Short-Coherence Pulsed Source for Scintillation-Resistant FSO

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Solution Overview

Problem

FSO communication systems face challenges due to atmospheric interference, which limits data transmission distance and introduces bit errors, and existing optical systems like superluminescent diodes produce substantial noise, making them unsuitable for carrier-grade communications.

Innovation Solution

An optical communication system using short coherence length sources with modulated light pulses and a photoreceiver with specific detection thresholds and windows to mitigate atmospheric interference and noise, enabling reliable data transmission over long distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If superluminescent diodes are used for optical transmission, then data throughput can be increased, but substantial noise is produced making them unsuitable for carrier-grade communications

Engineering Contradiction:

Improvedata throughputVSAvoidnoise level

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent extracts and removes the harmful noise component from the optical transmission system by using a different light source architecture. Instead of using superluminescent diodes that produce substantial noise, the invention employs a laser source with specific pulse characteristics and coherence properties that eliminate scintillation noise while maintaining high data throughput capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes key parameters of the light source including coherence length (reducing to less than 400 microns), pulse duration (less than 100 picoseconds), and temporal distribution characteristics. These parameter changes transform the light source from a noisy continuous or long-pulse source to a precise short-pulse source that avoids scintillation noise while maintaining high productivity

Inventive Principle:

Principle #35Parameter changes

2Productivity

If optical transmission is used to increase data throughput, then radiofrequency spectrum limitations are overcome, but atmospheric interference limits transmission distance and introduces bit errors

Engineering Contradiction:

Improvedata throughputVSAvoidtransmission distance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent employs periodic pulsed action instead of continuous wave transmission. By using short light pulses with duration less than 100 picoseconds and specific repetition rates, the system achieves high data throughput while the periodic nature helps distinguish signal from atmospheric interference, extending reliable transmission distance

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent substitutes the continuous optical field approach with a pulsed temporal approach. By replacing continuous wave modulation with precise pulsed transmission and using temporal distribution characteristics, the system overcomes atmospheric interference that affects continuous signals, thereby extending transmission distance while maintaining high data throughput

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If light pulses with short coherence length are used, then scintillation noise is reduced, but detection precision requirements increase

Engineering Contradiction:

Improvescintillation noise reductionVSAvoiddetection window precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-shaping the pulse temporal distribution before transmission. By designing pulses with specific duration (less than 100 picoseconds) and coherence length (less than 400 microns) characteristics in advance, the system prepares the optical signal to naturally resist scintillation noise during atmospheric propagation, reducing the burden on detection precision requirements

Inventive Principle:

Principle #10Preliminary action

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

The system provides highly reliable and available data transmission over long distances, overcoming atmospheric interference and noise issues, enhancing optical transport efficiency.

Implementation Method 1

The series of light pulses may include a first light pulse having a coherence length of less than 400 microns

Methodology Applied

Scientific EffectCoherence length: Coherent Light

Implementation Method 2

When the first pulse travels through the variably refractive medium, photons in the first pulse may be refracted to travel along different ray paths having different lengths to the photoreceiver

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS12445207B2Reducing scintillation noise in free-space optical communications

Publication Date: 2025.10.14 ATTOCHRON LLC

AI summary

System, method, and instrumentalities are described herein for transmitting information optically. The optical source may be configured to generate a beam. The beam may include a series of light pulses. The beam of light may be modulated. A modulator may be configured to modulate the series of light pulses in response to a data transmission signal, thereby encoding transmission data into the series of light pulses. The modulated beam of light may be received and both amplified and filtered. The filtered beam of light may be transmitted from to a detector having a photoreceiver. The photoreceiver may be configured to extract the transmission data from the filtered beam of light.