Frequency-Equalized Electro-Optic (EO) Phase Modulators for High-Precision Interferometric Inertial Sensors

SRICO proposes to develop electro-Optic (EO) phase modulators with stable and flat frequency response, low switching voltage-length product, and multi-decade environmental lifetime for use in strategic-grade high-precision inertial sensor systems. The electro-optic modulator lies at the heart of interferometric fiber-optic gyroscopes (IFOG) and accelerometer sensor systems and ultimately determines system precision and stability. Integrated optic lithium niobate modulators based on annealed proton exchange (APE) are typically used in these systems. However, APE waveguides suffer from temperature and time dependent frequency response because they are produced through a relatively low temperature ion exchange process. Higher temperature Ti-diffused processes yield relatively stable waveguides, but suffer from non-flat frequency response and photorefractive effects. Thus, there remains a need for electro-optic modulators with flat and stable frequency response over the decades of life span of the sensor system. To meet this need, this proposal develops advanced waveguide technologies that emulates the material properties of APE waveguides but that exhibits the long term stability of the high temperature Ti-diffusion process. Successful completion of this effort will have confirmed the favorable properties of the proposed waveguide optical phase modulator technology for use in precision inertial sensor application.