Dual Grating Coupler Optical Module for Polarization Handling

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Solution Overview

Problem

Photonic integrated circuits (PICs) face challenges with grating couplers, which have low coupling efficiency, low alignment tolerance, and narrow bandwidth due to polarization sensitivity and alignment issues, limiting their effectiveness in receiving optical signals compared to edge couplers.

Innovation Solution

An optical module is designed with a combination of first and second grating couplers, each configured to receive transverse electric (TE) and transverse magnetic (TM) modes of optical signals, respectively, and arranged to overlap bandwidths for increased coupling efficiency and alignment tolerance, with multiple grating couplers improving bandwidth and reducing signal loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If grating couplers are used in photonic integrated circuits, then the device footprint is reduced and coupling position variation is allowed, but coupling efficiency and alignment tolerance deteriorate

Engineering Contradiction:

Improvedevice footprintVSAvoidcoupling efficiency

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The invention divides the single grating coupler into multiple grating couplers (first grating coupler and second grating coupler) that operate at different orientations. Each grating coupler is segmented to handle specific polarization modes (TE or TM), and their combined effect achieves high coupling efficiency while maintaining compact footprint.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The optical module is designed with multi-functionality to handle both TE and TM polarization modes through different grating couplers. This universal design allows the system to receive optical signals regardless of polarization state, improving alignment tolerance and coupling efficiency across different input conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Volume of moving object

If grating couplers are used, then compact design is achieved, but bandwidth and alignment tolerance are limited

Engineering Contradiction:

Improvedevice volumeVSAvoidbandwidth

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The bandwidth is segmented across multiple grating couplers with different orientation angles. Each grating coupler contributes to a specific portion of the overall bandwidth, and their combined response creates a broader total bandwidth while maintaining compact device volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges the bandwidth contributions of multiple grating couplers with different orientations to create an optical module with broader overall bandwidth. The combining of these segmented bandwidth portions achieves versatility comparable to edge couplers while maintaining the compact footprint of grating couplers.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If single grating coupler is used, then device simplicity is maintained, but signal loss increases due to polarization sensitivity

Engineering Contradiction:

Improvecoupler structureVSAvoidsignal loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The signal reception function is segmented across multiple grating couplers, each optimized for specific polarization modes. This segmentation reduces signal loss for each polarization type by directing it to the appropriately oriented coupler, while the overall structure remains relatively simple.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the orientation parameter of the grating couplers to optimize coupling for different polarization modes. By adjusting the orientation angles of different grating couplers, the system minimizes signal loss for both TE and TM modes without significantly increasing structural complexity.

Inventive Principle:

Principle #35Parameter changes

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

The optical module achieves higher coupling efficiency and alignment tolerance with a broader bandwidth, enabling efficient signal reception across a wider range of center wavelengths, comparable to edge couplers while maintaining a compact footprint.

Implementation Method 1

Grating couplers are used to confine and guide light from an optical fiber to an integrated chip with minimal attenuation

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

Grating couplers are used to confine and guide light from an optical fiber to an integrated chip with minimal attenuation

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS20250012954A1High efficiency optical coupler

Publication Date: 2025.01.09 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Some embodiments relate to an optical module including a substrate; a first grating coupler overlying the substrate; and a second grating coupler overlying the first grating coupler, where the second grating coupler is configured to receive a first transverse mode of an input optical signal while passing a second transverse mode of the input optical signal to the first grating coupler, and where the first grating coupler is configured to receive the second transverse mode of the input optical signal.