Optical Phase Difference Monitoring Using Coherent Detection

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Solution Overview

Problem

Current methods lack a simple and feasible way to estimate the optical phase difference between sub-signals in optical transmitters, leading to signal distortion and interference, which affects communication system performance.

Innovation Solution

An apparatus and method using coherent detection quantities of high-speed sub-signals and another high-speed signal to determine the optical phase difference, employing low-speed electrical devices for monitoring without requiring high-speed equipment, applicable to various optical transmitters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-speed equipment is used to monitor optical phase difference, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improveoptical phase difference measurement precisionVSAvoidequipment speed requirement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary low-speed electrical device that processes signals through electro-optical conversion units. This intermediary device enables optical phase difference measurement without requiring high-speed equipment, resolving the contradiction between measurement precision and device complexity by using a mediator to bridge the gap between the optical signal and the measurement system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces high-speed mechanical/electrical detection systems with an optical-based measurement approach. By using electro-optical conversion units and coherent detection operations, the system substitutes traditional high-speed electrical measurement with an optical measurement method that can be performed at low speeds, thereby reducing device complexity while maintaining measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If simple monitoring method is implemented, then ease of operation is improved, but measurement precision deteriorates

Engineering Contradiction:

Improvemonitoring implementation simplicityVSAvoidoptical phase difference measurement precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements a self-service monitoring method where the system uses its own output signals (first output signal and second output signal from the electro-optical conversion units) to measure the optical phase difference. This self-service approach simplifies operation by eliminating the need for external complex measurement equipment while maintaining precision through the inherent properties of the signals already present in the system.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The electro-optical conversion units serve multiple functions: they perform signal modulation, generate output signals for communication, and simultaneously provide signals for optical phase difference measurement. This multi-functionality enables simple monitoring implementation without adding separate dedicated measurement devices, thereby improving ease of operation while maintaining measurement precision through the universal use of existing system components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Accurately monitors optical phase differences between sub-signals, simplifying implementation and avoiding the need for high-speed equipment, while being flexible and applicable to diverse optical transmitter scenarios.

Implementation Method 1

input a first input signal to a first electro-optical conversion unit, to enable the first electro-optical conversion unit to modulate to-be-modulated light according to the first input signal and to obtain a first output signal

Methodology Applied

Scientific EffectElectro-optical modulation: Electro-Optic Effects

Implementation Method 2

performing a coherent detection operation based on the first output signal and the second output signal to obtain a first output quantity and a second output quantity

Methodology Applied

Scientific EffectCoherent detection: Homodyne Detection

Data Source

PatentUS20250211330A1Apparatus and method for determining optical phase difference of sub signal of optical transmitter

Publication Date: 2025.06.26 1FINITY INC

AI summary

An apparatus and a method for determining an optical phase difference of a sub-signal of an optical transmitter. The method including: inputting a first input signal to a first electro-optical conversion unit, to enable the first electro-optical conversion unit to modulate to-be-modulated light according to the first input signal to obtain a first output signal; inputting a second input signal to a second electro-optical conversion unit, to enable the second electro-optical conversion unit to modulate to-be-modulated light according to the second input signal to obtain a second output signal; where correlation of the second input signal and the first input signal is not 0. The method includes performing a coherent detection operation based on the first output signal and the second output signal to obtain a first output quantity and a second output quantity; and determining an optical phase difference.