Optical Sub-Assembly Layout for Bidirectional Laser Diode Cooling
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Solution Overview
Problem
Conventional optical sub-assemblies for laser diodes face inefficiencies due to limited heat dissipation, as diodes primarily dissipate heat in one direction through the submount structure and TEC device, leading to reduced efficiency and optical power output.
Innovation Solution
The optical sub-assembly design positions the diode between the diode submount structure and the thermoelectric cooler (TEC), utilizing a silicon photonics (SiPho) die with a waveguide overhanging the TEC to prevent underfill material coverage, and incorporating a thermally conductive and electrically insulating underfill material to enhance cooling, along with an aluminum nitride submount structure for improved thermal dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the diode is mounted on the submount structure with TEC cooling from below, then the structure is simple and easy to manufacture, but heat dissipation is limited to one direction reducing efficiency
Solution Approach 1:
The patent transitions from unidirectional cooling (one dimension) to bidirectional cooling (two dimensions) by positioning the diode between the submount structure and TEC, enabling heat to dissipate in opposite directions simultaneously. This dimensional change in heat flow path resolves the contradiction by maintaining manufacturing simplicity while dramatically improving thermal management efficiency.
2Temperature
If the SiPho die is positioned directly over the TEC, then cooling efficiency is maximized, but underfill material may cover the waveguide reducing optical performance
Solution Approach 1:
The patent employs asymmetric positioning where the SiPho die is deliberately offset from direct alignment with the TEC, creating an intentional misalignment. This asymmetric configuration allows the die to overhang the TEC edge, ensuring that underfill material does not cover the waveguide while still maintaining effective thermal contact between the diode and TEC for optimal cooling.
3Loss of energy
If the diode is positioned between the submount structure and TEC, then bidirectional heat dissipation improves efficiency, but the structural complexity increases
Solution Approach 1:
The patent merges multiple functions into the diode positioning structure: the same configuration that enables bidirectional heat dissipation also provides mechanical support, electrical connection, and optical alignment. By combining these functions into a unified structural arrangement rather than adding separate components, the patent achieves improved heat dissipation without proportionally increasing structural 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
This configuration significantly enhances thermal dissipation, achieving higher optical power output with lower total electrical energy consumption and reduced thermal impedance, as demonstrated by thermal field models showing a 20-degree reduction in laser junction active region temperature compared to conventional designs.
Implementation Method 1
a thermoelectric cooler (TEC) in thermal contact with the diode, wherein the diode is positioned between the diode submount structure and the TEC
Implementation Method 2
the TEC cools the laser diodes through the submount structure, and the diodes dissipate heat generally only in one direction through the submount structure and the TEC device
Implementation Method 3
the underfill material is a thermally conductive and electrically insulating material
Implementation Method 4
the SiPho die includes a waveguide, wherein light from the diode can exit the optical sub-assembly via the waveguide
Data Source
AI summary
An optical sub-assembly includes a diode submount structure, a diode mounted to the diode submount, and a thermoelectric cooler (TEC). The TEC is in thermal contact with the diode, and the diode is positioned between the diode submount structure and the TEC.