Optical Light Output Devices with On-Chip Back-Reflection Control
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Solution Overview
Problem
In photonics integrated circuits, back-reflected light from output facets can create false etalons and impact the stability of light sources, and existing solutions like anti-reflective coatings do not fully eliminate these reflections.
Innovation Solution
The integration of an on-chip lens in the slab waveguide, where the output waveguide terminates before the output side, allowing light to propagate through a free propagation region and be directed by an optical element to reduce back reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output waveguide is positioned close to the output side of the slab waveguide, then the light output efficiency is improved, but back-reflected light couples back into the output waveguide causing false etalons and instability
Solution Approach 1:
An optical element (lens or diffraction grating) is introduced as an intermediary component between the slab waveguide and the output waveguide. This intermediary changes the propagation direction of light, allowing the output waveguide to be positioned optimally for light extraction while preventing back-reflected light from coupling back into the waveguide, thus resolving the contradiction between output efficiency and source stability
Solution Approach 2:
The optical element manipulates light propagation by changing its direction in a different spatial dimension. By using a lens to focus light at a specific point or a diffraction grating to redirect light at specific angles, the system achieves efficient light extraction while spatially separating the output waveguide from the path of back-reflected light
2Reliability
If an optical element is added to reduce back reflections, then light source stability is improved, but device complexity increases
Solution Approach 1:
The optical element is integrated directly into the output facet of the slab waveguide, merging the light extraction function with the back-reflection prevention function in a single component. This integration approach reduces device complexity by eliminating the need for separate free-space optical components while maintaining light source stability
Solution Approach 2:
The optical element is fabricated using the same semiconductor manufacturing processes as the waveguide itself, allowing the waveguide structure to serve its own optical manipulation needs. The output facet is patterned or etched to create the optical element in-situ, eliminating the need for additional manufacturing steps or external components
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 significantly reduces back reflections into the output waveguide, enhancing the stability of light sources and minimizing the need for additional free space lenses, thus improving the efficiency and stability of the optical system.
Implementation Method 1
The output side of the slab waveguide forms or otherwise includes a lens that may change the direction that the light is propagating with respect to the optical axis
Data Source
AI summary
Configurations for an optical system used for guiding light and reducing back-reflection back in an output waveguide is disclosed. The optical system may include an output waveguide defined in a slab waveguide. The output waveguide may terminate before an output side of the slab waveguide, which may reduce the back-reflection of light from the output side back into the output waveguide. The output side may define an optical element that may steer the output light. The optical element may collimate the output light, cause the output light to converge, or cause the output light to diverge.