Low-noise co-arm differential sensor for an optical frequency comb sampling an E-field test system

Area of Science:

• Photonics
• Electromagnetics
• Sensor Technology

Background:

• Optical frequency comb (OFC) technology enables rapid, wide-bandwidth electric field (E-field) measurements.
• Existing OFC methods face challenges with high intensity noise, leading to low sensitivity and blind frequency regions.

Purpose of the Study:

• To propose and demonstrate a dual-path optical E-field sensor with a common reference arm.
• To enhance measurement sensitivity and eliminate blind frequency regions in E-field sensing.

Main Methods:

• Utilized a lithium niobate optical waveguide for sensor construction.
• Incorporated a common reference arm to improve optical path balance and integration.
• Designed a segmented electrode to ensure reverse electrical signal generation on two Mach-Zehnder interferometers (MZIs).
• Employed a differential photodetector (PD) to remove intensity noise.

Main Results:

• Achieved maximum intensity noise reduction of approximately 37 dB and an average reduction of 22.3 dB.
• Successfully eliminated the blind frequency region in measurements using the co-arm differential optical E-field (CDOE) sensor.
• Demonstrated a sensitivity better than 10 mV/m·√Hz across a 1 MHz–12 GHz bandwidth.

Conclusions:

• The proposed dual-path optical E-field sensor effectively mitigates intensity noise and blind frequency regions.
• This CDOE sensor offers improved sensitivity and a wider operational bandwidth for E-field measurements.
• The integrated design and noise reduction capabilities make it suitable for advanced electromagnetic field sensing applications.