Optical Frequency Comb Coherent Phase Recovery
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Solution Overview
Problem
The high cost of complex optical and opto-electronic components in coherent optics hinders large-scale deployments in short-haul networks, where stringent cost requirements exist, despite the superior performance of coherent optics in long-haul and metro applications.
Innovation Solution
Employing an optical frequency-comb source to replace high-cost tunable lasers, which simplifies coherent digital signal processing by leveraging phase coherence between channels, reducing the complexity of hardware and DSP requirements in short-haul applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex optical and opto-electronic components (tunable lasers, local-oscillators, high-speed modulators) are used in coherent optics, then system performance and receiver sensitivity are improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent merges the functions of multiple independent optical components (tunable laser, local oscillator, modulator) into a single integrated photonic circuit. The photonic circuit performs coherent modulation, generation of local oscillator signals, and signal combination in one unified structure, eliminating the need for separate high-cost components while maintaining system performance
Solution Approach 2:
The photonic circuit is designed to perform multiple functions simultaneously: coherent modulation of optical signals, generation of local oscillator tones through optical mixing, and signal combination. This multi-functional integration replaces several specialized components with a single versatile device
2Manufacturing precision
If high-performance tunable lasers and local-oscillators are deployed, then optical phase stability and frequency selectivity are improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces mechanical/tunable laser systems with an all-optical mixing approach in the photonic circuit. Instead of using tunable lasers that require precise mechanical control and stabilization, the system generates stable local oscillator signals through optical mixing of fixed-frequency lasers, eliminating mechanical complexity and reducing manufacturing cost
Solution Approach 2:
The photonic circuit self-generates the local oscillator signals required for coherent detection through internal optical mixing processes. The circuit automatically produces the necessary frequency components and phase relationships without requiring external tunable lasers or complex stabilization mechanisms
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 reduces the overall cost of coherent optical systems for short-haul applications by simplifying hardware and DSP complexity, while maintaining performance through joint signal processing and phase noise correlation.
Implementation Method 1
producing, with a frequency-comb source, a frequency-comb signal that includes a pilot tone and a first optical tone
Implementation Method 2
coherently modulating the first optical tone to yield a first modulated signal
Implementation Method 3
demodulating the first modulated signal by homodyning the first modulated signal with the first local-oscillator tone
Implementation Method 4
coherently detecting the first modulated signal to yield a first demodulated signal
Implementation Method 5
interferometrically detecting the pilot tone to yield a pilot beat signal
Data Source
AI summary
Coherent phase recovery method includes producing, with a transmit-side frequency-comb source, a first frequency-comb signal that includes a pilot tone and a first optical tone having a first center wavelength that differs from a pilot center wavelength of the pilot tone. The method also includes coherently modulating the first optical tone to yield a first modulated signal; and generating a second frequency-comb signal with a receive-side frequency-comb source driven by the pilot tone. The method also includes extracting, from the second frequency-comb signal, a first local-oscillator tone having the first center wavelength; and demodulating the first modulated signal by homodyning the first modulated signal with the first local-oscillator tone.