Mach Zehnder Modulator Asymmetry for Power Stability
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Solution Overview
Problem
Mach Zehnder modulators with unequal splitting ratios face issues due to differing light intensities in the two arms, leading to phase differences and potential malfunction when input light power changes, requiring adjustments in bias voltages to compensate.
Innovation Solution
The modulator splits incident light equally into two arms and introduces an intentional loss in one arm between the electrode and combiner to create asymmetry, maintaining an equal splitting ratio while ensuring minimal phase difference changes with varying input power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an unequal splitting ratio is used to achieve desired amplification and extinction ratios, then the power levels between on and off state are improved, but the phase difference between arms changes with input power causing malfunction
Solution Approach 1:
The patent introduces an intentional loss element in one arm to create asymmetry in light intensity after the electrodes, while maintaining equal splitting at the beginning. This asymmetric design allows different transmission characteristics in each arm to achieve desired power levels without causing phase instability
Solution Approach 2:
The modulator is divided into distinct functional segments: an equal splitter section followed by a section with intentional loss. This segmentation allows the equal splitting function to be separated from the intensity adjustment function, enabling stable operation across different input power levels
2Reliability
If equal splitting ratio is used to maintain stability, then phase difference consistency is improved, but amplification and extinction ratios are reduced
Solution Approach 1:
An intentional loss element is introduced as an intermediary component in one arm between the electrode and combiner. This mediator creates the necessary intensity difference to achieve high amplification and extinction ratios while the equal splitter maintains phase stability, resolving the contradiction between stability and power ratio
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 approach allows the modulator to maintain functionality across a wide range of input power levels by minimizing phase difference changes and absorption variations between the arms, ensuring consistent amplification or extinction without needing frequent bias adjustments.
Implementation Method 1
electrodes are present in connection with said arms for changing the refractive index in said arms in order to modulate incident light
Implementation Method 2
The MZ comprises a splitter for splitting incident light in said wave guide into two modulator arms of the MZ
Implementation Method 3
a part of one of the arms between said electrode and said combiner is designed to cause an intentional loss of light in the wave guide
Data Source
AI summary
A Mach Zehnder (MZ) modulator (1) includes a splitter (4) for splitting incident light in one wave guide (3) into two modulator arms (5,6) of the MZ and a combiner (7) that combines light from the two arms (5,6) into an output mode, where electrodes (9,10) are present in connection with the arms (5,6) for changing the refractive index in the arms in order to modulate incident light so that the light is amplified or so that an extinction, due to interference between the light in the two arms, takes place. The splitter (4) is arranged to split incident light equally into the two arms (5,6) and a part (11) of one of the arms (5) between the electrode (9) and the combiner (7) is designed to cause an intentional loss of light in the wave guide (5), whereby a desired asymmetry in transmission of the two arms (5,6) occurs.