Matrix Optical Device With Vertical MMI Coupler For Intrachip Wiring
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Solution Overview
Problem
Current optical devices for intrachip optical wiring face challenges in achieving high precision and low loss while maintaining a small size, particularly in three-dimensional structures with sub-micron dimensions and high alignment accuracy, due to limitations in alignment tolerance and coupling efficiency of existing optical couplers like MMI and taper waveguides.
Innovation Solution
The development of a matrix-form optical device with silicon photonic waveguides and control electrodes that apply voltage or current to control the phase of light, enabling three-dimensional direction control of output light beams, and the use of hydrogen-terminated amorphous silicon for low-loss optical propagation in multilayer optical wiring, including a vertical MMI optical coupler design with refractive index distribution for improved coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional optical couplers (MMI or taper waveguides) are used in three-dimensional structures with sub-micron dimensions, then device integration is achieved, but alignment tolerance is insufficient and coupling efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating a connection unit with a specific refractive index distribution that differs from the surrounding waveguide structures. The connection unit has a higher refractive index than the adjacent waveguides, forming a localized region with optimized optical properties. This local modification enables improved light coupling between waveguides in three-dimensional structures while maintaining sub-micron dimensions and providing sufficient alignment tolerance for manufacturing.
2Volume of moving object
If optical transmission is performed in space without constituent components, then device size is reduced, but alignment precision between transmission and reception units deteriorates
Solution Approach 1:
The patent introduces a connection unit as an intermediary component between transmission and reception waveguides. This connection unit acts as a mediator that facilitates optical coupling while compensating for alignment deviations. The specialized refractive index distribution in the connection unit creates a tolerance window that maintains coupling efficiency even when alignment precision is limited, thus enabling compact space transmission without requiring extremely precise alignment.
3Ease of manufacture
If multiple optical wiring layers are fabricated using backend CMOS process, then manufacturing cost is reduced, but alignment accuracy between layers becomes more difficult to maintain
Solution Approach 1:
The patent employs parameter changes by optimizing the refractive index distribution in the connection unit to create a system with inherent tolerance to alignment variations. By carefully controlling the refractive index difference between the connection unit and adjacent waveguides, the design achieves a balance where standard backend CMOS fabrication processes can be used without requiring ultra-precise alignment, thus reducing manufacturing cost while maintaining acceptable alignment accuracy.
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 a compact, efficient optical device with high alignment tolerance and reduced light loss, enabling precise control of output light direction and increased integration density in intrachip optical wiring.
Implementation Method 1
Due to strong optical confinement effect based on high refractive index difference, even a bent waveguide of which curvature radius is small can achieve a low level of radiation loss
Implementation Method 2
n×m third optical waveguides (22), in which are arranged in a matrix form, propagate the n×m lights which are output from the n second distribution devices (20), a plurality of control electrodes (30a, 30b) configured to apply a voltage or current to each of the third optical waveguides (22), and control the phase of the light propagating through the third optical waveguide (22)
Implementation Method 3
A photonic wire waveguide formed using hydrogen-terminated amorphous silicon (a-Si:H) deposited by plasma CVD at a low temperature of about 300 degrees Celsius on SiO2 has already realized low loss optical propagation property
Data Source
AI summary
An optical device according to an embodiment includes a laser light source, a first optical waveguide that propagates light being output from the laser light source, a first distribution device that distribute the light into n lights, n second optical waveguides that propagates the n lights being output from the first distribution device, n second distribution devices that distribute each of the n lights into m lights, n×m third optical waveguides arranged in a matrix form and propagates the n×m lights being output from the m second distribution devices, a control electrode that apply a voltage or current to each of the third optical waveguides, and control phase of the light propagating through the third optical waveguides, and an output end surface that output the n×m lights.