Integrated optic gyroscope and method of fabrication

An integrated optic gyro comprising:

• a multi-level optical coil having at least
• a top substrate, and
• a bottom substrate, the first and second substrates being bonded to each other, the top substrate having a top waveguide coil and the bottom substrate having a bottom waveguide coil, each spiral waveguide having an outer and inner port,
• means for optically coupling the top waveguide coil to the bottom waveguide coil so as to preserve the rotational sense of light launched into the top or bottom waveguide coil,
• a coupler having an input port and a first, second and third output port,
• a first optical fiber for coupling the top waveguide coil to the bottom waveguide coil, the coils being coupled to have a common rotational sense with respect to the gyro's sensitive axis,
• a second optical fiber for connecting the coupler's first output port to the top waveguide coil, and
• a third optical fiber for connecting the coupler's second output port to the bottom waveguide coil,
• a light source coupled to provide a light wave to the coupler's input port, the coupler splitting the light wave into substantially equal first and second output waves and outputting the first wave from its first output port to form a wave with a first rotational sense in the top and bottom waveguides and outputting the second wave from its second output port to form to form a wave with a second rotational sense in the bottom and top waveguides,
• a modulator means for modulating the phase of the first and second output waves forming the wave with a first rotational sense and the wave with a second rotational sense,
• a detector means coupled to receive light from the coupler's third output port and for providing a detected electrical signal.

The method of making a waveguide coil comprising the steps of:

• rotating an optical blank disk of optical material having a top and bottom surface between respective top and bottom laser beams, the laser beams being adjusted in power, and moved along a radial at a speed adapted to define opposing paths on the top and bottom surface, the waves beams focused and masked to form a guide of optical coil cores, the optical cores being joined by a continuous web region having a top and bottom surface;
• masking the top and bottom web surfaces to expose opposing optical core regions,
• doping the opposing core regions to produce a core having a higher index of refraction than that of the web regions joining the optical core regions, the web regions thereby defining the boundaries of optical core regions,
• removing the mask and
• cladding the top and bottom surfaces of the guide of optical cores with an optical material having substantially the same index of refraction as that of the web regions so as to form an optical substrate.

A method for making an integrated optic gyro comprising the steps of:

• forming a multi-level optical coil having at least a mounting plate having a top and bottom surface,
• a top substrate, and
• a bottom substrate, each substrate having a top and bottom surface, the top substrate bottom surface being bonded to the mounting plate top surface and the bottom substrate top surface being bonded to said mounting plate bottom surface,
• the top substrate having a top waveguide coil, and
• the bottom substrate having a bottom waveguide coil, the gyro having a sensitive axis substantially normal to the top substrate top surface,
• providing a coupler having an input port and a first, second and third output port,
• using a first optical fiber to couple the top waveguide coil to the bottom waveguide coil, the coils being coupled to have a common rotational sense with respect to the gyro's sensitive axis,
• using a second optical fiber to connect the coupler's first output port to the top waveguide coil, and
• using a third optical fiber to connect the coupler's second output port to the bottom waveguide coil,
• coupling a light source to provide a light wave to the coupler's first input port, the coupler splitting the light wave into substantially equal first and second output waves and outputting the first wave from its first output port to form a wave with a first rotational sense in the top and bottom waveguides and outputting the second wave from its second output port to form to form a wave with a second rotational sense in the bottom and top waveguides,
• coupling a modulator means to modulate the phase of the wave with a first rotational sense and the wave with a second rotational sense,
• coupling a detector means to receive light from the coupler's third output port and to providing a detected electrical signal.