Chamfered Photodetector Sidewalls for Low-Reflection Coupling

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Solution Overview

Problem

Existing photonics chips face challenges in optimizing the structure of photonic components to minimize optical reflection loss while maintaining high coupling efficiency and responsivity for photodetectors.

Innovation Solution

The structure includes a photodetector with a light-absorbing layer having slanted and transverse sidewalls, and a waveguide core with tapered sections adjacent to these sidewalls, designed to reduce optical reflection and enhance coupling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional photonic component structures are used, then manufacturing is simpler, but optical reflection loss increases and coupling efficiency decreases

Engineering Contradiction:

Improveoptical reflection lossVSAvoidphotonic component structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The photonic component features asymmetric sidewalls with different orientations - a first sidewall at a first orientation and a second sidewall at a second orientation relative to the longitudinal axis. This asymmetric geometry reduces optical reflection loss by minimizing facet reflections while maintaining structural functionality, directly resolving the contradiction between reducing energy loss and maintaining simple structure.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention introduces chamfered sidewalls that extend in multiple dimensions rather than simple vertical walls. The first and second sidewalls create a chamfered configuration that adds geometric complexity in the lateral dimension, reducing optical reflections through altered light propagation paths without significantly increasing manufacturing difficulty.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If conventional photonic component structures are used, then device structure is simpler, but coupling efficiency decreases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidphotonic component structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The asymmetric sidewall configuration with specific orientations enhances coupling efficiency by optimizing the interface between adjacent photonic components. The first sidewall orientation facilitates better optical field overlap with neighboring waveguides or components, improving coupling without requiring complex alignment mechanisms.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The chamfered sidewalls provide localized geometric modification at critical interfaces where optical coupling occurs. By concentrating the geometric optimization at the sidewall regions rather than redesigning the entire component, the invention improves coupling efficiency locally while maintaining overall structural simplicity.

Inventive Principle:

Principle #3Local quality

3Reliability

If conventional photonic component structures are used, then device structure is simpler, but responsivity for photodetectors decreases

Engineering Contradiction:

ImproveresponsivityVSAvoidphotonic component structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

For photodetectors, the asymmetric sidewall configuration optimizes light absorption by reducing reflections from vertical facets. The chamfered sidewalls with specific orientations minimize reflected light that would otherwise reduce the optical power reaching the active absorption region, thereby improving responsivity.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention converts what would normally be harmful reflective losses at the sidewalls into beneficial effects by orienting the sidewalls to direct reflected light away from the optical path or to convert it into useful absorbed energy in the photodetector active region, thereby improving responsivity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 proposed structure significantly reduces optical reflection loss while maintaining high coupling efficiency and responsivity for photodetectors, improving the performance of photonics chips.

Implementation Method 1

minimize optical reflection loss while maintaining high coupling efficiency and responsivity

Methodology Applied

Scientific EffectOptical reflection: Reflection

Implementation Method 2

a light-absorbing layer having a longitudinal axis, a first sidewall, and a second sidewall adjoined to the first sidewall at an interior angle

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS12541057B2Photonic components with chamfered sidewalls

Publication Date: 2026.02.03 GLOBALFOUNDRIES US INC

AI summary

Structures for a photonics chip that include a photonic component and methods of forming such structures. The structure may comprise a photodetector on a substrate and a waveguide core. The photodetector includes a light-absorbing layer having a longitudinal axis, a first sidewall, and a second sidewall adjoined to the first sidewall at an interior angle. The first sidewall is slanted relative to the longitudinal axis, and the second sidewall is oriented transverse to the longitudinal axis. The waveguide core includes a tapered section adjacent to the first sidewall and the second sidewall of the light-absorbing layer.