Electro-optic comb based real time ultra-high sensitivity phase noise measurement system for high frequency...

Area of Science:

• Microwave Engineering
• Optical Metrology
• Signal Processing

Background:

• Ultra-low phase noise microwave generation is critical for advanced systems.
• Current phase noise characterization methods are limited by time-consuming averaging and component availability at higher frequencies.
• Cross-correlation techniques can underestimate phase noise due to residual correlations.

Purpose of the Study:

• To develop a new method for ultra-high sensitivity phase noise measurements.
• To overcome limitations of existing characterization systems, particularly for microwaves above 10 GHz.
• To enable direct suppression of radio frequency (RF) oscillator phase noise.

Main Methods:

• A delayed self-heterodyne method is employed.
• Sensitivity is enhanced using higher-order comb modes from an electro-optic comb.
• The system utilizes the bandwidth of electro-optic modulators (up to 100 GHz), obviating the need for specialized high-frequency RF components.

Main Results:

• Achieved ultra-high sensitivity phase noise measurements without cross-correlation.
• Estimated noise floor as low as -171 dBc/Hz at 1 MHz offset frequency for a 10 GHz carrier.
• Demonstrated direct suppression of RF oscillator phase noise up to 100 kHz offset frequency.

Conclusions:

• The proposed method offers a significant advancement in phase noise characterization sensitivity and frequency range.
• Eliminates the need for complex and time-consuming cross-correlation techniques.
• Enables improved performance in microwave generation and related applications.