Active Integrated Optic Devices for Sensing: Optical Rate Gyroscopes and Stellar Interferometers.

Integrated optical devices are free from the alignment and stability issues that bedevil bulk optical devices and systems. Integrated optical devices are now widely deployed in fiber optic telecommunication systems and as sensor components. This thesis is a theoretical and experimental study of two new integrated optical sensors - an integrated optic ring resonator gyroscope for measuring angular rotation rate and an integrated optic beam combiner for stellar interferometry. Although passive integrated optic ring resonators for gyroscopes have been previously reported, little work has been performed for active rings. The sensitivity of the gyroscope is limited by the propagation losses in the ring, and hence can be improved by the introduction of loss-compensating gain inside the ring. In this thesis the first active ring resonator for gyroscopic applications is designed, fabricated and characterized. A 1.6 cm diameter active ring resonator is fabricated in a neodymium-doped glass by silver ion exchange. The finesse of the ring resonator is measured and is observed to increase from approximately 11 to 250 when the neodymium ions inside the ring are optically pumped to produce gain. The ultimate sensitivity of a ring resonator gyroscope is shown from theoretical considerations to be fundamentally limited by the spontaneous emission noise generated within the gain medium. A closed form expression for this sensitivity is derived. Integrated optic beam combiners offer many advantages over conventional bulk optic implementations for astronomical imaging. To date, integrated optic beam combiners have only been demonstrated at operating wavelengths below 2 $mu$m. Operation in the mid-IR, however, is highly desirable. In this thesis an integrated optic beam combiner for stellar interferometry that operates in the mid-IR is demonstrated for the first time. The device is fabricated on a lithium niobate substrate for operation in the vicinity of 3.4 $mu$m. Using this device, white-light, mid-infrared, fringes, as well as electro-optic on-chip fringe scanning, is demonstrated in the laboratory. A theoretical design technique based on three coupled waveguides is developed to achieve fully achromatic, broadband, polarization-insensitive, lossless beam combining. This design may make it possible to achieve the very deep broadband nulls needed for exoplanet searching.Ph.D.Electrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/77701/1/hkhsiao_1.pd