Mach-Zehnder Optical Modulator with Ring Resonance Phase Shifter
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Solution Overview
Problem
Conventional optical functional devices, such as Mach-Zehnder type optical modulators and attenuators, face challenges in reducing size while maintaining desired modulation or attenuation characteristics, leading to high fabrication costs and sensitivity to structural variations, which limits their application in optical information processing and interconnection fields.
Innovation Solution
The design incorporates a Mach-Zehnder type optical functional device with a ring-type optical waveguide optically coupled to branch waveguides, allowing for variation of the amplitude branching ratio to control light intensity, enabling downsizing and high-speed operation with reduced parasitic electric capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Mach-Zehnder type optical modulators are designed to maintain desired modulation characteristics, then the device size increases, but this leads to increased fabrication costs and reduced productivity
Solution Approach 1:
The patent changes the fundamental operating parameter from phase difference control to amplitude branching ratio control. By varying the amplitude branching ratio between the ring-type waveguide and straight waveguide, the device achieves modulation while reducing the required interaction length, thereby downsizing the device and reducing fabrication costs while maintaining reliable modulation characteristics
Solution Approach 2:
The patent introduces a dynamically adjustable amplitude branching ratio that can be controlled by external signals. This dynamic control mechanism allows the device to achieve desired modulation characteristics with a compact structure, as the branching ratio can be optimized for different operating conditions without requiring large device dimensions
2Productivity
If conventional optical modulators are downsized to reduce fabrication costs, then productivity improves, but the device becomes sensitive to structural variations
Solution Approach 1:
The patent incorporates preliminary design features in the ring-type waveguide structure that pre-compensate for structural variations. The amplitude branching ratio is designed to be inherently less sensitive to dimensional changes, and the structure includes features that maintain stable coupling even when fabrication tolerances cause variations, thereby reducing sensitivity without requiring large device sizes
Solution Approach 2:
The patent designs the waveguide coupling structure with built-in tolerance cushioning. The ring-type waveguide is configured to provide stable amplitude branching ratio over a range of structural variations, effectively cushioning against the impact of fabrication imprecisions and maintaining consistent device performance despite manufacturing tolerances
3Length of moving object
If conventional optical modulators are downsized, then device size decreases, but parasitic electric capacitance increases, limiting high-speed operation
Solution Approach 1:
The patent transitions from a planar two-dimensional layout to a three-dimensional ring-type waveguide structure. This dimensional change allows the light to propagate through a longer effective path within a compact footprint, reducing the required electrode length and associated parasitic capacitance while maintaining small device size and enabling high-speed operation
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 allows for the realization of compact optical modulators, attenuators, and switches with stable characteristics, capable of high-speed operation at lower power consumption and reduced manufacturing costs, thus facilitating mass production and improved performance in optical communication and information processing applications.
Implementation Method 1
consisting of: an input optical waveguide for receiving input of a light wave signal; first and second branch optical waveguides; a splitter connected to the input optical waveguide to branch the light wave signal into two parts to be routed to the first and second branch optical waveguides; an optical modulating unit provided for, at least, one of the first and second branch optical waveguides to modulate the light wave signal that propagates through the corresponding branch optical waveguide for which the optical modulating unit is provided; a combiner for recombining the light wave signals from the first and second branch optical waveguides; and an output optical waveguide for outputting the combined light wave signal. The optical modulating unit comprises: a ring-type optical waveguide disposed so as to be optically coupled to the corresponding branch optical waveguide; and a means for varying the amplitude branching ratio between the corresponding branch optical waveguide and the ring-type optical waveguide.
Implementation Method 2
a means for varying the amplitude branching ratio between the corresponding branch optical waveguide and the ring-type optical waveguide
Data Source
AI summary
Arranged for at least one of a pair of branch optical waveguides in a Mach-Zehnder type interference optical system is a ring resonance type phase shifter for modulating a light wave signal propagating through the branch optical waveguide. The ring resonance type phase shifter includes a ring-type optical waveguide arranged so as to be mode-coupled with the corresponding branch optical waveguide, and is configured so that amplitude branching ratio K between the corresponding branch optical waveguide and the ring-type optical waveguide can be varied with a change in refractive index or the like, accompanied by voltage application to a pn junction, for example. As amplitude branching ratio K is varied, the phase difference between the light wave signals propagating through the paired optical waveguides varies, to thereby control the intensity of the light wave signal output from the interference optical system.