Optical Frequency Comb Microwave Synthesis With Low Phase Noise
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Solution Overview
Problem
Conventional microwave signal generation methods fail to produce high-frequency signals with high stability and low phase noise, which are essential for next-generation electronic information systems, due to limitations in tuning mechanisms and the deterioration of phase noise with increased frequency.
Innovation Solution
A frequency synthesis system and method based on photoelectric synergy, utilizing an optical frequency comb to generate narrow optical pulse signals with high stability and low phase noise, followed by frequency doubling or dividing, photoelectric conversion, and electrical filtering and amplification, allowing for direct photoelectric conversion, electrical frequency synthesis, or optical frequency shifting to achieve ultra-wideband and continuous tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrical frequency doubling is used to generate higher frequency signals, then the output frequency increases, but the phase noise deteriorates logarithmically by 20 times
Solution Approach 1:
The patent replaces the conventional electrical frequency doubling mechanism with an optical frequency comb-based photoelectric conversion system. The optical frequency comb generates optical frequency signals that are converted to electrical signals through photoelectric detection, achieving high-frequency signal generation without the phase noise deterioration inherent in electrical frequency multiplication. This substitution of optical domain for electrical domain resolves the contradiction between frequency increase and phase noise maintenance.
Solution Approach 2:
The patent changes the fundamental operating parameter from electrical frequency to optical frequency. By operating in the optical domain where frequencies are three orders of magnitude higher than microwave frequencies, the system achieves the desired high-frequency output while maintaining excellent phase noise characteristics, as the phase noise performance is determined by the optical reference rather than being multiplied from a lower electrical frequency.
2Reliability
If conventional microwave oscillators are used, then the phase noise reaches −160 dBc/Hz or even lower, but the output frequency is only tens of MHz
Solution Approach 1:
The patent substitutes the microwave oscillator system with an optical frequency comb system followed by photoelectric conversion. This replacement enables the system to achieve both the low phase noise of reference-based generation and the high frequency output capability, as the optical frequency comb can be phase-locked to stable optical references while generating microwave signals through photoelectric detection at frequencies three orders of magnitude higher than conventional microwave oscillators.
Solution Approach 2:
The patent transitions from operating in the microwave frequency dimension to utilizing optical frequency dimension for signal generation. By generating signals in the optical domain and converting them to microwave frequencies through photoelectric conversion, the system accesses a higher frequency dimension while maintaining the stability and low phase noise characteristics through optical frequency reference locking.
3Reliability
If photoelectric oscillators or optical frequency combs are used for signal generation, then the phase noise achieves excellent performance, but the tuning mechanism is limited and cannot meet frequency synthesis requirements
Solution Approach 1:
The patent introduces dynamic tuning capability by enabling continuous adjustment of the optical frequency comb parameters and the photoelectric conversion process. The system can dynamically synthesize different microwave frequencies by adjusting the optical comb's repetition rate and offset frequency, providing continuous frequency tuning across a wide range while maintaining low phase noise through phase-locking to stable optical references.
Solution Approach 2:
The patent creates a universal frequency synthesis system that can generate a wide range of microwave frequencies with excellent phase noise performance. The optical frequency comb-based system serves multiple functions: it can generate single-frequency signals with low phase noise, synthesize multiple frequencies simultaneously, provide continuous frequency tuning, and maintain stability through optical reference locking, thereby meeting diverse frequency synthesis requirements.
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 system achieves a larger frequency range and higher performance, capable of generating frequencies three orders of magnitude higher than conventional microwave sources, with improved phase noise performance and continuous tuning capabilities.
Implementation Method 1
an optical frequency comb configured to generate narrow optical pulse signals with high stability and low phase noise
Implementation Method 2
a photoelectric conversion unit configured to perform photoelectric conversion on input optical pulse signals, and output an electrical frequency comb
Data Source
AI summary
A frequency synthesis system and a frequency generation method of microwave photons based on photoelectric synergy are provided, the system includes an optical frequency comb for generating narrow optical pulse signals with high stability and low phase noise through; an optical frequency doubling/dividing unit for performing frequency doubling or frequency dividing on a repetition frequency of the narrow optical pulse signals output by the optical frequency comb; a photoelectric conversion unit for performing photoelectric conversion on input optical pulse signals, and outputting an electrical frequency comb; a second electrical filter unit for filtering input electrical signals; and a second electrical amplifying unit for performing power amplification on the input electrical signals. An operation frequency and performance of the optical frequency comb is three orders of magnitude or higher than that of common microwave frequency sources, microwave frequency signals with larger frequency range and better performance can be generated.