Thermo-optic Phase Shifter with Integrated Resistive Heating
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Solution Overview
Problem
Thermo-optic phase shifters in photonics circuitry face challenges in achieving efficient heat coupling and minimizing optical insertion loss, particularly when a separate heating element is used in close proximity to the optical waveguide.
Innovation Solution
The apparatus integrates a contact region within the semiconductor layer to conduct electrical current along the optical waveguide, applying resistive heating, and utilizes an optical transition region with tailored shape and doping levels to concentrate heating and minimize optical loss, eliminating the need for a separate heating element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a separate heating element is placed in close proximity to the optical waveguide to improve heating efficiency, then heat coupling efficiency is improved, but optical insertion loss increases
Solution Approach 1:
The patent merges the heating function with the optical waveguide itself by doping the semiconductor layer to create regions with different doping levels. The waveguide structure serves dual purposes: guiding optical signals and generating heat through resistive heating in doped regions, eliminating the need for separate heating elements that would cause optical loss.
Solution Approach 2:
The semiconductor layer is designed to perform multiple functions simultaneously: it acts as both the optical waveguide and the heating element. By controlling doping levels in different regions of the same semiconductor layer, the structure provides both optical confinement and resistive heating capabilities without requiring additional components.
2Loss of energy
If thermally insulative material is used to isolate the heating element from other elements, then heat loss to substrate is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the heating function from separate heating elements and integrates it directly into the optical waveguide structure through doping. This eliminates the need for additional thermally insulative materials and complex isolation structures, as the heating is generated within the waveguide itself.
Solution Approach 2:
The patent changes the doping level parameter in different regions of the semiconductor layer to achieve both optical guidance and resistive heating. By modifying the electrical properties (doping levels) rather than adding physical insulation layers, the solution reduces structural complexity while maintaining thermal efficiency.
3Power
If the semiconductor layer is doped to carry current parallel to the waveguide, then resistive heating efficiency is improved, but optical loss may increase
Solution Approach 1:
The patent applies local quality by creating regions with different doping levels within the semiconductor layer. High doping regions are placed where heating is needed, while lower doping regions maintain optimal optical properties. This spatial variation in doping quality allows simultaneous achievement of efficient heating and low optical loss.
Solution Approach 2:
The semiconductor layer is segmented into regions with different doping levels: highly doped regions for resistive heating and lightly doped regions for optical guidance. This segmentation allows each region to be optimized for its specific function while working together as an integrated structure.
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
This approach enhances the efficiency of thermo-optic phase shifters by reducing heat loss to other elements and minimizing optical insertion loss, allowing for smaller, low-power devices with a greater tuning range within a given power budget.
Implementation Method 1
a first contact region formed in the semiconductor layer and intersecting the optical waveguide, and configured to conduct electrical current along a dimension of the optical waveguide to apply resistive heating to the optical waveguide
Data Source
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AI summary
Embodiments include a method and associated apparatuses for phaseshifting an optical signal. The method comprises receiving, at a first end of an optical waveguide formed in a semiconductor layer and extending along a first axis, an optical signal having a first phase. The method further comprises transmitting, at a second end of the optical waveguide opposite the first end, a modified optical signal having a second phase different than the first phase. Transmitting a modified optical signal comprises applying a voltage signal between a first contact region and a second contact region formed in the semiconductor layer apart from the first axis. Applying a voltage signal causes an electrical current to be conducted along a dimension of the optical waveguide. The electrical current causes resistive heating of the optical waveguide and a desired phase shift between the first phase and the second phase.