This project aims to develop a compact, highly innovative Inertial Reference/Measurement Unit (IRU/IMU) that pushes the state-of-the-art in high accuracy performance from a FOG with drastically reduced optical and electronic package volumes. The proposed gyroscope is based on an innovative approach using Photonic Crystal Fiber (PCF) coils that reduces the major gyro error sources and enables a radiation hard sensor in smaller volume compared to state-of-the-art. Phase 1 addressed the feasibility of the PCF FOG concept, demonstration of critical components, performance/size tradeoffs, and preliminary designs of FOG-based IRU and IMU, leading to a prototype gyro to be designed and built in Phase 2. In particular, Phase 1 involved a comprehensive study of available state-of-the-art PCF and associated components. Based on this, three different PCFs were obtained and extensively tested for suitability in small gyro applications emphasizing tight bending diameters and temperature tests. The tests demonstrated that the technology is sufficiently developed to enable implementation of advanced PCF-based FOGs in the near future. Phase 2 will (1) implement selected PCF for the gyro application, develop and evaluate components including the PCF coil, modulator and polarizers, and develop the required support infrastructure and tooling, (2) perform performance modeling and trade-offs followed by a complete PCF gyro design, (3) evaluate low-power solutions for the light source and electronics and preliminary valuation of unique electronic miniaturization designs, (4) deliver a tested and validated gyro sensor and electronics, and (5) design a compact open-loop PCF FOG-based 3-axis IRU system. The Phase 2 strategy includes a development and integration plan, potential demonstration opportunities, program schedule, transition activities, and estimated costs. Our Phase 2 base work plan is designed to advance the TRL to 5, with TRL 6 being obtained in a Phase 2-X program.