Slotted Waveguide Photodetector for Bandwidth-Responsivity Tradeoff

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Solution Overview

Problem

Existing photonics chips face a trade-off between photodetector bandwidth and responsivity, with improvements in one metric often degrading the other.

Innovation Solution

A photodetector structure with a waveguiding structure comprising a first and second waveguide core, a slot between them, and waveguide core segments adjoined to the photodetector's side edge, enhancing light transfer efficiency and bandwidth without altering the semiconductor layer's shape or size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If design modifications are made to improve the bandwidth of a photodetector, then the bandwidth increases, but the responsivity decreases

Engineering Contradiction:
ImprovebandwidthVSAvoidresponsivity
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The waveguide core is divided into multiple discrete segments positioned along the photodetector's side edge. These segmented waveguide core segments create multiple light coupling points that enhance bandwidth through parallel signal paths while maintaining overall responsivity through distributed light collection

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A dielectric material is introduced as an intermediary between the waveguide cores and the photodetector semiconductor layer. This dielectric intermediary optimizes optical coupling efficiency and enables polarization diversity while preserving both bandwidth and responsivity through controlled light interaction

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of moving object

If the footprint of the photodetector is reduced, then the area decreases, but the light absorption efficiency may be compromised

Engineering Contradiction:
ImprovefootprintVSAvoidlight absorption efficiency
Core Design Contradiction:
Area of moving objectVSReliability

Solution Approach 1:

The waveguiding structure extends light interaction into the lateral dimension along the side edge of the photodetector. By positioning waveguide segments along the perimeter rather than requiring larger top-area coverage, the design achieves enhanced light absorption within a compact footprint through three-dimensional optical path management

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 structure improves responsivity and coupling efficiency while maintaining or reducing the photodetector's footprint, supporting various polarization modes and enabling efficient light absorption.

Implementation Method 1

a waveguiding structure including a first waveguide core, a second waveguide core, a slot between the first waveguide core and the second waveguide core

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

A photodetector may be employed in the photonic integrated circuit to convert light, which may be modulated as an optical signal, into an electrical signal

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP4585980A1Photodetectors with an adjoined slotted waveguiding structure
Publication Date: 2025.07.16 GLOBALFOUNDRIES US INC
  • EP4585980A1 patent drawingFigure 1
  • EP4585980A1 patent drawingFigure 2~2A
  • EP4585980A1 patent drawingFigure 3

AI summary

Structures for a photonics chip that include a photodetector (14) and methods of forming such structures. The structure comprises a photodetector (14) including a pad (24) and a semiconductor layer (26) on the pad (24). The structure further comprises a waveguiding structure including a first waveguide core (12), a second waveguide core (13), a slot between the first waveguide core (12) and the second waveguide core (13), and a plurality of waveguide core segments (20). The waveguiding structure is adjoined to a side edge (23) of the pad (24) adjacent to the semiconductor layer (26). Each of the plurality of waveguide core segments (20) includes a portion that is disposed in the slot.