Hermetic PIC Assembly With Integrated Laser Die Alignment
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Solution Overview
Problem
The integration of laser dies onto photonic integrated circuits is inefficient due to active alignment processes, leading to increased costs and device size, and photonic integrated circuits on transparent substrates exhibit poor thermal properties, requiring separate thermally conductive packaging.
Innovation Solution
A hermetically-covered photonic integrated circuit on a substrate with an integrated laser diode is fabricated using a trench with pillars to set the laser die height, enabling efficient alignment and thermal conduction, and a wafer-level hermetic covering to reduce environmental exposure and packaging needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a directed alignment process is used to attach the laser die to the photonic integrated circuit, then alignment precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements preliminary action by pre-forming alignment features (trenches and pillars) on the photonic integrated circuit substrate before laser die attachment. The trenches define precise positioning locations and the pillars provide mechanical support and alignment references, enabling simplified laser die placement without requiring complex active alignment processes during assembly.
2Illumination intensity
If a transparent substrate is used for the photonic integrated circuit, then optical path clarity is improved, but thermal conductivity deteriorates
Solution Approach 1:
The patent applies local quality by creating a dual-function substrate structure where the photonic integrated circuit is fabricated on a transparent substrate for optimal optical performance, while a separate thermally conductive package is attached to the substrate to provide localized thermal management. This allows the transparent substrate to maintain its optical clarity while the thermally conductive package handles heat dissipation from the laser diode.
3Temperature
If a separate thermally conductive package is used for the laser, then thermal conductivity is improved, but device size and manufacturing complexity increase
Solution Approach 1:
The patent merges multiple functions into integrated structures: the thermally conductive package is directly attached to the photonic integrated circuit substrate, combining thermal management with the optical platform. Additionally, the trench structure serves both as an alignment feature and as a thermal management element by providing a pathway for heat dissipation from the laser die to the substrate.
4Ease of manufacture
If the laser die is attached without hermetic covering, then manufacturing simplicity is improved, but reliability deteriorates due to environmental exposure
Solution Approach 1:
The patent employs a hermetic cover structure that encapsulates the laser die and photonic integrated circuit components. This thin-film or shell-based hermetic cover provides environmental protection against moisture and contaminants while maintaining a compact form factor and not significantly increasing device bulk.
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 alignment complexity and costs, enhances thermal conductivity, and provides a compact, cost-effective optical component with improved reliability and efficiency.
Implementation Method 1
a cover wafer attached to the housing layer, the cover wafer to provide hermetic covering the photonic integrated circuit and the laser die
Implementation Method 2
enabling efficient alignment and thermal conduction
Data Source
AI summary
According to examples, an apparatus for implementing a hermetically-covered photonic integrated circuit on a substrate having an integrated laser diode is described. The apparatus may include a cover wafer, a housing layer including a waveguide, the waveguide including a photonic integrated circuit, a laser die including a laser cavity, and a base substrate. The base substrate may include an emission window to provide a reflective design and to eliminate a need for a polarized beam splitter, a through-wafer via element to electrical coupling to the laser die and one or more pillars to set a height of the laser die relative to the photonic integrated circuit.