Facet Coupling Fanout With Dual-Pitch Waveguides for Warped PIC Alignment
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Solution Overview
Problem
Photonic integrated circuits (PICs) with thin substrates are prone to warping, leading to misalignment and increased coupling loss when coupling with fiber array units (FAUs), especially when the substrate thickness is less than 150 μm, due to the displacement of optical waveguide cores.
Innovation Solution
A facet coupling fanout device with a first optical coupling side having a first pitch P1 matching the PIC waveguide cores and a second optical coupling side with a second pitch P2 greater than P1, reducing the pitch ratio R=P2/P1 to minimize the width of the coupling region and align the waveguide cores, thereby reducing misalignment and coupling loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the substrate thickness is reduced to less than 150 μm, then the device complexity is reduced and integration is improved, but the substrate becomes prone to warping causing misalignment and increased coupling loss
Solution Approach 1:
A facet coupling fanout device is introduced as an intermediary component between the thin PIC substrate and the FAU. This mediator device has a first pitch matching the PIC waveguide cores and a second pitch matching the FAU fibers, absorbing the pitch mismatch caused by substrate warping and enabling reliable coupling despite the thin substrate conditions
2Area of stationary object
If the pitch between waveguide cores is increased to match FAU fiber spacing, then the coupling region width is reduced, but the alignment precision between PIC and FAU deteriorates
Solution Approach 1:
The coupling system is segmented into two distinct pitch domains: a first pitch P1 for coupling to PIC waveguide cores and a second pitch P2 for coupling to FAU fibers. The facet coupling fanout device maintains these different pitches at its two optical coupling sides, allowing the coupling region width to be minimized by P1 while the FAU alignment is maintained by P2, resolving the contradiction between compact size and alignment precision
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 reduced pitch configuration significantly minimizes the relative displacement offset of optical waveguide cores, resulting in a substantial reduction of coupling loss penalties, even in warped substrates, by ensuring precise alignment and efficient optical coupling between PICs and FAUs.
Implementation Method 1
The first optical coupling side is configured to optically couple the plurality of multi-channel waveguides to a plurality of waveguide cores of a photonic integrated circuit (PIC)
Implementation Method 2
The second optical coupling side is configured to optically couple the plurality of multi-channel waveguides to optical fibers of a fiber array unit (FAU)
Data Source
AI summary
Disclosed is a facet coupling fanout device including a body, a first optical coupling side, and a second optical coupling side. The body defines a plurality of multi-channel waveguides therein. The first optical coupling side optically couples the plurality of multi-channel waveguides to a plurality of waveguide cores of a photonic integrated circuit (PIC). The a second optical coupling side optically couples the plurality of multi-channel waveguides to optical fibers of a fiber array unit (FAU). The first optical coupling side defines a first pitch P1 between the plurality of multi-channel waveguides and the second optical coupling side defines a second pitch P2 between the plurality of multi-channel waveguides where P2>P1. The first pitch P1 and the second pitch P2 define a pitch ratioR=P2P1.