Integrated Optical Circuit for Interferometric Gyroscope
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Solution Overview
Problem
Integrated optical circuits for interferometric gyroscopes face challenges in reducing size, weight, and cost while maintaining performance due to the limitations of using monolithic lithium niobate substrates, which hinder large-scale integration of functions.
Innovation Solution
The use of multiple substrates with different materials, where a first substrate with a waveguide for polarization and a second substrate with lithium niobate or lithium tantalate for phase modulation, optically coupled and potentially with additional substrates for further integration, allows for improved functionality and reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monolithic lithium niobate substrates are used for phase modulation, then phase modulation performance is improved, but device size and weight increase
Solution Approach 1:
The device is divided into two separate substrates: a first substrate for polarization functions and a second lithium niobate substrate for phase modulation. This segmentation allows each substrate to be optimized for its specific function while reducing the overall device size and weight compared to a monolithic structure.
Solution Approach 2:
The patent transitions from a single-plane monolithic structure to a multi-layer stacked architecture where the first substrate and second substrate are positioned at different vertical levels. This dimensional change enables better spatial utilization and reduces the footprint of the device.
2Reliability
If monolithic lithium niobate substrates are used for phase modulation, then phase modulation performance is improved, but integration of additional functions becomes difficult
Solution Approach 1:
By separating the polarization function (first substrate) from the phase modulation function (second substrate), the patent enables independent optimization and integration of different functional components. This segmentation facilitates the addition of other optical functions to either substrate without compromising phase modulation performance.
Solution Approach 2:
The first substrate is designed to perform polarization functions while the second substrate handles phase modulation, creating a modular system where each substrate can potentially accommodate multiple functions. This multi-functionality approach increases overall integration capability.
3Reliability
If titanium indiffused waveguides are used for phase modulators, then environmental stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent separates the waveguide structure into distinct regions: titanium indiffused waveguides in the second substrate for environmentally stable phase modulation, and annealed proton exchanged waveguides in the first substrate for polarization functions. This segmentation allows each waveguide type to be optimized for its specific requirements.
Solution Approach 2:
Different waveguide materials and structures are applied locally to different functional regions: titanium indiffused waveguides are used specifically where environmental stability is critical for phase modulation, while proton exchanged waveguides are used for polarization functions where different performance characteristics are needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables greater integration of components, reduces the size and weight of interferometric gyroscopes, and maintains high performance by utilizing different materials for polarization and phase modulation, achieving better mode confinement and environmental stability.
Implementation Method 1
The first waveguide includes a plurality of branches and is configured to polarize light beams that propagate through the first waveguide
Implementation Method 2
The plurality of electrodes is positioned proximate to the plurality of straight waveguides, the plurality of electrodes configured to modulate the phase of light beams that propagate through the plurality of straight waveguides
Implementation Method 3
lithium niobate does not lend itself to large scale integration of other functions due to the physical properties of the material
Data Source
AI summary
In an example, an integrated optical circuit (IOC) includes a first substrate formed of a first material and a first waveguide formed of a second material and positioned on the first substrate. The first waveguide includes a plurality of branches and is configured to polarize light beams that propagate through the first waveguide. The IOC further includes a second substrate formed of a third material, the second substrate coupled to or positioned on the first substrate. The IOC further includes a plurality of straight waveguides formed in the second substrate, each of the plurality of straight waveguides optically coupled to a respective branch of the plurality of branches of the first waveguide. The IOC further includes a plurality of electrodes positioned proximate to the plurality of straight waveguides, the plurality of electrodes configured to modulate the phase of light beams that propagate through the plurality of straight waveguides.