Optical Waveguide Module Filter Circuit for Flat Frequency Response
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Solution Overview
Problem
Existing optical waveguide elements face challenges in achieving flat frequency characteristics across a wide band, particularly in high frequency ranges, leading to jitter issues, which are exacerbated by the use of termination circuits and complex manufacturing processes for filter circuits with thin-film capacitors.
Innovation Solution
An optical waveguide element module with a filter circuit incorporating a single-layer capacitor with relative permittivity of 1000 or less, where the capacitor is strategically arranged on a relay substrate with conductive wire connections and optional film resistors, allowing for adjustable capacitance and resistance values to maintain flat electrical/optical response frequency characteristics beyond several tens of gigahertz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a termination circuit is used to adjust impedance, then frequency characteristics are improved, but flat frequency characteristics in high frequency range cannot be achieved
Solution Approach 1:
The patent changes the electrical parameters of the circuit by introducing a capacitor with specific capacitance value (0.5-5pF) and a resistor (10-100Ω) to form an RC circuit. This parameter change transforms the frequency response characteristics, enabling flat frequency characteristics from DC to high frequencies (several tens of GHz) that cannot be achieved with termination circuits alone.
2Manufacturing precision
If thin-film capacitors are used in filter circuits, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by using a thin-film capacitor only in the critical high-frequency path where precise capacitance control is needed, while other parts of the circuit use conventional components. This localized application of thin-film technology achieves the desired frequency characteristics without requiring the entire manufacturing process to be complex.
3Reliability
If the capacitance value is increased to improve low frequency response, then a resonance phenomenon occurs in the used frequency range
Solution Approach 1:
The patent precisely controls the capacitance value parameter within a specific range (0.5-5pF) to balance low-frequency response improvement with high-frequency resonance prevention. By optimizing this parameter, the RC circuit provides broadband frequency compensation without introducing harmful resonance effects in the operational frequency range.
4Manufacturing precision
If a filter circuit is added to improve frequency characteristics, then electrical/optical response flatness is improved, but device complexity increases
Solution Approach 1:
The patent merges the filter circuit functionality with the existing driver circuit by integrating an RC circuit that can be implemented on the same substrate or relay board. This merging approach provides frequency compensation without requiring a completely separate filter module, thus reducing overall device complexity while achieving flat electrical/optical response characteristics.
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 prevents signal deterioration and resonance phenomena, enabling flat electrical/optical response frequency characteristics in a wide band, simplifies manufacturing, and allows for easy adjustment of filter circuit components to suit various optical waveguide elements.
Implementation Method 1
The capacitor is a single-layer capacitor and the relative permittivity of a dielectric in the capacitor is equal to or less than 1000
Implementation Method 2
preventing the deterioration of an electric signal in the filter circuit or the occurrence of a resonance phenomenon within the frequency range used
Implementation Method 3
an optical waveguide element, such as an optical modulator, in which an optical waveguide is formed on a substrate having an electro-optical effect
Data Source
AI summary
Disclosed is an optical waveguide element module in which a filter circuit including a capacitor is provided on a line through which a modulation signal is input to a modulating electrode of an optical waveguide element. The module is capable of preventing the deterioration of an electric signal in the filter circuit or the occurrence of a resonance phenomenon within the frequency range used and obtaining flat electrical/optical response frequency characteristics in a wide band of more than several tens of gigahertz. The capacitor is a single-layer capacitor and the relative permittivity of a dielectric in the capacitor is equal to or less than 1000.