Dual comb gyroscope

在GPS盲区中，系统的精确导航和定位依赖于稳定准确的陀螺仪和绝对时钟。即使存在GPS信号欺骗和多路径检测等误差，也会影响准确定位。我提出了一种新颖的陀螺仪系统，当与便携式时钟相结合，将导致在一个非破坏性和准确的导航系统。 本论文的主要研究内容是基于光纤激光器双频梳干涉的主动光学陀螺的研制。这两个光梳在同一个激光腔内产生，具有相反的旋转方向。测量基于腔内相位干涉（IPI），其中两个频率梳之间的光程差被直接转换为两个载波频率的频率差。由于梳齿是在同一个机械腔中产生的，因此这种差分测量对机械噪声和声学噪声不敏感。差拍检测的分辨率超过每个梳的线宽几个数量级。IPI测量受益于频率测量的分辨率和动态，不像大多数基于亮度测量的干涉测量技术。在过去的十年里，我在IPI技术发展方面的努力得到了8项美国专利的认可。 提出了一种基于频域Sagnac效应测量的双梳状陀螺仪。沿激光器垂直轴的沿着旋转被转换成易于测量的射频。使用超短脉冲，可以很好地定义脉冲的交叉点，以减少散射耦合，散射耦合在连续波工作的激光陀螺中表现为“死区”。 我的研究重点是频率梳;从锁模激光器产生的具有长相干时间的稳定脉冲串在称为“频率梳”的频域中提供了定义明确的参考。每个齿的锐度与激光的相干时间成反比，并且扩展（梳的带宽）与可以由梳创建的最短脉冲的倒数成正比。我的提议是基于最稳定的系统可以用作超灵敏传感器的简单互易性的实现。 陀螺仪的主要特性之一是比例因子，其与面积/周长成比例。因此，大量的努力集中在制造巨大的干涉仪，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“无死区”系统中工作，2）采用拍音的Hz线宽，以10^（-7）rad/s的角旋转不确定性，3）仅在频域中工作，不受振幅噪声的影响4）利用光纤平台作为轻型便携式设备。

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.