SBIR-STTR Award

Development of a Precision Fiber Optic Gyro (PFOG) is proposed. The precision in the proposed PFOG is obtained by basic design and physical construction. It is a closed loop gyro where instead of measuring the Sagnac phase shift, we drive it zero continuously, thus, this driving effort becomes the measure of the angular rate. It is made up of fiber spool and a single chip hybrid. This eliminates many interfaces, and puts all the key components together, thus, reducing the errors introduced thermal gradients across the gyro. It also makes the gyro easy to assemble (only two guided splicing) and rugged in construction. The single chip hybrid consists of a LiNbO3 and silicon substrate bonded together via a strain relieved interface. Optical paths and components are micro machined in substrates using surface diffusion and bulk micromachining. Detailed design, analysis of a potential PFOG including some hardware experiments will be performed in Phase I to demonstrate the feasibility of the gyro. The device has many defense and commercial applications. It can be used in the emerging munitions systems to sense the high rates and to improve their guidance and control.

Keywords:
Angular Rate Sensors, Fiber Optic Gyro, Inertial Sensors, Navigation Systems, Integrated Sensors

The objective of the program is to develop a Precision Fiber Optic Gyro (PFOG) for the navigational grade inertial measurement units (IMUs) for use in the modern Position Navigation Time (PNT) applications. In Phase I of the program, a conceptual design of the PFOG was developed and its feasibility affirmed. The PFOG under development is a closed loop gyro. The key feature of the design is a functionally isolated multi-integrated optics chip (MIOC) mounted on a silicon substrate providing the electronics. The design incorporates a high degree of operational symmetry -- in optical, mechanical and electronic areas. The gyro operation at the highest point of sensitivity is ensured via a differential bias phase modulator (DBPM). For the closed-loop operation, a digitally synthesized phase ramp generator nulls the rotation rate induced Sagnac phase shift via a differential Sagnac phase modulator (DSPM). Six different methods of phase modulation for DBPM and DSPM were analyzed and the optimal one was selected for first fab iteration of the MIOC. The selected design yields four MIOC devices per 76mm LiNbO3 wafer. In Phase II, the PFOG prototype will be built to size using component design finalized during Phase I analysis and trade-off studies. It will be made up of a fiber spool and an electro-optics hybrid package. The hybrid package will consist of a LiNbO3 MIOC and a silicon substrate. Upon completing the development, a PFOG prototype unit will be built, tested, and delivered to AFRL at WPAFB for further evaluation.

Keywords:
Gyro, Fog, Ioc, Navigation, Optical Instrument