Vertical Optical Coupler with Angled Mirror for Silicon Photonics
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Solution Overview
Problem
Existing optical mode converters (OMCs) in silicon photonics systems face inefficiencies in optical coupling and bandwidth, and often exhibit polarization dependency, which limits their effectiveness in transferring light between silicon waveguides and optic fibers.
Innovation Solution
The implementation of a vertical optical coupler with an angled reflective mirror, formed by a dielectric interface, which uses total internal reflection to efficiently couple light between silicon waveguides and optic fibers, reducing numerical aperture and back-reflection through a spacer and anti-reflective coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing optical mode converters (OMCs) are used to improve optical coupling between silicon waveguides and optic fibers, then coupling efficiency is improved, but polarization dependency increases above desired levels
Solution Approach 1:
The patent transitions from horizontal optical coupling to vertical optical coupling by introducing a vertical cavity structure with a bottom mirror. Light is coupled vertically into the cavity through the top surface, perpendicular to the waveguide plane, eliminating polarization dependency while maintaining high coupling efficiency. This dimensional change from in-plane to out-of-plane coupling resolves the contradiction between coupling efficiency and polarization sensitivity.
2Reliability
If existing optical mode converters (OMCs) are used to improve optical coupling, then coupling efficiency is improved, but bandwidth is limited
Solution Approach 1:
The patent achieves broadband response by carefully controlling the cavity thickness parameter to be less than the coherence length of the light source. This parameter optimization allows the vertical cavity structure to maintain high coupling efficiency across a wide spectral range, resolving the contradiction between coupling efficiency and bandwidth. The cavity acts as a wavelength-insensitive coupling structure, enabling simultaneous achievement of high efficiency and broad bandwidth.
3Adaptability or versatility
If vertical optical coupling is implemented with a dielectric interface mirror, then polarization dependency is reduced, but back-reflection increases
Solution Approach 1:
The patent introduces a top mirror as an intermediary reflective element positioned above the vertical cavity. This top mirror, combined with the bottom mirror, creates a resonant cavity structure that directs light into the waveguide while minimizing back-reflection toward the light source. The intermediary mirror structure enables polarization-independent coupling while controlling harmful back-reflections through constructive and destructive interference within the cavity.
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 enhances optical coupling efficiency, reduces polarization dependency, and achieves broadband response, enabling more stable and efficient light transfer between silicon photonics devices and optic fibers.
Implementation Method 1
uses total internal reflection to efficiently couple light between silicon waveguides and optic fibers
Data Source
AI summary
Embodiments of the present disclosure are directed toward techniques and configurations for an optical coupler. In some embodiments, the device may include an optical waveguide to transmit light input from a light source. The optical waveguide may include a semiconductor layer, having a trench with one facet that comprises an edge formed under an approximately 45 degree angle and another facet formed substantially normal to the semiconductor layer. The edge may interface with another medium to form a mirror to receive inputted light and reflect received light substantially perpendicularly to propagate the received light. Other embodiments may be described and/or claimed.