Waveguide Facet Layout for Efficient Angled Optical Coupling
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Solution Overview
Problem
Conventional methods for coupling waveguides, such as those using cleaved or etched facets, face challenges in precision and efficiency, particularly in achieving high coupling efficiency due to refraction effects and unintended resonances in laser devices where tight length control and low fabrication errors are required.
Innovation Solution
The solution involves rotating waveguides relative to each other and using angled facets to align the propagation directions with the angle of refraction, thereby reducing upward light propagation and enhancing coupling efficiency, while maintaining precise control through etched facets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etched facets are used to improve manufacturing precision, then fabrication error is reduced to about ±200 nm, but unintended reflections occur from the opposite facet of another waveguide causing FP effects
Solution Approach 1:
The patent applies asymmetry by using a flat facet on the first waveguide and an angled facet on the second waveguide. This asymmetric configuration prevents unintended reflections from the opposite facet of the second waveguide that would otherwise cause Fabry-Perot effects, while maintaining the manufacturing precision benefits of etched facets.
Solution Approach 2:
Instead of making both facets flat or both angled, the patent inverts the conventional approach by using one flat facet and one angled facet. This inversion resolves the FP effect problem while maintaining coupling efficiency.
2Object-generated harmful factors
If an angled facet is used on the second waveguide to eliminate FP resonances, then unintended reflections are reduced, but coupling efficiency decreases due to refraction effects
Solution Approach 1:
The patent optimizes the angle parameter of the second facet to balance two competing requirements: it must be angled enough to eliminate FP resonances but not so angled that refraction losses become excessive. By carefully selecting this parameter, the patent achieves both goals simultaneously.
3Reliability
If deep etched gratings are used to achieve broadband reflectivity, then wavelength selectivity is improved, but fabrication becomes challenging due to high aspect ratio
Solution Approach 1:
The patent extracts the reflector function from the deep etched grating structure and implements it using simple facet configurations (flat and angled facets). This eliminates the need for challenging deep etching processes while maintaining broadband reflectivity performance.
4Ease of manufacture
If MMI reflectors or loop mirrors are used to achieve broadband reflectivity, then ease of fabrication is improved, but device footprint increases significantly
Solution Approach 1:
The patent uses simple facet structures that require minimal space compared to MMI reflectors or loop mirrors. These compact facet-based reflectors achieve the same function with a much smaller footprint, making them suitable for integrated devices where space is limited.
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 approach significantly increases the coupling efficiency between waveguides by minimizing refraction losses and reducing unwanted reflections, achieving improved performance in laser devices with a smaller footprint compared to traditional methods.
Implementation Method 1
at least one first waveguide, the first waveguide comprising at least one partially reflective output end facet
Implementation Method 2
at least one second waveguide receiving the light passing the output end facet of the first waveguide at an input end facet of the second waveguide and guiding the light in a second propagation direction
Data Source
AI summary
Proposed is an optical component comprising: at least one first waveguide, the first waveguide comprising at least one partially reflective output end facet, wherein light passing the output end facet of the first waveguide propagates along a first propagation direction, and at least one second waveguide receiving the light passing the output end facet of the first waveguide at an input end facet of the second waveguide and guiding the light in a second propagation direction, wherein the output end facet and the input end facet are spaced from each other; and wherein the first waveguide and the second waveguide are arranged such that the first propagation direction and the second propagation direction are different. This proposal provides a concept, which is more efficient in view of coupling efficiency between the waveguides of the optical component.