Same-Wavelength Optical Transmitter With Power-Level Multiplexing

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Solution Overview

Problem

Existing optical communication systems face bandwidth limitations despite utilizing WDM, as previous methods like amplitude modulation and digital domain power division multiplexing do not allow for simultaneous transmission by multiple light sources at the same wavelength, leading to inefficient bandwidth utilization and high processing complexity.

Innovation Solution

Implementing a system where multiple light sources transmit at different power levels on the same optical communication path, using detection models like Poisson probability distributions to differentiate data streams based on photon counts, allowing for increased bandwidth without requiring complex interference cancellation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple light sources transmit simultaneously at the same wavelength using conventional methods (amplitude modulation or digital domain power division multiplexing), then bandwidth utilization is improved, but processing complexity increases and interference cancellation becomes necessary

Engineering Contradiction:
Improvebandwidth utilizationVSAvoidprocessing complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent converts the harmful interference between simultaneous light sources into a beneficial distinguishing feature. By assigning different power levels to different light sources, the interference pattern becomes a useful signal for identification. The receiver uses these power level differences to distinguish between multiple data streams without requiring complex interference cancellation, thus improving bandwidth utilization while keeping processing simple.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the power level parameter of light sources to enable simultaneous transmission. By controlling different light sources to operate at distinct power levels (e.g., high power for first data stream, low power for second data stream), the system creates distinguishable signal characteristics. This parameter change allows multiple streams to coexist on the same wavelength without requiring complex processing to resolve interference.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If multiple light sources transmit simultaneously at the same wavelength, then bandwidth capacity is increased, but signal interference increases

Engineering Contradiction:
Improvebandwidth capacityVSAvoidsignal interference
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent transforms the harmful interference generated by simultaneous transmissions into a useful distinguishing characteristic. The interference pattern, caused by different light sources operating at different power levels, becomes the key signal feature that enables the receiver to identify and separate data streams. This approach increases bandwidth capacity while the interference itself serves as the identification mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces asymmetry in power levels among simultaneous light sources. Instead of all sources transmitting at equal power (which would create symmetric, indistinguishable signals), the system assigns asymmetric power levels to different sources. This asymmetry creates unique interference patterns for each data stream, enabling simple differentiation at the receiver without requiring complex processing.

Inventive Principle:
Principle #4Asymmetry

3Productivity

If conventional WDM is used with 80 channels at 40 Gbit/second, then transmission capacity is improved, but system complexity and infrastructure requirements increase

Engineering Contradiction:
Improvetransmission capacityVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges multiple data streams onto a single optical wavelength by utilizing power level differentiation. Instead of requiring separate wavelengths for multiple channels (conventional WDM), the system combines multiple streams at the same wavelength by assigning different power levels. This merging approach increases transmission capacity while reducing the number of separate channels needed, thereby lowering system complexity and infrastructure requirements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent adds a new dimension to optical communication by introducing power level as an additional modulation parameter. Traditional WDM only utilizes wavelength dimension, but this patent incorporates power level dimension to create distinct signal identifiers. This dimensional expansion allows multiple data streams to be multiplexed on the same wavelength, increasing capacity without proportionally increasing system complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 significantly increases bandwidth by enabling multiple data streams on a single optical link, doubling or tripling capacity, while using simple and efficient hardware for demultiplexing, and adapting to interference and transmitter aging.

Implementation Method 1

a light source at one end that transmits one or more data streams by modulating the data stream into light signals

Methodology Applied
Scientific EffectLight modulation:

Implementation Method 2

a receiver which employs a photon detection module to detect the light signals

Methodology Applied
Scientific EffectPhoton detection: Photoelectric Effect

Implementation Method 3

using detection models like Poisson probability distributions to differentiate data streams based on photon counts

Methodology Applied
Scientific EffectPoisson distribution: Poisson's Effect

Data Source

PatentEP3939181B1Transmitter for throughput increases for optical communications
Publication Date: 2025.09.24 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3939181B1 patent drawingFigure 1
  • EP3939181B1 patent drawingFigure 2
  • EP3939181B1 patent drawingFigure 3

AI summary

Disclosed in some examples, are optical devices, systems, and machine-readable mediums that send and receive multiple streams of data across a same optical communication path (e.g., a same fiber optic fiber) with a same wavelength using different light sources transmitting at different power levels - thereby increasing the bandwidth of each optical communication path. Each light source corresponding to each stream transmits at a same frequency and on the same optical communication path using a different power level. The receiver differentiates the data for each stream by applying one or more detection models to the photon counts observed at the receiver to determine likely bit assignments for each stream.