Optical Grating Coupler with Varying Period for Bandwidth
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Solution Overview
Problem
Integrated optical devices, such as silicon on insulator (SOI) optical circuits, face limitations in bandwidth due to static or progressively changing grating periods, which restrict their wavelength response and lead to clipping of photonic channels in multi-channel applications like wavelength-division multiplexing.
Innovation Solution
The electro-optic device features an optical grating coupler with alternating curved ridges and valleys, where the medial portion has a specific grating period based on a targeting wavelength, and the sides have varying grating periods, allowing for asymmetric or symmetric designs, enabling a wider bandwidth by varying the grating period and curvature within each groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a static grating period is used in the optical grating coupler, then the device structure is simple and easy to manufacture, but the bandwidth is limited and wavelength response is restricted
Solution Approach 1:
The patent applies local quality by varying the grating period across different regions of the optical grating coupler. The grating period is optimized locally for different wavelength channels, with shorter periods for blue wavelengths and longer periods for red wavelengths, enabling multi-channel operation while maintaining manufacturing feasibility through localized parameter adjustment
Solution Approach 2:
The patent implements parameter changes by systematically varying the grating period parameter across the coupler structure. This continuous parameter variation allows the device to accommodate multiple wavelength channels simultaneously, transforming a single-wavelength component into a multi-wavelength device without fundamental redesign
2Adaptability or versatility
If a progressively changing grating period is used to extend wavelength response, then the bandwidth increases, but the device complexity increases and manufacturing becomes more difficult
Solution Approach 1:
The patent applies segmentation by dividing the optical grating coupler into distinct regions with different grating period characteristics. This segmentation allows independent optimization of each region for specific wavelength ranges while simplifying the overall design and manufacturing process compared to a fully continuous gradient structure
Solution Approach 2:
The patent implements partial action by applying grating period variation only where necessary to achieve the desired wavelength response, rather than uniformly across the entire structure. This selective application reduces manufacturing complexity while maintaining the bandwidth extension benefit
3Manufacturing precision
If the grating period is optimized for a single targeting wavelength, then the device performance at that wavelength is maximized, but other photonic channels are clipped or lost
Solution Approach 1:
The patent applies universality by designing the optical grating coupler to serve multiple wavelength channels simultaneously through spatial variation of the grating period. Each region of the coupler is optimized for a specific wavelength range, enabling the single device to replace multiple wavelength-specific couplers and support multi-channel photonic 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
This design enhances the bandwidth of the optical grating coupler, allowing for minor attenuation across a broader spectral range, effectively supporting multiple photonic channels without clipping, and is tolerant to process and temperature variations.
Implementation Method 1
the shape and pattern of the optical grating defines the wavelength response of the optical grating
Data Source
AI summary
An electro-optic device may include a photonic chip including an insulator layer, and a semiconductor layer over the insulator layer and defining an optical grating coupler. The optical grating coupler may have a series of alternating curved ridges and valleys. The optical grating coupler has first and second sides and a medial portion. The medial portion has a medial grating period T based upon a targeting wavelength. One or more of the first and second sides have a side grating period different than T.