Optical Amplifier Folded Waveguide Eliminates Isolator
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Solution Overview
Problem
Conventional hybrid integrated optical amplifiers require isolators to minimize back reflection, which are difficult to integrate into photonic integrated circuits, and have limitations due to the need for large radius curved waveguides for proper confinement and amplification.
Innovation Solution
An optical amplifier design that eliminates the need for isolators by using a coupler to split the input signal into sub-beams, a reflector to redirect these sub-beams back through a gain medium, and a phase tuner to ensure coherence cancellation, thereby minimizing back reflection and maximizing output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If isolators are used to minimize back reflection, then back reflection is reduced, but device complexity increases and integration into photonic integrated circuits becomes difficult
Solution Approach 1:
The patent extracts and eliminates the isolator component from the optical amplifier system. Instead of using an isolator to minimize back reflection, the invention uses a reflector to redirect light back through the gain medium and a phase tuner to create coherent cancellation, thereby removing the need for isolators and reducing device complexity while maintaining integration capability
Solution Approach 2:
The patent converts the harmful back reflection into a beneficial effect by using a reflector to redirect the reflected light back through the gain medium for additional amplification. The phase tuner then creates coherent cancellation to minimize residual back reflection, transforming the harmful reflected light into a useful amplification mechanism
2Ease of manufacture
If a 180° curved waveguide is used in the gain medium, then input and output are provided at a single mating surface, but the radius of curvature must be kept relatively large which limits integration
Solution Approach 1:
The patent changes the spatial configuration from a planar 180° curved waveguide to a three-dimensional folded waveguide structure. The waveguide is folded back on itself within the gain medium, allowing input and output to be positioned at the same mating surface while using a much smaller radius of curvature, thereby reducing the area occupied and improving integration capability
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 design allows for efficient amplification without the need for isolators, improving integration with photonic integrated circuits and maintaining proper confinement and amplification while reducing back reflection.
Implementation Method 1
a gain medium optically coupled to the first and second input/outputs, capable of amplifying the first and second sub-beams forming first and second amplified sub-beams
Implementation Method 2
a reflector for reflecting the first and second amplified sub-beams back to the first coupler
Implementation Method 3
a first phase shifter capable of adjusting a phase of the first sub-beam and the first amplified sub-beam, so that the first amplified sub-beam combines coherently with the second amplified sub-beam causing coherent cancellation therebetween
Data Source
AI summary
Conventional integrated optical amplifiers, which combine different types of platforms, e.g. silicon photonic integrated circuit for the device layer, and a Group III-V material for the gain medium, typically include a curved waveguide extending through the gain medium coupled to waveguides in the main device layer. Unfortunately, the radius of curvature of the curved waveguide becomes a limiting factor for both size and amplification. Accordingly, an optical amplifier which eliminates the need for the curved waveguide by including a coupler for splitting an input optical signal into two sub-beams, for passage through the gain medium, and a reflector, such as a U-turn, for reflecting or redirecting the two sub-beams back through the gain medium to the coupler for recombination, would be a welcome improvement. A phase tuner may also be provided to ensure coherence cancellation between the two sub-beams to maximize output and minimize back reflection without requiring an isolator.