3x3 Evanescent Field Optical Router for Stable Power Splitting
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Solution Overview
Problem
Existing optical routers, such as Y junctions and evanescent field couplers, face stability issues with wavelength and temperature variations, and often result in unguided modes or power imbalances, which affect the accuracy and reliability of optical fiber gyroscopes and interferometers.
Innovation Solution
A 3x3 evanescent field optical coupler with a coupling length adjusted between 1.3154x and 2x the equally distributed coupling length, ensuring a 50-50 power split with high stability, guiding all optical beams and minimizing losses, by maintaining symmetry and optimizing the evanescent coupling zone length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Y junction is used as an optical router, then the device structure is simple and manufacturing is easy, but unguided modes are generated causing power loss and reduced reliability
Solution Approach 1:
The Y junction structure is segmented by introducing a lateral waveguide that captures and guides the antisymmetric mode separately, preventing it from propagating unguided and causing loss
Solution Approach 2:
A lateral waveguide acts as an intermediary element between the symmetric and antisymmetric modes, providing a dedicated pathway for the antisymmetric mode to be guided without interfering with the main signal path
2Reliability
If an evanescent field coupler is used as an optical router, then all optical beams are guided, but the device shows instability with wavelength and temperature variations
Solution Approach 1:
The device uses asymmetric coupling between symmetric and antisymmetric modes through the lateral waveguide, creating different propagation characteristics that are less sensitive to wavelength and temperature variations compared to symmetric evanescent couplers
Solution Approach 2:
The coupling length and waveguide geometry parameters are optimized to achieve stable 50-50 power splitting across a wide range of wavelengths and temperatures, reducing the device's sensitivity to environmental changes
3Reliability
If a standard evanescent field coupler is used, then all optical beams are guided, but power imbalance occurs affecting measurement precision
Solution Approach 1:
The device incorporates adjustable coupling length and waveguide parameters that can be dynamically optimized to achieve precise 50-50 power splitting, allowing fine-tuning of the power distribution between output ports
Solution Approach 2:
The design allows for feedback-based optimization of the coupling parameters to achieve and maintain balanced power splitting, ensuring high measurement precision in interferometric applications
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
The solution provides a stable and efficient 50-50 power split with high thermal and spectral stability, guiding all optical beams and preventing antisymmetric mode interference, thus enhancing the accuracy and reliability of optical fiber gyroscopes and interferometers.
Implementation Method 1
The device comprises a first waveguide, a second waveguide and a third waveguide arranged adjacently in an evanescent field optical coupling zone
Data Source
Figure 1A~2A
Figure 2B~3B
Figure 4~5
AI summary
The present invention relates to a bidirectional guided optical router comprising an evanescent-field optical coupler having three input gates, three output gates, a first central waveguide, a second lateral waveguide and a third lateral waveguide and an evanescent-field-based optical coupling zone in which said first, second and third waveguides are disposed in such a way as to allow evanescent-field-based coupling between the first central waveguide and either one of the second and third lateral waveguides. According to the invention, said 3x3 optical coupler has a length L of between 3154 x Leq and 2 x Leq in such a way that an optical beam coupled on the first input gate having a power p and propagating on the first waveguide in the forward direction is distributed according to the following distribution: a first secondary beam having a power greater than or equal to 90% of p/2 on the second output gate, another secondary beam having a same power greater than or equal to 90% of p/2 on the third output gate.