SHG Device for Optical Signal Detection

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Solution Overview

Problem

Current optical communication systems face challenges in suppressing Amplifiers Spontaneous Emission (ASE) noise without signal regeneration, especially in high bit rate systems and underwater communication links, where regeneration is impossible or costly.

Innovation Solution

Employing a Second Harmonic Generating (SHG) device to reduce ASE noise by converting an optical carrier signal modulated with data into a second harmonic signal, which effectively suppresses noise while preserving the data signal, allowing for detection with improved Optical Signal-to-Noise Ratio (OSNR) without active components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If signal regeneration is used to improve OSNR, then optical signal quality is improved, but system cost and complexity increase significantly

Engineering Contradiction:

Improveoptical signal qualityVSAvoidsystem cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the harmful ASE noise component from the optical signal using an SHG device, separating the noise from the useful signal. This allows signal detection without requiring full regeneration, thereby reducing system cost and complexity while maintaining signal quality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful ASE noise into a beneficial effect by using the SHG device to transform the noise at the fundamental wavelength into the second harmonic wavelength, where it can be filtered out. This converts the noise problem into a solvable wavelength transformation problem.

Inventive Principle:

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

2Reliability

If conventional regeneration blocks are used, then OSNR is improved, but device cost increases to $10k-$50k per channel

Engineering Contradiction:

ImproveOSNRVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive regeneration blocks with a much cheaper SHG device and filter combination. The SHG device and optical filters are significantly less costly than conventional regeneration blocks, reducing the cost per channel from $10k-$50k to a fraction of that amount.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the wavelength parameter of the optical signal using SHG, transforming the fundamental wavelength into the second harmonic wavelength. This parameter change enables noise suppression without requiring expensive regeneration equipment, as the wavelength transformation itself provides the noise reduction capability.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If passive components are used for noise suppression, then cost is reduced, but OSNR improvement is not achievable

Engineering Contradiction:

ImprovecostVSAvoidOSNR

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent substitutes the mechanical/electronic regeneration process with an optical nonlinear process (SHG). Instead of using electronic amplification and filtering in the conventional regeneration block, the system uses optical frequency doubling to suppress noise, achieving both cost reduction and OSNR improvement through purely optical means.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If SHG device is used to reduce ASE noise, then OSNR is improved without regeneration, but device complexity increases

Engineering Contradiction:

ImproveOSNRVSAvoiddevice structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the noise suppression function from the signal detection function. The SHG device handles the noise suppression at the fundamental wavelength, while a simple optical filter and detector handle the signal detection at the second harmonic wavelength. This segmentation allows each component to be optimized independently, reducing overall system complexity.

Inventive Principle:

Principle #1Segmentation

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 SHG device significantly reduces ASE noise, enabling high OSNR data detection in optical communication lines, even at high bit rates, with a cost-effective and passive solution that is independent of bit rate, making it a crucial enabler for systems where regeneration is not feasible.

Implementation Method 1

applying, at a point of interest, an optical carrier signal modulated by an optical data signal to an SHG (Second Harmonic Generating) device, and thereupon ensuring detection of said optical data signal now carried by a second harmonic optical carrier signal generated in the SHG device

Methodology Applied

Scientific EffectSecond Harmonic Generation: Second Harmonic Generation

Data Source

PatentUS8543013B2Technique for detection of optical data signals

Publication Date: 2013.09.24 ECI TELECOM LTD

AI summary

Technology for detecting an optical data signal carried in a combined optical signal that comprises a carrier optical signal modulated by the optical data signal and also comprises ASE noise. The proposed optical data detector/receiver is provided with an SHG device adapted to generate a second harmonic optical signal of the carrier optical signal modulated by the data signal. In the signal, generated by the SHG, the ASE noise will be essentially reduced.