Development of non-destructive photon detection method using radiation pressure

在这个研究项目中，我们的目标是开发一种新的光学测量方法，该方法基于一个原始的想法，即利用辐射压力可以无损地检测光子。为此，我们研究了a)一种针对单光子探测增强光子场的技术，b)一种具有超高灵敏度和低热噪声的力测量方法。利用所开发的方法，可以对单个光子进行重复观测，从而为测量光子的时空特性的多个参数提供了可能。例如，我们通过实验确定了光学微腔q值对应的增强因子。我们还估计了位置传感所需的期望位移和灵敏度等实验条件。根据这些估计，我们使用法布里-珀罗干涉仪设计了系统。此外，我们测量了在调频激光束照射下原子力显微镜金属涂层尖端的位移。我们成功地将辐射压力的振动分量从热变形中分离出来。根据这些结果，我们设计并开发了带有金属涂层尖端反射镜的法布里-珀罗干涉仪。此外，我们还研制了一种锥度光纤的制备装置，并确定了获得适合光耦合的锥度形状的最佳条件。我们使可靠地制备细（<1um）锥度成为可能。然后，我们开发了一种锥形光纤与微腔（如微球和环面）之间的耦合系统，提供了几乎达到完美状态的高效光耦合。

In this research project, we were aiming to develop a new optical measurement method based on an original idea that photons can be nondestructively detected by use of radiation pressure. For this purpose, we studied a) a technique for enhancing the photon field towards the single photon detection, b) a force measurement method with ultra high sensitivity and with low thermal noise. By using the developed method, a single photon can be observed repeatedly, so that this method will make it possible to measure multiple parameters of temporal and spatial properties of photon. For example, we experimentally determined the enhancement factor corresponding to Q-value of an optical microcavity. We also estimated the experimental conditions such as the expected displacement and sensitivity necessary for position sensing. From these estimations, we designed the system using Fabry-Perot interferometer. In addition, we measured the displacement of a metal-coated tip of an atomic force microscope that was irradiated with frequency-modulated laser beam. We have successfully detected the vibration component of radiation pressure separately from the thermal deformation. From these results, we designed and developed the Fabry-Perot interferometer with a mirror of the metal-coated tip. Furthermore, we developed an apparatus for preparing a tapered optical fiber, and determined the optimal conditions for obtaining the taper shape suitable for optical coupling. We made it possible to reliably prepare fine (<1um) taper. Then, we developed a coupling system between the tapered fiber and microcavities such as microspheres and toroids, which provided highly efficient optical coupling nearly reaching to perfect condition.