Optical Waveguide Element with Intermediate Sections
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Solution Overview
Problem
Optical waveguide elements with reduced slab film thickness experience increased DC drift and reduced lifetime due to large temporal changes in operating points, while attempts to reduce propagation loss and driving voltage are hindered by connection losses from discontinuous slab film thickness variations.
Innovation Solution
An optical waveguide structure with varying ridge widths and slab film thicknesses, including intermediate waveguide parts with specific configurations to minimize connection loss and DC drift, featuring a larger slab film thickness in the DC part and reduced slab film thickness in the RF part, along with a third intermediate waveguide part to optimize light confinement and reduce propagation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the slab film thickness is reduced to enhance light confinement and reduce driving voltage, then the light confinement effect is improved and driving voltage is reduced, but DC drift increases and device lifetime is shortened
Solution Approach 1:
The optical waveguide is divided into multiple sections with different slab film thicknesses: a first section with reduced thickness for low driving voltage and light confinement, and a second section with increased thickness for reduced DC drift and improved stability. This segmentation allows each section to optimize for its specific function while working together as a complete system.
Solution Approach 2:
Different regions of the optical waveguide are given different local properties through varying slab film thicknesses. The first section has thin slab film for enhanced light confinement where modulation occurs, while the second section has thick slab film for DC drift compensation where stability is critical. This local differentiation resolves the contradiction between driving voltage and device lifetime.
2Loss of energy
If the slab film thickness is varied discontinuously to optimize light confinement, then light confinement is improved, but connection loss increases due to discontinuous variation
Solution Approach 1:
A third section with intermediate slab film thickness is introduced between the first thin section and the second thick section. This intermediate section acts as a transition zone that gradually bridges the thickness difference, reducing the abrupt discontinuity and thereby minimizing connection loss while maintaining the benefits of both thin and thick section configurations.
Solution Approach 2:
The solution transitions from a one-dimensional abrupt change in slab film thickness to a multi-dimensional gradual transition by adding an intermediate thickness section. This creates a stepped profile that reduces the shock of discontinuity and improves light coupling between sections with different thicknesses.
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 proposed structure effectively reduces DC drift, propagation loss, and driving voltage, while maintaining light confinement and reducing connection losses, thereby enhancing the longevity and efficiency of optical modulation elements.
Implementation Method 1
an optical modulator using a c-axis oriented lithium niobate film... When voltage is applied between a pair of electrodes, a sufficient electric field can be applied to the optical waveguide
Data Source
AI summary
An optical waveguide element includes: an optical waveguide having a ridge part and a slab part having a thickness less than the ridge part. The optical waveguide includes: a first waveguide having a first ridge with and a first slab film thickness; a second waveguide having a second ridge width and a second slab film thickness; a first intermediate waveguide connected to the first waveguide and having a third ridge width and the first slab film thickness; and a second intermediate waveguide connected to the second waveguide and having a fourth ridge width and the second slab film thickness. The first waveguide, the first intermediate waveguide, the second intermediate waveguide, and the second waveguide are arranged in this order; the second slab film thickness is larger than the first slab film thickness; and the third ridge width is larger than the fourth ridge width.