Optical Modulator Heater AC Drive for Electromigration Control
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Solution Overview
Problem
Optical modulators face reliability issues due to electromigration (EM) caused by heat generated from large currents, leading to hillocks and voids that can result in short or open circuits.
Innovation Solution
Employing a heater driven by alternating current (AC) signals to thermally adjust the resonant wavelength, which reduces electromigration by alternating the direction of current flow and maintains thermal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heater driven by large current is used to thermally adjust the resonant wavelength, then the thermal efficiency is improved, but electromigration occurs causing hillocks and voids that degrade reliability
Solution Approach 1:
The patent applies periodic action by using alternating current (AC) instead of direct current (DC) to drive the heater. The AC current periodically reverses direction, creating cyclic heating cycles that maintain thermal efficiency while preventing the continuous unidirectional electron flow that causes electromigration. This periodic reversal prevents metal atom displacement and accumulation, eliminating hillock and void formation while preserving the necessary thermal adjustment capability.
2Adaptability or versatility
If large current is applied to the heater, then the resonant wavelength adjustment capability is improved, but electromigration induces short circuits or open circuits
Solution Approach 1:
The AC current implementation uses periodic reversal of current direction to maintain the necessary current magnitude for wavelength adjustment while preventing electromigration damage. The periodic nature ensures that metal atoms are not continuously pushed in one direction, preventing hillock and void formation that lead to short or open circuits.
Solution Approach 2:
The patent inverts the conventional DC current approach by using AC current that periodically reverses direction. This inversion of the current flow direction prevents the unidirectional momentum transfer to metal atoms that causes electromigration, while still delivering the necessary current magnitude for effective wavelength adjustment through the cyclic heating action.
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
Prevents electromigration in the heater, enhancing its reliability while maintaining thermal efficiency, thus improving the stability and performance of the optical modulator.
Implementation Method 1
the heater may generate heat induced by large current
Data Source
AI summary
The present disclosure provides a semiconductor device, a photonic circuit, and a method for adjusting a resonant wavelength of an optical modulator. The semiconductor device includes a first waveguide, a second waveguide spaced apart from the first waveguide by a first distance, and a heater disposed on the second waveguide. The heater is configured to receive a first electrical signal and a second electrical signal and to carry a time-varying current in response to the first electrical signal and the second electrical signal. The first electrical signal includes a first pulse and the second electrical signal includes a second pulse, and the first pulse and the second pulse share a non-overlapped period during which the first pulse and the second pulse include a predetermined voltage.