Ridge Waveguide Laser Package Molding Alignment
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Solution Overview
Problem
Existing planar lightwave circuits (PLCs) face challenges in reducing costs while increasing quality and reliability, particularly due to the need for stringent process control and active alignment in directing light using gratings or micro-lenses, which are costly and limited by available incident angles, leading to increased package size.
Innovation Solution
A chip package design with a ridge waveguide structure formed after securing the laser diode in place using a molding compound layer, eliminating the need for additional alignment devices and procedures, achieved through a method involving an adhesive layer, molding compound layer, waveguide layer, redistribution layer, and upper cladding layer, patterned using photolithographic techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gratings or micro-lenses are used to direct light in PLCs, then light propagation can be achieved, but stringent process control and active alignment are required, increasing device complexity and manufacturing cost
Solution Approach 1:
The patent extracts and removes the complex alignment devices (gratings and micro-lenses) from the PLC structure. By eliminating these components, the invention achieves light coupling between the laser diode and waveguide without requiring stringent process control or active alignment procedures, thereby reducing device complexity while maintaining light propagation functionality
Solution Approach 2:
The patent employs preliminary action by pre-forming the waveguide structure and laser diode mounting before final assembly. The waveguide is fabricated with predetermined geometry and positioning features that automatically align with the laser diode, eliminating the need for post-assembly alignment adjustments and complex alignment devices
2Reliability
If gratings or micro-lenses are used for light coupling, then light direction is achieved, but the package size increases due to limited available incident angles
Solution Approach 1:
The patent transitions from angular-based light coupling (using gratings/micro-lenses that require specific incident angles) to a dimension-based approach where the waveguide is positioned in close proximity to the laser diode emitting surface. This dimensional change allows light coupling without requiring large package volumes to accommodate alignment mechanisms or provide sufficient incident angle ranges
3Manufacturing precision
If additional alignment devices and procedures are used, then light coupling precision is improved, but manufacturing cost and production time increase
Solution Approach 1:
The patent implements self-service by designing the waveguide structure with inherent alignment features that automatically position themselves relative to the laser diode during assembly. The waveguide's geometric configuration and the molding compound layer work together to provide self-alignment, eliminating the need for external alignment devices and complex alignment procedures, thereby reducing manufacturing cost while maintaining 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
This design reduces the need for costly alignment devices and time-consuming procedures, resulting in cost savings and improved quality by accurately positioning the laser diode and forming the waveguide structure post-assembly, thereby enhancing the reliability and reducing the chip package size.
Implementation Method 1
A molding compound layer is deposited over the adhesive layer, the IC die and the LD die. The molding compound layer is cured and partially removed by a mechanical grinding process
Implementation Method 2
The waveguide structure for guiding light includes a core layer in which light propagates and a cladding layer encompassing the core layer and having an index of refraction greater than that of the core layer. In some cases the refractive index of the core layer is larger than the refractive index of the clad layer by 0.025 and results in total reflection during light transportation
Data Source
AI summary
An apparatus and method of forming a chip package with a waveguide for light coupling is disclosed. The method includes depositing an adhesive layer over a carrier. The method further includes depositing a laser diode (LD) die having a laser emitting area onto the adhesive layer and depositing a molding compound layer over the LD die and the adhesive layer. The method still further includes curing the molding compound layer and partially removing the molding compound layer to expose the laser emitting area. The method also includes depositing a ridge waveguide structure adjacent to the laser emitting area and depositing an upper cladding layer over the ridge waveguide structure.