Hybrid Laser Evanescent Coupling for SOI CMOS Integration

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Solution Overview

Problem

Current silicon photonics hybrid laser systems face challenges in achieving efficient and compact designs with low power consumption, due to limitations in alignment requirements, material confinement factors, and integration with optical networks.

Innovation Solution

A hybrid laser design utilizing CMOS technology to define critical parts of the laser cavity, including gratings and reflectors, with an evanescent coupling interface between passive and active waveguides, allowing for efficient radiation coupling and reduced footprint, and enabling better control over wavelength and gain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If fiber coupling an external packaged laser to the silicon chip is used, then thermal isolation is improved, but footprint and coupling cost increase

Engineering Contradiction:
Improvethermal isolationVSAvoidfootprint
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The patent merges the laser source with the silicon photonic chip through hybrid integration, combining the III-V laser die with the silicon waveguide platform. This integration eliminates the need for external fiber coupling while maintaining thermal isolation through the bonded interface, thereby reducing footprint without sacrificing thermal management.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If individual laser dies are flip chip mounted to the optical wafer, then integration is improved, but alignment complexity increases

Engineering Contradiction:
ImproveintegrationVSAvoidalignment
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent implements preliminary alignment features during the fabrication process, including pre-defined alignment marks and registration structures on both the III-V laser die and silicon wafer. This preliminary preparation enables accurate alignment through standard bonding processes without requiring complex real-time alignment systems, thus achieving high integration with manageable manufacturing precision.

Inventive Principle:
Principle #10Preliminary action

3Loss of energy

If evanescent coupling interface is used between waveguides, then coupling efficiency is improved, but confinement factor decreases

Engineering Contradiction:
Improvecoupling lossVSAvoidconfinement factor
Core Design Contradiction:
Loss of energyVSQuantity of substance

Solution Approach 1:

The patent optimizes the evanescent coupling interface by carefully controlling the gap distance, waveguide dimensions, and material composition at the bonding interface. By adjusting these parameters, the system achieves efficient power transfer through evanescent coupling while maintaining sufficient optical confinement in the active region to ensure adequate gain for laser operation.

Inventive Principle:
Principle #35Parameter changes

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 results in a compact, efficient hybrid laser with improved wavelength accuracy and reduced power consumption, suitable for integrated photonic circuits and applications requiring high data bandwidth and miniaturization.

Implementation Method 1

an evanescent coupling interface is defined between the second optical waveguide and the first optical waveguide for coupling radiation from the second optical waveguide to the first optical waveguide

Methodology Applied
Scientific EffectEvanescent coupling: Total Internal Reflection

Data Source

PatentEP2539979B1Laser light coupling into SOI CMOS photonic integrated circuit
Publication Date: 2018.05.23 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP2539979B1 patent drawingFigure 1~2A
  • EP2539979B1 patent drawingFigure 2B~2C
  • EP2539979B1 patent drawingFigure 3A~3B

AI summary

A hybrid laser (100) is described for generating radiation, the hybrid laser (100) comprising an optical passive material (110) and an optical active material (120). The hybrid laser (100) furthermore comprises a first optical waveguide (112) and optical laser components (114) comprising reflectors in the optical passive material (110). The first optical waveguide (112) is adapted for coupling out radiation from the hybrid laser. The laser also comprises a second optical waveguide (122) defined in the optical active material (120). The optical laser components (114) comprise reflectors defining a cavity and furthermore are adapted for providing laser cavity confinement in the first optical waveguide (112) and the second optical waveguide (122). The second optical waveguide (122) thereby is positioned at least partly over the first optical waveguide (112) so that an evanescent coupling interface is defined between the second optical waveguide (122) and the first optical waveguide (112) and the evanescent coupling interface is positioned within the laser cavity.