Multi-Step Waveguide Tapering for Low-Loss Ridge Modulator Coupling
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Solution Overview
Problem
Integrated optical modulators with CMBH waveguides face challenges in high-frequency operation due to additional capacitance from current blocking regions, limiting their performance.
Innovation Solution
A multi-step tapered waveguide design is employed to couple light from a CMBH waveguide laser source to a ridge waveguide modulator, featuring high misalignment tolerance and reduced capacitance, allowing efficient light coupling with lower signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current blocking regions are added to CMBH waveguide to minimize current leakage, then current leakage is reduced, but additional capacitance is added which prevents high-frequency operation
Solution Approach 1:
The patent extracts the current blocking function from the traditional abrupt junction structure and relocates it to the tapered waveguide region. This separation allows the active region to maintain low capacitance while current confinement is achieved through the tapered geometry and graded indexing, enabling high-frequency operation without sacrificing current leakage control
Solution Approach 2:
The patent applies local quality by creating a tapered waveguide with gradually changing refractive index and cross-sectional dimensions. The taper region provides localized current blocking through its geometric configuration rather than through abrupt doping junctions, reducing overall capacitance while maintaining effective current confinement in the active region
2Loss of energy
If single-taper waveguide is used to couple CMBH laser to ridge waveguide, then light coupling is achieved, but misalignment tolerance is low and signal loss is high
Solution Approach 1:
The patent segments the waveguide structure into multiple functional regions: a wide-input section for efficient laser coupling, a tapered transition section for mode transformation, and a narrow-output section for ridge waveguide coupling. This segmentation allows each section to be optimized independently, providing both low signal loss and high misalignment tolerance through the expanded interaction area in the wide-input section
Solution Approach 2:
The patent employs a multi-dimensional tapered waveguide structure that varies in both横向 (cross-sectional) and longitudinal dimensions. The vertical taper combined with lateral expansion creates a three-dimensional mode transformation path that gradually adapts the optical mode from the laser to the ridge waveguide, increasing tolerance to manufacturing variations and reducing coupling losses
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 multi-step tapered waveguide enables high-speed operation up to 75 GHz with reduced chip dimensions and manufacturing costs, while maintaining high efficiency and misalignment tolerance.
Implementation Method 1
A multi-step tapered waveguide design is employed to couple light from a CMBH waveguide laser source to a ridge waveguide modulator
Data Source
AI summary
A waveguide for an optical modulator system includes multiple tapered portions, or regions, designed to couple a CMBH laser light source to a ridge modulator. Using a waveguide with different tapered portions, transmission efficiency between the CMBH light source and the ridge modulator is improved, thus allowing the optical modulator to be used in high-speed applications. Waveguide described herein may include tapered portions in which, along a single direction, include one portion that tapers to a reduced width while another portion tapers to an increased width.