Mach-Zehnder Superstructure Modulator Linearization

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Solution Overview

Problem

Conventional optical modulators, such as IQM optical modulators, introduce insertion loss and distortion in optical signals due to non-coherent signal combining, affecting the fidelity and transmission of modulated data in high-speed optical communication systems.

Innovation Solution

The implementation of a Mach-Zehnder superstructure modulator system that uses two high-speed phase modulators for in-phase and quadrature components, employing a coherent signal combining approach with both DC and AC bias signals to reduce modulated optical insertion loss and improve signal linearity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional IQM optical modulators are used, then amplitude and phase modulation can be achieved, but modulated optical insertion loss increases

Engineering Contradiction:

Improvemodulation capabilityVSAvoidmodulated optical insertion loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The modulator is divided into two independent Mach-Zehnder modulators (one for in-phase component, one for quadrature component) that operate separately and then combine their outputs. This segmentation allows each modulator to be optimized independently, reducing the overall insertion loss while maintaining full IQ modulation capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from conventional single-path modulation to a two-dimensional superstructure approach with separate in-phase and quadrature modulation paths. This dimensional expansion enables independent optimization of each path's insertion loss characteristics while achieving comprehensive modulation functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If conventional IQM optical modulators are used, then modulation functionality is achieved, but signal linearity deteriorates

Engineering Contradiction:

Improvemodulation functionalityVSAvoidsignal linearity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

By segmenting the modulation function into separate in-phase and quadrature Mach-Zehnder modulators, each unit can be precisely controlled and optimized for linear operation. The independent control of each segment prevents the signal distortion that occurs in integrated conventional modulators.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces separate optical paths and combination mechanisms as intermediaries between the input signal and output. This intermediary structure allows for precise control and linearization of each modulation component before combination, maintaining signal fidelity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If conventional signal combining is used, then modulation is achieved, but constellation point separation decreases

Engineering Contradiction:

Improvemodulation capabilityVSAvoidconstellation point separation

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent employs a two-dimensional superstructure with separate in-phase and quadrature modulation dimensions. This dimensional separation ensures that constellation points are properly spaced in the I-Q plane, improving separation and reducing symbol error rates compared to conventional single-path approaches.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11385483B2Linearization and reduction of modulated optical insertion loss for quadrature optical modulator

Publication Date: 2022.07.12 II VI DELAWARE INC

AI summary

An optical Mach-Zehnder superstructure modulator and method that can simultaneously linearize in-phase and quadrature components of optically modulated optical signals and reduce the modulated optical insertion loss (MOIL) by in-phase addition of the in-phase and quadrature components of an amplitude and/or phase modulated optical signal using two high-speed phase modulators embedded in the optical Mach-Zehnder superstructure modulator.