Variable Grid Spacing Interleaver for WDM Systems

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Solution Overview

Problem

Current optical transmission systems using wavelength division multiplexing (WDM) face challenges in increasing transmission capacity due to the need for multiple interleavers to handle different frequency spacings, leading to increased system scale, power consumption, and cost, as existing interleavers can only interleave signals in fixed band ranges.

Innovation Solution

An optical transmission apparatus with a bandwidth variable interleaver that adjusts grid spacing and center frequency based on monitoring results to optimize light intensity, allowing for flexible support of various optical modulation schemes and multiplexing schemes using a single apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple interleavers are used to handle different frequency spacings, then support for multiple optical modulation schemes is improved, but system complexity increases

Engineering Contradiction:

Improvesupport for multiple optical modulation schemesVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a single interleaver that can operate with multiple frequency spacings (50 GHz, 100 GHz, 200 GHz) by dynamically adjusting its filter characteristics. This multi-functional design eliminates the need for separate interleavers for different modulation schemes, thereby reducing system complexity while maintaining versatility

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The interleaver's grid spacing and center frequency are made dynamically adjustable based on the optical modulation scheme being used. The system can switch between different frequency spacings and bandwidths in real-time, allowing one device to adapt to multiple operational requirements that previously required multiple fixed devices

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multiple interleavers are used to handle different frequency spacings, then support for multiple optical modulation schemes is improved, but power consumption increases

Engineering Contradiction:

Improvesupport for multiple optical modulation schemesVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

By designing a single interleaver that can perform multiple functions across different frequency spacings, the system eliminates redundant hardware components. This consolidation reduces the total power consumption while maintaining the ability to support various optical modulation schemes

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If multiple interleavers are used to handle different frequency spacings, then support for multiple optical modulation schemes is improved, but cost increases

Engineering Contradiction:

Improvesupport for multiple optical modulation schemesVSAvoidcost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent reduces system cost by implementing a single universal interleaver that can be manufactured and deployed once, rather than requiring multiple specialized interleavers. This approach lowers both manufacturing costs and deployment expenses while maintaining full support for multiple optical modulation schemes

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of manufacture

If a fixed band range interleaver is used, then manufacturing simplicity is improved, but adaptability to different frequency spacings deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidadaptability to different frequency spacings

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The interleaver incorporates dynamic control mechanisms that allow adjustment of grid spacing and center frequency based on the required frequency spacing. This dynamic capability enables a single manufactured device to adapt to different operational requirements without requiring multiple fixed-bandwidth devices

Inventive Principle:

Principle #15Dynamics

5Productivity

If grid spacing in interleaver is changed, then frequency efficiency is improved, but light intensity stability deteriorates

Engineering Contradiction:

Improvefrequency efficiencyVSAvoidlight intensity stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The system employs feedback control where the monitor detects light intensity of the composite light and the control circuit adjusts grid spacing and center frequency based on monitoring results. This feedback mechanism optimizes frequency efficiency while compensating for intensity variations to maintain stable output

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8774642B2Optical transmission apparatus and optical interleaving control method

Publication Date: 2014.07.08 FUJITSU LTD

AI summary

An optical transmission apparatus includes an interleaver configured to filter an optical carrier, a multiplexer configured to combine lights output from the interleaver to generate a composite light, a monitor configured to monitor a light intensity of the composite light, and a control circuit configured to change a grid spacing in a filter characteristic of the interleaver in a direction in which an amount of change in a light intensity of the composite light increases, on the basis of a monitoring result measured while changing a center frequency in the filter characteristic of the interleaver and to change the center frequency in the filter characteristic in a direction in which a maximum value of the light intensity increases, on the basis of the monitoring result.