used to control the spacing between the nanobeams, which in turn results in tuning of the cavity resonance. The observed tuning trends were confirmed through simulations that modeled the electrostatic actuation as well as the optical resonances in our reconfigurable geometries.;Finally we demonstrate reconfiguration of coupled cavities by using optical gradient force induced mechanical actuation. Propagating waveguide modes that exist over wide wavelength range are used to actuate the structures and in that way control the resonance of a localized cavity mode. Using this all-optical approach, more than 18 linewidths of tuning range is demonstrated. Using an on-chip temperature self-referencing method that we developed, we determined that 20% of the total tuning was due to optomechanical reconfiguration and the rest due to thermo-optic effects. By operating the device at frequencies higher than the thermal cut-off, we show high speed operation dominated by just optomechanical effects. Independent control of mechanical and optical resonances of our structures, by means of optical stiffening, is also demonstrated.
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机译：我们研究了高品质因数光子晶体纳米束腔的设计，制造和实验特性，理论品质因数在硅中为1.4 x 107，工作于〜1550 nm。通过检测来自垂直入射激光束的交叉偏振共振散射光，我们可以测量到接近7.5 x 105的品质因数。我们展示了使用波导和基于逆锥度几何的模式尺寸转换器对腔的片上集成，以及我们还研究了耦合腔，并表明单纳米束腔模式耦合为偶数和奇数叠加模式。利用静电力并利用偶数模式的高度分散性来进行纳米束分离，我们展示了可动态重新配置的滤光片，可在9.5 nm波长范围内连续且可逆地调谐。通过将偏置电压直接施加到纳米束而获得的静电力用于控制纳米束之间的间距，进而导致谐振腔的调谐。通过对静电驱动以及我们可重构几何结构中的光学共振进行建模的仿真，可以确认观察到的调谐趋势。最后，我们通过使用光学梯度力诱导的机械驱动来演示耦合腔的重构。存在于较宽波长范围内的传播波导模式用于致动结构，并以此方式控制局部腔模式的共振。使用这种全光学方法，演示了超过18个线宽的调谐范围。使用我们开发的片上温度自参考方法，我们确定总调谐的20％是由于光机械重构，其余是由于热光效应。通过以高于热熔关断的频率操作设备，我们显示出高速操作仅受光机械效应支配。还展示了通过光学加固来独立控制我们的结构的机械共振和光学共振。
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