High-Power Laser Array Thermal Reflow Stability
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Solution Overview
Problem
Integrating high-power III-V laser chips onto silicon substrates for optical interconnects is challenging due to misalignment and thermal reflow compatibility issues, leading to high costs and reduced yield in hybrid approaches.
Innovation Solution
A packaged laser array design that includes a III-V laser array integrated with a silicon substrate, featuring a lens array, an isolator with a permanent magnet, and couplers to maintain magnetization during thermal reflow, enabling surface-normal output and improved stability with angled facets and expanded optical mode for reduced reflection and increased beam size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a packaged laser with surface-normal output is actively aligned to a grating coupler on a silicon chip, then coupling efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-aligning the laser array to the silicon chip using a simplified alignment structure before final packaging. The alignment marks and mechanical features are built into the packaging substrate during fabrication, eliminating the need for complex active alignment procedures after assembly. This allows high coupling efficiency to be achieved through pre-established geometric relationships rather than post-assembly adjustment.
Solution Approach 2:
The packaging substrate serves as an intermediary component that bridges the laser array and the silicon chip. It incorporates alignment marks, mechanical features, and optical coupling structures that facilitate precise positioning without requiring complex active alignment mechanisms. This intermediary structure simplifies the overall integration process while maintaining high coupling efficiency.
2Ease of manufacture
If an external laser with surface-normal coupling is used, then process flow interruption is minimized and integration complexity is reduced, but integration cost and yield are adversely affected
Solution Approach 1:
The patent merges the laser array, packaging substrate, and alignment features into a single integrated assembly. The laser array is mounted on a packaging substrate that already contains the alignment marks and mechanical features needed for integration with the silicon chip. This combined structure can be manufactured and tested as a complete unit before being integrated into the final device, improving yield by eliminating separate alignment and adjustment steps that would otherwise be required.
3Reliability
If a permanent magnet is added proximate to the isolator to maintain magnetization during thermal reflow, then isolator stability is improved, but device complexity increases
Solution Approach 1:
The permanent magnet provides a self-sustaining magnetic field that maintains the isolator's magnetization without requiring external power sources or active control mechanisms. The magnet is positioned in close proximity to the isolator during packaging, creating a localized magnetic field that preserves the isolator's optical properties throughout the thermal reflow process and subsequent device operation. This passive, self-service approach maintains reliability without adding complex active control systems.
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 design facilitates low-cost, high-yield integration of high-power laser arrays, enhancing communication performance by maintaining isolation and stability during thermal reflow, and allowing for passive alignment with low coupling loss and good power uniformity.
Implementation Method 1
an isolator having a magnetization that rotates a polarization of the one or more optical signals
Implementation Method 2
an isolator having a magnetization that rotates a polarization of the one or more optical signals
Implementation Method 3
a permanent magnet proximate (such as adjacent, e.g., within 1 mm) to the isolator that at least partially maintains a magnetization of the isolator
Implementation Method 4
a lens array with one or more lenses disposed on the surface, where, during operation, the lens array refracts (such as focuses) the one or more optical signals
Implementation Method 5
one or more couplers that couple the one or more optical signals along a direction out of the substrate
Data Source
AI summary
A high-power packaged laser array that is thermal reflow compatible is described. Notably, a high-power III-V laser array is integrated on a silicon substrate with a matching array of ball lenses, an isolator and a coupler (such as a reflective layer) to achieve an edge-coupled or a surface-normal output laser array. In some embodiments, an isolator with a permanent magnet is used to preserve the magnetic domain or state of the isolator during the thermal reflow(s), which can involve temperatures up to 250 C. In order to relax the misalignment tolerance when integrating with the silicon chip, a laser array with a larger optical mode may be used to increase the output beam size. Moreover, a III-V laser array with an angled output optical waveguide can be used to improve the stability of the lasers at high power.