Hybrid Optical Source with Semiconductor Reflector for Low-Loss Coupling
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Solution Overview
Problem
Current optical interconnects in high-performance computing face challenges with low wall-plug efficiency, high power consumption, and wavelength instability due to inefficient coupling between III-V semiconductor laser sources and silicon optical waveguides, leading to increased optical coupling loss and unsuitable wavelength stability for dense wavelength-division-multiplexing links.
Innovation Solution
A hybrid optical source is designed with a semiconductor reflector optically coupled to a semiconductor-on-insulator chip, featuring a diffraction grating coupler and a III-V semiconductor optical amplifier, which redirects light in a surface-normal direction to reduce optical loss and enhance wavelength control, creating a high-efficiency optical cavity with tunable wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If III-V semiconductor laser sources are used for optical interconnects, then high output power (2-4 mW) can be achieved, but large optical coupling loss (3-10 times efficiency reduction) occurs between the laser source and silicon optical waveguide
Solution Approach 1:
The patent introduces a semiconductor reflector as an intermediary component between the III-V semiconductor laser source and the silicon optical waveguide. This reflector redirects the light in a surface-normal direction, creating an optical cavity that enables efficient coupling. The intermediary structure transforms the emission pattern and facilitates mode matching between the laser source and waveguide, thereby reducing optical coupling loss while maintaining high output power.
2Use of energy by stationary object
If uncooled laser sources are used to reduce power consumption, then wall-plug efficiency can reach around 10%, but wavelength stability becomes larger than 100 pm which is unsuitable for dense wavelength-division-multiplexing links
Solution Approach 1:
The patent employs parameter changes by creating a hybrid optical cavity with specific geometric and optical parameters. The cavity length, reflector positioning, and grating coupler design are optimized to provide wavelength selection and stabilization. This allows the uncooled laser source to maintain narrow linewidth and stable wavelength operation without requiring thermal-electric cooling, achieving both high wall-plug efficiency and wavelength stability suitable for dense wavelength-division-multiplexing.
3Stability of the object's composition
If thermal-electric cooling is used to maintain wavelength stability, then good wavelength control can be achieved, but power consumption increases significantly with wall-plug efficiency reduced to only 1-2%
Solution Approach 1:
The patent extracts the wavelength stabilization function from the thermal-electric cooling system and implements it through the optical cavity structure itself. The semiconductor reflector and grating coupler form a resonant cavity that provides inherent wavelength selection and stabilization through optical feedback, eliminating the need for power-consuming thermal-electric cooling while maintaining narrow linewidth and stable wavelength operation.
4Reliability
If optical amplifiers and reflectors are integrated to create optical cavities, then high wall-plug efficiency and narrow linewidth can be achieved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a unified hybrid optical source structure. The semiconductor reflector, optical amplifier, and grating coupler are integrated to form a compact optical cavity that simultaneously provides light amplification, wavelength selection, and directional coupling. This merging of components achieves high wall-plug efficiency and narrow linewidth while minimizing the overall device footprint and complexity compared to separate systems.
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 hybrid optical source achieves low-power operation (<1 pJ/bit) with high wall-plug efficiency and narrow lasing linewidth, facilitating efficient silicon-photonic interconnects and enabling high-performance computing applications with improved alignment tolerance and reduced footprint.
Implementation Method 1
a semiconductor reflector, mechanically and optically coupled to the optical amplifier, which reflects the optical signal over the range of wavelengths to change a direction of propagation of the optical signal
Implementation Method 2
The optical coupler includes a diffraction grating
Implementation Method 3
an optical amplifier that provides an optical signal having a range of wavelengths; the optical amplifier includes a semiconductor optical amplifier
Implementation Method 4
the optical amplifier, the semiconductor reflector, the optical coupler, the optical waveguide and the reflector define an optical cavity in the hybrid optical source
Data Source
AI summary
A hybrid optical source that provides an optical signal having a wavelength is described. This hybrid optical source includes an edge-coupled optical amplifier (such as a III-V semiconductor optical amplifier) aligned to a semiconductor reflector (such as an etched silicon mirror). The semiconductor reflector efficiently couples (i.e., with low optical loss) light out of the optical amplifier in a direction approximately perpendicular to a plane of the optical amplifier. A corresponding optical coupler (such as a diffraction grating or a mirror) fabricated on a silicon-on-insulator chip efficiently couples the light into a sub-micron silicon-on-insulator optical waveguide. The silicon-on-insulator optical waveguide couples the light to additional photonic elements (including a reflector) to complete the hybrid optical source.