Parallel Rib Optical Waveguides for Lower Propagation Loss
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Solution Overview
Problem
Existing optical devices face increased propagation loss and potential breakdown due to high signal light intensity in rib optical waveguides, particularly in silicon photonics-based devices, leading to inefficiencies and potential device failure.
Innovation Solution
The implementation of a rib optical waveguide with parallel waveguides connected to a split coupler, featuring non-conductive slab regions and doped regions, allows for shared electrodes to attenuate signal light intensity through free carrier absorption, reducing optical absorption by the silicon substrate and minimizing electricity consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single rib optical waveguide is used to attenuate signal light intensity, then the device structure is simple, but propagation loss increases and device breakdown may occur when signal light intensity is high
Solution Approach 1:
The patent divides a single rib optical waveguide into N parallel waveguides (first waveguide, second waveguide, etc.), where each waveguide receives a portion of the total signal light. This segmentation reduces the light intensity in each individual waveguide, thereby reducing optical absorption by the silicon substrate and preventing device breakdown while maintaining the attenuation function through the PIN diode structure in each waveguide.
2Power
If electrodes are connected to both sides of the rib optical waveguide to enable free carrier absorption, then signal light intensity can be attenuated, but electricity consumption increases
Solution Approach 1:
The patent merges the electrode connections by providing a first electrode connected to the P-doped region and a second electrode connected to the N-doped region, where the electrodes are positioned at opposite ends of the parallel waveguide structure. This merging approach allows voltage to be applied across the entire structure, enabling free carrier absorption in all parallel waveguides simultaneously while optimizing the electrical configuration to reduce overall power consumption compared to individual electrode connections in each waveguide.
3Reliability
If N parallel waveguides are used to reduce propagation loss, then optical input tolerance increases, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by integrating the PIN diode structure within each parallel waveguide, allowing the same structural element (waveguide) to serve dual purposes: guiding light and enabling electro-optic modulation through free carrier absorption. The P-doped and N-doped regions are formed in the slab areas adjacent to each waveguide, creating a unified structure where electrical control is applied across all waveguides simultaneously, reducing the need for separate control mechanisms and thereby limiting the increase in device complexity.
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 configuration effectively reduces propagation loss and increases optical input tolerance while significantly decreasing electricity consumption compared to conventional devices.
Implementation Method 1
intensity of signal light is attenuated by absorption of signal light guided through the rib optical waveguide due to free carrier absorption of the electric current flowing through the rib optical waveguide
Implementation Method 2
when intensity of signal light input into the rib optical waveguide increases in the optical device 100, light absorption by the Si substrate 121 increases, and propagation loss in the rib optical waveguide 102 thus increases
Data Source
AI summary
An optical device includes a rib optical waveguide including N parallel waveguides connected to outputs of a split coupler of 1 input×N outputs, and a first electrode and a second electrode that are connected to the rib optical waveguide. The rib optical waveguide includes a non-conductive slab region formed between the waveguides, a P-doped region and an N-doped region. The P-doped region is formed in a first slab region outside one of outermost waveguides of the N waveguides and is connected to the first electrode. The N-doped region is formed in a second slab region outside the other one of the outermost waveguides of the N waveguides and is connected to the second electrode.