Optical Waveguide Emitter Turning Section Refractive Index
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Solution Overview
Problem
Coherent modulators in silicon face high loss due to phase and amplitude modulation, requiring high transmitter insertion loss and introducing excess noise with inline amplifiers, which limits data transmission distance and increases fabrication costs.
Innovation Solution
An optical waveguide emitter with evanescently coupled waveguides that selectively propagate a single optical mode, featuring a refractive index-increasing feature in the turning waveguide section and scalable design for improved coupling efficiency and reduced intrinsic losses, integrated directly with a silicon substrate for simplified fabrication and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coherent modulators in silicon are used for long-haul and metro applications, then data transmission capability is improved, but insertion loss increases to 25-29 dB
Solution Approach 1:
The optical waveguide emitter is divided into multiple evanescently coupled waveguides, each contributing to the overall optical output. This segmentation allows the system to achieve higher total output power while maintaining low loss per waveguide, directly addressing the high insertion loss problem of conventional silicon coherent modulators.
Solution Approach 2:
Multiple optical waveguides are merged into a single emitter structure that combines their optical outputs. The evanescent coupling between adjacent waveguides enables coherent combination of optical fields, achieving constructive interference that boosts output power without the high losses associated with traditional silicon modulators.
2Power
If inline amplifiers are added to compensate for high loss, then output power is improved, but excess noise is introduced
Solution Approach 1:
The waveguide emitter performs power amplification intrinsically through the evanescent coupling mechanism before the signal enters the transmission fiber. This preliminary action achieves power boosting without requiring subsequent inline amplifiers, thereby preventing the introduction of excess noise that would otherwise be necessary to compensate for high losses.
3Shape
If a turning waveguide section is added to the optical path, then spatial configuration is improved, but optical loss typically increases
Solution Approach 1:
The turning waveguide section employs a curved geometry to redirect the optical path. By optimizing the curvature radius and transition profiles, the design achieves the necessary spatial reconfiguration while minimizing radiation losses and mode distortion, preventing the typical increase in optical loss associated with waveguide bends.
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 enhances coupling efficiency, reduces noise, and allows for higher optical powers while maintaining low intrinsic losses, supporting increased data rates and longer transmission distances with improved fabrication efficiency.
Implementation Method 1
An optical waveguide emitter with evanescently coupled waveguides that selectively propagate a single optical mode
Implementation Method 2
featuring a refractive index-increasing feature in the turning waveguide section
Data Source
AI summary
Aspects described herein include an optical waveguide emitter that includes a first optical waveguide and a second optical waveguide that are evanescently coupled and collectively configured to selectively propagate only a first mode of a plurality of optical modes. Each of the first optical waveguide and the second optical waveguide extend through an input waveguide section, a turning waveguide section, and an output waveguide section. One or more of the input waveguide section, the turning waveguide section, and the output waveguide section includes an optically active region. The optical waveguide emitter further includes a refractive index-increasing feature in the turning waveguide section.