Funnel Laser Coupler for Photonic Integrated Circuit Alignment
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Solution Overview
Problem
Conventional semiconductor technologies face challenges in coupling light to and from optical chips due to strict alignment tolerances, resulting in low yields for photonic integrated circuit (PIC) assemblies that meet coupling power requirements.
Innovation Solution
An optical coupling system comprising a multimode coupler that triggers higher-order modes from a single-mode input signal, a mode de-multiplexer to convert these modes into fundamental mode signals, and an optical combiner to produce a single output mode, enhancing alignment tolerance without increasing system size or altering the optical element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-mode to single-mode coupling is used, then coupling precision is improved, but alignment tolerance deteriorates
Solution Approach 1:
The coupling system is segmented into multiple functional components: a multimode coupler that accepts multiple modes, a mode converter that transforms higher-order modes to fundamental modes, and a single-mode waveguide. This segmentation allows each component to be optimized independently, with the multimode coupler providing large mode field overlap for tolerance while the mode converter ensures single-mode output for precision.
Solution Approach 2:
The multimode coupler acts as an intermediary between the laser and the single-mode waveguide. It receives the laser output in fundamental mode, converts it to multiple higher-order modes that are more tolerant to misalignment, then uses a mode converter to transform these back to fundamental mode for coupling into the waveguide. This intermediary structure decouples the alignment tolerance requirement from the coupling precision requirement.
2Productivity
If alignment tolerance is increased, then manufacturing yield is improved, but coupling efficiency deteriorates
Solution Approach 1:
The system dynamically adapts the mode field distribution to match the alignment conditions. The multimode coupler creates a dynamic mode profile that can accommodate larger positional variations, while the mode converter dynamically transforms these modes to ensure efficient coupling regardless of the initial misalignment, maintaining high coupling efficiency across a wider range of positions.
Solution Approach 2:
The invention changes the modal parameters of the optical signal by converting from fundamental mode to higher-order modes and back. This parameter transformation allows the system to operate with relaxed alignment parameters (larger tolerance) while maintaining the energy coupling efficiency through the mode conversion process, thereby improving yield without sacrificing efficiency.
3Manufacturing precision
If multimode coupling is used, then alignment tolerance is improved, but mode interference deteriorates
Solution Approach 1:
The mode converter extracts and eliminates the harmful higher-order modes by transforming them into fundamental modes that are then coupled into the single-mode waveguide. This extraction process removes the source of mode interference and instability, allowing the system to benefit from the alignment tolerance of multimode coupling without suffering from mode interference effects.
Solution Approach 2:
The invention converts the potentially harmful higher-order modes that arise from multimode coupling into beneficial fundamental modes. By intentionally generating higher-order modes that are then systematically converted to fundamental modes, the system transforms what would be sources of interference into a mechanism for achieving both large alignment tolerance and stable single-mode output.
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
Significantly increases tolerance to horizontal and vertical offset in laser placement, achieving high coupling efficiency and low coupling loss, thereby improving the yield of PIC assemblies.
Implementation Method 1
the multimode coupler triggers one or more higher-order modes from the input optical signal of the first mode
Implementation Method 2
an optical combiner configured to combine the respective output optical signals to produce a single output signal of the first mode
Data Source
AI summary
An optical coupling system for coupling a light source to a photonic integrated circuit (PIC) comprises a multimode coupler configured to receive an input optical signal of a first mode. The multimode coupler triggers one or more higher-order modes from the input optical signal of the first mode. The optical coupling system also includes a mode de-multiplexer and an optical combiner. The mode de-multiplexer transfers the input optical signal of the first mode and one or more optical signals of the triggered one or more higher-order modes to respective output optical signals of the first mode. The optical combiner combines the respective output optical signals to produce a single output signal of the first mode.