Grant: Discovery Grants Program - Individual

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.