Optical Modulator Relay Substrate Electromagnetic Wave Absorbing Unit
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Solution Overview
Problem
In high-speed optical fiber communication systems, particularly at transmission rates above 400 Gb/s, crosstalk between high-frequency signal lines on the relay substrate of optical modulators is significant due to leaked microwaves, which deteriorates optical modulation characteristics and is not effectively addressed by existing technologies.
Innovation Solution
An optical modulator with an electromagnetic wave propagation suppressing unit made of a material that absorbs electromagnetic waves, protruding from the surface of the relay substrate along its sides, is used to mitigate the impact of leaked microwaves by blocking or suppressing diffracted waves generated at signal connection points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the relay substrate is miniaturized to reduce the size of the optical modulator, then the housing size is reduced, but crosstalk between high-frequency signal lines increases due to leaked microwaves
Solution Approach 1:
An electromagnetic wave absorbing member is introduced as an intermediary substance between the signal lines on the relay substrate. This member absorbs leaked microwaves and diffracted waves generated at signal connection points, preventing them from causing crosstalk between adjacent signal lines, thus resolving the contradiction between miniaturization and crosstalk suppression
Solution Approach 2:
The physical and chemical properties of the relay substrate are changed by forming an electromagnetic wave absorbing film or coating it with absorbing material. This modifies the substrate's interaction with electromagnetic waves, enabling it to suppress diffracted waves and leaked microwaves while maintaining the miniaturized structure
2Speed
If high-frequency electrical signals are transmitted at higher rates to increase transmission capacity, then transmission speed increases, but crosstalk due to leaked microwaves becomes more significant
Solution Approach 1:
The electromagnetic wave absorbing member converts the harmful leaked microwaves and diffracted waves into thermal energy through absorption. By transforming the harmful electromagnetic radiation into heat, the member effectively suppresses crosstalk while allowing high-frequency signal transmission
Solution Approach 2:
The electrical and electromagnetic properties of the relay substrate are modified through the absorbing film or coating, changing its impedance characteristics and electromagnetic wave interaction properties to suppress crosstalk at high transmission rates
3Object-affected harmful factors
If the distance between adjacent signal lines is increased to reduce crosstalk, then crosstalk suppression improves, but the relay substrate area increases
Solution Approach 1:
The electromagnetic wave absorbing member acts as an intermediary that eliminates the need for increased spacing between signal lines. By absorbing leaked microwaves and suppressing diffracted waves, it enables tight signal line spacing while maintaining low crosstalk levels
Solution Approach 2:
The electromagnetic wave absorbing properties are applied locally at critical positions where diffracted waves are generated, such as signal connection points and between adjacent signal lines, rather than uniformly across the entire substrate, thus minimizing area increase
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 configuration effectively reduces crosstalk between signal lines, ensuring appropriate optical modulation characteristics even at high transmission rates, thereby stabilizing the operation of optical modulators.
Implementation Method 1
an electromagnetic wave propagation suppressing unit made of a material that absorbs electromagnetic waves and having a height protruding from a surface of the relay substrate is provided along at least one side connecting an end portion of the signal input side and an end portion of the signal output side in a plan view
Data Source
AI summary
An optical modulator includes an optical modulation element having a plurality of signal electrodes, a plurality of signal input terminals, a relay substrate on which a plurality of signal conductor patterns that electrically connect the signal input terminals and the signal electrodes and a plurality of ground conductor patterns are formed, and a housing. A signal input side and signal output side of the relay substrate face each other in a plan view, and electromagnetic wave propagation suppressing units that are made of a material that absorbs electromagnetic waves and have a height protruding from a surface of the relay substrate are provided, along at least one side of an end portion of the signal input side and an end portion of the signal output side in the plan view.