Optical Modulator Thermal Management via Ground Electrode
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Solution Overview
Problem
High-frequency optical modulators, particularly DP-QPSK optical modulators, face reliability issues due to heat generation from termination resistors, which leads to temperature drift and reduced performance, especially in miniaturized multi-element configurations.
Innovation Solution
The optical modulator incorporates a thicker ground electrode connected to the termination resistor, strategically positioned to disperse heat away from the optical waveguide substrate, and uses a heat conductive member to efficiently release heat to the housing, while optimizing the spacing and resistance value of termination resistors to minimize localized heat concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple termination resistors are provided on the same termination substrate to miniaturize the packaged optical modulator, then the device size is reduced, but heat generated by the termination resistors concentrates locally and deteriorates the characteristics of the termination resistors and impairs reliability
Solution Approach 1:
The invention transitions from two-dimensional heat dissipation on the substrate surface to three-dimensional heat management by forming a heat dissipation structure that extends downward from the termination substrate. The heat dissipation groove is formed to a depth of 0.5-2.0 mm into the termination substrate, creating a vertical heat conduction path that increases the heat dissipation volume and surface area, thereby reducing local heat concentration while maintaining miniaturization.
Solution Approach 2:
The invention introduces a heat dissipation groove filled with heat dissipation material (such as metal filler or conductive adhesive) as an intermediary between the termination resistor and the housing. This heat dissipation material acts as a thermal conductor that efficiently transfers heat from the termination resistor through the groove to the housing, preventing heat accumulation at the termination resistor location while maintaining compact device dimensions.
2Volume of moving object
If the termination substrate is disposed close to the optical waveguide substrate for miniaturization, then the device size is reduced, but heat generated at the termination resistor affects the optical waveguide device and causes temperature drift
Solution Approach 1:
The invention extracts the heat dissipation function from the termination substrate surface by forming a heat dissipation groove that extends downward. This groove physically separates the heat generation region (termination resistor) from the heat-sensitive region (optical waveguide substrate) by creating a vertical heat conduction path directed toward the housing, thereby preventing lateral heat transfer to the optical waveguide substrate and eliminating temperature drift while maintaining close proximity of substrates for miniaturization.
Solution Approach 2:
The invention addresses the thermal interference problem by transitioning from horizontal heat dissipation on the substrate surface to vertical heat conduction through the substrate thickness. The heat dissipation groove extends 0.5-2.0 mm downward, creating a three-dimensional heat management structure that directs heat away from the optical waveguide substrate toward the housing, thereby preventing temperature drift while maintaining compact device dimensions.
3Ease of manufacture
If a thin ground electrode is used in the termination substrate, then the manufacturing is simpler, but heat generated by the termination resistor cannot be effectively dissipated and the characteristics of the termination resistor deteriorate
Solution Approach 1:
The invention enhances heat dissipation capability by extending the ground electrode into the heat dissipation groove formed in the termination substrate. This vertical extension of the ground electrode creates additional heat conduction paths from the termination resistor through the ground electrode to the housing, significantly improving heat dissipation efficiency without requiring a thicker substrate or more complex manufacturing processes.
Solution Approach 2:
The invention creates an asymmetric ground electrode structure where the ground electrode thickness varies through the substrate depth. The ground electrode is formed with greater thickness in the region extending into the heat dissipation groove compared to the surface region, optimizing heat conduction where needed while maintaining manufacturing simplicity in other areas. This asymmetric design improves heat dissipation without uniformly increasing substrate complexity.
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 solution effectively disperses and releases heat generated by termination resistors, enhancing the reliability of the optical modulator by suppressing temperature drift and maintaining performance in high-frequency applications.
Implementation Method 1
for preventing heat generated by the termination resistor from being concentrated on a local portion in the termination substrate or conducted to the optical waveguide substrate
Implementation Method 2
uses a heat conductive member to efficiently release heat to the housing
Data Source
AI summary
Provided is an optical modulator capable of effectively dispersing and releasing heat generated by termination resistors, improving the reliability of a termination substrate including the termination resistors, and reducing influence of heat on an optical waveguide. In an optical modulator including an optical waveguide substrate on which an optical waveguide is formed, a signal electrode is provided on the optical waveguide substrate for applying an electric field, a termination resistor terminating the signal electrode, and a termination substrate on which the termination resistor is disposed, at least a plurality of the termination resistors are provided for a single termination substrate, and for preventing heat generated by the termination resistor from being concentrated on a local portion in the termination substrate or conducted to the optical waveguide substrate, a ground electrode provided on the termination substrate and electrically connected to the termination resistor is formed to be thicker than 0.1 μm.