Optical Transceiver Combed EMI Shielding Structure
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Solution Overview
Problem
Conventional optical transceivers face challenges in reducing electromagnetic interference (EMI) radiation, particularly at higher frequencies, due to small gaps and misalignment between the face panel and cage, as well as inherent gaps in ground fingers, which lead to leakage of EMI radiation.
Innovation Solution
The optical transceiver incorporates a combed structure within its housing, featuring a series of fins that attenuate electromagnetic radiation, with the distance between fins optimized to less than a quarter wavelength of the noise frequency, effectively functioning as a waveguide cavity to suppress EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If ground fingers are used to fill gaps and contact the cage, then EMI radiation is reduced, but at higher frequencies (exceeding 10 GHz), small gaps between fingers and misalignment cause EMI leakage
Solution Approach 1:
The housing is segmented into multiple combed structures with numerous fins, creating multiple small apertures instead of relying on a few large ground fingers. This segmentation allows the structure to maintain EMI shielding effectiveness even with minor misalignments, as each fin acts as an independent shielding element.
Solution Approach 2:
The patent changes the physical parameters of the shielding structure by creating fins with specific dimensions where the distance between adjacent fins is less than a quarter wavelength of the noise frequency. This parameter optimization enables the combed structure to function as a waveguide cavity that suppresses EMI radiation at high frequencies.
2Object-affected harmful factors
If conventional ground fingers are used, then EMI shielding is provided, but the inherent gaps between adjacent fingers cause EMI radiation leakage at higher frequencies
Solution Approach 1:
The shielding structure is divided into multiple combed structures, each containing numerous fins. This segmentation creates many small apertures that collectively provide superior EMI shielding compared to conventional ground fingers, while the modular combed design maintains manufacturing feasibility.
Solution Approach 2:
The patent transitions from a one-dimensional ground finger approach to a two-dimensional combed structure with multiple fins extending in perpendicular directions. This dimensional expansion creates a more effective shielding barrier that blocks EMI radiation paths that would penetrate between conventional ground fingers.
3Ease of operation
If external optical connectors are used, then optical coupling is achieved, but small gaps form between the connector and inner wall of the optical receptacle causing EMI leakage
Solution Approach 1:
The combed structures act as intermediary shielding elements positioned between the optical receptacle and the external environment. These fins create a protective barrier that addresses EMI leakage from connector gaps without interfering with the optical coupling function, effectively mediating between optical performance and EMI shielding requirements.
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 achieves a significant reduction in EMI radiation, with a 37% improvement measured at 20.625 GHz, by converting the combed structure into a perfect magnetic conductor for the H-field vector, effectively blocking electromagnetic waves within the operating frequency range of the transceiver.
Implementation Method 1
the combed structure into a perfect magnetic conductor for the H-field vector, effectively blocking electromagnetic waves within the operating frequency range of the transceiver
Implementation Method 2
a combed structure to attenuate the electromagnetic radiation
Data Source
AI summary
An optical transceiver that reduces the EMI radiation leaked therefrom is disclosed. The optical transceiver includes a top cover and the bottom base to form a cavity into which a TOSA, a ROSA, and a circuit are set. The top cover provides a combed structure in a rear portion thereof, where the combed structure has a plurality of fins with a distance preferably less that quarter wavelength λ/4 of the noise wavelength to be reduced. The combed structure operates as a short stub for the electromagnetic wave traveling longitudinally in the cavity.