Photodetector Array Coating Layout for Optical Crosstalk Mitigation

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Solution Overview

Problem

Optical crosstalk between neighboring photodetectors in detector arrays of optical receivers, caused by light reflection from metal structures, negatively impacts the accuracy of light measurement and image generation.

Innovation Solution

A method of manufacturing a photodetector device that involves providing a photodetector array with metal structures arranged in a specific pattern, applying an antireflective coating on a transparent substrate matching the metal structure pattern, and coupling the substrate to the array such that the antireflective coating covers the metal structures, thereby reducing optical crosstalk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If metal structures are used around photodetectors for signal readout, then electrical signal reading is enabled, but optical crosstalk occurs due to light reflection from metal structures

Engineering Contradiction:

Improvesignal readout capabilityVSAvoidoptical crosstalk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A transparent substrate with patterned antireflective coating is introduced as an intermediary between the incoming light and the metal structures. The antireflective coating selectively absorbs reflected light at metal structure locations while allowing light transmission elsewhere, thereby mediating between the electrical signal readout function and the optical crosstalk problem

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The antireflective coating is applied in a patterned manner with different properties at different locations: it has high light absorption at metal structure locations (where crosstalk occurs) and is transparent or absent at photodetector locations (where light detection is needed). This local differentiation resolves the contradiction by applying the antireflective property only where harmful reflection occurs

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If antireflective coating is applied to cover metal structures, then optical crosstalk is reduced, but manufacturing complexity increases due to pattern matching requirements

Engineering Contradiction:

Improveoptical crosstalkVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The transparent substrate with antireflective coating is prepared in advance with the correct pattern before assembly. The coating is applied to match the metal structure pattern beforehand, and then the substrate is aligned and coupled to the photodetector array. This preliminary preparation simplifies the final assembly process by pre-establishing the complex pattern relationship

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The antireflective coating pattern on the transparent substrate is designed to match and copy the metal structure pattern on the photodetector array. By creating a corresponding pattern on the separate substrate, the complex pattern matching requirement is transformed into a replication task that can be achieved through standard photolithography and alignment techniques

Inventive Principle:

Principle #26Copying

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 solution effectively reduces optical crosstalk by absorbing incoming light with the antireflective coating, thereby improving the accuracy of light measurement and image generation in optical receivers.

Implementation Method 1

The solution effectively reduces optical crosstalk by absorbing incoming light with the antireflective coating

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

the metal structures have a reflectivity that may exceed 70%. As a result, some light received at the detector array may be reflected back by the metal structures towards the receiver optics

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS12211868B2Optical crosstalk mitigation for a detector array in an optical receiver

Publication Date: 2025.01.28 INFINEON TECHNOLOGIES AG

AI summary

A photodetector device includes a photodetector array comprising an array of photodetectors and a plurality of metal structures arranged between photodetectors of the array of photodetectors, wherein the plurality of metal structures are arranged in a first pattern; and a transparent substrate comprising a plurality of diffusion structures being patterned according to a second pattern that matches the first pattern. Each diffusion structure of the plurality of diffusion structures is configured to redirect light that is incident thereon. Additionally, the transparent substrate and the photodetector array are coupled together such that the first pattern is aligned with the second pattern and the plurality of diffusion structures covers the plurality of metal structures.