Description: The fast-light effect in a cavity, produced by anomalous dispersion, has emerged as an important mechanism for enhancing the sensitivity of many devices. There are two modes of operation of such a cavity. In the active mode, the system is a superluminal ring laser (SRL) that experiences an anomalous dispersion caused by the gain medium. In the passive mode, the system is a white light cavity (WLC) that experiences an anomalous dispersion caused by an intra-cavity medium or via coupling to another cavity or another mode in the same cavity. We will investigation the development several closely related technologies based on the fast light effect: gyroscopes, accelerometers and general purpose fiber-optic sensors. For each technology, we will primarily pursue the active approach. The gyroscope will be based on using a pair of spatially overlapping SRLs realized via Raman gains, with Raman depletion used for anomalous dispersion. The accelerometer will be realized by using a similar system, but with two lasers that are spatially shifted with respect to each other. The fiber-optic sensor will be based on using a pair of Brillouin gain based SRLs, where the anomalous dispersion is produced via coupling to a cavity. In addition, for each device, we will investigate theoretically some passive techniques in order to determine relative advantages and tradeoffs between the two approaches. Specifically, for the gyroscope and the accelerometer, we will investigate the use of couple cavity based WLCs; for the fiber-optic sensor, we will investigate the use of a WLC realized by dual-peaked Brillouin gain. The particular mode of operation to be pursued for developing a practical version of each of these devices under Phase II will be established in accordance with the findings of the Phase I effort, and potential feedback and guidance received from the NASA program manager. Northwestern University, with Prof. Shahriar as the PI, will be a subcontractor.

Benefits: The gyroscopes and accelerometers developed in this program will have substantially improved sensitivity and reduced SWaP compared to conventional technology. These will find use for navigation of NASA space vehicles of all sorts, where SWaP concerns and precise navigation are critical. These technologies may also enable an array of new scientific missions, such as gravitational mapping of subsurface geologic features and gravity wave detection. An ultrasensitive gyroscope may also enable a critical test of general relativity via measurement of the gravitational frame dragging effect to an unprecedented accuracy. An ultra-sensitive fiber-optic sensor may be enable precise measurement of strain, temperature, magnetic field and other effects under conditions relevant to NASA missions.

The gyroscopes, accelerometers, and sensors developed in this program will enable improved navigation accuracy at reduced SWaP cost, much as they do in NASA space vehicles. In addition, they can be used in atmospheric and terrestrial vehicles and ordnance for positioning and navigation in GPS-denied environments, a critical need for many military applications. The improved SWaP performance of these systems would be particularly useful in UAV navigation. High-sensitivity accelerometers can also be used in improved vibration sensors, with an array of applications in seismometry and subsurface explosion detection for nuclear non-proliferation applications. Improved strain and displacement sensors would also have a wide array of applications in monitoring the structural health of buildings and infrastructure.