Optical Phased Array Light Splitting Network
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Solution Overview
Problem
Optical phased arrays face challenges in achieving high sidelobe suppression ratios and scalability due to sensitivity to process deviations and limitations in adjusting light intensity distribution, particularly with uniform light splitting networks like directional couplers and star couplers.
Innovation Solution
A tree topology light splitting network with adjustable elements, such as multimode interferometers or other multi-branch components, allows for flexible light intensity distribution and robustness against process deviations by using a minimal number of splitter types, enabling non-uniform light splitting and scalable design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If directional coupler structure is used to build light splitting network, then light intensity can be adjusted, but the structure is sensitive to process deviation and actual device performance differs from design value
Solution Approach 1:
The light splitting network is divided into multiple 1×2 MMI stages arranged in a binary tree structure. Each stage independently splits light into two paths, and by cascading multiple stages, the system achieves flexible light intensity distribution without requiring precise control of individual component parameters, thereby reducing sensitivity to process deviations.
Solution Approach 2:
The patent changes the structural parameters of the MMI components, specifically using different propagation length ratios (L1/L2) between parallel waveguides to achieve different splitting ratios. This allows the system to achieve desired light intensity distribution through structural design rather than precise fabrication control, reducing sensitivity to process variations.
2Device complexity
If uniform light splitting network is used, then structure is simple, but sidelobe suppression ratio is limited to about 13 dB
Solution Approach 1:
The patent applies different splitting ratios to different regions of the light splitting network. By assigning different L1/L2 ratios to different MMI stages, non-uniform light intensity distribution is achieved at the output ports. This local variation in splitting quality enables sidelobe suppression ratios greater than 13 dB while maintaining a relatively simple binary tree structure.
3Illumination intensity
If star coupler is used to build light splitting network, then Gaussian distributed output can be achieved, but the network cannot flexibly set output light intensity of each port and has poor scalability
Solution Approach 1:
The patent creates a dynamically configurable light splitting network where the splitting ratio of each stage can be independently adjusted by changing the L1/L2 ratio of MMIs at different positions. This dynamic configurability allows flexible setting of output light intensity for each port while maintaining scalability, as the same binary tree architecture can be extended to any number of output ports by adding more stages.
4Productivity
If multiple 1×2 MMIs are cascaded to form full binary tree light splitting network, then light can be evenly distributed across all ports, but only uniform light splitting is achieved and sidelobe suppression ratio is limited
Solution Approach 1:
The patent introduces asymmetry into the otherwise symmetric binary tree structure by using different L1/L2 ratios in different MMI stages. This asymmetric design causes non-uniform light splitting at various stages, resulting in controlled non-uniform intensity distribution at output ports that achieves sidelobe suppression greater than 13 dB while maintaining efficient light distribution across all ports.
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 achieves higher sidelobe suppression ratios, improved scalability, reduced area occupancy, and enhanced robustness against process deviations, allowing for efficient adjustment of light intensity and optimized processing technology.
Implementation Method 1
multiple 1×2 multimode interferometers (MMIs) can also be cascaded to form light splitting network. A single MMI device can divide the input light into two equal parts and then output
Data Source
AI summary
An optical phased array device, which can flexibly set the light splitting weight and has good scalability, includes a light splitting network, phase shifters, and emission units. Among them, the light splitting network of the device can set the optical power weight of the array element freely and has good scalability. The light splitting network of optical phased array consists of a series of basic elements, each of which can realize uniform or non-uniform light splitting of N channels. The light splitting network adopts a tree topology. The tree network structure can be freely designed, and the components used by the network nodes can also be freely selected. By freely designing the structure of the light splitting network and the components used by each node, the optical output distribution of the network can be set, so that the far field distribution of the optical phased array can be optimized.