Optical Millimeter-Wave Signal Generation with Phase-Locked Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for generating high-frequency, high-quality optical millimeter-wave signals face challenges such as requiring high-quality RF signals, limited spectral purity, and significant phase noise due to incoherence between laser sources, and traditional delay measurement techniques suffer from narrow bandwidth and high loss.
Innovation Solution
A device incorporating a millimeter-wave signal generating structure, modulation structure, optical path delay phase detection structure, and feedback control loop, utilizing a master and slave laser with adjustable optical fiber delay, and a phase-locked loop to stabilize and tune millimeter-wave signals, improving frequency stability and phase noise characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical heterodyne method is used to generate millimeter-wave signals, then the frequency can be very high and the bandwidth can be wide, but the phase noise becomes large due to incoherence between two laser light sources
Solution Approach 1:
The patent employs a feedback control mechanism where the phase difference between the master and slave lasers is detected and fed back to adjust the slave laser's frequency. This closed-loop system continuously corrects phase deviations, transforming the incoherent relationship between lasers into a coherent locked state, thereby reducing phase noise while maintaining high frequency generation capability
Solution Approach 2:
The patent equalizes the optical paths of the master and slave lasers by introducing adjustable optical delay lines to compensate for path length differences. This creates equipotential conditions for phase comparison, enabling accurate phase-locked operation and reducing phase noise by ensuring both lasers operate under identical phase reference conditions
2Device complexity
If traditional coaxial cables are used for signal delay, then the structure is simple, but the bandwidth is narrow and loss is large
Solution Approach 1:
The patent replaces the traditional mechanical/coaxial delay structure with an optical delay system using optical fibers. This substitution leverages optical properties (low loss, high bandwidth) to achieve signal delay functionality, thereby increasing the usable bandwidth and reducing loss compared to electrical coaxial cables
Solution Approach 2:
The patent uses adjustable optical delay lines that can change the optical path length parameter to achieve variable signal delay. This parameter adjustment capability allows the system to adapt to different delay requirements while maintaining high bandwidth performance, overcoming the fixed and lossy nature of traditional coaxial delay structures
3Ease of manufacture
If electro-optic modulation method is used to generate millimeter-wave signals, then the process can be implemented, but high-quality RF signals are required and spectral purity is limited by the modulator
Solution Approach 1:
The patent introduces an optical heterodyne intermediate step where two lasers with stable frequencies are combined to generate the millimeter-wave signal. This optical intermediate approach bypasses the need for high-quality RF signals and avoids the spectral purity limitations of electro-optic modulators, as the frequency is determined by the stable laser sources rather than the modulator's characteristics
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 device achieves wide-range frequency tuning and improved locking range, phase noise reduction, and frequency stability of millimeter-wave signals, enabling generation of high-quality optical millimeter-wave signals with enhanced tunability and precision.
Implementation Method 1
The millimeter-wave signal generating structure obtains a millimeter-wave signal through the beat frequency of the optical signals generated by a master laser and a slave laser
Implementation Method 2
The millimeter-wave signal is modulated to the optical carrier of the master laser through an electro-optical modulation structure
Implementation Method 3
an optical fiber delay structure based on the change of optical fiber optical path proposed. The position of the internal mirror is adjusted by a stepper motor, so as to change the spatial optical path of light propagation and achieve the purpose of adjusting the delay
Implementation Method 4
the phase detector structure composed of the mixer and the low-pass filter, if and only when the input two signals have the same frequency and are orthogonal, the output error signal is 0
Data Source
AI summary
A device for generating wide capture range frequency tunable optical millimeter-wave signal includes a millimeter-wave signal generating structure, a millimeter-wave signal modulation structure, an optical delay phase detection structure and a feedback control loop. The millimeter-wave signal generating structure obtains millimeter-wave signal by beat frequency of the optical signal generated by a master laser and a slave laser, the millimeter-wave signal is modulated onto an optical carrier of the master laser by the electro-optical modulation structure, and then passes through the optical delay phase detection structure to generate an error signal associated with a frequency of the millimeter-wave signal. The error signal is controlled by the feedback control loop to change temperature and driving current of the slave laser, and adjust a difference between output wavelengths of the master laser and the slave laser, and at last maintain the frequency and phase of the millimeter-wave be stable.