Beam Expansion for Vertically-Emitting Photonic Integrated Circuits
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Solution Overview
Problem
Efficiently and cost-effectively aligning optics to couple light into and out of photonic integrated circuits (PICs) is challenging due to slow and incompatible attachment methods, leading to yield and throughput issues in conventional semiconductor packaging processes.
Innovation Solution
A photonic integrated circuit (PIC) die with vertical couplers and a glass microoptic substrate where micromirrors reflect and collimate light to propagate parallel to the PIC die's surface, allowing for a low-profile and compatible integration that avoids glass-air interfaces, enabling efficient light coupling and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional optical attachment methods are used to couple light into PICs, then light coupling can be achieved, but the process is slow and incompatible with semiconductor packaging, resulting in low yield and throughput
Solution Approach 1:
The patent replaces mechanical alignment and attachment methods with a planar integrated optical system. The micromirrors and waveguides are fabricated using semiconductor-compatible processes, eliminating the need for slow mechanical optical alignment. The light coupling is achieved through integrated vertical couplers and planar waveguide interfaces that work seamlessly with standard semiconductor packaging workflows, thereby improving both productivity and manufacturing ease.
Solution Approach 2:
The patent transforms the optical coupling approach by changing the spatial parameters of light propagation. Instead of using vertical light paths that require complex alignment, the system redirects light to propagate parallel to the PIC surface using micromirrors. This parameter change enables compatibility with semiconductor packaging processes while maintaining efficient light coupling, resolving the contradiction between productivity and ease of manufacture.
2Ease of operation
If vertical light coupling is used in PICs, then light can be coupled into waveguides, but the required optical components increase device complexity and profile height
Solution Approach 1:
The patent merges multiple optical functions into a single planar integrated structure. The micromirrors, beam expansion optics, and waveguide interfaces are combined into one cohesive device layer that is fabricated using standard semiconductor processes. This integration eliminates the need for separate, complex optical components and reduces overall device complexity while maintaining efficient light coupling operations.
Solution Approach 2:
The patent transitions from vertical light coupling to parallel light propagation by introducing micromirrors that redirect light at 45-degree angles. This dimensional change in light path orientation allows the optical system to be flattened into a planar configuration, reducing profile height and simplifying the overall device structure while preserving light coupling efficiency.
3Area of moving object
If beam expansion is performed vertically, then light can be expanded to desired size, but the optical substrate thickness must be substantial, increasing device profile
Solution Approach 1:
The patent performs beam expansion in the lateral dimension rather than the vertical dimension. Micromirrors redirect expanded light beams to propagate parallel to the substrate surface, allowing beam size to increase without requiring increased substrate thickness. This dimensional transformation enables low-profile device design while achieving the desired beam expansion for effective light coupling.
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 solution enables efficient light coupling and alignment with improved yield and throughput by using micromirrors in the glass microoptic substrate to reflect and collimate light, reducing the thickness and complexity of the optical alignment process while maintaining compatibility with semiconductor packaging.
Implementation Method 1
a micromirror in the glass substrate reflects the beam to propagate parallel to the surface of the PIC die
Implementation Method 2
A second micromirror in the glass substrate then collimates the beam, directing it out of the top surface of the glass microoptic substrate
Data Source
AI summary
Technologies for beam expansion for vertically-emitting photonic integrated circuits are disclosed. In the illustrative embodiment, waveguides in a photonic integrated circuit (PIC) die guide light to vertical couplers, which direct the light from the waveguides out of the top surface of the PIC die. A glass microoptic substrate is mounted on the top surface of the PIC die, positioned over the vertical couplers. A mirror in the glass microoptic substrate reflects the light from the vertical couplers to propagate in a direction parallel to the top surface of the PIC die. Another set of mirrors in the glass microoptic substrate focus the light from each waveguide into a collimated beam directed out of the top surface of the glass microoptic substrate.