Optical Modulator With Offset Waveguide Inputs
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Solution Overview
Problem
The integration of multiple Mach-Zehnder type optical waveguides in a single substrate for optical modulators increases the longitudinal size due to the lengths of relay and arm waveguides, and while offsetting input ends can reduce this size, it leads to asymmetric arrangements causing optical property deterioration, particularly in extinction ratio.
Innovation Solution
The optical modulator design includes a substrate with a pair of relay optical waveguides branching from an input waveguide, connected first Mach-Zehnder type optical waveguides with input ends deviating in the longitudinal direction, and second Mach-Zehnder type optical waveguides arranged symmetrically with respect to a straight line passing through the branch point, reducing waveguide lengths and optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the input ends of multiple MZ optical waveguides are arranged at positions that deviate from one another in the longitudinal direction of the substrate, then the lengths of relay optical waveguides and arm waveguides are reduced, but asymmetric positions cause difference in optical losses and deterioration of optical properties such as extinction ratio
Solution Approach 1:
The patent applies asymmetry principle by intentionally deviating the input ends of first MZ optical waveguides from symmetric positions in the longitudinal direction. This asymmetric arrangement reduces the lengths of relay optical waveguides and arm waveguides, thereby reducing the longitudinal size of the substrate while managing optical loss differences through compensatory design measures
Solution Approach 2:
The patent applies local quality principle by making different parts of the optical waveguide structure have different characteristics. Specifically, the input ends of first MZ optical waveguides are positioned at different longitudinal locations, creating local variations in the optical path that reduce overall device length while maintaining functional performance through localized optimization
2Device complexity
If multiple MZ optical waveguides are integrated into an optical waveguide group on a single substrate, then the device complexity is reduced and integration is improved, but the longitudinal size of the substrate is increased due to the lengths of relay and arm waveguides
Solution Approach 1:
The patent applies merging principle by integrating multiple MZ optical waveguides into a single optical waveguide group on one substrate. This consolidation reduces device complexity and improves integration while the asymmetric positioning of input ends is used to minimize the longitudinal footprint of the integrated structure
Solution Approach 2:
The patent applies dimensionality change principle by utilizing the longitudinal dimension of the substrate more efficiently through asymmetric positioning. Instead of arranging all waveguide input ends at the same longitudinal position (one-dimensional arrangement), the invention uses varied longitudinal positions to reduce overall length while maintaining integration
Data Source
AI summary
An optical modulator includes a substrate and an optical waveguide group. The optical waveguide group includes a pair of relay optical waveguides, a pair of first Mach-Zehnder type optical waveguides, and a pair of second Mach-Zehnder type optical waveguides. The pair of the first Mach-Zehnder type optical waveguides are connected to the pair of the relay optical waveguides and includes input ends arranged at positions that deviate from each other in a longitudinal direction of the substrate. The pair of the second Mach-Zehnder type optical waveguides are provided on a pair of branched waveguides of each of the first Mach-Zehnder type optical waveguides and includes input ends arranged at symmetric positions with respect to a straight line that passes through an input end serving as a branch point of the branched waveguides and that extends in the longitudinal direction of the substrate.