Isotopic Quantum Non-Degeneracy based Superluminal Laser Gyroscopes and Accelerometers for GPS Denied Navigation

For navigation under GPS denied conditions, there is a need for better inertial sensors.  Over the last few years, with support from NASA, MDA, DARPA and AFOSR, and different branches of AFRL, namely AFRL/RVSVC and AFRL/RWWG, and in collaboration with Honeywell, we at Digital Optics Technologies (DOT), in partnership with Northwestern University (NU), have been developing a superluminal laser accelerometer and gyroscope (SLAG) that can improve the accuracy of rotation sensing and accelerometry by as much as six orders of magnitude.  Alternatively, for a given level of sensitivity, the SLAG can be very small.  The process that makes the SLAG so sensitive is critically tuned anomalous dispersion, corresponding to group velocity of light far exceeding the vacuum speed of light.  This is the so-called fast-light effect. This dispersion is produced by introducing a narrow dip in the gain profile.  This is made possible by using a combination of Raman gain in one isotope of Rb, and Raman depletion in another isotope of Rb, via careful juxtaposition of non-degenerate quantum transitions in these isotopes.  Previously, we had built a compact SLAG;  however, it was not optimized enough to achieve quantum noise limited sensitivity.  During the initial four months of Phase I, we improved the stability of the SLAG by employing a vacuum enclosed, magnetically shielded cavity mounted on an Invar base.  We have also developed improved servos,  achieving temperature stability of ~0.05 deg C for the gain cells, limited by measurement accuracy, and frequency stability of ~15 kHz for the pump lasers, exceeding the stated goal of 50 kHz.  We have also developed a comprehensive numerical code for modeling accurately the behavior of the SLAG, which takes into account all Zeeman sublevels, and can be used to determine how the behavior of the SLAG varies as functions of temperature, residual magnetic field, and power and frequency of pump lasers.   By the end of Phase I, we expect to demonstrate, using this highly stable SLAG, an enhancement in sensitivity by a factor of ~one hundred thousand, under quantum noise limited conditions, thus establishing the feasibility of using three SLAGs to realize a three-axes superluminal inertial measurement unit (SIMU) for GPS denied navigation.  In Phase II, we will combine three SLAGs, oriented orthogonally to one another, to realize a three-axes Superluminal Inertial Measurement Unit (SIMU), within a volume of one liter (10 cm X 10 cm X 10 cm), with a sensitivity to rotation and acceleration that far exceeds, by as much as five orders of magnitude,  that of the state of the art IMUs.  Currently, AFOSR is supporting our work on developing chip-scale integrated photonic technology based components; this technology will enable further miniaturization of the SIMU.  We have two patents issued this year for the core technologies underlying the SLAG.  Prof. Selim Shahriar of NU, the inventor of the SLAG, is the PI for this project.