Supermode Filtering Waveguide Emitters for Single-Mode Low-Loss Modulation
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Solution Overview
Problem
Coherent modulators in silicon are inherently high-loss due to modulating both phase and amplitude, leading to significant transmitter insertion loss and excess noise when amplifiers are used to increase output power, which is a challenge for high-data-rate applications like 600 GB, 800 GB, and 1 TB optical links.
Innovation Solution
A supermode filtering waveguide (SFW) emitter is used, comprising a first optical waveguide and a second optical waveguide evanescently coupled with a spacer layer, configured to selectively propagate only a single mode of optical modes, providing improved coupling efficiency and scalability to higher optical powers while minimizing intrinsic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If amplifiers are used to increase output power of coherent modulators, then output power is improved, but excess noise increases
Solution Approach 1:
The patent extracts and eliminates higher-order optical modes that carry noise through the supermode filtering mechanism. By designing the waveguide structure to support only the fundamental mode, noise-containing higher-order modes are filtered out, achieving noise reduction without requiring amplifiers
Solution Approach 2:
The patent dynamically adjusts the optical mode distribution through the evanescent coupling between waveguides. The coupled waveguide structure enables controlled mode propagation where the fundamental mode is maintained while higher-order modes are suppressed, providing dynamic mode filtering without active amplification
2Adaptability or versatility
If coherent modulators modulate both phase and amplitude, then modulation capability is improved, but insertion loss increases
Solution Approach 1:
The patent segments the optical modulation function into separate phase and amplitude components. By using independent waveguides for phase modulation and amplitude modulation, each component can be optimized separately, reducing the overall insertion loss while maintaining full coherent modulation capability
Solution Approach 2:
The patent introduces an intermediary optical coupling mechanism between waveguides that enables efficient power transfer with minimal loss. The evanescent coupling acts as a low-loss intermediary that connects different modulation functions without significant energy dissipation
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 SFW emitter enhances coupling efficiency, reduces fabrication costs, and supports high-data-rate applications by enabling efficient propagation of a single optical mode, thereby reducing noise and increasing output power without the need for additional amplifiers.
Implementation Method 1
The second optical waveguide is evanescently coupled with the first optical waveguide and is configured, in conjunction with the first waveguide, to selectively propagate only a first mode of a plurality of optical modes
Data Source
AI summary
An optical apparatus comprises a semiconductor substrate, and a supermode filtering waveguide (SFW) emitter disposed on the semiconductor substrate. The SFW emitter comprises a first optical waveguide, a spacer layer, and a second optical waveguide spaced apart from the first optical waveguide by the spacer layer. The second optical waveguide is evanescently coupled with the first optical waveguide and is configured, in conjunction with the first waveguide, to selectively propagate only a first mode of a plurality of optical modes. The SFW emitter further comprises an optically active region disposed in one of the first optical waveguide and the second optical waveguide.