Optoelectronic Oscillator Frequency Tuning for PSK Phase Lock
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Solution Overview
Problem
Coherent optical receivers for phase-shift keying (PSK) signals face challenges in accurately synchronizing the phase of the optical local oscillating signal with the reference optical signal, particularly in higher-order PSK schemes, due to limitations in phase tracking and clock recovery mechanisms.
Innovation Solution
An optoelectronic circuit incorporating an optical thyristor and waveguide structure, coupled with control circuitry, generates an optical clock signal that can be frequency-adjusted and used within an optical phase lock loop for precise phase synchronization, enabling effective phase tracking and clock recovery across various PSK schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical phase lock loops are used for phase synchronization in coherent PSK receivers, then basic phase tracking is achieved, but accurate phase recovery and frequency alignment fail particularly in higher-order PSK schemes
Solution Approach 1:
The patent implements dynamic frequency tuning of the optical local oscillating signal through a controllable delay line and feedback mechanism. The delay line duration is adjustable based on detected frequency mismatches, allowing the system to adaptively track and correct frequency deviations in real-time, thereby achieving reliable phase synchronization in higher-order PSK schemes where static approaches fail
Solution Approach 2:
The patent employs a feedback circuit that continuously monitors the phase-differenced signal and adjusts the delay line control accordingly. When a frequency mismatch is detected through phase errors in the feedback signal, the system automatically modifies the delay line duration to correct the mismatch, creating a self-correcting phase lock loop that maintains accurate synchronization
2Productivity
If higher-order PSK schemes are implemented to increase data rate, then productivity improves, but phase synchronization accuracy deteriorates due to reduced phase separation and increased sensitivity to frequency mismatches
Solution Approach 1:
The dynamic delay line provides continuous frequency adjustment capability that compensates for the reduced phase separation in higher-order PSK. By adaptively tuning the local oscillator frequency to match the incoming signal frequency, the system maintains accurate phase detection even when constellation points are closely spaced, enabling reliable high-order modulation schemes
Solution Approach 2:
The patent changes the delay line parameter (duration) dynamically based on the detected frequency mismatch. This parameter adjustment modifies the phase relationship between the local oscillating signal and incoming signal, allowing the system to optimize phase alignment for different operating conditions and maintain detection accuracy across various higher-order PSK schemes
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 solution enables robust phase synchronization and clock recovery for both lower and higher-order PSK schemes, improving the accuracy and reliability of data recovery in optical communication systems.
Implementation Method 1
an optical thyristor 307... generates an optical clock signal
Implementation Method 2
a waveguide structure... configured to split an optical pulse produced by the optical thyristor such that a first portion of such optical pulse is output as part of the optical clock signal and a second portion of such optical pulse is guided back
Data Source
AI summary
An optoelectronic circuit for producing an optical clock signal that includes an optical thyristor, a waveguide structure and control circuitry. The waveguide structure is configured to split an optical pulse produced by the optical thyristor such that a first portion of such optical pulse is output as part of the optical clock signal and a second portion of such optical pulse is guided back to the optical thyristor to produce another optical pulse that is output as part of the optical clock signal. The control circuitry is operably coupled to terminals of the optical thyristor and receives first and second control signal inputs. The control circuitry is configured to selectively decrease frequency of the optical clock signal based on the first control signal input and to selectively increase frequency of the optical clock signal based on the second control signal input.