Tapered Optical Features for Fiber-to-PIC Alignment
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Solution Overview
Problem
The challenge of minimizing coupling loss between an optical fiber and a photonic integrated circuit (PIC) waveguide due to misalignment, particularly with the small mode field diameter of optical fibers, necessitates precise alignment within 1-2 μm, which is difficult to achieve efficiently.
Innovation Solution
The use of tapered optical features on the end face of the optical fiber and the surface of the PIC die, fabricated using two-photon polymerization, allows for beam expansion and alignment tolerance up to 20 μm without requiring active alignment, reducing production time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If precise alignment within 1-2 μm is implemented to minimize coupling loss, then coupling efficiency is improved, but manufacturing complexity and time increase significantly
Solution Approach 1:
The patent changes the physical parameters of the optical interface by introducing tapered features with specific geometric parameters (taper angle, length, diameter). These parameter changes transform the coupling characteristics, allowing efficient light coupling with relaxed alignment tolerances of 10-20 μm compared to the traditional 1-2 μm requirement, thereby reducing manufacturing complexity and production time while maintaining low coupling loss
2Manufacturing precision
If active alignment is used to achieve precise fiber-to-waveguide alignment, then coupling precision is improved, but device complexity and production cost increase
Solution Approach 1:
The tapered optical features are designed to self-align and self-couple light efficiently within a broad tolerance range of 10-20 μm. This self-service mechanism eliminates the need for complex active alignment systems, automated positioning devices, and iterative adjustment procedures, thereby reducing device complexity and production cost while maintaining high alignment precision
Solution Approach 2:
The tapered features are pre-formed on the optical fiber and/or waveguide surfaces before the coupling assembly. This preliminary action of creating the tapered geometry in advance allows the system to inherently accommodate misalignments without requiring complex real-time adjustment mechanisms, thus simplifying the overall 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 tapered optical features facilitate efficient alignment and coupling of optical signals between the fiber and PIC die, offering a compact and time-efficient solution with reduced system complexity and lower production costs.
Implementation Method 1
the first and second tapered optical features may be operable to expand a beam of light incident on the first tapered optical feature from the optical fiber to the second tapered optical feature at the PIC die
Implementation Method 2
fabricated using two-photon polymerization
Data Source
AI summary
An apparatus includes an optical fiber coupled with a photonic integrated circuit (PIC) die. A first optical feature is at an end face of the optical fiber. The first optical feature tapers in a first longitudinal direction from a first base end proximal to the end face to a first tapered end. A second optical feature is at a surface of the PIC die. The second optical feature tapers in a second longitudinal direction from a second base end proximal to the surface to a second tapered end. The first optical feature is adjacent to, and may be longitudinally aligned with or parallel to, the second optical feature.