Photonic Chip Optical Path Folding for Alignment Tolerance
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Solution Overview
Problem
Existing photonic integrated circuits face challenges in efficiently coupling light beams with external devices due to alignment tolerance issues and manufacturing complexities, particularly with integrated lenses, which are sensitive to environmental conditions and require precise angular alignment.
Innovation Solution
A photonic chip design incorporating a light-guiding layer with integrated reflective structures and a collimation structure within the light-guiding layer, allowing for optical path folding to expand beam diameter and simplify manufacturing through standard processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If integrated lenses are used to broaden and collimate light beams, then alignment tolerance between chip and optical fiber is improved, but manufacturing complexity increases due to precise angular alignment requirements and sensitivity to environmental conditions
Solution Approach 1:
The patent replaces the mechanical alignment system (integrated lenses requiring precise angular alignment) with an optical path folding system using reflective structures. The light beam is reflected at 45-degree angles through the substrate thickness to achieve beam broadening and collimation without requiring精密 mechanical lens alignment, thereby substituting a mechanically complex system with a simpler optical path design
Solution Approach 2:
The patent utilizes the substrate thickness dimension (z-direction) to fold the optical path, transforming the two-dimensional lens alignment problem into a three-dimensional optical path design. By reflecting light through the substrate thickness at 45-degree angles, the system achieves beam collimation and broadening in the lateral plane without requiring precise lens positioning in the vertical direction
2Loss of energy
If anti-reflective coatings are applied to integrated lenses, then light coupling efficiency is improved, but reliability decreases due to fragility in hot and humid environments
Solution Approach 1:
The patent extracts and eliminates the anti-reflective coating component from the system by replacing the lens-based approach with a reflective structure-based optical path folding approach. This removes the source of reliability problems (fragile anti-reflective coatings) while maintaining optical coupling efficiency through the reflective 45-degree angle structures
Solution Approach 2:
The patent converts the potential harm of Fresnel reflections at substrate interfaces into a beneficial effect by using controlled reflection at 45-degree angles through the substrate thickness. The reflective structures intentionally utilize interface reflections to fold the optical path and achieve beam collimation, transforming what would normally be a loss mechanism into the core functioning principle of the system
3Ease of manufacture
If surface coupling gratings are used for light injection/extraction, then coupling between waveguides and optical fibers is achieved, but alignment tolerance is insufficient requiring complex active alignment techniques
Solution Approach 1:
The patent uses the substrate thickness dimension to fold the optical path and broaden the beam in the lateral plane, effectively decoupling the alignment tolerance from the grating-fiber interface. The optical path folding occurs in the vertical dimension while the beam broadening effect manifests in the lateral dimension, allowing for simpler alignment operations
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
Enhances alignment tolerance and reduces manufacturing complexity by using digital lens structures that are less sensitive to environmental conditions, enabling efficient light coupling with external devices.
Implementation Method 1
a reflective structure (152) on the rear face (F2) of the substrate (10), the arrangement of reflective structures (151, 152) ensuring propagation of light between the vertical coupler (122) and the collimation structure (14) along an optical path having at least one fold
Implementation Method 2
a collimation structure (14) formed at least in part in the light-guiding layer (12), allowing for optical path folding to expand beam diameter
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5c
AI summary
The invention relates to a photonic chip (1) comprising a light-guiding layer (12) supported by a substrate (10) and covered by an encapsulation layer (13). The chip has a front face (F1) on the side of the encapsulation layer (13) and a back face (F2) on the side of the substrate (10). The light-guiding layer includes a light-guiding structure (121) optically coupled to a vertical coupler (122) configured to receive light from the waveguide and form a beam of light directed towards one of the front and back faces. The chip further includes a collimation structure (14) formed at least partially within the light-guiding layer (12), and an arrangement of one or more reflective structures (151, 152), each on one of the front and back faces.This arrangement is designed to ensure the propagation of light between the vertical coupler and the collimation structure along an optical path with at least one fold.