Tapered Dielectric Waveguide Optical Absorber
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Solution Overview
Problem
Current methods for creating optical absorbers for dielectric optical waveguides are complex and prone to back-reflection, often requiring additional transition structures or costly materials like germanium, which can affect yield and introduce unwanted reflections.
Innovation Solution
An optical absorber integrated with a dielectric optical waveguide featuring a waveguide cladding, a tapered or wedge-shaped dielectric optical waveguide core, and an absorption material layer that reduces back-reflection by gradually increasing the optical mode dimension, allowing for complete light absorption without the need for ion implantation or germanium, and can be arranged in a spiral or folded-loop shape to enhance integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transition structure is used to transmit light from dielectric optical waveguide to silicon absorber, then light absorption is achieved, but device complexity increases due to additional structures
Solution Approach 1:
The patent merges the waveguide core and absorber into a single tapered structure. The dielectric optical waveguide core itself is designed with a tapered geometry where the width gradually decreases from the input end to the output end, eliminating the need for separate transition structures. This integrated design allows the waveguide to directly function as both light transmission and absorption medium.
Solution Approach 2:
The patent changes the geometric parameters of the waveguide core by implementing a tapered profile. The width of the waveguide core varies continuously along its length, creating a gradual transition that enables adiabatic mode expansion. This parameter change allows the optical mode to expand gradually, increasing interaction with the absorption material without requiring additional transition structures.
2Reliability
If germanium absorber is used on silicon waveguide, then light absorption is improved, but manufacturing yield is influenced by epitaxial growth and cost increases
Solution Approach 1:
The patent replaces expensive germanium absorbers with a tapered dielectric waveguide structure that uses standard materials. The absorption function is achieved through the geometric design rather than requiring costly germanium epitaxial growth, thereby eliminating the manufacturing yield issues associated with germanium integration while maintaining effective light absorption.
3Reliability
If germanium absorber is used on silicon waveguide, then light absorption is improved, but back-reflection is introduced at the interface
Solution Approach 1:
The patent changes the geometric parameters of the waveguide core by implementing a tapered profile. The width of the waveguide core varies continuously along its length, creating a gradual transition that enables adiabatic mode expansion. This parameter change allows the optical mode to expand gradually, increasing interaction with the absorption material without requiring additional transition structures.
Solution Approach 2:
Instead of using a sudden interface between different materials (which causes back-reflection), the patent inverts the approach by using a continuous geometric transition within the same material. The tapered dielectric waveguide core provides a gradual impedance transition that eliminates back-reflection while maintaining absorption efficiency.
4Reliability
If ion implantation doping is used to create silicon absorber, then light absorption is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex ion implantation doping processes with a geometric design approach. The absorption function is achieved through the tapered geometry of the dielectric waveguide core rather than requiring additional doping steps, thereby simplifying the manufacturing process while maintaining absorption efficiency.
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 effectively reduces back-reflection and enhances light absorption efficiency, particularly for TM polarized light, improving the performance and manufacturability of optical integrated circuits without introducing additional complexity or costly materials.
Implementation Method 1
the evanescent tail of the optical mode starts to contact the absorption material layer above, and the absorption material layer introduces absorption, thus attenuating the optical power propagating along the waveguide
Implementation Method 2
the gradient of an adiabatic mode is smooth enough to avoid abrupt transitions, thus the back-reflection can be significantly reduced
Implementation Method 3
a silicon (Si) waveguide, as a semiconductor waveguide, can be formed into an optical absorber through doping by an ion implantation process, so that light can be eliminated by free carrier absorption
Implementation Method 4
a material of the absorption material layer is silicon that can be used to absorb light with a certain wavelength (such as visible light wavelength range)
Data Source
AI summary
The invention provides an optical absorber and an optical absorption chip integrated with a dielectric optical waveguide. The optical absorber comprises a waveguide cladding, a dielectric optical waveguide core and an absorption material layer, wherein the waveguide cladding surrounds the dielectric optical waveguide core and the absorption material layer, the dielectric optical waveguide core comprises a first end and a second end, a radial dimension of the dielectric optical waveguide core gradually decreases from the first end to the second end, a material of the absorption material layer can be metal or silicon, and the absorption material layer can be located on an upper layer of the dielectric optical waveguide core, or on a side of the dielectric optical waveguide core, or on a lower layer of the dielectric optical waveguide core, so that the optical absorber can reduce back-reflection and allow light to be completely absorbed.