On-Substrate Photonic Isolators With Bias-Controlled Sputtering
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Solution Overview
Problem
Existing optical isolators face challenges in achieving high Faraday rotation and integration with silicon-based photonic integrated circuits due to the need for expensive garnet substrates and additional lithography steps, leading to dimensional and mode incompatibilities with on-chip lasers.
Innovation Solution
A method for fabricating optical isolators directly on a substrate using planar processing techniques, such as RF sputtering, without a seed layer, by monitoring and maintaining bias voltage during deposition to achieve high Faraday rotation, enabling integration with silicon-based photonic circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional optical isolators are fabricated using garnet substrates with additional lithography steps, then high Faraday rotation can be achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the seed layer from the traditional fabrication process. By directly depositing the magneto-optic material layer on the substrate without requiring a separate seed layer and additional lithography steps, the method simplifies the fabrication process while maintaining high Faraday rotation performance.
Solution Approach 2:
The patent merges the substrate and magneto-optic material layer into a direct integration structure. The magneto-optic material is deposited directly on the substrate, combining what were previously separate components (substrate + seed layer + magneto-optic layer) into a simplified integrated structure, reducing fabrication complexity.
2Manufacturing precision
If traditional optical isolators are fabricated using garnet substrates with additional lithography steps, then high Faraday rotation can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent removes the expensive seed layer and additional lithography steps from the fabrication process. By directly depositing the magneto-optic material on the substrate, it eliminates costly materials and processing steps while achieving the same high Faraday rotation performance.
Solution Approach 2:
The patent replaces expensive garnet substrates and seed layers with a more cost-effective direct deposition approach on standard substrates. The method uses readily available substrates and simplifies the material stack, reducing overall manufacturing cost while maintaining performance.
3Productivity
If optical isolators are integrated with silicon-based photonic circuits, then compact size and computation speed are improved, but dimensional and mode incompatibilities arise
Solution Approach 1:
The patent applies local quality by optimizing the magneto-optic material layer properties specifically for integration with silicon photonic circuits. The direct deposition method allows precise control of layer thickness and composition to match the dimensional requirements of silicon-based waveguides and lasers, ensuring mode compatibility.
Solution Approach 2:
The patent changes the deposition parameters and material composition to achieve dimensional and mode compatibility with silicon photonic circuits. By controlling the direct deposition process, the magneto-optic layer can be precisely tailored to match the waveguide dimensions and optical modes of silicon-based lasers.
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 allows for compact, cost-effective, and reliable production of optical isolators with high Faraday rotation, compatible with silicon-based photonic circuits, enhancing computation and communication speed in computing platforms.
Implementation Method 1
performing sputtering of at least one target according to the at least one sputtering process parameter to deposit the optical isolator active layer on the substrate
Implementation Method 2
When this beam is passed through a magneto-optic material under application of magnetic field, it experiences a phenomenon called Zeeman splitting—a splitting of the dispersion curves of the two polarizations. This leads to a difference in refractive index at all wavelengths to some degree, which means the two polarizations have different velocities. This difference is called the magneto-optic circular birefringence, also known as Faraday rotation
Implementation Method 3
An optical isolator is the optical analogue of an electronic diode that only allows light to propagate in a forward direction, and attenuates or blocks back reflected light that propagates in a backward direction
Data Source
AI summary
A method of fabricating a gyrotropic device (e.g., an optical isolator) includes: providing a substrate comprising a waveguide layer and forming an optical isolator active layer on the waveguide layer of the substrate. Forming the optical isolator active layer includes, for a specified composition of the optical isolator active layer, deriving at least one sputtering process parameter, performing sputtering of a plurality of targets according to the at least one sputtering process parameter to deposit the optical isolator active layer on the waveguide layer of the substrate, measuring an initial value of a bias voltage at a first target of the plurality of targets; and throughout deposition of the optical isolator active layer, maintaining the bias voltage at the initial value to within a predetermined threshold of the initial value.