Optical Splitter Absorptive Core Reflective Grating

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Solution Overview

Problem

In optical networks, particularly passive optical networks (PONs), upstream insertion losses at splitters are significant due to leaky modes, resulting in high signal power loss and reduced bandwidth, making it costly to compensate for these losses with amplifiers in each tributary branch.

Innovation Solution

An optical splitter design featuring a light-absorptive core and a selectively reflective grating in the main branch, which absorbs upstream light from tributary branches and reflects downstream light back through the absorptive core, reducing leaky mode propagation and increasing signal power transmission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a conventional optical splitter is used to distribute optical signals from OLT to multiple ONUs, then the downstream direction can achieve acceptable signal distribution, but the upstream direction suffers from very high insertion losses (only about 1/100 of optical signal power reaches the OLT)

Engineering Contradiction:

Improveupstream insertion lossVSAvoidsignal transmission efficiency

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent converts the harmful leaky modes in the upstream direction into beneficial reflected signals. By placing a reflective grating in the main branch, the leaky light that would normally be lost is reflected back through the absorptive core, transforming the harmful energy loss into useful signal transmission that can reach the OLT with much lower attenuation

Inventive Principle:

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

Solution Approach 2:

The reflective grating acts as an intermediary element between the tributary branches and the OLT. It mediates the upstream signal transmission by reflecting the optical signals back through the main branch, enabling efficient upstream communication without requiring expensive amplifiers in each tributary branch

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If optical amplifiers are placed in each tributary branch to compensate for upstream losses, then signal transmission efficiency can be improved, but the system cost increases significantly

Engineering Contradiction:

Improvesignal transmission efficiencyVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of multiple components into a single integrated splitter structure. The reflective grating and absorptive core are combined within the main branch of the splitter, eliminating the need for separate amplifiers in each tributary branch and significantly reducing system cost while maintaining signal transmission efficiency

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The main branch of the splitter is designed to perform multiple functions: it serves as the signal distribution path for downstream transmission, contains the reflective grating for upstream signal reflection, and includes the absorptive core for mode filtering. This multi-functionality eliminates the need for additional expensive equipment

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If high insertion losses occur in the upstream direction, then bandwidth and transmission distance are reduced, but placing amplifiers to compensate increases system cost

Engineering Contradiction:

Improvebandwidth and transmission distanceVSAvoidamplification equipment cost

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of high insertion losses into a beneficial outcome. By using the reflective grating to reflect upstream signals back through the absorptive core, the system transforms the previously lost energy into useful signal transmission, thereby increasing bandwidth and transmission distance without requiring additional amplification equipment

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

This design reduces upstream insertion losses by up to 50%, enhancing bandwidth and transmission distance while minimizing the need for additional amplification equipment, thereby reducing costs.

Implementation Method 1

The absorptive core can absorb light that is arriving from the tributary branches and transmit light that is traveling from the main branch toward the reflective grating

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The reflective grating can reflect light from the main branch back through the absorptive core to the main branch

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

Light arriving from the tributary branches exchanges mode with light reflected by the reflective grating

Methodology Applied

Scientific EffectMode exchange: Waveguide (optics)

Data Source

PatentUS9389364B1Optical splitter with absorptive core and reflective grating

Publication Date: 2016.07.12 FUTUREWEI TECHNOLOGIES INC

AI summary

An optical splitter has a main branch coupled to a number of tributary branches. The main branch includes a light-absorptive core and a light-reflective grating. The absorptive core can absorb light arriving from the tributary branches and transmit light arriving from the main branch to the reflective grating. The reflective grating can reflect light from the main branch back through the absorptive core to the main branch. Light arriving from the tributary branches exchanges mode with light reflected by the reflective grating.