Integrated Optical Coupler for Flared Laser Wavefront Matching
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Solution Overview
Problem
The challenge of efficiently coupling a flared laser source with a photonic chip waveguide is exacerbated by the elliptical spatial distribution of the optical signal from the flared laser source, which is difficult to align with the single-mode waveguide due to their differing dimensions and complex production of planar gradient-index lenses.
Innovation Solution
An optoelectronic system with a coupler, intermediate waveguides, and a combiner on a photonic chip that includes a central correction section to align and focus the optical signal, using curved waveguides and phase shifters to ensure identical optical paths and minimize phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planar gradient-index lenses (photonic crystal type) are used to collimate the optical signal, then collimation function is achieved, but production complexity increases and manufacturing precision is strongly impacted by imperfections
Solution Approach 1:
The patent introduces an intermediate photonic crystal layer with a specific periodic structure that acts as a mediator between the flared laser source and the output waveguide. This intermediate structure provides the necessary phase correction and mode matching without requiring complex planar gradient-index lenses, thereby reducing manufacturing precision requirements while maintaining collimation functionality.
Solution Approach 2:
The patent modifies the periodicity and geometric parameters of the photonic crystal structure to achieve the desired optical transformation. By carefully designing the lattice constant, hole radius, and filling fraction, the system achieves efficient coupling without the need for complex gradient-index profiles that are sensitive to manufacturing imperfections.
2Reliability
If free-space optical coupling with collimation and focusing lenses is used, then coupling between flared laser source and single-mode fiber is achieved, but device complexity increases and alignment sensitivity increases
Solution Approach 1:
The patent merges the collimation and focusing functions into a single integrated photonic crystal structure that is directly coupled to both the flared laser source and the output waveguide. This eliminates the need for separate free-space lenses and their complex alignment, reducing device complexity while maintaining reliable coupling performance through direct waveguide-to-waveguide coupling.
3Device complexity
If the optical signal with highly elliptical spatial distribution is directly coupled to the single-mode waveguide, then coupling difficulty increases due to dimension mismatch, but no additional optical components are needed
Solution Approach 1:
The patent employs an intermediate photonic crystal coupling section that transforms the highly elliptical spatial distribution of the flared laser source into a mode compatible with the single-mode output waveguide. This intermediate structure acts as a mode converter, bridging the dimension mismatch without requiring precise alignment of multiple components, thus reducing alignment sensitivity while maintaining low device complexity.
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 system achieves high collection and transmission efficiency of the optical signal, optimizing coupling performance by aligning the wavefronts and reducing manufacturing complexity and alignment sensitivity.
Implementation Method 1
an array of intermediate waveguides, coupled to the curved output of the coupler to receive the collected optical signal and transmit it to the curved input of the combiner
Implementation Method 2
a combiner, coupled to intermediate waveguides to receive the optical signals transmitted by the latter, and focus them to an input of the output waveguide, and being a planar focusing lens
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a coupling device between a flared laser source (10) and an output waveguide (3), comprising a coupler (20), a combiner (40), and an array of intermediate waveguides (30) located between the coupler and the combiner and comprising a central correction section (Sc) in which an effective index associated with the guided modes is adapted so that the optical paths of the intermediate waveguides (30) between the coupler (20) and the combiner (40) are identical to each other.