Passive Optical Alignment Using WDM Couplers
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Solution Overview
Problem
Current optical alignment systems for multi-channel integrated photonics dies and fiber arrays are costly and inefficient, relying on active components that require external power and precise positioning, limiting real-time adjustment and increasing manufacturing and operational costs.
Innovation Solution
The use of wavelength division multiplexing (WDM) couplers and low-loss waveguide crossings in a passive optical alignment system that allows simultaneous optical alignment and operation, eliminating the need for external power and enabling real-time adjustment by separating alignment and operational light beams through distinct wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active optical components (photodiodes requiring external power) are used for optical alignment, then alignment monitoring capability is improved, but manufacturing cost and operational cost increase
Solution Approach 1:
The patent extracts the alignment monitoring function from active photodiodes and implements it through passive optical circulation using WDM couplers. The system separates alignment light (monitoring function) from operational light by wavelength, eliminating the need for power-consuming photodiodes while maintaining alignment monitoring capability through optical field circulation.
Solution Approach 2:
The patent introduces WDM couplers as intermediary components that mediate between alignment light and operational light. These couplers enable wavelength-based separation and optical circulation, allowing alignment monitoring without direct electrical detection, thus reducing system complexity and cost.
2Device complexity
If passive optical alignment systems without additional channels are used, then device size and manufacturing cost are reduced, but alignment precision and real-time adjustment capability deteriorate
Solution Approach 1:
The patent implements continuous optical circulation through the waveguide loop, allowing alignment light to continuously traverse the photonic circuit paths. This continuous circulation enables real-time monitoring and adjustment capability without requiring additional dedicated alignment channels, maintaining precision while reducing device complexity.
Solution Approach 2:
The patent makes the existing photonic circuit waveguides serve dual functions: operational light transmission and alignment light monitoring. By circulating alignment light through the same waveguide paths used for operations, the system achieves multi-functionality without adding dedicated alignment channels.
3Ease of manufacture
If two-step alignment approach (coupling laser to photonics die then to fiber array) is used, then alignment process is simplified, but real-time optical adjustment capability is lost
Solution Approach 1:
The patent enables continuous real-time adjustment by circulating alignment light through the complete optical path including fiber array coupling. The optical circulation allows monitoring and adjustment to occur continuously during the alignment process, eliminating the sequential two-step limitation while maintaining process simplicity.
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 reduces manufacturing and operational costs, minimizes transmission losses, and allows multiple devices to operate simultaneously, enabling real-time alignment and adjustment without the need for hypersensitive receivers or additional power for alignment purposes.
Implementation Method 1
The use of wavelength division multiplexing (WDM) couplers and low-loss waveguide crossings in a passive optical alignment system that allows simultaneous optical alignment and operation, eliminating the need for external power and enabling real-time adjustment by separating alignment and operational light beams through distinct wavelengths
Implementation Method 2
a first optical signal being propagated from the first waveguide crossing into the second waveguide crossing
Data Source
AI summary
A system for optically aligning a photonics die to a fiber array, the fiber array comprising a first and a second fiber channels, the system comprising: the photonics die having: a first and a second optical channels; a first and a second wavelength division multiplexing (WDM) couplers each comprising a bar port, a cross port, and a common port, the first and the second WDM couplers being optically connected to the first and the second optical channels, respectively, via the bar ports and the common ports; and a waveguide crossing optically connecting the cross ports of the first and the second WDM couplers; the system being adapted to couple an optical signal received from the first fiber channel into the cross port of the first WDM coupler and into the waveguide crossing, the optical signal being propagated from the waveguide crossing into the cross port of the second WDM coupler.