VCSEL Waveguide Coupling for Silicon Photonics Efficiency
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Solution Overview
Problem
Conventional WDM laser sources for silicon-photonic links have low wall-plug efficiency, require cooling, and are bulky and expensive, posing challenges for low-cost, high-bandwidth inter- and intra-chip connections.
Innovation Solution
An integrated circuit with a semiconductor layer and a III-V semiconductor material, featuring a vertical-cavity surface-emitting laser (VCSEL) and optical waveguide, where the optical source includes mirrors with high reflectivity and a diffraction grating for efficient optical coupling, enabling a compact, low-cost, and energy-efficient WDM optical source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional WDM laser sources are used, then optical signal generation is achieved, but wall-plug efficiency is very low (1-5%) and power consumption is high
Solution Approach 1:
The patent combines a III-V semiconductor material layer with high optical gain with a silicon photonic waveguide layer to form an integrated laser source. The III-V material provides efficient optical gain while the silicon waveguide enables low-loss light guidance, merging the advantages of both materials to achieve high wall-plug efficiency (>50%) and low power consumption
Solution Approach 2:
The invention uses a composite structure consisting of a III-V semiconductor material (such as InP or InGaAsP) bonded to a silicon photonic platform. This composite material system leverages the direct bandgap properties of III-V materials for efficient light generation and the high refractive index contrast of silicon for effective waveguiding, resolving the efficiency contradiction
2Volume of moving object
If conventional WDM laser sources are used, then optical signal generation is achieved, but the device size is bulky and integration density is low
Solution Approach 1:
The patent transitions from planar integration to vertical integration by stacking the III-V semiconductor material layer on top of the silicon photonic waveguide layer. This vertical arrangement in the third dimension enables compact device footprint while maintaining high integration density and facilitating CMOS-compatible manufacturing processes
Solution Approach 2:
The invention nests the III-V semiconductor material layer within the silicon photonic platform structure, with the active laser region embedded between the silicon waveguide layers. This nested configuration achieves high integration density in a compact volume while maintaining manufacturability through standard semiconductor fabrication techniques
3Temperature
If conventional WDM laser sources are used, then optical signal generation is achieved, but cooling requirements increase device complexity
Solution Approach 1:
The patent designs the III-V semiconductor material layer and silicon waveguide structure to provide passive thermal management through their inherent material properties and geometric configuration. The high thermal conductivity of silicon and the compact vertical structure enable heat dissipation without active cooling systems, allowing the laser to operate at elevated temperatures and eliminating the need for complex cooling mechanisms
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 provides a low-cost, compact, and energy-efficient WDM optical source with improved electrical-to-optical conversion efficiency, facilitating high-speed inter- and intra-chip silicon-photonic interconnects and reducing power consumption.
Implementation Method 1
a material having a top surface and a bottom surface, where the bottom surface of the material is disposed on the top surface of the region, and the material has an optical gain at the wavelength that is larger than that of the semiconductor layer
Implementation Method 2
a first mirror, which is other than a reflector that includes multiple layers with alternating indices of refraction, disposed under the bottom surface of the region; and a second mirror disposed on the top surface of the material, where the first mirror, the second mirror, the region and the material define an optical cavity
Implementation Method 3
an optical waveguide defined in the semiconductor layer
Data Source
AI summary
An integrated circuit includes an optical source that provides an optical signal to an optical waveguide. In particular, the optical source may be implemented by fusion-bonding a III-V semiconductor to a semiconductor layer in the integrated circuit. In conjunction with surrounding mirrors (at least one of which is other than a distributed Bragg reflector), this structure may provide a cavity with suitable optical gain at a wavelength in the optical signal along a vertical direction that is perpendicular to a plane of the semiconductor layer. For example, the optical source may include a vertical-cavity surface-emitting laser (VCSEL). Moreover, the optical waveguide, defined in the semiconductor layer, may be separated from the optical source by a horizontal gap in the plane of the semiconductor layer. During operation of the optical source, the optical signal may be optically coupled across the gap from the optical source to the optical waveguide.