Photonic Integrated Circuit With SOA Array for Chromatic Dispersion Compensation

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Solution Overview

Problem

Current optical Ethernet transceivers face limitations in chromatic dispersion compensation, particularly with increasing symbol rates, as existing methods like dispersion compensating fiber and fiber-Bragg grating are bulky and provide fixed, non-tunable compensation, which is not suitable for high-speed IM-DD systems.

Innovation Solution

A photonic integrated circuit (PIC) with an array of semiconductor optical amplifiers (SOAs), optical delay lines, and phase-shifters, controlled by a digital signal processor or current distribution circuit, for flexible chromatic dispersion compensation, enabling tunable and automatic adjustment to mitigate chromatic dispersion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dispersion compensating fiber (DCF) or fiber-Bragg grating (FBG) is used for chromatic dispersion compensation, then chromatic dispersion can be compensated, but the device becomes bulky and cannot be put into hot-pluggable form factors

Engineering Contradiction:

Improvechromatic dispersion compensationVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces bulky mechanical optical components (DCF, FBG) with a photonic integrated circuit that uses semiconductor optical amplifiers and waveguides to achieve chromatic dispersion compensation. This substitution of mechanical systems with integrated photonic circuits dramatically reduces device size while maintaining compensation functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent combines multiple chromatic dispersion compensation functions into a single integrated photonic circuit module that can be hot-plugged. By merging the splitter, SOA array, delay lines, phase shifters, and coupler into one compact unit, the system achieves both size reduction and functional integration.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If dispersion compensating fiber (DCF) is used, then chromatic dispersion compensation is provided, but the compensation is fixed and not tunable

Engineering Contradiction:

Improvechromatic dispersion compensationVSAvoidtunability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic controllability by using controllable semiconductor optical amplifiers with adjustable gain coefficients and phase shifters with variable phase shifts. These dynamic elements allow the chromatic dispersion compensation to be tuned in real-time based on different transmission conditions, replacing the fixed compensation of DCF.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameters of the semiconductor optical amplifiers (gain coefficients) and phase shifters (phase shift values) to achieve tunable chromatic dispersion compensation. By adjusting these parameters, the system can adapt to different dispersion compensation requirements for various symbol rates and transmission distances.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the symbol rate is increased to achieve higher data rates, then data throughput is improved, but the impact of chromatic dispersion becomes severe and limits transmission reach

Engineering Contradiction:

Improvedata rateVSAvoidtransmission reach

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies chromatic dispersion compensation before direct detection using the photonic integrated circuit. By performing the compensation action preliminarily in the optical domain before the signal is detected, the system eliminates chromatic dispersion effects that would otherwise limit transmission reach at high symbol rates.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If digital signal processing technique is used to mitigate chromatic dispersion, then processing flexibility is improved, but the technique is ineffective because optical carrier phase information is lost after direct detection

Engineering Contradiction:

Improveprocessing flexibilityVSAvoidchromatic dispersion mitigation effectiveness

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs chromatic dispersion compensation in the optical domain before direct detection occurs. This preliminary action ensures that the compensation is applied when the optical carrier phase information is still intact, making the mitigation effective unlike post-detection DSP approaches.

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 PIC design allows for compact, tunable, and automatic chromatic dispersion compensation, enhancing signal quality and compatibility with high-speed IM-DD transmission systems, fitting into small form factors like QSFP and SFP, and optimizing performance and cost.

Implementation Method 1

an 1:N optical splitter to split an input optical signal into N copies

Methodology Applied

Scientific EffectOptical splitting:

Implementation Method 2

an array of N semiconductor optical amplifiers (SOAs) to receive and amplify the N optical outputs from the optical splitter

Methodology Applied

Scientific EffectSemiconductor optical amplification:

Implementation Method 3

an array of optical delay lines to receive the outputs from the N SOAs, wherein the delay coefficients for the array of optical delay lines are {0, T, 2T, . . . (N−1) T}

Methodology Applied

Scientific EffectOptical delay:

Implementation Method 4

each optical path with odd index (1, 3, 5, . . . N−1) from the N optical paths includes a 90-degree phase-shifter

Methodology Applied

Scientific EffectPhase shifting:

Implementation Method 5

an optical N:1 coupler to re-combine all N optical paths

Methodology Applied

Scientific EffectOptical coupling:

Implementation Method 6

The PIC takes an input optical signal, processes the chromatic dispersion of the input signal to produce an output optical signal, and the output optical signal is then converted into an electrical signal by a photo-detector

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS11522332B2Optical receiver using a photonic integrated circuit with array of semiconductor optical amplifiers

Publication Date: 2022.12.06 HUNG NGUYEN TAN

AI summary

In one embodiment, an intensity modulated (IM) direct detection (DD) optical receiver using a photonic integrated circuit (PIC) with an array of semiconductor optical amplifiers (SOAs) for flexible chromatic dispersion compensation (CDC) is provided. The PIC comprises an 1:N optical splitter to split an input optical signal into N copies; an array of N semiconductor optical amplifiers (SOAs) to receive the N optical outputs from the optical splitter; an array of optical delay lines to receive the outputs from the N SOAs, wherein the delay coefficients for the array of optical delay lines are {0, T, 2T, . . . (N−1) T}, where T=½B, where B is the system symbol rate, and each optical path with odd index (1, 3, 5, . . . N−1) from the N optical paths includes a 90-degree phase-shifter; and an optical N:1 coupler to re-combine all N optical paths. A method for automatically controlling a PIC based on the feedback signal from the Rx DSP in an optical receiver is also provided.