Rib Waveguide High-Order Mode Filter With Doped Mesa Region
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Solution Overview
Problem
High-order mode filters struggle to effectively eliminate high-order mode light from optical waveguides without causing stray light, which degrades performance in silicon optical integrated circuits and other optical elements by increasing noise and affecting multiplexing/branching devices.
Innovation Solution
A rib waveguide type high-order mode filter is designed with a plate-like slab region, a projection portion, and a mesa region made of the same material, where the mesa region includes a doped area with impurity doping for optical absorption, effectively confining and absorbing high-order mode light to minimize stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-order mode filter is used to eliminate high-order mode light from the optical waveguide, then the high-order mode light is effectively eliminated, but the eliminated light becomes stray light that disperses through the clad region or slab region and causes noise in other optical signals
Solution Approach 1:
The patent converts the harmful stray light into useful absorbed energy by introducing a doped region with high optical absorption coefficient. The doped region captures the high-order mode light that would otherwise become stray light and converts it to thermal energy through absorption, thereby eliminating the harmful effect while maintaining the benefit of high-order mode elimination
Solution Approach 2:
The patent applies local quality by creating a doped region with specific impurity concentration only in the area where high-order mode light is eliminated, while keeping other regions undoped. This localized doping provides targeted optical absorption exactly where needed, converting the local stray light problem into a controlled energy dissipation zone
2Object-generated harmful factors
If impurity doping is applied to the mesa region to add optical-absorption function, then stray light is suppressed, but the device complexity increases due to additional doping process
Solution Approach 1:
The patent merges the high-order mode elimination function and the optical absorption function into a single integrated structure - the doped mesa region. This unified design eliminates the need for separate absorption components and reduces overall device complexity despite adding the doping process
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 solution significantly reduces fundamental mode loss and efficiently eliminates high-order mode light, suppressing stray light and maintaining low propagation losses in optical elements.
Implementation Method 1
the mesa region includes a doped area in which an optical-absorption function is added by impurity doping into the material
Data Source
AI summary
A rib waveguide type high-order mode filter includes a plate-like slab region 1; a projection portion 2 formed in a stripe along a waveguiding direction of light on the slab region 1; and a mesa region 4 having a bottom surface positioned at the same level as that of the bottom surface of the slab region 1 and a top surface positioned at a higher level than that of the top surface of the slab region 1, on at least one side of the slab region 1, wherein the projection portion 2, the slab region 1, and the mesa region 4 are made of the same material; and the mesa region 4 includes a doped area 4a in which an optical-absorption function is added by impurity doping into the material.