Surface-Mounted Optical Device with Faraday Cage for EMI Immunity
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Solution Overview
Problem
Existing optical communication systems face challenges with electromagnetic interference (EMI), cross talk, and galvanic isolation in multi-layer printed circuit boards (PCBs), particularly in achieving maximum optical throughput and protecting photodetectors from interference during light coupling.
Innovation Solution
An electro-optical apparatus with a printed circuit board (PCB) featuring optical waveguides and apertures, where optical elements are surface-mounted on substrates with encapsulation for alignment and protection, and a Faraday cage is formed using conductors and ground planes to prevent EMI, allowing for efficient and cost-effective optical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple layers of copper are used in PCBs to increase speed and complexity, then the functionality and processing speed improve, but electromagnetic interference (EMI) and cross talk interference increase
Solution Approach 1:
The patent extracts the optical transmission function from the electrical copper layers and places it in a dedicated optical layer within the PCB. This separates optical signals from electrical signals, eliminating EMI and cross talk while maintaining high-speed communication capabilities.
Solution Approach 2:
The patent introduces an optical layer as an intermediary between electrical components, using optical signals as the medium for high-speed data transmission. This intermediary layer provides galvanic isolation while enabling fast communication, resolving the contradiction between speed and EMI.
2Ease of operation
If out-of-plane coupling with multiple independent components is used to couple light to and from the EOCB, then optical coupling capability is achieved, but manufacturing complexity and alignment difficulty increase
Solution Approach 1:
The patent merges the optical coupling function directly into the EOCB structure by creating optical apertures and positioning optical elements within the board plane. This integration eliminates the need for multiple separate out-of-plane components and simplifies alignment, reducing manufacturing complexity while maintaining optical coupling capability.
3Ease of manufacture
If conventional surface mount opto-electronic components are used for optical interconnection, then ease of implementation is improved, but flexibility in routing and implementing complex optical elements is reduced
Solution Approach 1:
The patent transitions from three-dimensional surface mount components to a two-dimensional integrated optical layer within the PCB. This allows optical waveguides to be routed flexibly across the board plane, enabling complex optical paths, splitters, and combiners while maintaining ease of manufacturing through standard PCB fabrication processes.
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 enables reliable, cost-effective, and high-volume production of optical interconnects with improved alignment accuracy and EMI immunity, reducing the risk of malfunction and increasing yield.
Implementation Method 1
the encapsulation forms and/or encapsulates an optical guide for direction of light into or out of the waveguide
Implementation Method 2
a Faraday cage is formed using conductors and ground planes to prevent EMI
Implementation Method 3
an EOCB comprising a printed circuit board having at least one waveguide within the board
Data Source
Figure 1(a)
Figure 1(b)
Figure 2
AI summary
An electro optical apparatus has an EOCB (2) with a printed circuit board and at least one waveguide (3, 10), at least one optical aperture (20, 21, 114) in the board with a side wall aligned with a termination (116) of the waveguide. An electro optical device (30) has an optical element (31) with components (35) in encapsulation (36) on a substrate is located within the aperture (20) by the substrate (32/37) being attached to the board around a rim of the aperture by surface mount attachment with reflow of solder. The substrate may include an interposer (32) to allow design flexibility. The encapsulation (36) provides optical alignment of the component (35) with the EOCB waveguide so that the arrangement is robust, reliable and easy to manufacture. In some examples the substrate (501) and the EOCB (550) provide a Faraday cage (505, 554, 553) around the aperture and hence the optical element (530).