Coherent Optics Transceiver Crosstalk Mitigation

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Solution Overview

Problem

Existing coherent transceiver designs for bidirectional transmission in access networks suffer from significant crosstalk due to conventional implementations of single laser sources for both transmitters and local oscillators, limiting the effectiveness of coherent optics technology in expanding fiber capacity.

Innovation Solution

The implementation of coherent optics transceivers with optical circulators to separate downstream and upstream signals, allowing for simultaneous bidirectional transmission over a single fiber using a single laser source, thereby mitigating crosstalk and enhancing spectral efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If conventional single laser source implementations are used for both transmitters and local oscillators in bidirectional transmission, then device complexity is reduced, but significant crosstalk occurs that limits transmission effectiveness

Engineering Contradiction:

Improvetransceiver design complexityVSAvoidcrosstalk

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the optical signal paths by introducing optical circulators that separate downstream and upstream signals into distinct path segments. This segmentation prevents the mixing of signals that causes crosstalk while maintaining the simplicity of single laser source architecture.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Optical circulators serve as intermediary devices that mediate between the single laser source and the bidirectional transmission paths. These intermediaries direct signals in specific directions and prevent harmful interactions between upstream and downstream signals.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If more fiber strands are added between headend and fiber node to increase capacity, then transmission capacity is improved, but retrenching becomes costly and time consuming

Engineering Contradiction:

Improvetransmission capacityVSAvoidinfrastructure deployment cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent makes existing single fiber strands perform multiple functions by enabling bidirectional transmission. The same fiber infrastructure that originally carried unidirectional signals now carries both upstream and downstream coherent optical signals, effectively doubling capacity without additional fiber deployment.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent enables continuous bidirectional transmission over the existing fiber infrastructure, maximizing the utility of already-deployed assets. By implementing full-duplex coherent optics, the system maintains continuous useful action on both directions simultaneously rather than requiring separate fibers for each direction.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If bidirectional transmission is implemented on a single fiber to double transmission capability, then spectral efficiency is improved, but crosstalk from conventional designs prevents full utilization

Engineering Contradiction:

Improvespectral efficiencyVSAvoidsignal quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The optical circulator segments the signal paths into distinct downstream and upstream channels, preventing signal mixing and crosstalk. This segmentation enables reliable bidirectional transmission by ensuring that transmitted and received signals remain separate throughout the transmission medium.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes coherent detection parameters and optical circulator characteristics to change the operational parameters of the transmission system. By implementing full-duplex coherent optics with proper parameter control, the system achieves high spectral efficiency while maintaining signal quality through reduced crosstalk.

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

This approach effectively doubles the spectral efficiency of existing coherent transmission systems by enabling simultaneous bidirectional data transmission with reduced crosstalk, optimizing power usage, and improving signal quality over shorter distances.

Implementation Method 1

The first and second optical circulators are configured to separate the downstream optical signal from the upstream optical signal

Methodology Applied

Scientific EffectOptical circulator:

Data Source

PatentUS11716164B1Systems and methods for full duplex coherent optics

Publication Date: 2023.08.01 CABLE TELEVISION LAB INC

AI summary

A full duplex communication network includes an optical transmitter end having a first coherent optics transceiver, an optical receiver end having a second coherent optics transceiver, and an optical transport medium operably coupling the first coherent optics transceiver to the second coherent optics transceiver. The first coherent optics transceiver is configured to simultaneously transmit a downstream optical signal and receive an upstream optical signal. The second coherent optics transceiver is configured to simultaneously receive the downstream optical signal from the first coherent optics transceiver and transmit the upstream optical signal first coherent optics transceiver. At least one of the downstream optical signal and the upstream optical signal includes at least one coherent optical carrier and at least one non-coherent optical carrier.