Multimode Fiber Dispersion Profile for Broadband VCSEL

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Solution Overview

Problem

Current multimode fibers (MMFs) optimized for narrow spectral windows around 850 nm struggle to maintain high modal bandwidth and modal-chromatic dispersion compensation over a broad range of wavelengths, limiting data rates and channel reach in VCSEL-based communication systems.

Innovation Solution

The development of MMFs with a refractive index profile that modifies the alpha parameter (α-parameter) to produce negative relative group delays over a broad spectral window, using dopants like Boron, Fluorine, and Phosphorous to create a concave or convex dispersion parameter profile, which compensates for modal and chromatic dispersion, enhancing bandwidth up to 50% and maintaining low inter-symbol interference and mode partition noise penalties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional MMFs are optimized for narrow spectral window around 850 nm, then modal bandwidth is improved at that wavelength, but bandwidth and dispersion compensation deteriorate over broad spectral ranges

Engineering Contradiction:

Improvemodal bandwidthVSAvoidspectral window coverage

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent modifies the refractive index profile parameters (alpha parameter and dispersion parameter) of the MMF to create a profile that maintains optimal characteristics across a broad spectral window (800-950 nm), enabling high bandwidth and dispersion compensation over extended wavelength ranges

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a universal MMF design that simultaneously provides high modal bandwidth, negative group delay compensation, and broad spectral coverage, making the fiber adaptable to various VCSEL wavelengths and future wavelength-division multiplexing applications

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If VCSEL modulation rates are increased by incorporating indium, then data rates are improved, but emission wavelength increases

Engineering Contradiction:

Improvedata rateVSAvoidemission wavelength

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent introduces a specially designed refractive index profile as an intermediary between the VCSEL transmitter and the optical channel, compensating for modal and chromatic dispersion effects to enable high data rate transmission without requiring wavelength shifts that would result from indium incorporation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If chromatic dispersion is reduced, then signal quality is improved, but bandwidth is limited

Engineering Contradiction:

Improvesignal qualityVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent optimizes the dispersion parameter profile to achieve negative group delays that compensate for chromatic dispersion, maintaining signal quality while enabling broader bandwidth operation through the interaction of modal and chromatic dispersion effects

Inventive Principle:

Principle #35Parameter changes

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 enables higher channel bandwidth, faster data rates, and longer reaches while maintaining the cost and reliability advantages of VCSEL-MMF channels, supporting data rates above 50 Gbps and extending the spectral window for modal-chromatic dispersion compensation.

Implementation Method 1

An important dispersive phenomenon in an MMF is a result of modal and chromatic dispersion

Methodology Applied

Scientific EffectModal dispersion: Dispersion (of waves)

Implementation Method 2

Chromatic dispersion is caused by the wavelength dependence of the material refractive index

Methodology Applied

Scientific EffectChromatic dispersion: Dispersion (of waves)

Implementation Method 3

the refractive indices of the core and cladding are selected to modify the shape of the profile dispersion parameter

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentEP3175269B1Multimode optical fiber and methods of manufacture thereof

Publication Date: 2020.12.30 PANDUIT CORP

Figure 1a~1b
Figure 2
Figure 3(a)~3(b)

AI summary

The present invention generally relates to the field of fiber optics, and more particularly, to apparatuses, systems, and methods directed towards improving effective modal bandwidth within a fiber optic communication environment. In an embodiment, a multimode optical fiber in accordance with the present invention comprises a core and cladding material system where the refractive indices of the core and cladding are selected to modify the shape of the profile dispersion parameter, y, as a function of wavelength in such a way that the alpha parameter (α- parameter), which defines the refractive index profile, produces negative relative group delays over a broad range of wavelengths. The new shape of the profile dispersion parameter departs from traditional fibers where the profile dispersion parameter monotonically decreases around the selected wavelength that maximizes the effective modal bandwidth (EMB).