Optical Out-Coupler Unit for Photonic Integrated Chips
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Solution Overview
Problem
Existing optical out-couplers on photonic integrated chips face challenges in minimizing reflection and transmission losses, leading to incomplete coupling of light from waveguides into free space or adjacent materials.
Innovation Solution
An optical out-coupler unit with a substrate and waveguide featuring a reflective surface inclined at 45° or more, a transparent filler portion, and an anti-reflection coating, which reduces back-reflection and enhances light coupling efficiency by utilizing total internal reflection and refractive index differences between materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional out-coupler is used to couple light vertically out of a waveguide, then light can be extracted from the waveguide, but reflection and transmission losses are not minimized leading to incomplete coupling
Solution Approach 1:
The out-coupler is divided into multiple functional segments: a facet for light entry, a reflective surface at 45° for directional reflection, and a transparent filler portion for optical path management. This segmentation allows each component to optimize its function, minimizing losses at each interface while maintaining high coupling efficiency.
Solution Approach 2:
A transparent filler portion is introduced as an intermediary medium between the facet and the reflective surface. This filler material with optimized refractive index reduces reflection losses at interfaces and manages the optical path, enabling more complete light coupling from the waveguide into free space.
2Volume of moving object
If the reflective surface is arranged close to the facet, then the device size is reduced, but back-reflection into the waveguide increases
Solution Approach 1:
The reflective surface is positioned asymmetrically at a 45° angle relative to the waveguide facet, rather than being parallel or symmetrically arranged. This asymmetric configuration causes reflected light to exit at a different angle, preventing back-reflection into the waveguide while maintaining a compact device footprint.
Solution Approach 2:
The reflective surface is oriented at a 45° angle, introducing a spatial dimension change that redirects light from the vertical waveguide axis to a horizontal exit path. This dimensional transformation separates the light extraction path from the waveguide axis, eliminating back-reflection while keeping the device compact.
3Device complexity
If the reflective surface is inclined at a small angle, then the device complexity is reduced, but beam divergence increases
Solution Approach 1:
The reflective surface is set at a specific 45° inclination angle, optimizing the balance between device simplicity and beam control. This parameter optimization ensures that the reflected beam maintains minimal divergence while the device structure remains relatively simple and manufacturable.
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 solution achieves efficient vertical out-coupling of light with minimal back-reflection and beam divergence, improving light transmission and reducing losses, thereby enhancing the performance of photonic integrated chips.
Implementation Method 1
the reflective surface is inclined with respect to a normal to the top surface by 45° or more
Implementation Method 2
the filler portion is made of material having a first refractive index and the reflection layer is made of material having a second refractive index, wherein the first refractive index is greater than the second refractive index
Data Source
AI summary
An optical out-coupler unit for out-coupling light from a waveguide, comprising a substrate having a planar top surface, a waveguide arranged on the top surface of the substrate and having a facet, a reflective surface, wherein the reflective surface is arranged spaced apart from the facet and opposing the facet, wherein the reflective surface is inclined with respect to a normal to the top surface of the substrate by more than 45°. The optical out-coupler may be part of a photonic integrated chip (PIC).