Optical Resonator Demodulation for WDM Phase Signals

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Solution Overview

Problem

Existing phase modulation receivers for optical signals, particularly in WDM systems, are complex and require sophisticated optics and a local coherent clock source, making them inefficient for simultaneous detection and demodulation of multiple optical signals with differing wavelengths.

Innovation Solution

An optical signal receiver system utilizing an optical resonator, such as a Fabry-Perot filter or micro-ring, that converts phase-encoded signals into intensity-encoded signals, allowing for simultaneous detection and demodulation without a coherent clock source, and accommodating various modulation rates and encoding techniques across multiple wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple complex phase receivers are used to receive multiple wavelengths in WDM systems, then the ability to detect multiple optical signals is improved, but the device complexity increases significantly

Engineering Contradiction:
Improveability to detect multiple optical signalsVSAvoidreceiver system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple phase detection functions into a single receiver by combining multiple optical resonators (each tuned to different wavelengths) that all feed into one photodetector. This allows simultaneous detection of multiple WDM channels without requiring multiple separate coherent receivers, thereby reducing device complexity while maintaining multi-wavelength detection capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal receiver structure where a single photodetector serves multiple wavelengths by receiving input from multiple optical resonators. Each resonator is tuned to a specific wavelength, but all resonate and convert their respective phase-modulated signals into intensity variations that the single photodetector can detect, making the receiver multi-functional across different wavelengths.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If precision optics and local oscillators are used in phase modulation receivers, then the demodulation accuracy is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvedemodulation accuracyVSAvoidoptical component complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical/optical coherent detection system (requiring precision optics, local oscillators, and complex interferometers) with a resonant oscillation-based system. Optical resonators naturally resonate at specific frequencies and convert phase modulations into intensity variations through their resonant properties, eliminating the need for complex coherent detection hardware while maintaining demodulation accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating principle from coherent detection (which requires precise phase and amplitude control) to resonant detection. By tuning the resonant frequency of optical resonators to match the optical signal wavelengths, the system converts phase information into intensity information that can be detected by simple photodetectors, thereby reducing the required measurement precision parameters for optical components.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a local coherent clock source is used for phase demodulation, then the demodulation performance is improved, but the system complexity and synchronization requirements increase

Engineering Contradiction:
Improvedemodulation performanceVSAvoidclock source and synchronization complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service demodulation where the optical resonators themselves provide the reference frequency needed for demodulation. Each resonator is tuned to resonate at the same frequency as the corresponding optical signal, so the resonator's natural oscillation serves as its own local oscillator, eliminating the need for external clock sources and complex synchronization mechanisms.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Instead of using an external clock source to drive the demodulation process, the patent inverts the approach by having the optical resonators naturally resonate at the signal frequency and use this self-generated resonance as the reference. This reverses the traditional coherent detection architecture where an external local oscillator drives the mixing process.

Inventive Principle:
Principle #13The other way round (Inversion)

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

Enables flexible and simplified detection of phase-encoded information in optical signals across multiple wavelengths, reducing the complexity of receiver systems and eliminating the need for a local coherent clock source, while maintaining effective demodulation capabilities.

Implementation Method 1

the optical resonator configured to receive optical signal energy of a plurality of wavelengths via the aperture, accumulate resonant optical signal energy inside the optical resonator

Methodology Applied
Scientific EffectOptical resonance: Resonance

Implementation Method 2

an optical resonator, such as a Fabry-Perot filter/resonator, for converting multiple received optical wavelengths, which may include phase-encoded information, into intensity-encoded optical wavelengths

Methodology Applied
Scientific EffectPhase-to-intensity conversion via optical resonance: Resonance

Data Source

PatentEP3711197B1Systems and methods for demodulation of wave division multiplexed optical signals
Publication Date: 2025.01.15 RAYTHEON CO
  • EP3711197B1 patent drawingFigure 1~2
  • EP3711197B1 patent drawingFigure 3
  • EP3711197B1 patent drawingFigure 4

AI summary

Optical signal receivers and methods are provided that include an optical resonator that allows optical signal energy of multiple wavelengths to enter and accumulate inside the optical resonator. A portion of optical signal energy of each wavelength is emitted from the optical resonator at an output, and the individual wavelengths may be separated. A detector aligned with the output detects the emitted optical signal energy of at least one of the wavelengths. The detector is configured to detect disturbances to the emitted optical signal energy and determine a modulated characteristic in the received optical signal energy of the wavelength.