SOI Mode Converter Using Perturbation Segments for High-Order Modes
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Solution Overview
Problem
On-chip mode division multiplexing (MDM) faces challenges in processing high order modes, particularly in achieving compact and efficient mode converters for converting high order modes to the fundamental mode, which limits the operational bandwidth and device size.
Innovation Solution
The development of ultra-compact silicon-on-insulator (SOI) mode order converters using a machine-learning-assisted optimization method, where perturbation segments with a lower refractive index are arranged in a guide material with a higher refractive index to convert TE0, TE1, and TE2 modes with high efficiency, enabling broader bandwidth and compact footprint designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mode converters are used to convert high order modes to fundamental mode, then mode conversion can be achieved, but the device size becomes large and bandwidth is limited
Solution Approach 1:
The mode converter is divided into multiple sections with alternating high and low refractive index materials. This segmentation allows the device to achieve mode conversion through periodic modulation rather than requiring a long gradual transition, thus reducing device length while maintaining conversion efficiency and bandwidth.
Solution Approach 2:
The patent employs periodic modulation of the refractive index parameter along the propagation direction. By changing the refractive index parameter in a controlled periodic manner, the device achieves efficient mode conversion over a broad bandwidth without requiring large physical dimensions.
2Length of stationary object
If photonic crystal waveguides are used for mode conversion, then compact size can be achieved, but the design complexity increases and manufacturing precision requirements are higher
Solution Approach 1:
The patent uses composite waveguide structures combining different materials with distinct refractive indices. This composite approach enables compact mode conversion through material properties rather than complex geometric structures, reducing manufacturing precision requirements while achieving ultracompact footprints.
Solution Approach 2:
The patent implements localized refractive index modifications in specific regions of the waveguide. By concentrating the mode conversion function in small localized areas with tailored material properties, the device achieves compact size without requiring high precision across the entire structure.
3Reliability
If mode converters are designed for high efficiency, then conversion efficiency improves, but the device footprint increases
Solution Approach 1:
The patent employs periodic modulation of the waveguide properties along the propagation direction. This periodic action creates multiple interaction opportunities for mode conversion within a short distance, achieving high conversion efficiency while maintaining a compact footprint through distributed rather than concentrated conversion.
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 approximately 85% efficiency in mode conversion over 100 nm bandwidth with a footprint of around 4 µm length, allowing for compact and efficient processing of high order modes, including alternative functionalities like crossing and bending, while maintaining low crosstalk and reflection.
Implementation Method 1
the mode converter includes a guide material having a first refractive index and perturbation segments each having a second refractive index, wherein the first refractive index is greater than the second refractive index
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3A~3C
AI summary
A photonic device for converting optical modes of optical beams incudes a first port to receive a first beam having a first mode, a mode converter and a second port to transmit the first beam. The mode converter is configured to broaden the first beam to convert the first mode into a second mode and narrow the broadened first beam at an output side of the mode converter, wherein the mode converter includes a guide material having a first refractive index and perturbation segments each having a second refractive index, wherein the first refractive index is greater than the second refractive index, wherein the perturbation segments are arranged in the guide material to cross the first beam.