Dual comb gyroscope

系统在GPS盲区的精确导航和定位有赖于稳定、准确的陀螺仪和绝对时钟。即使在GPS信号存在的情况下，欺骗和多径检测等误差也会影响准确定位。我提出了一种新的陀螺仪系统，当与便携式时钟相结合时，将产生一个无干扰和准确的导航系统。本文的研究内容是基于光纤环形激光器内部干涉双频梳的新方法研制有源光学陀螺。这两个光梳是在同一个激光腔内产生的，具有相反的旋转感。测量基于腔内相位干涉术(IPI)，其中两个频率梳之间的光程差直接转换为两个载波频率的频率差。由于梳子是在同一个机械腔中产生的，这种差动测量对机械和声学噪声不敏感。拍子检测的分辨率超过了每个梳子的线宽几个数量级。与大多数基于亮度测量的干涉技术不同，IPI测量得益于频率测量的分辨率和动态特性。我在过去十年里为IPI技术的发展所做的努力已经获得了8项美国专利的认可。提出了一种基于频域Sagnac效应测量的双梳陀螺结构。沿激光垂直轴的旋转被转换成容易测量的无线电频率。利用超短脉冲，可以很好地定义脉冲的交叉点，以减少散射耦合，这种耦合在连续波工作的激光陀螺中表现为“死带”。我的研究重点是频率梳；锁模激光产生的具有长相干时间的稳定脉冲序列在被称为“频率梳”的频域中提供了一个明确的参考。每个齿的锐度与激光的相干时间成反比，而扩散(梳子的带宽)与梳子所能产生的最短脉冲的倒数成正比。我的建议是基于一个简单的互惠原则，即最稳定的系统可以用作超灵敏的传感器。陀螺仪的主要特点之一是比例因子，它与面积/周长成正比。因此，很多工作都集中在制造巨型干涉仪，如激光干涉仪引力波天文台(LIGO)。相反，考虑到小型化和便携性，我的重点是通过以下方式实现陀螺系统的增强：1)在“无死带”系统中工作，2)使用拍频音符的Hz线宽来应对10^(-7)rad/S的角度旋转不确定，3)仅在频域中工作，没有幅度噪声4)利用光纤平台实现轻便设备。

Accurate navigation and positioning of a system in GPS blind zones relies on a stable and accurate gyroscope and absolute clock. Even in the presence of a GPS signal spoofing and errors such as multipath detection will affect accurate positioning. I propose a novel gyroscope system that when combined with a portable clock would result in a non-disruptive and accurate navigation system. My proposed research is on the development of active optical gyroscope based on a novel method of interfering dual frequency combs inside a fiber ring laser. The two optical combs are generated inside the same laser cavity with the opposite sense of rotation. The measurement is based on Intra-cavity Phase Interferometry (IPI), in which an optical path difference between the two frequency combs is directly converted to a frequency difference of two carrier frequencies. Since the combs are generated in the same mechanical cavity, this differential measurement is insensitive to mechanical and acoustic noise. The resolution in beat detection surpasses the line width of each comb by orders of magnitude. The IPI measurement benefits from the resolution and dynamics of frequency measurement, unlike most interferometric techniques that are based on measurement of brightness. My efforts in the development of IPI technique in the past decade have been recognized in 8 US patents. I propose construction of a dual comb gyroscope based on the measurement of the Sagnac effect in frequency domain (IPI). The rotation along the perpendicular axis of the laser is converted to an easily measurable radio frequency. Using ultrashort pulses, the crossing point of the pulses can be well defined to reduce scattering coupling which manifests itself into a "deadband" in laser gyros operating with continuous waves. My research focuses on frequency combs; stable train of pulses with a long coherence time generated from a mode locked laser provides a well-defined reference in a frequency domain known as "frequency comb". The sharpness of each tooth is inversely proportional to the coherence time of the laser and the spread (bandwidth of the comb) is proportional to the inverse of shortest pulse that can be created by the comb. My proposal is based on the realization of a simple reciprocity that the most stable system can be used as an ultrasensitive sensor. One of the major characteristics of gyroscope is the scale factor, which is proportional to area/ perimeter. Hence, a lot of effort has been concentrated on making giant interferometers such as Laser Interferometer Gravitational-Wave Observatory (LIGO). Instead, keeping the miniaturization and portability in mind, my focus is on achieving enhancement in Gyro systems by 1) working in a "deadband free" system, 2) employing the Hz linewidth of the beat note to uncertainty in angular rotation of 10^(-7) rad/s, 3) working solely in frequency domain free from amplitude noise 4) utilizing the fiber platform for a light and portable device.