Mach-Zehnder Semiconductor Phase Control via Carrier Injection
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Solution Overview
Problem
Conventional Mach-Zehnder type semiconductor devices face challenges in adjusting phase differences between waveguides with deviated lengths, leading to fluctuations in modulation voltages and increased optical loss due to electro-optical effects, making them impractical for efficient operation.
Innovation Solution
A Mach-Zehnder type semiconductor device with a phase adjusting electrode group comprising a positive bias electrode and negative bias electrodes is used to inject and remove carriers in the waveguide, leveraging the plasma effect to change the refractive index and adjust the phase difference, while minimizing optical loss and preventing eye pattern deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional MZ type semiconductor device uses waveguides with deviated lengths, then manufacturing tolerance is accommodated, but phase difference adjustment becomes difficult and modulation voltage fluctuates
Solution Approach 1:
The patent applies parameter changes by introducing bias voltages to electrodes that modify the refractive index of the waveguides through electro-optic effects. By changing the electrical parameters (bias voltages applied to first and second electrodes), the optical path lengths of the waveguides are adjusted, thereby compensating for manufacturing deviations and enabling precise phase difference control despite waveguide length variations.
2Ease of operation
If modulation voltage is increased to adjust phase difference, then phase control is achieved, but optical loss increases due to electro-optical effects
Solution Approach 1:
The patent uses parameter changes by applying bias voltages to electrodes that modify the refractive index through electro-optic effects, enabling phase control without requiring large modulation voltages that would cause excessive optical loss.
Solution Approach 2:
The patent replaces direct mechanical/path-length adjustment with an electrical field-based approach. Instead of physically altering the waveguide structure or using large modulation voltages, the invention uses electric fields applied through electrodes to change the refractive index, thereby achieving phase control with minimal optical loss.
3Ease of operation
If positive bias voltage is applied to adjust phase, then phase difference is corrected, but eye pattern deteriorates due to carrier injection
Solution Approach 1:
The patent applies parameter changes by using bias voltages to adjust the refractive index and phase difference. By carefully controlling the voltage parameters applied to the electrodes, the system achieves phase control while avoiding excessive carrier injection that would deteriorate the eye pattern.
Solution Approach 2:
The patent applies local quality by positioning electrodes at specific locations where they can influence the refractive index without causing harmful carrier injection into the optical mode. The electrodes are strategically placed to create localized electric fields that modify phase while minimizing interference with the optical signal quality.
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
The solution effectively adjusts phase differences between waveguides, reduces optical loss, and maintains the integrity of the eye pattern, enhancing the operational efficiency and practicality of the Mach-Zehnder type semiconductor device.
Implementation Method 1
The positive bias electrode changes a refraction index of the second branch waveguide by applying a positive bias voltage across the positive bias electrode and the common electrode so as to inject carriers to the second branch waveguide
Implementation Method 2
A refraction index of the first branch waveguide 34 which exists under the first modulating electrode 42 is changed in response to a voltage applied to the first modulating electrode 42
Data Source
AI summary
A Mach-Zehnder type semiconductor device includes electrodes for injecting carriers into first and second branch waveguides so as to change reflection indexes of the first and second branch waveguides. The device further includes electrodes which are placed above either one of the first or second branch waveguides or both of the first or second branch waveguides so as to remove the carriers. The Mach-Zehnder type semiconductor device can adjust a phase difference between first and second split light transmitted through the first and second branch waveguides, respectively, even if the lengths of the first and second branch waveguides deviate from designed values. The Mach-Zehnder type semiconductor device also can suppress optical loss of the first and second light, and generate outgoing light without deterioration.