Nest MZI Modulator Phase Shifter Power Reduction

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Solution Overview

Problem

Hybrid integrated-type nest MZI modulators face high power consumption due to the use of TO phase shifters for bias adjustment, which increases the complexity and cost of driving circuits and reduces compatibility with existing monolithic-type modulators.

Innovation Solution

Implementing a phase shifter with an electro-optic effect that allows both arm waveguides to undergo phase changes in the same direction, eliminating the need for TO phase shifters and enabling bias adjustment using only EO phase shifters, thereby reducing power consumption and simplifying the driving circuit design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If TO phase shifters are used for bias adjustment in hybrid integrated-type nest MZI modulators, then bias adjustment capability is achieved, but power consumption increases and driving circuit complexity increases

Engineering Contradiction:

Improvebias adjustment capabilityVSAvoidpower consumption

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent replaces thermal-optic (TO) phase shifters with electro-optic (EO) phase shifters. TO phase shifters use thermal effects which consume high power, while EO phase shifters use electric field effects which consume minimal power. This substitution eliminates the need for complex heat dissipation structures and high-power driving circuits, directly resolving the contradiction between achieving bias adjustment capability and reducing power consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If TO phase shifters are used for bias adjustment, then bias control is enabled, but driving circuit complexity and cost increase

Engineering Contradiction:

Improvebias controlVSAvoiddriving circuit complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent substitutes TO phase shifters with EO phase shifters, replacing thermal control mechanisms with electrical control mechanisms. EO phase shifters require simple voltage control circuits rather than complex thermal management systems, directly reducing driving circuit complexity and cost while maintaining full bias control functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If TO phase shifters are used, then bias adjustment is possible, but compatibility with existing monolithic-type modulators decreases

Engineering Contradiction:

Improvebias adjustmentVSAvoidcompatibility with existing modulators

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent adopts EO phase shifters which use the same electro-optic effect principle as monolithic-type nest MZI modulators. This creates a universal control interface across different modulator types, allowing existing bias control circuits designed for monolithic devices to be directly applied to hybrid integrated devices, thereby improving compatibility and adaptability while maintaining bias adjustment capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of operation

If TO phase shifters are used for phase adjustment, then bias control is achieved, but heat dissipation requirements increase

Engineering Contradiction:

Improvebias controlVSAvoidheat dissipation

Core Design Contradiction:

Ease of operationVSTemperature

Solution Approach 1:

The patent replaces thermal-optic phase shifters with electro-optic phase shifters, substituting a thermal control mechanism with an electrical control mechanism. EO phase shifters operate at room temperature without generating significant heat, completely eliminating heat dissipation requirements while maintaining full bias control functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces power consumption in both the phase adjusting section and the driving circuit, allows for high-speed bias control, and enables direct use of existing bias control circuits, lowering chip costs and eliminating heat dissipation requirements.

Implementation Method 1

Implementing a phase shifter with an electro-optic effect that allows both arm waveguides to undergo phase changes in the same direction

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS8965146B2Advanced-format optical modulator with low power consumption and low-loss characteristics

Publication Date: 2015.02.24 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

In a nest MZI modulator in which each arm includes a child MZI, the power consumption is reduced. The hybrid integrated-type nest MZI modulator of the embodiment 1a is configured so that, instead of placing a relative phase adjusting section in a parent MZI, a bias electrode Bias 90° in which an electric field is applied in the same direction to the polarization direction in both of the upper and lower arms is placed in each child MZI (see FIG. 4B). The bias electrode Bias 90° provided in each child MZI constitute the entirety of a relative phase adjusting section. The optical signals are subjected to a phase change after the output from the child MZI (see FIG. 1A), because such relative phase adjusting section can subject the optical signals of the upper and lower arms of the child MZI to a shift change in the same direction, respectively.