Integrated optics chip and method of connecting optical fiber thereto

Claim 1

A fiber optic rotation sensor, comprising: an optical signal source; a substrate formed of a chip of an optically active material; first, second and third optical waveguides formed in the substrate to guide optical signals from the optical signal source along selected axes of propagation, first, second and third slots being formed in edges of the integrated optics chip to correspond to the optical waveguides such that an end wall of each slot includes an end surface of the corresponding optical waveguide, the end surfaces of the optical waveguides being formed to make selected angles with the axes of propagation of light in the optical waveguides to reduce the effects of light reflected at the end surfaces of the optical waveguides in the direction of propagation of light in the optical waveguides, the first second and third optical waveguide being connected at a junction to form a Y-coupler such that optical signals input to the integrated optics chip at the first optical waveguide propagate to the Y-coupler and divide between the first and second optical waveguides and optical signals input to the integrated optics chip at the second and third optical waveguides combine at the Y-coupler and interfere with one another, the second and third optical waveguides having different optical path lengths from the junction to their respective end surfaces to reduce polarization cross coupling; a first optical fiber mounted in the first slot to guide light from the optical signal source to the first optical waveguide; an optical fiber sensing coil having its ends mounted in the second and third slots, the optical fibers being butt-coupled to the end surfaces of the optical waveguides to form interfaces where light may propagate between the optical waveguide and the optical fiber, the angles of the end of the optical waveguides being formed such that a portion of the light reflected at the interfaces back into the optical fibers refracts into the cladding; means for controlling the polarization of light guided by the optical waveguides; means for modulating the phase of light guided by the optical waveguides; means for detecting the interference pattern of light waves that combine in the Y-coupler; and signal processing means for determining the rotation rate of the optical fiber sensing coil.